CPITN â community periodontal index for treatment need ... Calculation of family material possession index (FMPI). 45 ..... 1989), or unsuitable presentation of.
Oral health status, knowledge, attitudes and behaviour of adults in Guangdong, China
Lin, Huancai; 林煥彩
O R A L H E A L T H STATUS， K N O W L E D G E , ATTITUDES AND B E H A V I O U R O F ADULTS IN GUANGDONG, CHINA
L I N Huancai Ph.D. Thesis
THE UNIVERSITY OF HONG KONG 1999
Abstract of thesis entitled
Oral health status, knowledge, attitudes and behaviour of adults in Guangdong, China submitted by L i n Huancai for the degree of Doctor of Philosophy at The University of Hong Kong in December 1998
Proper evaluation of oral health status, knowledge, attitudes and behaviour among people is a basis for planning preventive and curative oral health care programs, and for developing training programs for dental personnel. However, such information is lacking in China, especially among adults and among rural residents. The objectives of this study were to describe the oral health status and treatment needs of 35-44 and 65-74 year-old Chinese in Guangdong Province, to explore the oral health knowledge, attitudes and behaviour in these two age groups, and to determine factors affecting their oral health status and oral health behaviour.
An oral health survey was conducted in Guangdong Province in Southern China in 1996-97. A sample of 1,573 35歸44-year鍋old and 1,515 65-74-year-old Chinese was recruited from 8 urban sites and 8 rural sites through multi-stage cluster sampling. In the survey, the subjects were first interviewed by trained interviewers using a structured questionnaire. Then they underwent a clinical examination carried out by one of three calibrated examiners. The examination procedures, instruments and diagnostic criteria used followed those recommended by the World Health Organization (1997) for oral health surveys.
The subjects' oral health knowledge was found to be poor but their oral health attitudes were generally positive. Almost all of the dentate elderly surveyed claimed that they brushed their teeth every day and used toothpaste. However， most of them did not know i f their toothpaste contained fluoride. Their dental service utilization was low and problem-driven. Less than one-quarter of the subjects had visited a dentist within a year. Social and economic factors were found to relate to oral health knowledge, attitudes, and oral health behaviour in this population. The mean DMFT score was 4.6 in the 35-44-year-olds and 15.6 in the 65-74-yeai>olds. MT was the major component of the DMFT score in both age groups. Rural residents, women and those who were less wealthy had higher DMFT scores. Presence of calculus and shallow periodontal pockets was prevalent but not for deep periodontal pockets. However， loss of periodontal attachment was prevalent and severe in the surveyed adults. Men exhibited worse periodontal status than women but rural residents and urban residents exhibited similar periodontal destruction. Only 4^o of the elderly surveyed were edentulous. Almost all of the 35-44-year-olds and most of the 65,74year-olds had at least 20 teeth present. Rural residents had a similar number of missing teeth but a greater number of teeth indicated for extraction than urban residents. Only a small proportion of the middle-aged and less thaii half of the elderly were found to have a dental prosthesis in either jaw. The prevalence of normative dental treatment need among the adult Southern Chinese was found to be high but the treatments were mainly simple ones. However， the prevalence of perceived treatment need in this population was low and the correlation between these two types of treatment needs was low.
PAGE Abstract of thesis
List of abbreviations
List of Tables
List of Figures
1, INTRODUCTION l丄 Background of the present survey
1.2. Dental care policy and organization in Mainland China
1.3. Guangdong Province
2. LITERATURE REVIEW
- review of oral health surveys among adults in China 2.1. National oral health surveys
2丄1. The First National Oral Health Survey
2.1.2. The Second National Oral Health Survey
2.2. Major regional and local surveys related to caries in
adults in Mainland China 2.2.1.
Study population and sampling methods
Methodology and reliability
2.3. Major regional and local surveys related to periodontal
status in adults in Mainland China 2.3.1.
Study population and sampling methods
Methodology and reliability
PAGE 2.4. Major regional and local surveys related to tooth loss and
prosthetic status in adults in Mainland China 2.5. Major regional and local surveys related to oral health
knowledge, attitudes and behaviour in adults in Mainland China 2.6. Major oral health surveys among Hong Kong adults
2.6.1, Methodology of the 1984 Hong Kong Adult Oral 31
Health Survey 2.6.2, Methodology of the 1991 Hong Kong Adult Oral
Health Survey 2.6.3, Major results of the two Hong Kong adult oral
health surveys 2.7. Summary of literature review
35 3. AIM AND OBJECTIVES 37 38
4， MATERIALS AND METHODS 4.1. Study population and sampling methods
4.2. Recruitment of subjects
4.3. Fieldwork procedures
4.3.2. Clinical examination
4.4. Testing of water fluoride level in survey sites
4.5. Data processing and analyses
5, RESULTS 5.1. Background of study population
5.2. Inter-examiner reliability
5.3. Oral health knowledge, attitudes and oral hygiene habits
5.4. Utilization of dental services
5.5. Coronal and root caries
PAGE 5.6. Periodontal diseases
5.7. Tooth loss and prosthetic status
5.8. Treatment needs
6.1.1. Sampling methods and recruitment of subjects
6.1.2. Variables and measurements
6.2. Results 6.2.1. Inter-examiner reliability and intra-examiner
reliability 6.2.2. Oral health knowledge, attitudes and oral hygiene
habits 6.2.3. Utilization of dental services
6.2.4. Coronal and root caries
6.2.5. Periodontal diseases
6.2.6. Tooth loss and prosthetic status
6.2.7. Treatment needs
10. APPENDICES 1.
Questionnaire used in the survey (Chinese version)
Questionnaire used in the survey (English version)
Record form used in the clinical examination for 35-44year-olds (Chinese version)
Record form used in the clinical examination for 35-44year-olds (English version)
Record form used in the clinical examination for 65-74year-olds (Chinese version)
Record form used in the clinical examination for 35-44year-olds (English version)
LIST OF ABBREVIATIONS
AMT — adjusted missing teeth ANOVA — analysis of variance ANCOVA — analysis of covariance CI — calculus index CPI — community periodontal index CPITN — community periodontal index for treatment need CV — coefficient of variation DF-Root — decayed and filled root DFT —- decayed and filled teeth DI — debris index DMFT —- decayed, missing and filled teeth (permanent dentition) dmft --- decayed, missing and filled teeth (primary dentition) DT -- decayed teeth FMPI — family material possession index FT — filled teeth GI — gingival index IMT — indicated missing teeth LOA — loss of attachment MT — missing teeth NCOH — National Committee for Oral Health NTN — normative treatment need OHI — oral hygiene index PDI — periodontal disease index P1I — plaque index PTN — perceived treatment need RCI — root caries index WHO — world health organization
LIST OF TABLES PAGE 2-1
Major regional and local surveys and results related to dental caries of the middle-aged and elderly.
Major regional and local surveys related to periodontal conditions of the middle-aged and elderly.
Percentages of individuals by maximum CPITN in the Chinese middle-aged and elderly age groups as reported in previous studies.
Calculation of family material possession index (FMPI).
Variables from questionnaire and their grouping or scoring used in data analyses.
Variables from clinical examination and their grouping or scoring used in data analyses.
Analytic model for the study indicating the incorporated variables.
Variables used in the analyses of covariance for knowledge score, attitude score, DMFT, and AMT in the 35-44-year誦olds and 65-74-y earmolds.
Sample size according to age group, gender and location.
Selected demographic characteristics of the subjects (percentage).
Kappa statistics for inter-ex雄iner reproducibility.
Mean numbers of DMFT, DF-Root, and MT by examiner.
Percentage of persons with periodontal pockets and LOA by examiner.
Percentage of Chinese adults who indicated various causes of dental caries according to age group and location of residency (multiple response analysis).
Percentage of Chinese adults who indicated various preventive methods against dental caries according to age group and location of residency (multiple response analysis).
Percentage of Chinese adults who indicated various causes of gum disease according to age group and location of residency (multiple response analysis).
Percentage of Chinese adults who indicated various preventive methods against gum disease according to age group and location of residency (multiple response analysis).
Relationship between dental knowledge score and selected independent variables in 3 5-44-year-olds (result of ANCOVA analysis).
Relationship between dental knowledge score and selected independent variables in 65-74-year-olds (result of ANCOVA analysis).
Channels through which the respondents received their oral health information (multiple response analysis).
Proportion of subjects with a positive dental health belief or attitude.
Relationship between dental attitude score and selected independent variables in 35-44-year-olds (result of ANCOVA analysis).
Relationship between dental attitude score and selected independent variables in 65-74-year-olds (result of ANCOVA analysis).
Distribution of Chinese adults according to reported oral hygiene practice (%).
Result of a logistic regression analysis on toothbrushing frequency (once or less vs twice or more daily) in 35"44-yeaxolds (n=1573).
Result of a logistic regression analysis on toothbrushing frequency (once or less vs twice or more daily) in 65-74-yearolds(n=1515)*
Recency of last dental visit in the two age groups according to location of residence (Percentages).
Distribution of participants by reasons given for not making a dental visit within the past three years according to location of residency (multiple response analysis).
Treatments received in the last dental visit among those who had visited a dentist within the past three years (multiple response analysis).
Selected factors in relation to use of dental services in the 3544-year-olds.
Selected factors in relation to use of dental services in the 6574-y ear-olds.
Result of a logistic regression analysis on recent use of dental services (less than 2 years vs. more than 2 years) in the 35-44year-olds.
Result of a logistic regression analysis on recent use of dental services (less than 2 years vs. more than 2 years) in the 65-74year-olds.
Caries status according to age group, gender and location of residency among adults in Guangdong.
Comparison of DMFT scores in different subject groups among the 35-44-year-olds.
Comparison of DMFT scores in different subject groups among the 65-74-year-olds.
Relationship between DMFT scores and dental knowledge, attitude and FMPI scores (Pearson,s correlation coefficient).
Relationship between DMFT scores and selected independent variables among the 35-44-year-old Chinese (result of ANCOVA analysis).
Relationship between DMFT scores and selected independent variables among the 65-74,year-old Chinese (result of ANCOVA analysis).
Percentage distribution of the 35-44-year-olds according to highest CPI score.
Percentage distribution of the 65-74-year-olds according to highest CPI score.
Mean number of sextants by CPI score in the 35-44- year-olds.
Mean number of sextants by CPI score in the 65-74-year-olds,
Percentage distribution of the 3 5-44,year-olds according to their maximum LOA.
Percentage distribution of the 65-74-year-olds according to their maximum LOA.
Mean number of sextants by LOA in the 35-44-year»olds.
Mean number of sextants by LOA in the 65-74-year-olds.
Missing teeth (MT) indicated missing teeth (IMT) and adjusted missing teeth (AMT) among adults in Guangdong.
Relationship between AMT and selected independent variables in the 35»44-yeaj>olds (result of ANCOVA analysis).
Relationship between AMT and selected independent variables in the 65-74-year-olds (result of ANCOVA analysis).
Percentage of 35"44-year-old subjects with dental prostheses by arch.
Percentage of 65-74-year-old subjects with dental prostheses by arch.
Percentage of subjects with dental prostheses according to location of residency.
Percentage distribution of subjects and mean number of teeth (in parentheses) according to type of tooth-based treatment need and location of residency.
Percentage distribution of the 35-44-year-old subjects according to their normative prosthetic treatment need by arch.
Percentage distribution of the 65-74-year-old subjects according to their normative prosthetic treatment need by arch.
Percentage distribution of dentate subjects and mean number of sextants (in parentheses) according to periodontal treatment need category and location of residency.
Percentage distribution of subjects according to holistic treatment need category and location of residency.
Percentage distribution of 35-44-year-old subjects according to their perceived treatment need (PTN) and normative treatment need (NTN).
Percentage distribution of 65-74-year-old subjects according to their perceived treatment need (PTN) and normative treatment need (NTN).
LJST OF FIGURES PAGE 4-1
Location of Guangdong Province and survey regions.
Sampling method of the Guangdong Oral Health Survey 1996-97.
Procedure in fieldwork of Guangdong Oral Health Survey 1996-97.
Mean dental knowledge score (Maximum = 12) of men and women in urban and rural areas in Guangdong.
Mean dental attitude score (Maximum = 8) of men and women in urban and rural areas in Guangdong.
Proportions of FT and DT in DFT according to gender and location of residency in 35-44-year-olds and 65-74-year-olds,
Cumulative percentage distribution of 35-44-year-old subjects by location and gender according to adjusted missing teeth (AMT).
Cumulative percentage distribution of 65-74-year-old subjects by location and gender according to adjusted missing teeth (AMT).
Proportions of missing teeth (MT) and indicated missing teeth (IMT) by tooth type in the 35-44-year-old subjects.
Proportions of missing teeth (MT) and indicated missing teeth (IMT) by tooth type in the 65,74一year-old subjects.
1 • 1.
Background of the present study
There is a general agreement in the dental professional community that the two most prevalent oral diseases, dental caries and periodontal diseases axe preventable through a combination of professional and self care activities and that people's attitudes and behaviour play an important role in the development and prevention of oral diseases (Gje皿o, 1986; Schou and Blinkhom, 1993; Cohen and Gift, 1995》 Concern has been expressed that improvements in oral health conditions were taking place in many Western countries whereas deterioration in oral health has been taking place in many developing countries (WHO, 1989; Barmes, 1989). Proper evaluation of such trends needs appropriate data which will be of use for planning preventive and curative oral care programs and developing training programs for dental personnel. However， only a few studies have been carried out in Mainland China with collaborating investigators from abroad using internationally recognized methods, among which most were conducted in Northern China (Powell W a/.， 1986; Baeluni Yang
a/" 1988a; Luan W
1989a; Luan W "/.， 1989b; Wright W a/" 1989;
a/., 1992; Douglass " a/., 1994; Petersen & a/" 1997). In Hong Kong, both
descriptive and analytic epidemiological oral surveys have added considerably to the knowledge concerning oral health of the population and provided a basis for oral health policy there (Corbet and Lo, 1994; Corbet" a/.， 1994; Holmgren " "/., 1994; I i m W a/" 1994;
and Schwarz, 1994a; Lo and Schwarz, 1994b; Lo W
Schwarz and Lo, 1994a; Schwarz and Lo, 1994b; Schwarz "
into Guangdong Province in Southern China will provide basic data related to the oral health status， knowledge, attitudes and behaviour of the people in Guangdong
Province for formulating strategies for oral health prevention and treatment. It will also help to fill the gaps in the understanding of oral health developments in Hong Kong which is culturally closely related to Guangdong Province with most of Hong Kong people being descendants of the province. This research project surveyed selected age groups (5-6， 12， 35-44, 65-74 year-olds) and was conducted during 1996 to 1997. The project received support from the Faculty of Dentistry, The University of Hong Kong and also from the Department of Preventive Dentistry and Department of Epidemiology, Sun Yat-sen University of Medical Sciences in Guangzhou (capital city of Guangdong Province). This thesis reports major results of the 35-44-year-olds and the 65-74-year-olds with regard to their dental caries， periodontal disease, tooth loss， and treatment needs as well as salient factors for oral health knowledge, attitudes and behaviour.
1.2. Dental care policy and organization in Mainland China For a long period, oral health care had not been perceived as important in Mainland China. The situation began to change since 1980s with the growth in the economy, increase in international interflow, and more and more demand for oral health care. In 1981， a WHO Collaborating Centre for Dental Research and Training was set up in the Beijing Medical University to provide fiirther training for dentists from different parts of China. In 1983, the first national oral health survey was conducted among 131 ，340 primary and secondary school students using methodology recommended by WHO. In 1988， the First National Conference for Preventive Dentistry was held in Tianjing and with the support of the Ministry of Public Health, The National Committee for Oral Health was set up in the same year. In 1989, the Ministry of Public Health and related authorities designated the 20th of September
as the national " Love Teeth Day" (Bian " a/" 1995), Each year on this day, numerous oral health education activities are conducted across the country to disseminate oral health messages to the public and these provide a national focus on the improvement of oral health attitudes and behaviour. Fluoridated toothpaste has become available in China since early 1990s and is gradually spreading throughout the country. School-based fissure sealant programmes have been introduced in some schools in the major cities but the coverage is still very limited. In 1995, the second national oral health survey was conducted among both children and adults in selected provinces.
The National Committee for Oral Health (NCOH) which mainly comprises oral health experts from different provinces of China is under the Department of Disease Control, the Ministry of Public Health. The main task of the committee is to assist the Ministry of Public Health to make policies for the prevention and treatment of dental diseases, to draw up a plan for manpower and personnel training, to coordinate the dental prevention and treatment work，tofoster academic exchange and to introduce new methods and new techniques (Li, 1993), Special sub committees for oral health education and promotion, primary health care, school dental health care， use offluorides,and evaluation of dental care products have been set up under the NCOH. At present, all the provinces, autonomous regions, and metropolitans directly under the central Chinese government have established their own committee for oral health under their local Department of Public Health.
It has been long recognized that several different types of dental personnel are fundamental to the efficient provision of dental care. Different countries may have
different types of dental personnel. In Mainland China, the types mainly include dentist， middle-level dentist, dental n腦e， and dental technician.
The dentists (stomatologists) usually graduate from a university after 5 years of study. There are at least 27 universities which provide such training of dentists (Bai and Zhang, 1990). Before students enter the universities, they have studied 6 years in a primary school and 6 years in a secondary school. As the competition is keen， only those who obtain the high grades in the national university entrance examination can enter the universities. In the universities, they usually spend three years in the study of general medical courses, one year in the study of theoretical and experimental courses of dentistry, and one year in practice in dental hospitals. After graduation, they usually work in state-owned hospitals. Some of them will continue to study for postgraduate qualifications in or outside China. There are some dentists who are promoted from middle-level dentists (described in next paragraph) after many years of work and after passing a special test. But such promotion becomes more and more difficult because more dentists graduate from universities and the policy becomes stricter for such promotion.
The middle-level dentists graduate from health worker training schools after 3 years of study. In the late 1980s, there were 30 schools registered with various provincial Departments of Public Health or with the National Education Committee and they provided training for middle-level dentists (Bai and Zhang, 1990). Before students enter the health schools, they usually have received 9 years of education (lower secondary level). After graduation, they may work in state-o雨ed hospitals or in private dental clinics. Finding a job in state-owned hospitals becomes more and
more difficult for them. The number of health worker training schools which provide training for middle-level dentists has increased in recent years but the exact number is unknown.
Few schools provide special training for dental surgery assistants in Mainland China, Dentists are assisted by 'dental nurses' in their clinical work. Nurses usually receive three years training in a health worker training school after they finish lower secondary school education. When they work in dental hospitals or clinics, they receive a short period of training before they start working as dental nurses. They have the same knowledge as other medical nurses so that they can work in an oral surgical ward nursing in-patients as well as work in dental clinics. Most private dental clinics have no dental nurse.
Dental technicians also graduate from the health worker training schools. They also receive three years training after completing lower secondary school education. The number of schools which provide training for dental technicians is less than those which provide the training for middle-level dentists. The student dental technicians learn how to fabricate c r o 糧 s ， bridges and dentures in the schools. After graduation, they usually work in big hospitals or clinics.
Private dental clinics axe not yet as common in Mainland China as in many other countries but the tendency is to increase. Almost all the dental hospitals and dental clinics in general hospitals belong to and get support from the government They are supervised by public health bureaus in the cities or counties which report to the Department of Public Health of the province. Medical insurance usually covers basic
dental health care in Mainland China， such as filling and tooth extraction but not for orthodontics and dental prosthesis. Government employees and people who work in state-owned
institutions and companies
usually can get partial or total
reimbursement of the expenditure on basic dental health care in appointed hospitals. The proportion of the reimbursement varies from one work place to another. People who are not working in state-owned work places, like farmers, usually have no or little medical insurance and they can go to any dental hospitals or dental clinics to get dental care services. Private dental clinics are more common in towns and small cities than in big cities because the hospital coverage is better in big cities and people working in the cities usually have medical insurance which requires them to go to visit a dentist in a state-o猶ed hospital for dental care.
1.3. Guangdong Province There are 23 provinces, five autonomous regions, four metropolitans directly under the central government in China. Guangdong Province located in the southern part of China is one of the big provinces in population and an important province in economic terms in China. It has a land area of 178,100 square kilometers and a 0
3,368 kilometers long coastline. Annual average temperature is 21.7 C (Editing Committee of Guangdong Encyclopedia, 1995). Administratively, it is divided into 21 cities (administrative regions) and can be fUrther subdivided into 42 urban districts and 78 rural counties or county-level cities. The resident population in 1995 was 68 million and the male to female ratio was 1.05 : 1 (Guangdong Statistical Bureau, 1996). Furthermore, there were more than 3 million immigrant workers coming from other provinces. In 1995, only about 2% of the population had attended tertiary or post-secondary education. Results of the 1990 population census of
Guangdong Province (Population Census Office of Guangdong Province, 1992) showed that 30% of the population were 0-14 years old and 9% were 60 or more years old. Around 60% of the working population were agricultural workers. Another 22% of the work force were manual workers. The annual gross national product in Guangdong Province was RMB¥ 1,403 billion (about USD 2，480 per capita) in 1995 (Guangdong Statistical Bureau, 1996》
There are 16 dental hospitals in the major cities in Guangdong Province (Guangdong Statistical Bureau, 1996) and there are dental clinics in most of the county-level and city-level hospitals. However, about half of the 1，500 township hospitals do not provide dental services (Zhang " a/" 1993b). There are approximately 1.5 university trained dentists per 100，000 population (Zhang
1993b). In addition, there are
about 1,000 middle-level dentists who have received 3 years of basic dental training in a health worker training school. Thus, the overall dentist to population ratio is about 1: 33,000. It should be pointed out that the geographic distribution of dentists is very uneven， there are many more dentists in the major cities and urban areas than in the towns, and hardly any in the rural areas.
In the rural areas of Guangdong Province, like in other provinces, there are some dental care providers who have been trained in traditional apprenticeship rather than in dental schools. They mainly provide relief of dental pain, tooth extraction and prosthetic treatment. However, no information is available regarding their number and distribution.
Guangdong Province is the only province that has experienced community water
fluoridation in Mainland China. In July 1965, community water fluoridation was introduced in a district of Guangzhou City， Fangcun District, and this extended to other parts of the city in November of the same year (Luo " a/" 1988). At the beginning, the average concentration of fluoride was 0.8 ppm, i.e. 0.8-1.0 ppm between November to April and 0.6-0.8 ppm between May to October. Some surveys were conducted several years after water fluoridation to evaluate the effect and it was reported that dental caries had been reduced by 40-60% in children (Guangzhou Work Group for Water Fluoridation Programme, 1972; 1973). However, dental fluorosis was found to have increased and the concentration of fluoride was adjusted to 0.7 ppm in March of 1975 (Department of Stomatology of Second Affiliated Hospital of Zhongshan Medical College, 1979). During 19761978 (two and half years)， water fluoridation was interrupted because of a lack of sodium silicofluoride from local factories. After this, the program was continued in Fangcun District, but was basically stopped in other districts of Guangzhou (Shen and Gu, 1985》In 1978， the Epidemic Prevention Station and some dental academics in Guangzhou suggested to stop the water fluoridation program. There were different views held by the medical and dental professionals in Guangzhou with regard to this proposal. The reduction of dental caries was generally acknowledged but different extent of the reduction of caries and different results of dental fluorosis were reported (Guangzhou Work Group for Water Fluoridation Programme, 1972; Department of Stomatology of Second Affiliated Hospital of Zhongshan Medical College, 1979; Shen " a/., 1982). In September 1983, the Public Health Bureau of Guangzhou City told the water supply company to stop water fluoridation because it claimed that according to the report from the Epidemic Prevention Station， the average prevalence of dental fluorosis among the children職s as high as 53%
although the average prevalence of dental caries had decreased from 62% to 42% (Shen, 1989). In a town of Guangdong Province, Guangcheng， water fluoridation was introduced in 1974 and stopped in the late 1980s. However, no study was conducted to evaluate the effect of this programme.
2. L I T E R A T U R E R E V I E W - review of oral health surveys among adults in China
Although there is computer software and databases in China similar to Medline for searching medical articles written in Chinese, the number of articles in dentistry is limited and thus the retrieval of relevant Chinese dental literature is very difficult. Several methods were used in this review to search for articles. A search on the Medline Express CD-ROM system was performed using key words such as "China"， "caries", and "periodontal" to look for articles published in English and in Chinese. In addition, a Chinese periodical, " A catalogue of scientific and technical data in Chinese - Medical section" (Zhongwen Keji Ziliao Mulu - Yixue Fence), was used to search for articles in Chinese. Major dental journals in Chinese (Schwarz and Lin, 1997) in which articles on oral epidemiology and behavioural science were usually published were also checked year by year to find the relevant articles. The publications listed in the reference section of the retrieved articles were also checked.
It was found that published information from oral epidemiological studies in Mainland China was scarce although there were several articles which summarized the caries status in some population groups in Mainland China mainly based on unpublished papers collected by authors (Yue, 1980; Editorial Board of Chinese Journal of Stomatology, 1983; Editorial Board of West China Journal of Stomatology, 1988).
Most of the study populations in the reported oral health surveys in Mainland China
were children and adolescents and from urban areas of big cities. Studies on middleage adults and elderly were much less common. Moreover, many of these studies are difficult to interpret because of unknown sampling method (Fan and Cai， 1988》 poorly defined criteria (Zhang and Li, 1995), frequent lack of stratification by important variables such as age (Xu W
results (Zhang W
1989), or unsuitable presentation of
1993a). The present literature review focuses on reported
surveys on oral health status, knowledge, attitudes, and behaviour in adults in Mainland China. No major review of this kind was found to have been performed earlier.
2.1. National oral health surveys
Two national oral health surveys have been conducted in Mainland China. The first one職s conducted among children and adolescents in 1983 and the second one was conducted among both children and adults in 11 selected provinces in 1995.
2丄1, The First National Oral Health Survey The First National Oral Health Survey was carried out in 29 provinces of China (Ministry of Public Health， 1987). A total of 131 ，340 students aged 7, 9， 12， 15 and 17 years old were selected through stratified sampling with respect to age， gender， location Ourban or rural)，fluorideconcentration of water and ethnicity. About half of the students were selected from rural areas. Dental caries, periodontal diseases, dental fluorosis and tetracycline stain were examined in the survey based on WHO criteria. The mean dmft among 7-year-old children was 4,8 in urban areas and 2.6 in rural areas with prevalences of 84% and 62% respectively. The mean DMFT score among 12-year-old children was 1.0 in urban areas and 0.7 in rural areas with prevalences of 46% and 31% respectively. Mean number of sextants with gingivitis (bleeding on probing) and calculus were 2.5 and 1.7 with prevalences of 77% and 0
62 /o respectively. Considerable variations between coastal and inland provinces were also reported.
2丄2. The Second National Oral Health Survey The Second National Oral Health Survey was conducted among 140，712 subjects in 11 selected provinces in 6 selected age groups， namely the 5， 12， 15， 18， 35-44, 6574 years. The ratio of subjects from rural areas to those from urban areas was about
1:2. Guangdong Province was selected to represent the southern part of China. The procedure and the major statistical tables of this survey have been reported recently (Technical Instruction Group for The Second National Oral Health Survey, 1998). Multi-stage cluster sampling was used in this survey. Clinical examination was conducted in all 6 age groups whereas interview was conducted only in the 12, 18， o
35-44, and 65鋒74-year-olds. About 20 /o of the subjects in these four age groups were interviewed.
In the clinical examination of adults, coronal and root caries， CPITN, prosthetic status and treatment need were recorded. It was reported that the clinical diagnostic criteria used were those recommended by WHO (1987) except the criteria for the diagnosis of root caries. However, only 28 teeth (excluding the third molars), instead of 32 teeth as recommended by WHO， were examined in this survey. At least in Guangdong Province, the examiners for this survey came from local hospitals in the survey regions (3 survey regions in each province) and were responsible for the examination of subjects in their own region. As no duplicate examination was performed in this survey to monitor examiner variation, the degree of error is unknown. Examination conditions, e.g. light， chair for examinees had not been mentioned
The mean DMFT of the 35-44-year-olds was reported to be 2.11 (2.14 in urban areas and 2.03 in rural areas) with a prevalence of 63%. The respective mean DT, MT and FT scores were 1.10, 0.59， 0.42. Mean number of teeth present in the 35-44-yearolds was 27.12. It is interesting to note that the sum of this number and MT does not equal the number of teeth examined. It was described in "Oral Health Surveys -
Basic Methods" (WHO, 1987) that MT comprised teeth missing due to caries as well as other reasons for subjects aged 30 years and older. Therefore, the sum of the number of teeth present and MT should equal the number of teeth examined. The number of teeth present in the 65-74-year-olds was reported to be 18.14. The mean DFT was reported to be 2.49 (2.36 in the rural areas and 2.74 in the rural areas).
According to the highest CPITN score, 2.1% of the 35-44-yeax-olds and 4.3% of the 65-74-year-olds had deep periodontal pocket and 11.2% of the 35-44-year-olds and 17.9% of the 65-74»year-olds had shallow pocket. 10.5% of the 65"74纖year-olds were edentulous and 8.4% had complete dentures in both jaws. The proportion of subjects who claimed to brush their teeth twice and once daily were 32% and 53% respectively in the 35訓44-year-olds and 23% and 48% respectively in the 65-74year-olds. Only 20% of both the 35-44-year-olds and the 65-74-year-olds had visited a dentist within the preceding 12 months.
2.2. Major regional and local surveys related to caries in adults in Mainland China
2'2丄Study population and sampling methods Some of the major regional and local surveys related to caries in adults in Mainland China are listed in Table 2-1. Most studies only included urban residents but a few also included rural residents. The ratio of urban subjects to rural subjects was about 1:1 in two surveys (Liu " "/.， 1984; Chen W
1993》about 1:2 in the survey in
Jiangxi Province (Yan, 1995) and about 2:1 in the survey in Beijing (Luan
1989a). The urban subjects mainly came from big cities and only three surveys included urban subjects from middle-sized or small cities (Petersen W a/.， 1997; Chen Wa/" 1993; Yan, 1995).
Different sampling methods were used in the surveys. Some surveys did not describe the sampling methods used (Hu and Zhu, 1964; Liu " a/., 1984; Yi " a/" 1985; Yan， 1995). Some surveys were performed on convenience samples. Powell d (1986) examined staff aged 35-44 years available for examination in a dental faculty in Shandong Province, Zhang
(1988) examined the elderly who attended a
health care clinic. Several surveys used multi-stage cluster sampling (Chen W a/.， 1993; Petersen et al" 1997; Feng
a/" 1998) whereas Luan
a/. (1989a) applied a
systematic stratified sampling procedure to select the young adults and the middleaged.
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Sample size in each age group (class interval was usually 5 years or 10 years) was usually 200 to 400 in the surveys but more than one thousand 35-44-year-olds were surveyed by Chen " a/. (1993). The report of the survey conducted by Feng W a/. (1998) did not give sample size for each age group.
2*2.2. Methodology and reliability Most of the surveys reported that they performed the clinical examination based on the methods recommended by WHO. One survey recorded coronal and root caries by surface and recorded the depth of coronal caries (Luan & a/" 1989a), One survey used the diagnostic criteria recommended by the Chinese Ministry of Public Health (Yan W a/.， 1983). Two surveys did not report the diagnostic criteria of dental caries (Chen
"/., 1985; Zhang "
Mouth mirror and explorer were usually used in the clinical examination. Only two surveys reported that they used artificial light during clinical examination (Powell "/.， 1986; Luan " (Liu
1989a). Another three reported that they used natural light
a/.， 1998) Avhile the others did not
mention about this. Most surveys conducted after the 1970s had their data analyses performed on computers except three which did not mention the method of data analysis (Yi "
1985; Zhang W a/.， 1988; Yan, 1995).
The survey conducted in Guangdong Province (Chen " a/" 1993) recruited nondental university students and trained them to be examiners. Half of the surveys did
not report on the number of examiners employed in the survey (Hu and Zhu, 1964; Yi " a/., 1985; Zhang "
" / • ， 1993; Yan, 1995). Only some listed
surveys mentioned the examiner calibration methods and results. Coefficient of variation (CV) was used by two surveys (Liu " a/.， 1984; Yan, 1995) to assess interexaminer reliability and a CV smaller than 0.2 was set as the acceptable level by these surveys. Kappa statistic was more frequently used in the recent surveys and the results were reported to be 0.79-0.93 (Luan 1997), and over 0.4 (Feng
a/" 1989a)， over 0.85 (Petersen " a/.,
a/.， 1998). However， none of these surveys had carried
out duplicate examinations during the main survey to monitor examiner reliability.
2.2.3. Major results Yue (1980) reviewed published and unpublished surveys conducted between the 1940s and the 1970s. These data comprised a total of 4.6 million people (unknown age group) from different parts of China and the average dental caries prevalence rate was 37*3% with an average of 2.47 carious teeth for each subject affected. Most 0
study subjects were from urban areas and only 1.6/o were from rural areas. Only a very small percentage of the subjects were adults. The majority of the surveys were conducted in Shanghai. The author summarized: (1) Because such collected data had not been appropriately designed with age group， diagnostic criteria, sampling methods, and had not been reported appropriately in papers, the difference among provinces and the difference between cities and rural areas could not be established. The mean DMFT/dmft scores and percentage of people affected according to age groups also had not been reported. (2) Different ethnic groups did not exhibit significantly different level of dental caries when they lived in the same areas. (3)
Higher fluoride concentration in drinking water was associated with lower prevalence rates of carks.
Table 2-1 shows the mean DMFT or DFT in the middle-aged and the elderly which were mainly from surveys conducted after 1980. The mean DMFT in the 35-44year-olds was from 1.5 to 6.0. Results from studies conducted in Beijing and Guangdong gave relatively high DMFT scores. The mean DMFT of the 65-74-yearold age group in Hubei based on 28 teeth was reported to be 8.9 (Petersen
1997). Another survey based on 28 teeth reported the mean DMFT in 65-69-year-old Shanghai elderly to be 12.1 (Feng W a/" 1998). Based on 32 teeth， Luan W a/. (1989a) reported a mean DMFT score of 16.6 in 60-69-year-old Beijing elderly. Some surveys just gave the results of DFT rather than DMFT. DFT ranged from 1.4 to 3.7 in the middle-aged and from 3.5 to 15.2 in the elderly.
Women were usually reported to have a higher mean DMFT or DFT score than men (Liu W a/" 1984; Powell W a/.， 1986; Cooperation Group for Beijing Elderly Oral Health Survey, 1988; Luan " " / . ， 1989a; Petersen
1997), While an early
survey in Western China reported that urban residents had a higher DMFT score than rural residents in the 35-44-year-olds (Liu & a/" 1984), several recent surveys in Beijing， Guangdong Province and Jiangxi Province found higher DMFT scores in rural residents (Luan W a/.， 1989a; Chen
a/" 1993; Yan， 1995). Besides gender
and location, analysis of the relationship between dental caries and other demographic characteristics such as education level， occupation, aiid income of adults was uncommon. A few studies tried to find out factors which influenced dental caries. Chen & a/. (1993) found that people (combination of children and
adults) who were older or had periodontal disease, malocclusion, bad oral hygiene, and frequent intake of sweet food tended to have more caries. Petersen " a/ (1997) found that women, those who had visited a dentist in five years, and those who reported using fluoride toothpaste daily in the 35-44-year-olds had higher DMFT scores.
Surveys on root caries were uncommon and only a few surveys reported the root caries status by prevalence and/or mean number of teeth affected. The prevalence of root caries in the 60-69-year-olds was reported to be 32% to 50% with 0.9 to 1.9 teeth affected per person examined (Cooperation Group for Beijing Elderly Oral Health Survey, 1988; Luan
"Z" 1989a; Zhang and Li， 1995), For a caries lesion
affecting both the root and coronal surfaces, the lesion was recorded as originating in the root b
& a/. (1989a). Other surveys did not clearly describe the criteria
for the diagnosis of root caries. One survey among Shanghai elderly using Root Caries Index (RCI) reported that the RCI was 5.42 in 65-69-year-olds (Liu " 1992).
2.3. Major regional and local surveys related to periodontal status in adults in Mainland China
2.3丄Study population and sampling methods Some major surveys related to periodontal conditions of the middle-aged and the elderly in Mainland China are listed in Table 2-2. Most of these surveys were conducted among urban residents in big cities， such as Beijing, Tianjing and Shanghai, Only a few surveys comprised some rural residents.
Some of the listed surveys used convenience samples (Diao, 1986; Powell W a," 1986; Pilot "
1989) and some did not describe their sampling methods (Shi W
a/" 1983; Liu " a/" 1984; Wang W a/, 1987; Wei, 1987). Diao (1986) examined military staff attending a clinic. Powell W a/. (1986) examined 35-44-year-old staff in a dental faculty in Shandong Province. Pilot W
(1989) examined factory
workers in three factories in Shanghai. A multi-stage cluster sampling was used in the survey in Wuhan (Petersen
1997). Hu W a/. (1990) reported that they used
a stratified multi-stage random sampling method but did not describe the sampling procedure. Most of these surveys recruited their subjects from factories (Shi & 1983; Liu W " / • ， 1984; Wang " " / • ， 1987; Wei， 1987; P i l o t " " / • ， 1989).
Sample size in each age group (class interval was usually 10 years or 5 years) was usually 150 to 400 in these surveys. A bigger sample size of around 500-700 35-44year-olds was found in the surveys conducted by Diao (1986) and by Pilot (1989). A survey report by Wang "
(1987) did not give individual sample size
for each age group.
ID ID ID ID
20-80 35-44, 65-74
Baelumef a/., 1996 Petersen "a/., 1997
35>44 60 sind over
Pilote〖a/.， 1989 Hu efa/.， 1990
Bleeding, calculus, plaque, UDA
51 o o o
22 18-50 20-75
Debris, calculus, gingivitis, periodontitis
19 and over
7 to > 70
Wang efa/., 1987 Wei, 1987
Diso, 1986 Shandong
Liu efa/., 1984
Powell efa/., 1986
Shi efa/., 1983
S6l6Ct6d o o> o CD 5
• z z
Author and date published
2.3.2. Methodology and reliability Some internationally accepted indices for periodontal status and oral hygiene were used in the surveys listed in Table 2-2. CPITN was the most common index used. Two composite indices, the Periodontal Disease Index (PDI) developed by Ram^ord (1959) and the Periodontal Index (PI) developed by Russell (1956), were used in some surveys in the 1980s. The Plaque Index (P1I) developed by Silness and Loe (1964) and the three indices developed by Greene and Vermillion (1960), i.e. Debris Index (DI), Calculus Index (CI) and Oral Hygiene Index (OHI) were used in some surveys to measure plaque and calculus. Liu
a/. (1984) used the criteria defined by
WHO (1977). Loss of periodontal attachment (LOA) in adults in Mainland China was seldom studied. Although the scoring of PDI includes the measurement of LOA， PDI itself just gives a mean score for the periodontal condition in a group of people. One survey in Beijing had measured LOA in adults by teeth (Baelum & a/., 1996).
Concerning the instruments used， CPITN probe was most often used to measure CPITN. Two of the three studies using PDI used GUckman，s periodontal probe (Shi " 1 9 8 3 ; Wang & a/" 1987) and the other one did not mention the instrument used (Diao， 1986). Only some of the surveys used artificial light (Powell W a/.， 1986; Wang " a/" 1987; Baelum W "/., 1996). Others conducted the clinical examination under natural light or did not mention this. Some surveys carried out calibration sessions before the main survey but the results of calibration for periodontal status were seldom reported. None of the reviewed studies conducted duplicate examinations during the main survey to monitor examiner reliability.
2.3.3. Major results Percentages of the middle-aged and the elderly survey subjects according to maximum CPITN score are shown in Table 2-3. In the 35-44-year-olds， the percentages of subjects with deep pockets ranged from 0.7% to 11% and the percentage of subjects with shallow pockets as their maximum CPITN score ranged from 6.5% to 44%. Deep and shallow pockets as maximum CPITN score were found in 22% and 16% of the 65-69-year-olds in Shanghai (Hu W a/,, 1990) and 3.8% and 16.2% in the 65-74-year-olds in Wuhan， Hubei Province (Petersen
Although the CPITN index was also used in a survey of Beijing adults (Wei, 1987), the results were not reported according to the standard format recommended by WHO (1987). It seems that in this study the percentages were calculated based on the occurrence of the corresponding score in one or more of the six sextants in a person. The mean numbers of sextants with no periodontal disease, bleeding or higher score， calculus or higher score, shallow or deep pockets， deep pockets and excluded sextants were reported to be 0.7， 5.3， 4.8， 1.3， 0.2， 0.0 respectively in the 35誦44一year一olds (Pilot " a/" l卿）and 0.2, 4.2, 3.8, 0.7, 0.3, 1.7 respectively in the
65-69~year-olds (Hu W
Table 2-3. Percentages of individuals by maximum CPITN in the Chinese middle-aged and elderly age groups as reported in previous studies. Maximum CPITN score (%) Age group
Powell efa/.， 1986
Pilot efa/., 1989
Hu efa/., 1990
The percentages of "PDI>0" (with periodontal disease) and "PDI>3" (with loss of attachment) were reported to be 92.9% 3nd 42.6% with a me3n PDI score of 2.83 in Tianjin residents aged from 7 to more than 70 years (Shi W
1983). In another
survey in Tianjin, the corresponding percentages in adults aged 18-50 years were 98.8% and 44.4% respectively (Wang W
1987). The PDI scores were not
reported individually by age groups in either paper. It was reported that the mean PDI score increased from 0.70 in men aged 20-24 to 0.96 in men aged 35-44 (Diao, 1986). Hu and Pan (1984) found that the mean PDI score of the elderly with diabetes was higher than that of the elderly in a control group. Based on the examination of all teeth in a group of 35-39-year-olds, Baelum & a/. (1996) found that 63% were affected by attachment loss of 4 mm or more and 11% by attachment loss of 7 mm o
or more. The corresponding percentages in the 65-69-year-olds were 100X> and 807o respectively.
(1983) reported that the mean P1I score in 35-39-year-olds was 1.64 and
the score increased with age. The same study also found that farmers had the highest P1I and CI scores among all occupation groups. Diao (1986) reported that the percentages of men aged 19-54 with debris and calculus were 99% and 94% respectively. The mean DI, CI and OHI scores increased with age and positive relationships existed among DI, CI and PDI in the subjects surveyed. Baelum W a/. (1996) found a mean of 19.9 and 25.8 teeth in the 35-39-year-olds having calculus and plaque respectively. It can be summarized that plaque and calculus as measured by these studies were common in the adults in Mainland China.
2 A Major regional and local surveys related to tooth loss and prosthetic status in adults in Mainland China
Surveys focusing on tooth loss and prosthetic status were uncommon and mainly conducted in urban areas and in the elderly. As recognized widely in the world， dental caries and periodontal disease are two important reasons causing the loss of teeth. A survey of the elderly in Chengdu reported that 77% of tooth loss was due to caries and 16% due to periodontal disease (Chen W a/" 1985). The proportions were somewhat different from the results of two studies based on clinical records which o
got a lower proportion (45-53^0) due to caries and a higher proportion (22-40 /o) due to periodontal disease (Lei W a/., 1987; Tian " a/., 1995). The survey in Chengdu (Chen "
1985) collected oral health data from a
convenience sample of 926 elderly from some factories, government organizations and residential areas. One or more missing teeth were found in 95% of the subjects. On average, each person had lost 14.2 teeth， excluding third molars. In the 60-69 and 70-79 year-old groups， the mean numbers of missing teeth were 10.4 and 15,8 respectively, A survey of 2,191 elderly, aged 60 years and over，from9 residential areas and a village of Beijing reported that 91% of them had lost one or more teeth and the mean number of missing teeth was 11, excluding third molars (Cooperation Group for Beijing Elderly Oral Health Survey, 1988). The mean number of missing teeth in the 60-69»year,olds was reported to be 8.4. Another survey in Beijing recruited 1,744 20-80-year-olds from 3 urban districts and a rural village by systematic sampling and found a mean of 29.1 and 20.2 teeth present in the 30-39year-olds and 60-69-year-olds respectively (Luan W
1989b). A follow-up study
in these study subjects indicated that the incidence of tooth loss was much higher in
the elderly than in the young adults (Luan
1994). Generally speaking， men
retained more teeth than women and urban residents retained more teeth than rural residents (Chen " a/" 1985; Cai, 1987; L 腿 " 1 9 8 9 b ) . Furthermore, more upper teeth than lower teeth and more posterior teeth than anterior teeth were missing (Chen " a/,, 1985; Cai, 1987; Xu " a/" 1989).
The prevalence of complete edentulousness was reported to be 5% to 8% in the 6069,year-olds in Beijing (Cooperation Group for Beijing Elderly Oral health Survey, 1988; Zhang "
1988; Luan " a/" 1989b) and 11% in the 60-69-year-olds in
urban areas of Chengdu, Western China (Chen
According to the criteria of WHO (1977, 1987, 1997), the M-component of DMFT includes all missing teeth due to any reasons for subjects 30 years and older. Therefore, the M-component of DMFT should be the number of missing teeth for those subjects aged 30 years and above. However, some surveys on dental caries listed in Table 2-1 only give the results of DFT. A small score of MT， 1.1, was recorded by Powell " a/. (1986) for the 35-44-year-olds in a university in Shangdong Province. The MT scores of the 35-44-year-oWs and the 65-75-year薩olds in urban areas in Hubei Province were recorded as 0.7 and 6.1 respectively based on 28 teeth examined (Petersen "
1997). Another survey based on 28 teeth
recorded the M-component in the 35-39-year-olds and 65-69-year-olds in urban areas of Shanghai to be 0.5 and 8.9 respectively (Feng "
Percentages of the 60-69-year-olds in Beijing with a foil denture in one or both jaws
were reported to be 8% and 6% respectively
1989b). Percentages of
dentate subjects with one or more bridges and one or more partial dentures were 6% and 14%> in this age group. The corresponding percentages in the 30-39-year-olds were 10% and 5% respectively. Also from Beijing， the percentages of the 60-69year-olds with full denture and with partial denture or bridges were reported to be 7% and 27% respectively (Cooperation Group for Beijing Elderly Oral Health Survey, 1988). A survey of a group of 45-49-year-olds and 65-69-year-olds in the urban areas of Hebei Province showed that 5% and 6% of the middle-aged and 10% and 39% of the elderly had one or more bridges and one or more partial dentures respectively (Zhang, 1985).
The proportion of edentulous elderly who had received prosthetic treatment ranged fom 64% to 87% and the prevalence of dental prosthesis among those who had lost some of their teeth ranged from 18% to 30% (Chen
a/., 1985; Cai, 1987; Xu "
1989). Partial dentures were more frequently seen in urban residents than in rural residents, while bridges were more common among rural residents than in urban residents (Luan
a/.， 1989b). The fact that women and the older elderly usually
received less treatment was considered a reflection of their attitudes to tooth loss and their economic status (Chen W a/" 1985). The government officials, professionals and people with high educational level usually lost fewer teeth and received more treatment than farmers， manual workers and housewives (Cai， 1987).
2.5. Major regional and local surveys related to oral health knowledge, attitudes and behaviour in adults in Mainland China
Reported surveys on oral health knowledge, attitudes and behaviour in adults in Mainland China were relatively uncommon and were usually without a good design. Study subjects usually came from convenience samples in urban areas with a wide age range, from children to middle-aged (Tai "
1992; Zhu, 1993). Surveys on
the elderly were scarce. Results of oral health knowledge or attitudes were usually reported by individual knowledge item (Tai
a/" 1993). Results
of oral health behaviour were mainly related to toothbrushing habits. Due to these shortcomings the validity and generalizability of the results may be questionable.
It has been reported that more than 90% of Chinese children or adults， aged from 10 years， thought that sugar was harmful to teeth (Zhu， 1993; Peng W a/" 1997). When a group of mothers of primary school students were asked to give the causes of dental caries, sugar was mentioned by 42% of them, bacteria by 35%， and worms by 10% (Petersen and Zhou, 1998). In the same study, 59% of the mothers mentioned incorrect tooth cleaning, 32% mentioned general illness and 23% mentioned unhealthy diet (23%) as a cause of bleeding gum. Toothbrushing and restriction of sugar were most frequently recommended by the mothers to prevent dental caries but use offluorideswas recommended only by 18%. Peng "
(1997) reported that
around half of the residents in Wuhan， Hubei Province knew that fluoride may prevent dental caries and that the answers given by the adolescents, younger adults and middle-aged were similar. It was reported that most urban residents thought that dental diseases were harmftd to the body as whole (Tai "
1992; Zhu, 1993).
Almost all younger adults in urban areas brushed their teeth at least once daily (Luan W " / • ， 1993; Peng
" / . ， 1997). A survey of Shanghai elderly reported that 8/o of 0
the dentate elderly did not brush their teeth daily and the proportion increased to 44% among those aged 80 years and over (Hu " a/.， 1988). A mass campaign on "Love Teeth Day" has been carried out nationwide each year in China since 1989 to raise the people's awareness of dental health， and to promote community involvement in oral health education programs and self-care (Bian
Better dental knowledge and toothbrushing behaviour were found in Wuhan residents after six years of "Love Teeth Day" campaigns (Peng
It has been reported that 22% of the 35-44-year-olds and 35% of the 65-74-year-olds in urban areas in Hubei Province had been to the dentist within a year and the major reasons for not visiting a dentist were 'no serious dentai problem' and no 'need' (Petersen W a/" 1997). Around half of the adults in urban areas in Hubei Province and Hunan Province stated that their main reason for visiting a dentist was toothache (Zhu， 1993; Peng W a/" 1997). A collaborative questionnaire survey conducted in some provinces reported that only 15% of the urban residents and 5% of the rural residents had visited a dentist when they had dental problems (Sun, 1992). The main reasons for not visiting a dentist given by the urban residents were "inconvenience" (21%)，
"no need" (16%), "too busy"
"afraid of seeing dentist" (15%)， and
"too expensive" (6 /o), The main reasons given by the rural residents were "inconvenience" need"
"too busy" (24%), "afraid of seeing dentist" (10%), "no
and "too expensive" (9%). However, the age of the subjects surveyed
was not reported.
2.6. Major oral health surveys among Hong Kong adults
Although there were a number of oral health surveys conducted among Hong Kong adults, only the two major surveys are reviewed here. They were the first and second Hong Kong adult oral health surveys conducted by the Department of Periodontology and Public Health， Faculty of Dentistry， The University of Hong Kong in 1984 and in 1991 respectively.
2.6丄Methodology of the 1984 Hong Kong Adult Oral Health Survey A multi-stage cluster sampling was used in this survey (Lind " a/., 1986, 1987a & 1987b). In the first stage, a region with a population of about 300,000 was selected taking into consideration convenience of the location and representativeness of the major socioeconomic strata in Hong Kong. After the region was chosen， living quarters were selected by systematic sampling and within each living quarter all persons aged 15-19 and 35-44 years comprised the sample. Through conducting home visits and follow-up telephone calls, 563 15-19-year-olds and 676 35-44-yearolds were finally recruited.
A questionnaire designed for self-completion was used in this survey to collect socio垂cultural data focusing on oral health related perceptions, knowledge and behaviour of the subjects. The subjects were also clinically examined for presence of dental caries and treatment need, dental prosthetic status， periodontal conditions and teeth present. The diagnosis of dental caries and assessments for treatment need were carried out according to World Health Organization (1979) criteria. Periodontal conditions were assessed by applying the CPITN using index teeth* Examiner
calibration was carried out prior to the survey and inter-examiner reliability was monitored by duplicate examinations during the survey. The survey was carried out in the Prince Philip Dental Hospital.
Methodology of the 1991 Hong Kong Adult Oral Health Survey This study was planned to follow the guidelines for the International Collaborative Study I I (Chen W
1997). For the 35-44-year-old age group， the survey areas,
sampling and subject recruitment methods were essentially the same as those applied in the 1984 survey (Schwarz
1994). A total of 398 35-44-year-olds were
recruited for this study. For the 65-74-year-old age group, subjects were recruited from elderly centers in different districts of Hong Kong. Face-to-face interview, instead of a self-completion questionnaire used in the 1984 survey, was used in this survey. The information collected in the interviews included the subject's socioeconomic background, dental knowledge, attitudes and behaviour. A dental knowledge score (0-12) was constructed according to the subject's responses to four questions about tooth decay and gum disease (Schwarz and Lo， 1994a). After the interview, the subjects were clinically examined according to the procedures and diagnostic criteria recommended by WHO (1987).
2,6.3. Major results of the two Hong Kong adult oral health surveys In the 1984 survey， 25% of the 35-44-year,olds did not know the causes of dental caries and 56% did not know the causes of gum disease (Lind
a/., 1987b). These
proportions were reported to be 8% and 27% in the 1991 survey (Schwarz and Lo， 1994a). For the 65-74-year-olds, around half of them were reported to be unaware of the causes of dental caries and gum disease (Schwarz and Lo, 1994a). In both
surveys, almost all the dentate subjects claimed to brush their teeth once or more daily (Lind " " / • ， 1987b; Um W a/" 1994). Some respondents were found to hold Chinese health belief towards periodontal disease in both surveys (Lind W a/" 1987b; LimW"/., 1994).
Compared to the findings of 1984 survey, a slight change in dental visit pattern was found in the 1991 survey， with 5-6% increase in the proportion of 35-44-year-olds having seen a dentist within the preceding year. However, use of dental services in Hong Kong was generally lower than in many industrialized countries (Schwarz and Lo, 1994b). The main reported reason for not having visited a dentist was no perceived dental problem (Lind W a/" 1987b; Lo and Schwarz, 1994a).
In the 1984 survey, teeth judged to be unerupted or extracted as a result of trauma or for orthodontic reasons were excluded from the calculation of DMFT index in the 35-44—year-olds. After being adjusted accordingly, it was found that the caries situation as measured by the DMFT index was very similar to that found in the 1991 survey (Lo and Schwarz, 1994b). The mean DMFT score was found to be 8.7 in the 35-44,year-olds and 18.9 in the 65-74-year-olds in 1991. The respective mean DT, MT and FT were 1.0, 4.5， 3.2 for the middle-aged and 1.4， 17.0， and 0.5 for the elderly. For the root conditions, there was a reduction in the prevalence of root caries in the 35,44year-olds, from 15% found in 1984 to 7% in 1991. It was suggested that the possible reasons for this improvement were the benefits of 30 years of water fluoridation and the introduction offluoridatedtoothpaste in the late 1970s (Lo and Schwarz, 1994b).
The periodontal condition of the 35-44-year-old subjects as expressed by prevalence and mean number of sextants per person according to highest CPI score was very similar in the two surveys. In the 1991 survey, it was found that 17% of the 35-44year-olds and 15% of the 65-74-year-olds had deep periodontal pockets and 57% of the 35-44-year-olds and 51% of the 65-74-year-olds had shallow pockets (Holmgren 自 / " 1994).
In the 1984 survey, it was found that 20% of the 35-44嗎year-olds were denture wearers (Lind W a/" 1996). In the 1991 survey， 127o of the 35-44-yerar-olds had a denture or dentures， 17% had a bridge or bridges, and 1% had both (Corbet and Lo， 1994). Of the 65-74-year-olds, 12% were edentulous. Only 29% of the elderly had no prosthesis, 52% had a denture or dentures， 33% had a bridge or bridges, and 13% had both.
In the 1991 survey, some holistic treatment need categories were used so as to provide some information for dental manpower planning. It was found that the treatment need of the vast majority of the middle-aged and the elderly was simple ones. Only about one垂fifth of the subjects in both age groups required some complex treatments (Lo " " / • ， 1994).
2,7. Summary of literature review
No major review has previously been carried out on the reported socio epidemiologic studies in Mainland China. Most oral health surveys among adults in Mainland China were conducted after the 1970s. Study subjects of regional and local surveys were mainly urban residents living in big cities. Surveys conducted among farmers were uncommon although the farmers comprised around three-quarters of China's population. Most surveys were in or around Beijing, Shanghai, Chengdu (in Western China) and Wuhan (in Central China) which are also the location of major medical universities. Surveys in adults in Southern China were uncommon. Dental caries and periodontal disease were the major dental diseases studied. Only a few surveys on people's oral health knowledge, attitudes, and behaviour were conducted in recent years and mainly in Hubei Province. Published papers concerning dental treatment needs and utilization of dental services among adults in Mainland China we;r6 scarcc，
Sample size was usually not a major problem in these surveys but many surveys used convenience samples or did not describe the sampling methods. In some surveys, the diagnostic criteria used were poorly defined and thus caused difficulty in the interpretation of their results. Recent surveys usually claimed to use internationally accepted criteria, such as those described by WHO.
Reported mean DMFT was low in adults in Mainland China. Most studies reported a DMFT of between 2 and 6 in the 3 544-year-olds and between 9 and 16 in the elderly younger than 75 years. Calculus and gingivitis were reported to be common
in adult Chinese but the reported proportion of subjects with shallow and deep periodontal pockets was not high. Complete edentulousness in the 60-69-year亀olds was usually reported to be less than 10%. According to the data from the second national survey in China， about 14% of the 35-44-year-olds and 19% of the 65-74year-olds did not brush their teeth daily and only 20% of both the 35-44-year-olds and the 65-74-year-olds had visited a dentist within the preceding 12 months.
. A I M S AND O B J E C T I V E S
The aim of this study was to describe the oral health knowledge, attitudes, behaviour and oral health status of adults in Guangdong Province in relation to their personal characteristics.
The objectives of this study were: (1)
to describe the oral health knowledge, attitudes and behaviour of 35-44 and 65-74-year-old Chinese in Guangdong Province,
to describe the oral health status and treatment need of these two age groups,
to identify the socio-demographic characteristics which affected the oral health behaviour and oral health status of these population groups.
4. M A T E R I A L S AND METHODS
4.1. Study population and sampling methods
The sites for carrying out this survey were in four regions in the Guangdong Province illustrated below:
Fig. 4-1. Location of Guangdong Province and survey regions.
The age groups surveyed in the present study comprised the 35-44 and 65-74 yearolds. These are the standard target age groups for oral health surveys in adults recommended by the World Health Organization (1997) in order to provide cross national comparisons. Based on the situation in the Guangdong Province, a
combination of multi-stage cluster sampling and convenience sampling was used in this study (Fig. 4-2). At the first stage, four of the 21 major administrative regions of the province, one each from the central, eastern, western, and northern parts of the province were selected as the survey areas. They were Guangzhou (capital city of the province representing the south/central), Shantou (east)， Zhanjiang (west), and Qingyuan (north) respectively. In this study, urban residents were sampled from the biggest city in each survey region and rural residents were sampled from the countryside and villages in the region. Two urban districts and one rural county were sampled at random from the urban and rural areas of each selected region. One subdistrict from each sampled urban district and two townships from the sampled county were selected at random. The population of a typical subdistrict or township was between 15,000 and 50,000. In each subdistrict or to糧，around 100 subjects (male to female ratio was around 1:1) were recruited in each age group. Thus, around 400 subjects were recruited in each survey location and totally around 1,600 examinees in each age group.
Urban district 1
Urban district 2
Fig, 4-2, Sampling method of the Guangdong Oral Health Survey 1996-97.
4.2. Recruitment of subjects
With assistance from the Department of Public Health of Guangdong Province and the Sun Yat-sen University of Medical Sciences, relevant authorities in the survey sites were contacted before the fieldwork started. Meetings were held to disseminate the aims of the study, and the detailed plans for the fieldwork were introduced to the persons in charge. The Bureau of Public Health, neighborhood committee in urban areas and the township government in rural areas were usually very helpfUl in the recruitment of study subjects and the arrangement of logistics in the study.
The 35-44-year-olds in urban areas were mainly recruited from factories because manual workers constitute over 20% of the working population in the province and other occupation groups like professionals, technicians, clerical workers, and administrators can also be found in the factories. In each urban survey site, i f the number of the 35,44-year-olds found in a factory was not sufficient, other places of work， e.g. schools, government offices and commercial companies, were contacted to recruit more subjects. The 65-74-year-olds in the urban areas were recruited from their homes with the aid of neighborhood committees in the selected subdistricts. Administrators of the committee informed the resident elderly in the subdistrict of the survey and invited them to go to the examination venue which was usually set up at the neighborhood committee office or an elderly center.
Almost all of the study subjects in the rural areas were farmers or retired farmers, They were recruited from the villages where they lived with the aid of the local government. I f an audio amplifier system was available, it was used to broadcast
information concerning the survey and to invite the fanners in the selected age groups to attend an examination. Despite this， the most effective way to recruit subjects was when the leaders in the villages went to contact the villagers personally and to encourage them to participate in the survey. The examination site was usually set up in a convenient place in the village.
4.3. Fieldwork procedures
The main fieldwork procedures included registration of examinee， confirmation of correct age range, interview and clinical examination. One member in the survey did the registration. Questionnaires were filled out by interviewers during the face-to-face interviews. The completed questionnaires were checked by the examiners before clinical examination. After the clinical examination, a souvenir was given to each surveyed subject (Fig. 4-3).
4.3.1. Interview A structured questionnaire was developed especially for the interview in this study. The questionnaire included six sections: perceived oral health conditions, oral health knowledge, oral health attitudes, oral hygiene habits， use of dental services, and demographic background (Appendices 1 and 2). A pilot test was carried out on 2030 patients in each age group in a dental hospital in Guangzhou and amendments were made before the main survey.
Four questions (Q12 - Q15)， which were used in the 1991 Hong Kong Adult Oral Health Survey (Schwarz and Lo, 1994a)， were asked so as to measure the dental knowledge of the subjects. Two questions were on the causes and prevention methods of tooth decay and the another two were on gum disease. Up to three answers were accepted for each question. A knowledge score, ranging from 0 to 12， was computed for each subject according to how many answers he/she could give to these four questions in total. There were no directly wrong answers, but "no answer" and "do not know" were considered as an inability to answer the question, and were scored 0. Thus, the higher the knowledge score the more oral health knowledge was evident in the examinee.
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Eight statements (Q24) about the importance of oral health, importance of retaining natural teeth, dental service utilization, and dental health beliefs were set to explore the subjects, attitudes towards oral health. An attitude score， ranging from 0 to 8, was computed for each subject according to the number of positive responses to these eight statements. The higher the score, the more positive the examinee's attitude was considered.
Perceived oral health condition and perceived need for treatment were assessed by Q3 to Ql 1 in the questionnaire. Ql 1 was set to assess the problem of dentures worn by the subjects. Reported oral hygiene habits, includingfrequencyof toothbrushing， use of toothpaste, other methods used to clean teeth， and tobacco smoking were recorded during the interview (Q18 - Q23). Q25 to Q31 were set to explore the use of dental services by the subjects. One single question (Q32) was set to assess the subjects' dental fear (Neverlien, 1990).
The main demographic variables included gender, age， location of residence, education and economic status. Age was the age of the subjects at their last birthday in years. Education was measured as the educational level at which the respondent left the education system， e.g. no schooling, primary school， etc. Because reliable information about income was difficult to obtain， the "Family Material Possession Index" (FMPI) which had been previously used in Hong Kong (Ng, 1987; Schwarz " a / " 1994) was used to measure the economic status of the subjects surveyed. The FMPI score can range from 0 to 100 based on the subject's possession of 17 items of family commodities, e.g. television, air-conditioner, motorcycle, washing machine, etc. Each item is assigned a score according to its average price， rarity and quantity
in the households (Table 4-1). If a given commodity is not recorded, a zero score is returned. The total FMPI is the summation of the item scores. A higher score is taken as an expression of more material wealth of the subject.
Table 4-1- Calculation of family material possession index (FMPI)
Item Air-conditioner Washing machine High-fidelity sound system Video tape recorder Microw3V6 oven Water hester
C3mer3 Television Dish washer Personal computer Pi3n0 Bathtub Wooden floor Telephone Refrigerator Motorbicycle Laser displayer
Score for price Score for rarity 4 2 3 1 3 2 3 2 2 3 2 1 2 2 4 1 2 4 4 4 4 5 4 2 4 4 1 2 4 1 4 2 4 3
Score for extra quantity 1，2
Questionnaires were filled out by the interviewers during the face-toface interview. Because some of the subjects could only speak local dialects, interviewers were recruited from staff of the local hospitals or government offices who had at least secondary school education level. Three interviewers were employed in each survey site and they attended a 3-hour training session before they started work.
4.3丄 Clinical examination The clinical examination recorded tooth status, tooth-based treatment need, periodontal health status, prosthetic status and treatment needs， and oral mucosal lesions (Appendices 5 and 6). Oral mucosal lesions will not be reported in this thesis as they were not prevalent in the population studied. 45
The instruments, examination procedures, and diagnostic criteria recommended by the WHO (1997) were adopted. An over-head light, a mouth mirror and a Community Periodontal Index (CPI) probe were used during clinical examination. All the instruments used were sterilized using a portable autoclave. Even though some of the examination venues were indoors while some were outdoors, an overhead light was always used during clinical examinations. Portable chairs were carried to the survey sites so that the subjects could be examined in supine position and to increase standardized examination conditions overall. The order of the clinical examination was: tooth status and treatment needs, prosthetic status and treatment needs， oral mucosal lesions, CPI and loss of attachment (LOA). The diagnostic criteria used are described in the following paragraphs.
Both the status of the tooth crown and the root were primarily assessed by visual inspection and secondarily confirmed by tactile inspection using a WHO CPI probe. The teeth were neither cleaned nor dried before the assessment, but food debris obscuring visual inspection was removed by the probe. No radiographs were taken. Coronal caries was recorded as present when there was a cavity， undermined enamel， or a detectable softened floor or wall. A residual root left behind as a result of gross caries was scored as coronal caries only. Where any doubt existed， caries was not recorded as present. Root caries was recorded as present when a lesion located on the root surface or presumed to have commenced on the root surface felt soft with the probe. If it was not possible to judge the original site of a single carious lesion affecting both crown and root, both were recorded as present.
When calculating DMFT or DF-Root scores， only permanent restorations that were judged to be placed for caries treatment and with no decay were included in the Fcomponent. Teeth not present for any reason were included in the M-component The DF-Root score was computed by summing up the numbers of decayed root (DRoot) and filled root (F-Root).
Periodontal status was defined as being healthy, exhibiting bleeding on probing， having calculus， having shallow or having deep pockets. LOA was categoried by the amount of attachment loss. A CPI probe was used for the assessment of periodontal status and LOA. The recommended use of a sensing force with the CPI probe was practised by placing the probe tip under the thumb nail and pressing with a force until
(17， 16,11 ，26,27,37,36,31,46,47) for the six sextants were assessed for CPI and LOA. A sextant was examined only if there were two or more teeth present which were not indicated for extraction. I f no index teeth or tooth was present in a sextant qualifying for examination, all the remaining teeth in that sextant were examined and the highest score was recorded as the score for the sextant For the 65-74-year-olds, the periodontal status of all teeth not indicated for extraction was assessed. However, the calculation of CPI and LOA for this age group was still based on index teeth， according to the method described above. The prevalence of the highest CPI and LOA score， and mean number of sextants in each CPI and LOA category for the 3544-year-olds and the 63-74-year-olds were computed.
Teeth not present for any reason, were defined as missing teeth (MT)， including third molars. Loss of permanent teeth can result from one of two ways. Either the
progression of dental and periodontal diseases is such that teeth can be lost spontaneously or else teeth may be extracted by oral health care providers. The latter is closely linked to the provision of and access to dental care services. People living in developing countries, especially those living in rural areas, have less access to dental health care services than urban dwellers of those countries and less than those living in industrialized countries. Therefore, it is assumed this lack of access will result in more teeth which should be extracted still remaining in the mouth in these population. Some authors have mentioned the state of " teeth indicated for extraction" in developing countries when they described the condition of tooth loss (Ekanayaka, 1984; Manji " a/" 1988; Luan " a/" 1989b). According to WHO (1997) criteria, a tooth was indicated for extraction when caries had so destroyed the tooth that it could not be restored, when periodontal disease had progressed so far that the tooth could not be restored to a functional state in the clinical judgement of the examiner, when a tooth needed to be extracted to make way for a prosthesis, when extraction was required for orthodontic or cosmetic reasons or because of impaction. No recording was made of the reason for indicating a tooth as requiring extraction. For convenience of description, the teeth indicated for extraction were defined as "indicated missing teeth (IMT)". The adjusted missing teeth (AMT) therefore is the sum of MT plus IMT.
Prosthetic status was recorded for each subject by arch according to the criteria recommended by WHO (1997). This was classified as no prostheses, one bridge， two or more bridges, partial denture, bridge and partial denture, or complete denture. Only subjects who were wearing or who could show their dentures at the examination were recorded as denture wearers.
According to the recommendations by WHO (1997), examiners are encouraged to use their own clinical judgement when making decisions on what type of treatment would be most appropriate in the community or country. Tooth-based treatment need, e.g. filling and extraction, was determined tooth bytoothimmediately after the assessment of tooth status. The treatments considered included those relating to the removal of caries and restoration of lost tissue, endodontics, replacement of existing faulty restorations and extraction of the tooth or retained root Filling was indicated for cervical abrasion lesions that had extended to or beyond a depth of two millimeters. The assessment of prosthetic treatment need followed the assessment recommended by WHO and used the criteria that had been used in the 1991 Hong Kong Adult Oral Health Survey (Lo " a/" 1994). The need for fixed or removable dental prosthesis was not considered separately, instead whether the need was for a one-unit or a multiple-unit prosthesis was recorded. A prosthodontic treatment need was indicated for subjects without an existing prosthesis i f there were, or as indicated by assessed need for extraction there were going to be， fewer than 20 teeth (pontic of bridges being counted as teeth); i f there was tooth space anterior to the premolars; or if the existing prosthesis was assessed as in need of replacement.
The need for oral hygiene and periodontal care was derived from the CPI which was used to measure the periodontal status of the subjects. A subject would be assessed as not having any periodontal treatment need if the highest CPI score was zero or if he was， or as indicated by assessed need for extraction going to be， edentulous. If a subject had calculus on the index teeth or had periodontal pockets (CPI scores 2 and above), then he was assessed as having a need for scaling and instruction in oral
hygiene. Need for complex periodontal care was indicated for subjects who had probing depth of 6mm or more in any of the index teeth or their substitutes.
In addition, for an overview of the different types of treatment that the subjects needed, a holistic approach, similar to that used in the Hong Kong survey (Lo W a/.， 1994), was used to categorize the subjects into one of the following five groups according to the various combinations of normative treatment needs: 1) no need for any treatment; 2) dental prosthesis only; 3) scaling and oral hygiene instructions only; 4) simple treatments including scaling, filling, extraction and prosthesis but no complex care; and 5) involving endodontics or complex periodontal care.
All the clinical examinations were completed by one of three examiners. In addition to the present investigator, the other two examiners were recruited from Sun Yat-sen University of Medical Sciences in Guangzhou. They graduated from the university with a B.D.S. degree and had several years of experience in clinical work. There were two training and calibration exercises for the examiners, one prior to the fieldwork in 1996 and another prior to the fieldwork in 1997. Two epidemiologists and one periodontist were responsible for the training course. One in ten subjects were reexamined by another examiner throughout the survey. The results of these duplication examinations were used to monitor and assess the inter-examiner reliability.
4.4. Testing of water fluoride level in survey sites
Two to three samples of community water were taken from each survey site to assess the fluoride concentration. Water samples were taken from tap water in urban areas and in the rural areas both tap water and well water samples were taken. The tests were performed in the University of Hong Kong using Benchtop PH/ISE Meter (Model 920A) (Orion Research Incorporated, 1992) and Fluoride/combination fluoride Electrode (Model 96-09) (Orion Research Incorporated, 1991).
Most of the samples taken contained less than 0.4 ppm offluoride.Three samples of well water from villages of two townships contained more than 1 ppm of fluoride. However， we were informed by the local Public Health Bureau that the people in these villages had stopped using the well water and changed to tap water several years ago due to the high fluoride level. Because the fluoride level was generally low in the survey sites and people used different resources of water in rural areas， fluoride level was not used as an independent variable of dental caries in data analysis.
4.5. Data processing and analyses
Data collected were input into computer and were processed using the software Access 2.0. All data input was done by one person in Guangzhou simutaneously as data collection went on. Acceptable and unacceptable values were predefined in the Access databases to avoid or to identify possible errors arising from data entry or recording. After all data were input， proof-reading was performed by the same person. A logistic check was performed before data analyses. When errors were found, original forms were inspected to correct the errors. After data cleaning was completed, 1% of the questionnaires and clinical record forms were checked and 0.1% of the questionnaires and 0.04% of the clinical record form entries were found to be wrong. These error levels were considered to be acceptable.
Data analyses were mainly performed using SPSS for Windows. Multiple comparison following the analysis of covariance (ANCOVA) was performed using SAS for Windows.
Variables obtained from interview and clinical examination are listed in Table 4-2 and Table 4-3 respectively. Some categorical variables were regrouped in consideration of thefrequencydistribution and the need of data analyses to explore the meanings of the data.
Table 4-2. Variables from questionnaire and their grouping or scoring used in data analyses Variable
Grouping / scoring
Education level (for 35-44-year-olds)
no schooling/primary, secondary, post-secondary
Education level (for 65-74-year-olds)
no schooling, primary, secondary and above
Perceived appearance of teeth
satisfied, no comment, not satisfied
Perceived condition of teeth
Good / no comment' bad
Teeth caused pain
Perceived need for treatment
yes, no / do not know
smoker/former smoker, nonsmoker
Receipt of dental education
once or less daily, twice or more daily
Use of toothpaste
Toothpaste contain fluoride
yes, no, do not know
Use of toothpicks
Time lapsed since last dental visit
< 2years， 2-5 years, > 5 years
examination, scaling, fi川ng, extraction, fixed prosthesis, dentures, others
Reasons not visit dentist within 3 years
no need, problem not serious, could not afford, too busy, afraid of dentist, others
Dental knowledge score
Dental attitude score
Table 4-3. Variables from clinical examination and their grouping or scoring used in data 3n3lys6s. Variable
Missing teeth (MT)
Indicated missing teeth (IMT)
Adjusted missing teeth (AMT)
no bleeding, bleeding, calculus, shallow pocket, deep pocket
Loss of attachment (LOA)
0-3 mm, 4-5 mm, 6-8 mm, 9-11 mm, 12+ mm
no prostheses, bridge, partial denture, full denture
Prosthetic treatment need
no prosthesis needed, 1-unit prosthesis, 2+-units prosthesis, complete denture
Holistic treatment need
No need, prosthesis only,〇HI and scaling only, Simple treatment, complex care
Cohen, s kappa (Landis and Koch, 1977) was used to measure the reliability between examiners. Because the variables evaluated were nominal data， e.g. crown caries and CPI, unweighted kappa was chosen (Bulman and Osborn, 1989). After getting the frequency counts of the reproducibility data using SPSS for Windows， kappa statistics were calculated using Excel for Windows. The calculation of kappa statistics for crown and root caries was made on the original categories recorded.
The guide for data analysis was similar to the model used in the Second International Collaborative Study (Chen " a/" 1997). The model postulates that system-level variables, socioenviro腿ental characteristics and oral health care system， together with personal predisposing and enabling characteristics will affect an individual's oral health behaviour and consequently oral health status. Predisposing variables, such as gender， education level, oral health knowledge
predispose an individual to engage or not engage in certain oral health behaviour, while enabling variables, such as income， might facilitate or impede the individual's practice of such behaviour. However, system-level variables were not used in this study because basically the same social, economic and oral health care systems were in operation in all survey sites and age groups. In this simplified model， it was postulated that an individual's oral health behaviour was influenced by his or her predisposing and enabling characteristics. This would in turn, together with the predisposing and enabling factors, affect the oral health status of the individual. The variables and their classification used in this study axe shown in Table 4-4.
Table 4-4. Analytic model for the study indicating the incorporated variables. Predisposing factors
Enabling factors Behaviour factors
Oral health status (Outcome factors)
Oral hygiene practices
Location of residency
Use of dental service
Dental knowledge score
Loss of attachment
Dental attitudes score
Teeth cause pain Perceived condition of teeth Perceived need for treatment
T-test and analysis of variance (ANOVA) were performed to highlight the possible differences in continuous variables between (or among) groups. Chi-square test was performed to study whether the difference in distribution of categorical variables between (or among) groups were statistically significant. Pearson, s correlation coefficient was calculated to detect a possible relationship between two continuous variables. Spearman,s correlation
relationship between two categorical variables.
was calculated to detect the
Logistic regression analysis was performed to determine factors which affected toothbrushing frequency, and factors which affected recent use (within 2 years) of dental services in the 35-44-year-olds and the 65-74-year-olds. Similar to the linear regression analysis, logistic regression analysis is used to study how the dependent variable is affected by a set of independent variables. Logistic regression analysis is appropriate when the dependent variable is dichotomous (Lindsey, 1995a). Location, gender, education level, dental knowledge score， dental attitude score, and FMPI were selected as possible factors influencing toothbrushing frequency. Location, gender, education level, perceived dental conditions, toothbrushing frequency, dental fear, teeth caused pain， perceived need for treatment, dental knowledge score， dental attitude score, and FMPI were selected as possible factors influencing recent use of dental services.
Analysis of covariance (ANCOVA) was performed to determine the factors affecting dental knowledge score， dental attitude score, DMFT， and AMT in the 3544-year-olds and 65-74-year"olds. The ANCOVA analysis is actually equivalent to a multiple linear regression analysis where the categorical independent variables are represented by indicator variables (dummy variable) (Lindsey, 1995b). However， the use of ANCOVA prevented the creation of indicator variables in the present study since most of the independent variables involved in the multivariate analysis were categorical. The dependent variables and corresponding independent variables for the ANCOVA analysis are listed in Table 4-5.
Following each ANCOVA analysis, multiple comparison analysis was performed to investigate the difference between groups of categorical variables. In the present
study, Bonferroni，s method, Tukey,s method as well as Schefffs methods for multiple comparison were all performed and the one with narrowest confidence interval was chosen. This method is proper since it does not depend on the observed data (Netere/^/.， 1990).
Table 4-5. Variables used in the analysis of covariance for knowledge score, attitude score, DMFT， and AMT in the 35-44-year-olds and 65,74-year-olds. Dependent variables Independent variables Dental knowledge score Location, gender, education level, receipt of dental education, FMPI Dental attitude score
Lx)cation， gender, education level, dentel knowledge score, FMPI
Location, gender, education level, toothbrushing frequency, dental fear, time lapsed since last dental visit, FMPI， dental knowledge score, dental attitude score
Location, education level, toothbrushing frequency, tobbaco smoking, dental fear, time lapsed since last dental visit, FMPI, dental knowledge score, dental attitude score
5. RESULTS 5丄Background of study population
A total of 3,088 adults， 1,573 3544-year-olds and 1,515 65-74-year-olds， were surveyed in this study. Sample size according to age group, gender and residence is shown in Table 5-1. Selected demographic characteristics of the subjects are shown in Table 5-2. The male to female ratio was around 1:1 which was similar to the situation in the province. The urban to rural resident ratio was around 1:1 in this study but the ratio in the province in 1995 was 1:2.3 (Guangdong Statistical Bureau, 1996). Almost half of the 65-74-year備olds had not attended schools. The finding that the 3 5-44-year-olds had higher education level than the 65-74»year-olds was in accordance with the situation in the province. Data from the Population Census Office of Guangdong Province (1992) showed that 8°/o of the 3 5-3 9»year-olds and 60% of the 65+ year-olds had no schooling. The occupations recorded for the retired 65-74-year-olds were their reported former occupation before they retired. Two major occupation groups, agricultural workers and manual workers constituted 41% and 18% of the 35-44-year-old and 50% and 23% of the 65-74-year-old subjects respectively, compared to 60^o and 22% in the province (Population Census Office of Guangdong Province, 1992),
Table 5-1. Sample size according to age group, gender and location. 35-44-year-olds Urban
Table 5-2. Selected demographic characteristics of the subjects (percentage) Guangdong
(6 years and above) 15
Legislator & administrator
Professionals & technician
D e 他 l knowledge score
/ C D "S CO CD to CD < CO
s z 0 一q ws JL
c CD 2
90 80 70 60 50
30 20 •''《"
Fig* 5-3. Proportions of FT and DT in DFT according to gender and location of residency in 35"44-year-olds and the 65-74-year-olds.
Statistically significant differences (p 5 ，rs/nonuser
Satisfied / no comment Not satisfied Good / no comment
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