Porcelain veneer restorations: a clinician's opinion about a disturbing trend

Clinical management of vital and non-vital discolored tooth preparation stump shades: A clinical case series

OBJECTIVE

Traditional and modern-day laboratory techniques can be used to mask vital and non-vital discolored teeth.

CLINICAL CONSIDERATIONS

Two clinical case reports are presented showing different treatment approaches to differing clinical scenarios of partial coverage veneer and full coverage crown restorations, respectively.

CONCLUSIONS

Feldspathic ceramics should be considered when customization of stump shade correction and equalization is required with minimum facial reduction with veneer restorations. Translucent zirconia (5 mol% Y2 O3 ) can be used to mask metal posts and core restorations on non-vital teeth using an opaquer material that is infused into the intaglio surface in the green state.

CLINICAL SIGNIFICANCE

Different clinical scenarios will present to the clinician in regard to discolored stump shades where understanding what laboratory material treatment options are available that will help guide definitive restoration types and ultimately tooth preparation design.

Laminate veneer ceramics in aesthetic rehabilitation of teeth with fluorosis: a 10-year follow-up study

Background

Fluorosis is one of the color anomalies seen in teeth. White lines and blurred areas associated with mild fluorosis are barely noticeable; in its severe form, tooth enamel surface changes ranging from staining and pitting may be observed. The treatment of fluorosis not only provides aesthetic and functional correction but also helps to improve the patient's self-esteem.

Methods

The present retrospective study evaluated the clinical quality, success rate, and estimated survival of porcelain laminate veneers in teeth with anterior fluorosis. Three hundred fifty-eight porcelain laminate veneers (254 in the anterior maxilla and 104 in the mandible) were "functional" restorations that covered the incisal edge and part of the palatal/lingual side of the tooth with a 1 mm high palatal bevel. Ceramic veneers were fabricated with lithium disilicate reinforced glass–ceramic material (IPS e.max Press, Ivoclar Vivadent, Schaan, Liechtenstein). The modified United States Public Health Service criteria were used for clinical evaluation of the restorations.

Results

On the basis of these criteria, marginal adaptation, color match, marginal discoloration, surface roughness, restoration fracture, tooth fracture, restoration wear, antagonist tooth wear, caries and postoperative sensitivity were evaluated yearly. The survival rate in the current study was ≥ 0.997 for 10 years.

Conclusions

The results of this clinical study should encourage clinicians to consider ceramic veneers over crown restorations when restoring the smile of patients with advanced fluorosis.

Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus

By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

Effect of tooth substrate and porcelain thickness on porcelain veneer failure loads in vitro

STATEMENT OF PROBLEM

Bonded porcelain veneers are widely used esthetic restorations. High success and survival rates have been reported, but failures do occur. Fractures are the commonest failure mode. Minimally invasive or thin veneers have gained popularity. Increased enamel and porcelain thickness improve the strength of veneers bonded to enamel, but less is known about dentin or mixed substrates.

PURPOSE

The purpose of this in vitro study was to measure the influences of tooth substrate type (all-enamel, all-dentin, or half-dentin-half-enamel) and veneer thickness on the loads needed to cause initial and catastrophic porcelain veneer failure.

MATERIAL AND METHODS

Model discoid porcelain veneer specimens of varying thicknesses were bonded to the flattened facial surfaces of incisors with different enamel and dentin tooth substrates, artificially aged, and loaded to failure with a small sphere. Initial and catastrophic fracture events were identified and analyzed statistically and fractographically.

RESULTS

Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. All specimens retained some porcelain after catastrophic failure. Cement failure occurred at the cement-porcelain interface not at the cement-tooth interface. Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or mixed substrates. Increased porcelain thickness substantially raised the loads to catastrophic failure on enamel substrates but only moderately raised the loads to catastrophic failure on dentin or mixed substrates. The veneers bonded to half-dentin-half-enamel behaved remarkably like those bonded wholly to dentin.

CONCLUSIONS

Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or half-enamel-half dentin.

In vitro evaluation of the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with composite fillings after cyclic loading

PURPOSE

There is insufficient data regarding the durability of porcelain laminate veneers bonded to existing composite fillings. The aim of the present study was to evaluate the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with existing composite fillings.

MATERIALS AND METHODS

Thirty maxillary central incisors were divided into three groups (for each group, n=10): intact teeth (NP), teeth with class III composite fillings (C3) and teeth with class IV cavities (C4). Porcelain laminate veneers were made using IPS-Empress ceramic and bonded with Panavia F2 resin cement. The microleakage of all of the specimens was tested before and after cyclic loading (1 × 10⁶ cycles, 1.2 Hz). The fracture resistance values (N) were measured using a universal testing machine, and the mode of failure was also examined. The statistical analyses were performed using one-way ANOVA and Tukey post hoc tests (α=.05).

RESULTS

There was a significant difference in the mean microleakage of group C4 compared with group NT (P=.013). There was no significant difference in the fracture loads among the groups.

CONCLUSION

The microleakage and failure loads of porcelain laminate veneers bonded to intact teeth and teeth with standard class III composite fillings were not significantly different.

Porcelain laminate veneers: reasons for 25 years of success

This article discusses failures that could occur if meticulous attention is not given to details such as planning the case, conservative (enamel saving) preparation of teeth, proper selection of ceramics to use, proper selection of the materials and methods of cementation of these restorations, proper finishing and polishing of the restorations, and proper planning for the continuing maintenance of these restorations. Some concerns as to newer products and methods and their effect on the continued success of this modality of treatment are also addressed.

Critical appraisal. Porcelain veneer outcomes, part I

Etched porcelain veneers have now been used clinically for about 20 years. The profession was originally very skeptical about bonding thin shells of a brittle ceramic material to teeth. However, ceramic veneers have proved to be not only very esthetic but also extremely durable restorations. This two-part Clinical Appraisal reviews several articles related to veneer longevity and clinical factors contributing to--or detracting from--longevity. Part II will appear in the next issue of JERD.

Dynamometric assessment of the mechanical resistance of porcelain veneers related to tooth preparation: A comparison between two techniques

STATEMENT OF PROBLEM

There is little agreement regarding a palatal extension of the preparation for porcelain veneers, as it represents a more invasive technique than a preparation limited to the facial surface of a tooth.

PURPOSE

The purpose of this study was to detect the stress in maxillary anterior teeth restored with porcelain veneers and compare the resistance to fracture of porcelain veneers prepared using different preparation designs.

MATERIAL AND METHODS

Forty-five maxillary anterior teeth were restored with porcelain veneers and divided into 9 groups as follows: Ca, canines with no preparation; Ca-Ch, canines with palatal chamfer preparation; Ca-W, canines with window preparation; LI, lateral incisors with no preparation; LI-Ch, lateral incisors with palatal chamfer preparation; LI-W, lateral incisors with window preparation; CI, central incisors with no preparation; CI-Ch, central incisors with palatal chamfer preparation; CI-W, central incisors with window preparation. Shear-flexural fracture tests were performed. The fractured specimens were subjected to scanning electron microscope (SEM) analysis. Data were statistically analyzed with univariate analysis of variance and the Tukey post hoc test for multiple comparisons (alpha=.05).

RESULTS

The following mean fracture load values (N) were recorded: Ca, 395 +/- 6; Ca-Ch, 310 +/- 8; Ca-W, 322 +/- 8; LI, 309 +/- 8; LI-Ch, 242 +/- 6; LI-W, 225 +/- 8; CI, 298 +/- 8; CI-Ch, 255 +/- 8; CI-W, 221 +/- 6. The SEM analysis showed that both adhesive and cohesive fractures were primarily concentrated at the cervical region. Statistical analysis showed that both the type of tooth and the design of the preparation significantly influenced the resistance to fracture of the restored teeth (P<.001).

CONCLUSION

The chamfer preparation is recommended for central incisors, whereas the window preparation showed better results for canines. Both preparations can be adopted in the restoration of lateral incisors.

Surface Treatment Protocols in the Cementation Process of Ceramic and Laboratory-Processed Composite Restorations: A Literature Review

The clinical longevity of indirect restorations made of ceramics or indirect composite resins depends on their successful treatment and cementation. The cementation technique is determined by the type of restorative material-ceramics or indirect composite resins; thus, their intaglio surface treatment should be performed according to their particular compositions. The aim of this literature review was to define surface treatment protocols of different esthetic indirect restorative materials. A PubMed database search was conducted for in vitro studies pertaining to the most common treatment protocols of tooth-colored materials. Articles that described at least the surface treatment procedure, its effects on adhesion, its relationship with the material's composition, clinical aspects, and expected longevity were selected. The search was limited to peer-reviewed articles published in English between 1965 and 2004 in dental journals. Sandblasting, etching techniques, and silane coupling agents are the most common procedures with improved results.

CLINICAL SIGNIFICANCE

Tooth-colored restorative materials vary considerably in composition and require different protocols for adhesive cementation.