The International Journal of Periodontics & Restorative Dentistry

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Currently there are many different ceramic systems that can be used to achieve highly esthetic results. ... School of Dental Medicine, Boston, Massachusetts; Clinical Associate, Department of ..... sion, a 25,000-lux fiber optic (Sirona. Dental ...

The International Journal of Periodontics & Restorative Dentistry COPYRIGHT © 2005 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

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Optical Behavior of Current Ceramic Systems

Nicolas V. Raptis, DDS* Konstantinos X. Michalakis, DDS, PhD** Hiroshi Hirayama, DDS, DMD, MS***

The restoration of anterior teeth is a difficult task, even for an experienced operator. Currently there are many different ceramic systems that can be used to achieve highly esthetic results. These include metal-ceramics with porcelain margins, Dicor, In-Ceram, Cerestore, Hi-Ceram, IPS-Empress, Cerapearl, Optec, and CAD/CAM ceramics. While metal-ceramics have been used for more than four decades, the quest for a material that transmits and refracts light like a natural tooth has inspired research into all-ceramic restorations. The purpose of this paper is to briefly discuss the properties of each of the above-mentioned materials and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins; (2) InCeram Spinell restorations; and (3) IPS Empress restorations, and to compare these with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins. Light transmission characteristics and color matching were subjectively evaluated by five experienced prosthodontists who did not participate in this clinical study. (Int J Periodontics Restorative Dent 2006;26:31–41.)

*Private Practice in Prosthodontics, Athens, Greece. **Visiting Assistant Professor, Division of Postgraduate Prosthodontics, Tufts University, School of Dental Medicine, Boston, Massachusetts; Clinical Associate, Department of Fixed Prosthodontics, Aristotle University, Thessaloniki, Greece; Private Practice in Prosthodontics, Thessaloniki, Greece. ***Professor, Director of Graduate and Postgraduate Prosthodontics, Tufts University, School of Dental Medicine, Boston, Massachusetts. Correspondence to: Konstantinos X. Michalakis, 3, Greg. Palama str., Thessaloniki 546 22, Greece; fax: +30-2310-272-228; e-mail: [email protected].

In the last 15 years, there have been amazing developments in the field of new esthetic ceramic materials for dental prostheses.1–3 At the same time, various new techniques have been developed to accompany these new materials. However, the precise imitation of the beauty and characteristics of natural teeth remains a particularly complex and difficult procedure, both in the clinic and the laboratory. The shade and color of a tooth is influenced by several factors, such as4: (1) the spectral energy distribution of the light source, (2) the sensitivity of the observer’s eye, and (3) the tooth’s spectral characteristics in respect to light absorption, reflection, and transmission. It is clear that the fabrication of an ideal, natural-looking restoration requires not only the matching of the color components of hue, value, and chroma, but also the blending of the specific characteristics of the adjacent teeth.5 The total optical behavior of the restoration needs to be similar to that of the natural structure. The same deep translucency found in a natural tooth has to be provided to the restorations by controlling the light absorption,

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reflection, and transmission in the ceramic material. At the same time, the optical phenomena of opalescence and fluorescence that characterize natural tooth structure under certain lighting conditions must also be present in ceramic restorations. 6

Optical behavior of natural teeth

Fig 1 Slice of a natural tooth demonstrating light transmission through enamel, dentin, and cementum.

The optical behavior of a tooth is the outcome of the spectral characteristics of the varying structures by which it is formed.7 Enamel is very translucent and might transmit up to 70% of light through a section that is 1 mm thick. Approximately 97% of human enamel mass consists of mineral matter, mostly in the form of hydroxyapatite, whereas only 70% of dentin consists of hydroxyapatite. Dentin is less translucent than enamel and can transmit up to 30% of light through a 1-mm-thick section (Fig 1). As the light hits the tooth, some part of it is reflected on the enamel surface and produces the perception of luster and irregularities. The rest of the light enters the enamel surface and is subject to partial diffusion and scattering caused by the presence of fine hydroxyapatite crystals in the enamel. When the light reaches the dentinoenamel junction and the dentin, it is either diffused or reflected back to the enamel. The tooth is therefore semitranslucent. Dentin is the primary source of color, and the internally reflected rays of light are emitted through the enamel and modified by its thickness.8

Modern dental porcelains display varying degrees of translucency. They are manufactured by the addition of opaque materials to the matrix, and their refractive indices differ from those of feldspathic glass. Their volumetric content and, more recently, their size, can be balanced to simulate the different natural tooth structures quite successfully.9,10

Opalescence Opalescence is the term given to substances that exhibit properties similar to those of opal stone when subjected to transmitted and reflected light. In reflected light, an opal has a blue appearance, because most of the short wavelength is reflected back. However, when it is trans-illuminated, an opal will appear reddish to orange, depending on the angle of observation.11 This is a result of the light-scattering properties of the opal stone. This phenomenon is also found in the natural dentition. The incisal edge of a natural tooth develops a blue translucency when viewed under reflected light. Under transmitted light, the overall shade changes to reddish and orange. This optical effect is a result of the scattering of light by the hydroxyapatite crystals, which are smaller than the wavelength of the visible ray. Opalescence in dental ceramics is accomplished by the incorporation of fine-particle refraction oxides into the glass matrix. These particles need to be smaller than the wavelength of the light. The differing refractive indices of these particles and the feldspathic matrix causes the opal effect.12

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Fluorescence Natural teeth have the ability to fluoresce under ultraviolet radiation. This is particularly noticeable in nightclubs, where there are lamps that emit the blue end of the spectrum in addition to some ultraviolet radiation. This property makes teeth look whiter and brighter in the daylight. According to Clark,13 it is this fluorescence, which seems to come from inside, that gives natural teeth their living aspect. It is thought that the “fluors”— the compounds that cause fluorescence in natural teeth—are proteins. Moreover, it is proven that part of the inorganic matrix of teeth is also fluorescent, since even after inactivation of the protein by heat, teeth still exhibit fluorescent properties when subjected to ultraviolet radiation. Natural teeth fluoresce in both sunlight and in the lighting of nightclubs. Dental porcelain should therefore include substances that can make the ceramic material simulate this fluorescent property of the human tooth4 (Fig 2). Rare earths, such as europium, terbium, cerium, and ytterbium, are currently used as luminophores to provide ceramic materials with fluorescence. Vita Zahnfabrik has formulated special high-fluorescent ceramics called luminaries. These materials can be used as optical brighteners for the built-up porcelain in all-ceramic restorations. They can optimize the light distribution in the gingival and cervical area. Illumination of the gingiva can be improved by controlled use of fluorescence in luminaries, permitting the transmission of light from the crown to

Fig 2

Fluorescence of ceramic restorations when subject to ultraviolet radiation.

the overlying tissue, thus creating a natural and pleasing illusion.

Review of current ceramic systems It can be said that, after all the improvements made by manufacturers, dental porcelain can simulate the natural dental structures quite satisfactorily.14 However, problems arise from the fact that a substructure is necessary to reinforce the naturally brittle ceramic material.

Porcelain-fused-to-metal restorations Porcelain-fused-to-metal (PFM) restorations are the most effective and

widely used system in dental ceramics. They combine the strength of metal with the esthetic quality of the ceramic materials. The big disadvantage of this type of restoration lies in the increased light reflectivity from the opaque porcelains that are used to mask the metal coping. A natural tooth diffuses and transmits light, whereas a PFM restoration violates this property. It will only diffuse and reflect the light in the body area. As a result, PFM restorations often look brighter in the mouth.15 To reduce this reflectivity, dental material companies manufacture more opaque body porcelains with less light transmission than those produced for all-ceramic crowns. Unfortunately, an increase of the opacity in dentin porcelains will also cause an increase in reflectivity of the body porcelain itself.

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This is the reason why metal-ceramics tend to look less vital, with less depth of translucency, than natural teeth. The area where this problem of reflectivity becomes more severe is the cervical third of the restoration, because the porcelain becomes thinner in this section.16 Another problem encountered is a light gray discoloration that often occurs at the adjacent gingival tissues as a result of the reflection of light meeting the opaque substrate of the PFM restoration. In 1977 Sozio17 introduced the collarless PFM restoration to avoid the unpleasant “gray line” effect. But even when a porcelain labial margin is used, light is blocked between the root and the margin, resulting in a blue/gray shadow. For this reason, techniques for further reduction of the metal coping at the axial wall were suggested. In 1979 Vryonis18 developed an improved technique, with a larger reduction at the shoulder that was extended up to the axial wall by 0.4 mm. However, it became necessary to apply opaque to the apical margin of the metal to avoid the transmission of grayish shadows through the porcelain margin. This procedure left only a 0.2-mm depth for the margin material, which is considered insufficient for an esthetic result. However, light transmission properties from the coronal aspect of the tooth to the root were minimally improved over the conventional ceramic margin design. The quest for improved esthetics led to a further reduction of metal copings up to 3 mm short of the shoulder preparation.19 This technique represents the fullest extent by which the

casting can be reduced. However, this procedure is very time consuming, as the achievement of a clinically acceptable marginal fit often requires up to four or five porcelain margin firings. With this technique, both a diffuse transmission of the light from the crown to the root, as well as a reduction of the unesthetic grayish shadow, can be achieved.

All-ceramic restorations Research on porcelain over the last 30 years has produced many reinforced all-ceramic systems.20–23 Castable glass,24,25 heat-pressed ceramics,26,27 higher-strength core materials,28,29 and high-strength veneering porcelains have become valuable tools in the hands of clinicians and technicians, allowing previously unknown versatility. The absence of the metal framework in all-ceramic restorations minimizes the undesirable light reflection produced by the opaque layer. The veneer porcelains are more translucent compared to those formulated for PFM restorations. Therefore, increased light transmission and diffusion can be achieved, resulting in translucency with depth (Fig 3). The overall optical behavior of a permanently cemented all-ceramic restoration is dependent on three factors: (1) the underlying tooth structure, (2) the luting agent, and (3) the structure of the ceramic material. Underlying tooth structure Because of the increased light transmission of all-ceramic restorations, there is an influence from the underly-

ing tooth structure, whether normal, discolored, or treated with a post-andcore or a buildup. The recent technologies of ceramic, zirconium, and fiber-reinforced posts offer new possibilities and new restorative solutions to that aspect.30,31 Luting agent As early as 1933, Clark32 addressed the importance of the color of the luting medium in all-ceramic restorations. The extent to which the color of the luting agent could influence the overall result was estimated to be 10% to 15% by Touati et al in 1993.33 A 1996 study by Paul et al34 questioned these results and concluded that the influence of the luting agent is less than 5%. Therefore, varying changes in hue with light-transmitting composite luting agents are practically impossible. For this reason, the authors recommended the use of one rather translucent luting agent for all-ceramic restorations instead of working with multiple color variations. Structure of the ceramic material All-ceramic systems can be classified according to their optical behavior into semiopaque or semitranslucent.11 • Semiopaque systems. These include the aluminous porcelain jacket crown, Cerestore (Dentsply/Ceramco), HiCeram (HiCeram Dental Laboratories), and In-Ceram Alumina (Vita Zahnfabrik). These systems have all semiopaque cores, which provide strength and allow for partial light transmission at the same time. In-Ceram is the most fre-

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Fig 3 In an all-ceramic restoration, incidental light is transmitted and partially diffused through. On the other hand, when entering a PFM restoration, light is primarily reflected.

quently used semiopaque allceramic system today. The core is opaque and consists of aluminum oxide with a refractive index of 1.8 and feldspathic glass matrix with a refractive index of 1.5. There is no significant difference between these two refractive indices. This combination permits some diffusion of light into the core porcelain. A layer that is just 1 mm thick allows light to penetrate as much as 20%. • Semitranslucent systems. Dicor (Dentsply), Willi’s Glass crown (Geller WK), CeraPearl (Kyocera), Optec (Jeneric/Pentron), IPS Empress (Ivoclar Vivadent), and InCeram Spinell (Vita Zahnfabrik) are all examples of semitranslucent systems. Cast glass-ceramic systems can be taken to a point of crystallization where translucency is maximal. The IPS Empress System rep-

Fig 4 Metal–acrylic resin crowns on the right lateral and central incisors.

resents the most frequently used system of this category, with a heatpressed core that has superior light transmission.35,36 Vita has developed the In-Ceram Spinell system, which consists of a semitranslucent core of magnesium oxide and aluminum oxide over which a feldspathic porcelain (Vita-Dur) is applied.37

2 mm short of the shoulder preparation and 360-degree porcelain margins, (2) In-Ceram Spinell restorations, and (3) IPS Empress restorations. These were compared with metal-ceramic crowns with copings to the shoulder preparation and 180-degree porcelain margins (control).

Methods and materials All-ceramic crowns have set a standard that is difficult to be matched by PFM restorations because of the former’s increased light transmission and overall esthetic result. However, with so many all-ceramic systems available on the dental market, practitioners face the question as to which system to use. The purpose of this paper was to briefly review the esthetic properties of some all-ceramic systems and clinically evaluate the optical behavior of: (1) metal-ceramic crowns with castings

A young woman who needed two new restorations for the maxillary right central and lateral incisors was chosen for the purpose of this study. The patient originally had metal– acrylic resin crowns that needed to be changed because of unsatisfactory esthetics. Both teeth were vital (Fig 4). The patient was informed about and consented to the fabrication of four different sets of restorations.

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Clinical and laboratory procedures The old crowns were removed, and the maxillary right incisors were re-prepared to accommodate the construction of all-ceramic crowns. A welldefined 360-degree shoulder was prepared with a 1.5-mm labial and lingual reduction and a 0.5-mm proximal reduction. Incisally, the teeth were prepared by 2.0 mm, while facially and lingually the preparation was 1.5 mm, when compared with the maxillary left incisors. A well-defined shoulder preparation was preferred because it was believed to improve the fracture resistance of all-ceramic crowns. Impressions of the prepared teeth were taken using Impregum Penta (3M/ESPE Dental Products) polyether impression material. Master casts were fabricated using GC Fujirock EP type 4 dental stone (GC Europe). The construction of the crowns continued as follows: 1. Fabrication of metal-ceramic crowns with copings to the shoulder preparation and facial porcelain margins (control). Two layers of die spacer (Belle de St Claire, Kerr Labs) were applied on the dies, and wax patterns were constructed. Castings were performed using gold-palladium-indium (50.5%-38%-7%) metal-ceramic alloy (Olympia, Jelenko). The metal was reduced to expose the 360-degree shoulder. Porcelain (Willi Geller Creation, Klema) application followed.

2. Fabrication of metal-ceramic crowns with castings 2 mm short of the shoulder preparation and 360-degree porcelain margins. The laboratory procedure was the same as that mentioned previously, but the castings were reduced axially 2 mm off the shoulder preparation. 3. Fabrication of In-Ceram Spinell restorations. The laboratory procedure consisted of application of the slip on a special plaster die, sintering firing at 1,100°C in Vita In-Ceramat fur nace (Vita Zahnfabrik), glass infiltration of the Vita In-Ceram Alumina coping, and application of Vitadur Alpha porcelain. 4. Fabrication of IPS Empress restorations. Wax patterns were constructed on the dies with organic wax (SU Esthetic wax, Schuler Dental) and were later invested with the special investment (Schuler Dental). The leucite-reinforced ceramic was heat pressed into the mold using the IPS Empress 500 special furnace (Ivoclar). Low-fusing IPS Empress porcelain (Ivoclar) was later applied at the copings (Fig 5).

Preparation for esthetic comparisons For the evaluation of light transmission, a 25,000-lux fiber optic (Sirona Dental Systems) was placed on the cingulum of the restorations 2 mm below the palatal gingival margin. Photo slides were taken using 400-ASA film (Elite Chrome, Eastman Kodak) and a Nikon FG camera with a Vivitar macro lens and a Kenko 2 conversion lens. The camera was fixed on a tripod. No flash was used (Figs 6 to 10). Photo slides were also taken using 100-ASA film (Elite Chrome, Eastman Kodak). The camera’s settings were the same for all pictures. These slides were used for the clinical evaluation of color matching of the restorations (Figs 11 to 14). Light transmission and color matching were evaluated by five experienced prosthodontists who didn’t participate in this study. The examiners were shown both the clinical and the light transmission slides in random order. The prosthodontists who judged the light transmission and the color matching were asked to compare only the two central incisors.

The all-ceramic crowns were filled with water-soluble try-in paste (Choice, Bisco) and placed on the prepared teeth.

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Fig 5 (left) The four different restorations fabricated for the study. Fig 6 (right) The two PFM and two allceramic restorations illuminated with fiber optics.

Figs 7 to 10 Fiber optics are used to illuminate the restorations on the right central incisor.

Fig 7 (left) PFM restoration with 180degree porcelain margin. Fig 8 (right) PFM restoration with 2-mm off-the-shoulder short coping and 360degree porcelain margin. Fig 9 (left)

In-Ceram Spinell restoration.

Fig 10 (right)

IPS Empress restoration.

Figs 11 to 14 Clinical photographs taken of the restorations on the right central incisor for color matching purposes.

Fig 11 (left) PFM restoration with 180degree porcelain margin. Fig 12 (right) PFM restoration with 2-mm off-the-shoulder short coping and 360degree porcelain margin. Fig 13 (left) Fig 14 (right)

In-Ceram Spinell restoration. IPS Empress restoration.

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Clinical evaluation All five examiners agreed that: 1. The PFM restoration with a facial porcelain margin did not allow light transmission in the gingival and the central portion of the crown. 2. PFM restoration with a short coping and 360-degree porcelain margin permitted light transmission through the gingival but not the middle part of the tooth. 3. In-Ceram Spinell allowed much better light transmission than the PFM restorations. 4. IPS Empress revealed superior light transmission properties in comparison with the PFM crowns. However, there was no significant difference in comparison to the InCeram Spinell restoration. Regarding the reflection and the refraction of incidental light and color matching with the adjacent central incisor, all five examiners agreed that: 1. IPS Empress best resembled the adjacent tooth. 2. The PFM restoration with a facial porcelain margin presented more reflection than the rest of the restorations, and as a result appeared brighter than the left central incisor.

Four of the five prosthodontists believed that In-Ceram Spinell presented better reflection and refraction characteristics, as well as color-matching properties, than the PFM restoration with a short coping and 360degree porcelain margin. One of the examiners stated that there was no difference between In-Ceram Spinell and PFM restoration with a short coping and 360-degree porcelain margin.

Discussion PFM restorations have a long history of clinical success because they combine good esthetic results and inherent strength. Their major esthetic problem stems from the mirror and diffusive reflections of incidental light. Another major drawback of these restorations is the grayish color that is often observed at the adjacent gingival margin. Clinicians have tried to correct this fault with the use of the facial porcelain butt, which has partially improved esthetic results. However, in these restorations the light is still reflected as it reaches the lingual metal margin. As a result, this area is always brighter than in natural teeth. As shown by this clinical study, PFM restorations with facial porcelain margin do not permit light transmission through the middle and the gingival parts of the crown. This results in high direct and diffusive reflection, which is not observed in natural teeth.

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A technically demanding modification of the previously described restoration consists of a circumferential porcelain margin to overcome the esthetic problems associated with it. The extension of the porcelain margin to the lingual aspect of the tooth was made to improve light transmission and give the perception of depth in this esthetically demanding area of the restoration. The PFM restoration with a short coping and 360-degree porcelain margin, fabricated for the purposes of this study, demonstrated superior optical behavior when compared to the crown with a facial porcelain butt. Cervical depth transillumination was the main characteristic of this restoration, which competed successfully against the all-ceramic crowns. In-Ceram Spinell consists of a magnesium aluminate spinel and glass. The substitution of aluminum oxide found in the In-Ceram Alumina with magnesium aluminate decreases the inherent strength but increases the translucency of this restoration because it provides isotropic optical qualities and a lower index of refraction. As a result, In-Ceram Spinell cannot be used for the fabrication of fixed partial dentures, although it provides a very good restoration for the anterior esthetic zone. Its optical properties account for highly translucent crowns with low chroma. The results of this study indicate that this type of restoration provides excellent directive and diffusive light transmission, and, as a result, a lifelike appearance that permits blending of the restoration with the adjacent natural teeth.

IPS Empress is primarily a glass and a crystalline leucite. The latter is used to increase the strength of the ceramic material without significantly compromising its translucency. The material gains its strength by being pressed into a mold under a viscous flow, and by the heat treatments during the final product fabrication. This restoration exhibits excellent translucency that is further controlled with specially formulated dentin and lowfusing enamel porcelains. The final result closely matches the color and light transmission of natural teeth. As shown by this subjective study, IPS Empress presented the best optical properties and color matching of all materials tested. However, the light transmission characteristics of this restoration were not significantly different from those of the In-Ceram Spinell all-ceramic crown.

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Conclusion

References

The light transmission properties and color matching of four different types of restorations have been examined. Five experienced prosthodontists who did not participate in this study concluded that:

1. Geller W, Kwiatkowski SJ. The Willi’s glass crown: A new solution in the dark and shadowed zone of esthetic porcelain restorations. Quintessence Dent Technol 1987;11:233–242.

1. All-ceramic restorations exhibited superior light transmission when compared to PFM restorations with facial or circumferential porcelain margins. 2. IPS Empress and In-Ceram Spinell all-ceramic restorations demonstrated equally good light transmission properties. 3. IPS Empress best resembled the adjacent tooth. 4. In-Ceram Spinell presented better reflection and refraction characteristics, as well as color matching properties, versus a PFM restoration with a 2-mm short coping and 360-degree porcelain margin.

3. Wohlwend A, Strub JR, Schärer P. Metalceramic and all-porcelain restorations: Current considerations. Int J Prosthodont 1989;2:13–26.

This study included only a subjective evaluation. Further studies using a spectrophotometer would provide objective results. Clinicians should be aware of the advantages and disadvantages of each type of restoration so that they can choose the most appropriate type for a given clinical situation.

2. Malament KA, Grossman DG. The cast glass-ceramic restoration. J Prosthet Dent 1987;57:674–683.

4. Yamamoto M. Metal Ceramics: Principles and Methods of Makoto Yamamoto. Chicago: Quintessence, 1985:221–267, 345–347. 5. Aoshima H. A Collection of Ceramic Works. Tokyo: Quintessence, 1992:81–85. 6. Kelly JR, Nishimura I, Campbell SD. Ceramics in dentistry: Historical roots and current perspectives. J Prosthet Dent 1996;75:18–32. 7. Mc Lean JW. The art and science of dental ceramics. Oper Dent 1991;16:149–156. 8. Nakagawa Y. Analysis of natural tooth color. Shinkai Tenbo 1975;46:527–532. 9. Sproull DC. A history of porcelain in dentistry. Bull Hist Dent 1978;26:3–10. 10. Jones DW. Development of dental ceramics. Dent Clin North Am 1985;29:621-644. 11. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994:97–100, 134–138. 12. Yamamoto M. A newly developed “opal” ceramic and its clinical introduction with consideration of refraction indexes [in German]. Quintessence Zahntech 1989; 15:783–796. 13. Clark EB. The color problem in dentistry. Dent Dig 1931;6:37. 14. Johnston JF, Dykema RW, Cunningham DM. Porcelain veneers bonded to gold castings: A progress report. J Prosthet Dent 1958;8:120–122. 15. Wall JG, Cipra DL. Alternative crown systems. Is the metal ceramic crown always the restoration of choice? Dent Clin North Am 1992;36:765–782.

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16. Goodacre CJ, van Roekel NB, Dykema RW, Ullman RB. The collarless metal ceramic crown. J Prosthet Dent 1977;38: 615–619.

30. Kwiatkowski SJ, Geller W. A preliminary consideration of the glass ceramic dowel post and core. Int J Periodontics Restorative Dent 1989;2:51–55.

17. Sozio RB. The marginal aspect of the ceramometal restoration: The collarless ceramometal restoration. Dent Clin North Am 1977;21:787–801.

31. Ahmad I. Yttrium-partially stabilized zirconium dioxide posts: An approach to restoring coronally compromised non-vital teeth. Int J Periodontics Restorative Dent 1998; 18:455–465.

18. Vryonis P. A simplified approach to the complete porcelain margin. J Prosthet Dent 1979;42:592–593. 19. Chiche G, Radiquest J, Pinault A, Genini P. Improved esthetics for the ceramometal crown. Int J Periodontics Restorative Dent 1986;1:77–87. 20. McLean JW, Hughes TH. The reinforcement of dental porcelain with ceramic oxides. Br Dent J 1965;119:251–267. 21. Southan DE, Jorgensen KD. Precise porcelain jacket crowns. Aust Dent J 1972; 17:269–273. 22. Riley EJ, Sozio RB, Casthely F, Wilcko MT, Sotera AJ. Precision porcelain jacket crown technique. J Prosthet Dent 1975; 34:346–351. 23. Sozio RB, Riley EJ. The shrink-free ceramic crown. J Prosthet Dent 1983;49: 182–187. 24. Holmes JR, Bayne SC, Sulik WD, Holland GA. Marginal fit of castable ceramic (Dicor) crowns [abstract]. J Dent Res 1987;66:283.

32. Clark EB. Tooth color selection. J Am Dent Assoc 1933;20:1065–1073. 33. Tuati B, Miara P. Light transmission in bonded ceramic restorations. J Esthet Dent 1993;5:11–18. 34. Paul SJ, Pliska P, Pietrobon N, Schärer P. Light transmission of composite luting resins. Int J Periodontics Restorative Dent 1996;16:165–173. 35. Krejci I, Krejci D, Lutz F. Clinical evaluation of a new pressed glass ceramic inlay material over 1.5 years. Quintessence Int 1992;23:181–186. 36. Sorensen JA, Fanuscu MI, Choi C, Mito W. Status of clinical trial on Empress crowns [abstract]. J Dent Res 1995;74:159. 37. Paul SJ, Pietrobon N, Schärer P. The new In Ceram Spinell system: A case report. Int J Periodontics Restorative Dent 1995;15: 521–527.

25. Malament KA. The cast glass ceramic restoration. J Prosthet Dent 1987;57: 674–683. 26. Dong JK, Luthy H, Wohlwend A, Schärer P. Heat-pressed ceramics: Technology and strength. Int J Prosthodont 1992;5:9–16. 27. Richards MW, Kelly JR. Indentation strength of unpressed and pressed Empress disks [abstract]. J Dent Res 1994;73:191. 28. Seghi RR, Sorensen JA. Relative flexural strength of six new ceramic materials. Int J Prosthodont 1995;8:239–246. 29. Probster L, Diehl J. Slip-casting alumina ceramics for crown and bridge restorations. Quintessence Int 1992;23:25–31.

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