The influence of tooth color on preparation design for laminate veneers from a minimally invasive perspective: case report

Evaluation of marginal and internal adaptation of veneers generated by the guided prosthetic tooth preparation system

OBJECTIVE

This in vitro study aimed to assess and contrast the marginal and internal adaptation of all-ceramic prefabricated veneers manufactured via the FirstFit guided tooth preparation system against all-ceramic veneers produced using the chairside Computer-Aided Design/Computer Aided Manufacture (CAD/CAM) system following identical guided preparation protocols.

MATERIALS AND METHODS

Two main groups were included, with 16 lithium disilicate veneers per group. Four typodonts were used for the test (FirstFit) and control CAD/CAM groups. Intraoral scans created master casts and preparation guides. Guides performed preparations on typodont teeth (two central incisors and two lateral incisors). Prepared teeth were scanned (CEREC Omnicam) to design and mill CAD/CAM veneers. Marginal gap thickness and cement space thickness were measured using light microscopy at four locations: marginal, cervical internal, middle internal, and incisal internal.

RESULTS

No significant difference existed between groups for marginal adaptation (p = 0.058) or incisal internal adaptation (p = 0.076). The control group had significantly lower values for middle internal adaptation (p = 0.023) and cervical internal adaptation (p = 0.019).

CONCLUSIONS

Guided preparation evaluation showed no significant differences in marginal or incisal internal adaptation. The CAD/CAM group had significantly lower middle and cervical internal adaptation values.

The capacity of conservative preparations for lithium disilicate glass-ceramic laminates luted with different resin cements to mask different substrate shades: A minimally invasive esthetic approach

OBJECTIVE

Demonstrate the ability of 0.5 mm thickness lithium disilicate laminates associated with resin cement to mask different substrate saturations.

METHODS

60 specimens (n = 5) were prepared with CAD/CAM lithium disilicate glass-ceramic IPS e.max CAD, 0.5 mm thick, in three degrees of translucency (HT, MT and LT); cemented by Variolink Esthetic LC Light+ (L) and Neutral (N) on composite resin substrates A1 and A4 shades. Color measurements were performed by a spectrophotometer (CM-3700d -Konica Minolta). The L*, a*, b* parameters of the tri-layer structure (laminate/ resin cement/ substrate) were used to calculate color difference ( ∆ E 00 ) by CIEDE2000 formula and Translucency Parameter (TP 00 ). This study adopted ∆ E 00 = 0.8, as perceptibility threshold (PT), and ∆ E 00 = 1.8, as acceptability threshold (AT). Statistical analyses were performed by one-way ANOVA and Tukey tests (a = 0.05).

RESULTS

Color difference between resin cement shades showed statistical differences (p < 0.0001) and ∆ E 00 > 1.8 for all groups. Color difference between substrates saturations showed a significant statistical difference (p < 0.0001) and ∆ E 00 values above AT for all groups. TheTP 00 demonstrated significant statistical differences (p < 0.0001). The LTL combination, the opaquest set, showed the smallest ∆ E 00 values between substrate shades differences, however, above AT.

CONCLUSION

The translucency of the lithium disilicate, the substrate saturation and the resin cement opacity influenced final color of restoration. The ceramic translucency impact on final color was reduced by opaque resin cement. Furthermore, the LT lithium disilicate and the Light+ resin cement reduced the translucency of the restoration, contributing to mask saturated substrate.

CLINICAL RELEVANCE

This study shows the influence of conservative lithium disilicate laminates with different degrees of translucency associated with resin cement on final color of saturated substrate restorations. A minimally invasive esthetic protocol for masking substrates is demonstrated by associating low translucency ceramic laminates and opaque resin cement.

Digitally designed and additively manufactured tooth reduction guides for porcelain laminate veneer preparations: A clinical report

Porcelain laminate veneers are a conservative treatment to enhance esthetics, tooth shape, color, and contours. Enamel preservation during tooth preparation is essential for the long-term success of these micromechanically retained partial coverage restorations. Different methods have been described to clinically assess tooth preparation relative to definitive restorative contours. This clinical report describes a digital workflow to fabricate 3-dimensionally (3D) printed tooth reduction guides based on digital esthetic planning. These 3D printed reduction guides help clinicians visualize and gauge tooth preparations relative to the desired restorative contours, aid in enamel preservation, and overcome some of the limitations associated with conventionally fabricated tooth reduction guides.

Preparation of ultrathin translucent zirconia laminate veneers using 3D printing reduction guides

Minimizing and controlling the amount of tooth reduction during the preparation of ultrathin laminate veneers is a challenge for minimally invasive dentistry. The use of reduction guides is advised to reach the optimal space required for the definitive restoration without excessive reduction. The digital production of a reduction guide used to control tooth preparation for ultrathin laminate veneers is described.

Smile Design: Mechanical Considerations

Smile designing refers to the cosmetic and esthetic dental reconstruction that is visible during smiling. The use of modern digital tools requires adequate knowledge about the tooth shape and shade principles. Mechanical, biological, and psychological factors should be understood and tailor an individualized treatment accordingly to achieve pleasing esthetic outcomes. Dental therapy is becoming more appearance-driven, and thus, both patients and dental clinicians mainly emphasize on cosmetic dental and facial aspects of treatments.

In vitro study on how antioxidant solutions affect enamel surface characteristics and bonding interface of ceramic laminate veneers luting after dental bleaching

PURPOSE

This in vitro study aimed to determine the effect of antioxidant solutions used after dental bleaching on the shear bond strength and adhesive interface sealing of ceramic laminate veneer luting. Additionally, effects on the enamel surface characteristics of hydrogen peroxide neutralization, surface energy, total free interaction energy, morphology, and chemical composition of enamel were assessed.

MATERIAL AND METHODS

Total 127 bovine incisors were divided into experimental groups, according to the surface treatment (unbleached and bleached enamel), antioxidant types (control; 10% ascorbic acid and 10% α-tocopherol), and periods of luting of ceramic laminates (24 h and after 14 days). Shear bond strength was assessed using microtensile test before and after thermal cycling (5760 cycles, 5-55 °C) (n = 6). The sealing of the adhesive interface was assessed using a confocal laser scanning microscope (n = 3). Hydrogen peroxide neutralization analysis was performed using a spectrophotometer (n = 5). The surface energy and total free interaction energy (n = 10) were measured using an automatic goniometer, while enamel morphology and chemical composition were assessed by scanning eletron microscopy (n = 3). Shear bond strength and enamel surface properties data were subjected to ANOVA followed by Tukey's test (α = 0.05). Adhesive interface micrographs were evaluated by the inter-examiner Kappa test and subjected to Kruskal-Wallis and Dunn's tests (α = 0.05).

RESULTS

In general, thermal aging decreased the shear bond strength values of the luting agents to enamel (P < .05). The α-tocopherol solution was able to reverse the oxidizing effect from dental bleaching, increasing the shear bond strength values and preserving the integrity of the adhesive interface sealing (P < .05). Moreover, the α-tocopherol antioxidant agent promoted higher hydrogen peroxide neutralization after dental bleaching (P < .05). Dental bleaching influenced the enamel surface, decreasing the surface energy and total free interaction energy values (P < .05).

CONCLUSION

α-tocopherol was able to reverse the oxidizing effects of dental bleaching, improving the enamel surface properties, as well as the adhesion and interface sealing of ceramic laminate veneer restorations.

Survival of Hybrid Laminate Veneers using two different tooth preparation techniques: Randomized Clinical Trial

The aim of this study was to evaluate the survival of laminate veneers constructed using a recent polymer-infiltrated ceramic network material following the aesthetic pre-evaluative temporary (APT) technique of tooth preparation in comparison to traditional technique. Six patients received 54 laminate veneers. They were divided into two equal groups (n=27) according to the technique of tooth preparation: group T: traditional technique and group A: aesthetic pre-evaluative temporary technique. VITA ENAMIC material was used for CAD/CAM construction of laminate veneers. Cementation was performed using a light cured resin cement. The laminate veneers were evaluated at baseline, after 3, 6 and 12 months according to the modified United States Public Health Service (USPHS) criteriea. The data was collected, tabulated and statistically analyzed. Secondary caries, endodontic complications, cracks and loss of retention were not noted in any laminate veneer. Extensive fractures were not detected in both study groups through the study period. There was a statistically significant decrease of color match criteria between the two groups at the 6 and 12 months recalls. Based on this study, both preparation techniques resulted in successful clinical performance. After 12 months, all the veneers in both groups showed no post-operative sensitivity and all patients were highly satisfied regarding their veneers. However, there was a deterioration in color match criteria through the study period in both study groups.

A digital workflow with the virtual enamel evaluation and stereolithographic template for accurate tooth preparation to conservatively manage a case of complex exogenous dental erosion

OBJECTIVE

This article describes a digital workflow using virtual enamel evaluation and a stereolithographic template for accurate tooth preparation for a complex exogenous dental erosion.

CLINICAL CONSIDERATIONS

A 22-year-old man with different degrees of defects on the labial surface in esthetic area was diagnosed as exogenous dental erosion. The residual undamaged enamel area and depth of defect were measured and analyzed accurately by creating a digital virtual patient based on the pretreatment data. According to the different conditions of residual enamel and tooth defect, the treatment plans of porcelain veneer, crown and composite resin were chosen for corresponding involved teeth. Based on the virtual wax-up and the suggested material thickness, a template for tooth preparation was designed and three-dimensional printed. This template together with a special bur indicating the reduction depth accurately guided the teeth preparation and achieved a long-term effect.

CONCLUSIONS

The virtual enamel evaluation contributes to obtaining the appropriate corresponding treatment plan objectively. The stereolithographic template effectively meets the accuracy of tooth preparation, preserving the tooth hard tissue to the greatest extent.

CLINICAL SIGNIFICANCE

The digital workflow described here may provide a quantifiable evaluation method and an accurate tooth preparation method for exogenous dental erosion.

Impact of Bleaching before or after Veneer Preparation on Color Masking Ability of Laminate Veneers: An In Vitro Study

Purpose

This study evaluates the effect of bleaching before or after veneer preparation and the depth of preparation on color masking ability of laminate veneers. Methods. Sixty extracted premolars were artificially stained to vita shade A4, verified by digital spectrophotometer (Vita Easy Shade V), and then divided into three groups: NB = nonbleached, BBP = bleaching before preparation, and BAP = bleaching after preparation. Based on the preparation depths, each group was further divided into two subgroups: S1 = 0.5 mm and S2 = 1.0 mm. BBP and BAP were subjected to one session of in-office bleaching using 35% hydrogen peroxide. IPS e-max CAD veneers of 0.5 and 1.0 mm thickness (corresponding to the preparation depths) of the same shade and translucency (HT A1) were cemented immediately to the bleached surfaces. Immediately after cementation, the color change ΔE between the baseline (after staining) and the resulted shades was measured using the Vita Easy Shade V digital spectrophotometer and CIELab color system.

Results

Bleached groups exhibited a significant ΔE value compared to the nonbleached group (p < 0.05). BAP showed the highest ΔE value. No significant difference was found between BBP and BAP. S2 revealed a significant ΔE value than S1 (p < 0.05). No significant difference was found between S1of BAP and S2 of NB, BBP, and BAP (p > 0.05). Regarding the color coordinates, the difference between the tested groups was highly significant in lightness (ΔL∗) (p < 0.001), while no significant differences were found in green/red value (Δa∗) and yellow/blue value (Δb∗) (p > 0.05).

Conclusions

In cases of severe tooth discoloration, one session of in-office bleaching before or after veneer preparation and the preparation depth do not influence the color masking ability of laminate veneers.

Interdisciplinary rehabilitation of a patient with ectodermal dysplasia utilizing digital tools: A clinical report

The present clinical report describes the rehabilitation of a patient diagnosed with ectodermal dysplasia performed by an interdisciplinary team in a comprehensive approach aided by digital technology. The complexity of the treatment was related to predictability regarding timing and the type of approach. The patient was referred for treatment because of congenitally missing and abnormally shaped permanent teeth. The need for an interdisciplinary team involving orthodontic, periodontic, and prosthodontic specialists was identified. A virtual treatment plan was developed to guide tooth movement, placement of dental implants, and tooth preparation for indirect restorations. Therefore, each treatment phase could be communicated to the patient and treatment team in a predictable way.

Dentist-Ceramist Communication: Protocols for an Effective Esthetic Team

No matter how skilled and well trained esthetic dentists or technicians may be, they cannot deliver results without a proper partnership. Close ceramist-clinician communication is a critical component of successful esthetic dentistry. In order to design an esthetic vision, convey this vision to the patient, and then execute the vision successfully, there must be effective communication between the ceramist, the clinician, and (most importantly) the patient. This article highlights some of the authors' philosophies, as well as an overview of the key communication protocols that have proved effective for this team.

A stereolithographic template for computer-assisted teeth preparation in dental esthetic ceramic veneer treatment

OBJECTIVE

This article describes a digital dental esthetic ceramic veneer treatment workflow using a stereolithographic template for teeth preparation.

CLINICAL CONSIDERATIONS

We have presented the case of a 33-year-old woman with dental fluorosis who wanted an esthetic ceramic veneer treatment. A digital smile design was created on a virtual patient, and a virtual diagnostic wax-up was made. Based on the suggested ceramic material thickness, virtual teeth preparation was performed on the diagnostic wax-up. A special-teeth preparation template was then created digitally and fabricated using a stereolithographic technique. This template guided the teeth preparation using a special bur with a stopper. The veneers were fabricated by CAD/CAM and delivered good esthetics and function.

CONCLUSIONS

The stereolithographic tooth reduction template helps realize digital restorative planning. It provides better control of the reduction depth of the labial and incisal preparation, making the operation simpler.

CLINICAL SIGNIFICANCE

The digital dental esthetic ceramic veneer treatment workflow described here using a stereolithographic template for teeth preparation helped with the accurate control of reduction depth for minimally invasive teeth preparation, making the operation simpler, which is a significant improvement over the previous methods.

A Conservative Approach to Ceramic Veneers: A Case Report

Bonding to enamel has been shown to provide reliable results, and thus conservative tooth preparations are key to the success of ceramic bonded restorations. The wax-up is the first diagnostic tool available to evaluate discrepancies between current and ideal tooth proportions. The clinician's diagnostic mock-up provides the patient with a visual perception of the size and shape of the proposed restorations. The use of reduction guides assists the restorative dentist in evaluating the specific amount of tooth structure to be removed during preparation. Furthermore, total isolation with a rubber dam prior to bonding the final restorations is crucial for the success of adhesive protocols. The aim of this report is to demonstrate a conservative approach to tooth preparation with a complete isolation technique prior to bonding eight ceramic restorations.

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.

Does the presence of maxillary central incisor edge asymmetry influence the perception of dentofacial esthetics in video analysis?

OBJECTIVE

To investigate the influence of incisal edge asymmetry of the maxillary central incisors on dentofacial esthetics among orthodontists, prosthodontists, and laypersons using video analysis.

MATERIALS AND METHODS

Full-face films of a 52-year-old afro-descendant woman displaying various levels of incisal wear in the esthetic zone were captured. An acrylic resin mockup was made of the maxillary anterior region, enabling the reproduction of an attractive smile and restoring tooth wear. Four different levels of incisal asymmetry between the upper central incisors in 0.5 mm increments were prepared from this mockup. A film was made for each level of asymmetry (0.5, 1.0, 1.5, and 2.0) and one with no asymmetry, with the patient repeating a sentence, totaling five films. After a pilot study and sample calculation, the films were evaluated by 138 examiners: 46 orthodontists, 46 laypeople, and 46 prosthodontists. Each examiner evaluated the dentofacial esthetics of each film using visual analog scales. Data collected were statistically analyzed.

RESULTS

Highest scores were awarded to the film with no asymmetry between upper centrals and the one with 0.5 mm of asymmetry. The asymmetries of 1.5 mm and 2.0 mm had the lowest scores from all three groups.

CONCLUSIONS

The results of this video analysis indicate that asymmetries equal to or greater than 1.0 mm between the upper central incisors edges jeopardize dentofacial esthetics.

Laminated Veneers with Stratified Feldspathic Ceramics

Currently, there has been a growing demand for restorations of anterior teeth in the routine of doctors in dental offices. With advances in adhesive technology and good properties of the available ceramics, the use of ceramic veneers has been offered as a treatment option for cases where teeth have minor color changes and shape and position changes. Through careful treatment planning, it is possible to conservatively use ceramic veneers in the treatments, applying techniques with minimal wear of the teeth and obtaining excellent aesthetic results with mechanical stability and biocompatibility with the periodontal tissues and clinical longevity. This clinical case report was used to design the digital smile, which guided the production of the diagnostic waxing of the superior model. Silicone guides were then made to create the mock-up, orienting enamel/dentin wear and assisting the preparation of the crowns with bis-acryl resin. When the wear was finished, the gingival separation was performed using the double-thread technique. In the molding process, the second wire was withdrawn and the molding material flowed into the gingival groove, copying the terminal region. After analysis of the quality of the impression, the temporary crowns were made with bis-acryl resin, using the guide. The color of the cementing agent was chosen using a glycerin-based compound which simulates the final color of the cement. After two hours of drying, two different layers of silane were applied for 60 seconds. After the preparation of the piece, gingival isolation and separation were done. The dental substrate was degreased with detergent solution and conditioned with 37% phosphoric acid for 15 seconds and then washed for 45 seconds for subsequent drying, leaving the substrate moistened. The adhesive system was applied for 30 seconds, waiting for the adhesive to penetrate into the conditioned dentinal tubules. A light air jet was applied, and then each tooth was photopolymerized for 30 seconds. The resin cement was placed inside the pieces and placed in position and photopolymerized. The excess cement was removed; after a layer of glycerin in the cervical region, aiming to block the entry of oxygen and polishing was performed. The purpose of this case report was to describe a sequence of clinical steps, from planning to cementation, in a case of aesthetic correction using feldspathic ceramic veneers.

The Effect of Polymerization and Preparation Techniques on the Microleakage of Composite Laminate Veneers

BACKGROUND

Marginal leakage is the important factor influencing the maintenance of dental esthetic.

AIM

The purpose of this study was to evaluate the relationship between the preparation techniques and type of polymerization techniques on microleakage of composite laminate veneers.

MATERIALS AND METHODS

Ninety-one same sized, caries-free human maxillary central incisors were randomly assigned to 13 groups (n = 7) and were designed with four different preparation techniques (window type, feather type, bevel type, and incisal overlap type). One group determined as control group and any preparation was applied. Nanohybrid resin composite was used for restoration. Composite laminate veneers polymerized with three different techniques (direct light curing, indirect polymerization with a combination of pressure, light and heat using a light cup and heat cup, direct polymerization, and additionally heat cured in an oven). The specimens were thermocycled, and then immersed in 5% basic fuchsine solution. Following 24 h, all specimens were immersed in 65% nitric acid solutions for volumetric dye extraction test. Samples diluted with distilled water and centrifuged and microleakage determined by a spectrophotometer.

STATISTICAL ANALYSIS USED

Data were analyzed with two-way ANOVA and Tukey honest significant difference post hoc multiple comparisons test (P < 0.05).

RESULTS

For comparing the microleakage value of preparation and polymerization techniques, Window type preparation showed a significant difference in direct polymerization + additional cured group (P < 0.05). Control group was statistically different from the other groups (P < 0.05).

CONCLUSIONS

Window type laminate preparation can be preferred in indirect polymerization technique because it caused less leakage in this present study.

Reproducing Optical Properties of Anterior Teeth after Ultra-Conservative Preparation

OBJECTIVE

Selecting the appropriate material is essential when restoring color and appearance of esthetically compromised anterior teeth.

CLINICAL CONSIDERATIONS

Most of the conventional restorative techniques require tooth reduction in order to mimic optical properties of a natural tooth. Fortunately, bonding techniques associated with improvements on dental ceramics esthetics allow for highly conservative treatment options in which maximum preservation of dental tissues can be attained. An analysis of different ceramic materials available and different types of tooth preparation is presented in a format of a decision tree for treatment planning.

CONCLUSIONS

The suggested decision-making aims to facilitate clinicians' selection of the most appropriate restorative technique for reproducing color and appearance of anterior teeth after ultra-conservative preparation and according to different clinical scenarios CLINICAL SIGNIFICANCE: The selection of the appropriate ceramic material for each case is of major importance, since the entire treatment plan will be determined based on the type of ceramic material that will be used for the final restoration. Each restorative material has a specific tooth preparation requirement, indications, and limitations that shall be respected for maximum esthetical outcomes. (J Esthet Restor Dent 28:267-276, 2016).

Predictable Outcomes with Porcelain Laminate Veneers: A Clinical Report

This clinical report describes how to achieve predictable outcomes for anterior teeth esthetic restorations with porcelain laminate veneers by associating the digital planning and design of the restoration with interim restorations. The previous digital smile design of the restoration eliminates the communication barrier with the patient and assists the clinician throughout patient treatment. Interim restorations (diagnostic mock-ups) further enhance communication with the patient and prevent unnecessary tooth reduction for conservative tooth preparation. Adequate communication between patient and clinician contributes to successful definitive restorations and patient satisfaction with the final esthetic outcome.