Effect of impression disinfection on the wettability of ...

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siloxanes, polyether, polysulfide, and reversible hydrocolloid impression ... polyvinyl siloxane was significantly higher than that of the polyvinyl siloxane and ...
Effect of impression disinfection on the wettability of the impression and surface profilometry of model material (In vitro) ‫تأثير تطهير مواد الطبعة السنية على قابلية ابتالل الطبعة و خصائص السطح لمواد النماذج‬

Research project Submitted to the faculty of oral and dental medicine, Cairo University in partial fulfillment of the requirements for master degree in fixed prosthodontics (Goal5-ObjectiveB)

Noha Khaled Abdel Kader Eid B.D.S,6 October University (2010)

Faculty of oral and dental medicine Cairo University 2014 1

Introduction:

Dental professionals are predisposed to numerous occupational hazards. One among them is the infectious hazard through exposure to dental impressions. (1) After removal from the patient’s mouth, dental impressions are washed under tap water to get rid of saliva and blood which does not guarantee complete removal of micro-organisms. Therefore disinfection of dental impressions is a very important step to prevent cross contamination. (2, 3) The American Dental Association (ADA) and Center for Disease Control (CDC) have recommended disinfection of impressions immediately after removal from the mouth. (4,5) This prevent the transmission infectious diseases such as staphylococcal infections, hepatitis A, B, C, tuberculosis (TB), herpes and acquired immune deficiency syndrome from the patient to the dentist and lab technician .(2,6) Therefore, all dentists should be encouraged to disinfect impression materials as a routine procedure for infection control procedure. Elimination of most pathogenic microorganisms on impressions can be achieved by either physical and\or chemical methods.

Rational: Gypsum products are widely used as materials for the preparation of models in dentistry. Dental casts are transferred several times between the dental laboratory and the dental office. The potential contamination of these models by infectious human pathogens. It has been established that bacteria and viruses can be transmitted from patients to the gypsum models during the fabrication of the prosthesis, if the plaster is poured into contaminated impressions or through contamination of bite blocks and trial bases. However, an undesirable side effect of disinfection process is the potential for a change in the properties of the impression materials and dental stone either due to a chemical or physicchemical interaction between the set material and the disinfecting solution.(7) The disinfection agents can interfere in the chemistry of the setting reaction of the gypsum products, consequently altering their physical properties.

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The expected benefits of the study for the patient includes: Accurate reproduction of the prepared tooth is of clinical importance in the fabrication of fixed prosthesis because any inaccuracy in the replication process will ultimately have an adverse effect on the fit and adaption of final restoration in the patient mouth.

The expected benefits of the study for the clinician includes: Within these reactions, the surface hardness is of great influence in laboratories. Hardness prevents degradation during the wax sculptures, which requires cutting with sharp instruments. One of the important properties of impression materials is the wettability . It affects the number or volume of air bubbles generated during the pouring of gypsum casts, which finally affect the restoration quality. The interaction is determined by the hydrophilic or hydrophobic nature of elastomeric impression materials. The impression material should possess surface properties that allow it to be easily wet by a standard mix of gypsum. Inadequate wetting of an impression results in incorporation of air bubbles and voids in the casts which are often located in critical area of preparation such as margins and retentive grooves. Which makes the die stone cast unacceptable for further use.

Objective: The fit and ultimate clinical success of cast dental restorations are dependent upon the accuracy and completeness of the die reproduction, and upon the durability of the resultant die, which is subject to possible deformation during the fabrication of the pattern used to construct a cast restoration.

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Data base and search strategy Data sources: A search was conducted using MEDLINE\PubMed databases and other scholarly research bibliographic database using Medical Subject Headings (MeSH) .

The key words and synonymous: Impression materials, disinfection , disinfectant materials, wettability, surface hardness, surface roughness, surface profilometry , die materials , contact angle, depression, printing process, stamp, imprint , sterilization, sanitization, germicide, antimicrobial, severeness, stiffness, ruggedness, callosity, rigor, pitting, indentation, raggedness, disorderliness, crudeness, dice.

Inclusion and exclision criteria: Inclusion criteria

Exclusion criteria

1- Immersion disinfection.

1-Spray disinfection.

2- Surface hardness.

2-Microwave disinfection.

3- Surface roughness.

3-Dimensional stability.

4- English language.

4-Diminsional accuracy.

5- Depression.

5- Non elastic impression material.

6- Indentation.

6-Hydrocolloid impression material.

7- Surface wettability 8- Contact angle. 9- Die materials. 10- Date of articles from 1990 to 2013.

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Review of literature The different disinfection techniques may affect dental impressions as a function of altering the surface properties of the treated impressions. Pratten et al. 1990, evaluated the effect of various commercial disinfectant solutions on the wettability of four types of elastomeric impression material(Polysulfide, polyether, addition silicone and hydrophilic addition silicone). Disinfectant solutions used: alkaline glutaraldehyde (AL), acid glutaraldehyde (AC), chlorine dioxide (CD), iodophor (IO) and sodium hypochlorite (SH). Each type of impression material were immersed in the disinfectants for ten, thirty and sixty minutes.CD brought the greatest change of -48 degrees for polysulfide after sixty minutes.SH produced the greatest positive change in contact angle only on addition silicone and it was statistically significant at thirty and sixty minutes intervals. They found that the additional silicone was the material the most resistant to change in contact angle and that chlorine dioxide had the greatest beneficial effect on wettability.(7) Ragain et al. 2000, compared surface detail parameters, interfacial contact angles, and die hardness for some combinations of elastomeric impression and die materials. Polyvinyl siloxanes, polyether, polysulfide, and reversible hydrocolloid impression materials and Type IV, Type V, and resin reinforced–Type IV die materials were evaluated. For the evaluation of surface detail reproduction, the width of the thinnest continuous line observed and the visually observed shape of the thick line were determined from samples formed using a master die conforming to American Dental Association specification nineteen. The contact angle of freshly mixed die material on the set impression was measured using a contact angle goniometer. They concluded that the mean surface hardness of the Type IV die stone specimens formed against polyvinyl siloxane was significantly higher than that of the polyvinyl siloxane and Type IV–resin combination, and the polyether and Type IV stone combination was significantly higher in mean hardness than the polyether and Type IV–resin combination. For both contact angleand die hardness, a statistically significant interaction between the impression and die materials was found.(8) Kess et al. 2000, compared the effects of six treatment regimes(Control, saliva, saliva and sodium hypochlorite,saliva and two propanol based disinfectant, saliva, sodium hypochlorite and surfactant), saliva, two propanol based disinfectant and surfactant) on the hydrophilicity of three polyvinyl siloxane (VPS) materials (Dimension Garant L, Hydroflex and Imprint II) . They concluded that for all materials, treatments that included surfactants were among the groups with the lowest contact angle (θA )values and thus had the best wettability.(9)

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Milward et al. 2001, evaluated the effect of disinfection procedures and the use of a surface wetting agent on the wettability of four addition-polymerized silicone impression materials.They found that treatment with Actichlor (ten minute soak), Actichlor (ten minute soak) and Vacufilm,and Perform (ten minute soak) and Vacufilm had no significant effect on the wettability of the materials.While treatment with Vacufilm significantly reduced the contact angle for light-bodied President range 74.48◦±0.69◦ and Aquasil range 70.02◦±1.55◦. But treatment with Perform (ten minute-soak), significantly increased the contact angle for light range 86.77◦±4.43◦ and medium-bodied Extrude range 90.41◦±1.63◦ and Aquasil range 84.67◦±00.80◦.(10) Pasini et al. 2002, evaluated the dimensional change of two elastomers immersed into different disinfectant solutions and the Rockwell hardness of the stone cast after contact with the disinfected impression. They concluded that there was no statistically significant difference (p