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Purpose: To assess the mechanical performance and enamel-crack propensity of large MOD composite-resin restorations on maxillary molars with severely undermined cusps. Materials and Methods: Thirty-six extracted maxillary third molars (n = 12) received a standardized slot-type MOD preparation (5-mm depth by 5-mm bucco-palatal width) with severe undercuts, leaving unsupported buccal and lingual enamel cusps. A short-fiber reinforced composite resin base (SFRC, everX Flow, GC) was used for both the experimental direct approach and semi-direct CAD/CAM inlays (Cerasmart 270, GC). In the control group using a direct approach, Gradia Direct (GC) composite resin was used alone without SFRC. Optibond FL (Kerr) adhesive was used in all three groups (also for the immediate dentin sealing of inlays). Artificial masticatory forces were simulated under water using closed-loop servo-hydraulics (MTS Acumen 3). Each specimen was mounted at a 30-degree angle and positioned so that a cylindrical antagonistic cusp (actuator) contacted the internal palatal cusp slope of the restoration. Cyclic loading was applied at a frequency of 5 Hz, starting with a load of 200 N, increasing by 100 N every 2000 cycles. Samples were loaded until fracture and the number of endured cycles and failure modes of each specimen was recorded. Each sample was also evaluated for crack propensity during the experiment and for final failure mode (reparable failures above the CEJ [cementoenamel junction] vs irreparable failures below the CEJ). Results: Shrinkage-induced cracks (>3 mm) were found in most specimens for both direct groups (66% to 83%) but not with inlays. The survival of inlays with a SFRC base was superior to that of the direct SFRC restorations and Gradia Direct (control) restorations (Kaplan-Meier survival analysis and post-hoc log-rank test p < 0.000). The direct control group without SFRC exhibited not only the poorest survival but also 100% catastrophic failure (vs 42% and 17% for SFRC direct and SFRC inlays, respectively). Conclusion: Large MOD restorations with severely undermined cusps were most favorably restored with an SFRC base and a CAD/CAM inlay, yielding the highest survival rate, more reparable failures and absence of shrinkage-induced cracks. When a low-cost restoration must be chosen, the SFRC base will significantly improve the performance and failure mode of directly layered restorations. [ABSTRACT FROM AUTHOR]

Aim: The aim of the present retrospective study was to evaluate the long-term results, including technical and biologic outcomes, of maxillary extended porcelain veneers with an incisal edge thickness above 2 mm. Materials and methods: Patients treated with extended porcelain veneers performed by a single clinician at University of Geneva between 1990 and 2003 were identified and invited to an examination. Of the 37 identified patients, 10 patients with 50 veneers agreed to be examined and were included. A clinical examination was performed to assess survival rates as well as technical and biologic outcomes (modified United States Public Health Services criteria). Patient records were also reviewed to retrieve patient and reconstruction data and every complication event. Patient-reported outcome measures (PROMs) were evaluated using a visual analog scale to measure esthetic satisfaction, functional and phonetic comfort, masticatory improvement, tooth sensitivity, and acceptance of restoration replacement in case of failure. Data were descriptively analyzed, and Kaplan-Meier survival estimators were computed for survival rates and complication events. Results: The survival rate of the veneers was 96% after a mean follow-up of 20.7 + 3.7 years in function. The technical complication rate amounted to 30%, including two failures, nine repairable fractures, three cracks, and one displacement due to trauma. No cavitated caries lesions or endodontic complications were registered. PROMs were very high for esthetic satisfaction and phonetic comfort. Conclusions: Within the limitations of the present retrospective study, extended porcelain veneers appear to be a successful long-term treatment option in terms of clinical outcomes and patient satisfaction. [ABSTRACT FROM AUTHOR]

This study evaluates the fatigue resistance and failure mode of CAD/CAM composite resin and lithium disilicate–bonded screw-retained incisor crowns with long and short titanium bases. Sixty CAD/CAM implant restorations were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and composite resin (Block HC, Shofu). The central incisor crowns were bonded to a prefabricated titanium base 6 mm tall (groups: Emax6 and Shofu6; n = 15 each) or a modified abutment 4 mm tall (groups: Emax4 and Shofu4; n = 15 each). The intaglio surface of the restorations was conditioned according to the material and bonded to the titanium abutments/ bases using dual-cure cement. All assembled crowns were torqued onto implants and subjected to cyclic isometric loading at the incisal edge along the implant axis. Samples were loaded until fracture. Groups were compared using Kaplan-Meier survival analysis (log rank test at P = .05). The number of mean survived cycles differed significantly, with Emax6 and Emax4 at 48,448 and 43,727 cycles, respectively, and Shofu6 and Shofu4 at 44,124 and 37,620 cycles, respectively. Post hoc tests showed similar fatigue resistance for Emax6, Emax4, and Shofu6. Shofu4 was less resistant than all other groups (P < .03). All restorations survived significantly above physiologic load limits. Lithium disilicate screw-retained incisor crowns can be used with long and short titanium bases, while it is recommended to keep a long titanium base for screw-retained composite resin crowns. The composite resin material required the full height of the abutment for optimal strength but may offer enhanced shock absorption and wear-friendliness when considering function and antagonistic wear. [ABSTRACT FROM AUTHOR]

The purpose of the study was the investigation of the polymerization of a preheated composite resin beneath lithium disilicate. First, lithium disilicate discs in two shades (HT A2 and HT A4) and three different thicknesses (2, 4, and 6 mm) were bonded on dentine with preheated composite resin that was photo-polymerized for 20 s. The composite resin microhardness, the double bond conversion (DC) and their correlation were estimated. Second, standardized occlusal veneers of two shades and two different thicknesses (4 and 6 mm) were bonded with preheated composite resin and photopolymerized for 60 or 270 s. A microhardness line profiling was performed on the cross-section of each specimen and the correspondence DC was calculated. Shade and thickness of lithium disilicate were found to have a significant impact on micro-hardness and DC of the composite resin. Beneath standardized occlusal veneers DC can reach clinically acceptable level if photopolymerization duration is extended properly. [ABSTRACT FROM AUTHOR]

Although it is generally accepted that a prosthetic restoration must take into account the gingiva, smile, and patient's face, it is often difficult to determine precisely what facial references must be considered. The purpose of this study was to determine the correct vertical and horizontal facial reference planes in esthetic prosthetic treatment. Using photographic analysis of 160 individuals, the different facial reference planes (interpupillary, intermeatic, intercommissural, and incisal edge lines; facial midline; and Camper and Frankfort planes) were compared to the ideal prosthetic reconstruction axis. Additional measurements, including the human eye's ability to perceive parallelism, were recorded. Most participants (64%) exhibited facial asymmetry. Asymmetry was horizontal (difference between widths of the right and left sides; 52.4%), vertical (difference between heights of the right and left sides; 6.9%), or mixed (4.7%). The interpupillary line is the main horizontal reference in 88.4% of situations, with the intercommissural line the second most important. In the profile view, the horizontal plane was on average 6.5 degrees above the Camper plane and 9 degrees below the Frankfort plane. The human eye's ability to perceive parallelism between two lines was found to be limited to differences of approximately 1 degree. During anterior tooth reconstruction, it is necessary to take into account the right horizontal and vertical esthetic references. Knowledge of the biometric facial parameters in natural dentition is necessary to define the right reconstruction axes based on the facial symmetry or asymmetry. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to assess fatigue resistance and color modifications of endodonticaiiy treated incisors (ETIs) submitted to internal bleaching and restored using three different techniques. Materials and methods: Forty-five maxillary central incisors received endodontic treatment and were internally bleached. After the completion of bleaching, the ETIs were divided into three groups (n = 15) according to the different restoration procedures: 1) glass-ionomer cement base covered with composite resin (GI); 2) short fiber-reinforced composite resin base with composite resin (SF); 3) composite resin restoration over a fiberglass post (FP). Specimens were subjected to accelerated fatigue testing: frequency of 5 Hz, beginning with a load of 100 N for 5000 cycles and a 25-N load increase applied every 1700 cycles until a load of 1200 N was reached. Samples were loaded until fracture. The Kaplan-Meier survival analysis with the log-rank post hoc test were performed (a = 0.05). Tooth color was measured 4 weeks after the bleaching treatment and again after the final restoration procedure using a spectrophotometer and the Ccmmission Internationale de l'Eclairage (CIE) L*a*b* system. L* values of the specimens were analyzed using the Shapiro-Wilk and paired sample t tests (a = 0.05). Results: All groups showed similar survival mean cycles until failure (P = 0.332) and presented a major number of nonrestorable failures. The GI group presented the lowest number of nonrepairable fractures (GI = 68%, SF = 79%, FP = 86%) and showed the most stable L* value (P = 0.987). Conclusions: The fatigue survival of internally bleached ETIs was not affected by the restorative technique utilized. Retaining the glass-ionomer base and covering the surface with composite resin should provide optimal color stability. [ABSTRACT FROM AUTHOR]

Statement of problem: Ultrathin bonded posterior occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of erosive dental wear. Data regarding the clinical performance of ceramic and composite resin ultrathin occlusal veneers are lacking. Purpose: The purpose of this prospective randomized clinical trial was to evaluate the influence of computer-aided design and computer-aided manufacturing (CAD-CAM) restorative material (ceramic versus composite resin) on the clinical performance of ultrathin occlusal veneers bonded to worn posterior teeth. Material and methods: Eleven participants (mean age, 30.4 years) had their posterior teeth restored with 24 ceramic (e.max CAD) and 36 composite resin (Lava Ultimate) ultrathin occlusal veneers. The material type was assigned randomly. The tooth preparations were trial restoration driven and included immediate dentin sealing (OptiBond FL). The intaglio surfaces of the ceramic restorations were etched with hydrofluoric acid and silanated, and the composite resins were airborne-particle abraded and silanated. The tooth preparations were airborne-particle abraded and etched with phosphoric acid before restoration insertion. All restorations were adhesively luted with preheated composite resin (Filtek Z100). The participants were evaluated according to the modified United States Public Health Service (USPHS) criteria at baseline and then each year for up to 3 years. Survival rates were estimated with time to failure (primary outcome of interest) as the endpoint (scores 4 or 5). Results: No restorations were lost. Five partial failures, in the form of chipping (all scored 4), were observed in the composite resin group (Lava Ultimate). The Kaplan-Meier survival rates were 100% for ceramic and 84.7% (SE 0.065%) for composite resin. Differences between the 2 groups were not statistically significant (P=.124). In the surviving restorations, significant difference (P=.003) was found for surface roughness as restorations in the composite resin group experienced some surface degradation. Conclusions: The findings of this medium-term clinical trial suggest that ceramic (e.max CAD) and composite resin (Lava Ultimate) CAD-CAM ultrathin occlusal veneers presented statistically comparable performance regardless of the minor partial failures (restorable chipping) observed in the composite resin group. Higher surface degradation was observed in the composite resin group. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of the thickness and type of computer‐aided design and computer‐aided manufacturing (CAD‐CAM) material on the fatigue resistance and failure mode of endodontically treated teeth (ETT) restored with occlusal veneers (OV). Materials and methods: Seventy‐five (N = 75) ETT were restored with Herculite XRV in the endodontic access. Five experimental groups (n = 15) were tested. Four groups had two different thicknesses (0.6‐0.7 mm or 1.4‐1.6 mm) and two different CAD‐CAM materials: zirconia‐reinforced lithium‐silicate (LS/Celtra Duo) and composite resin (RC/Cerasmart). The fifth group (control) did not have occlusal veneers. All the specimens were subjected to accelerated fatigue (5 Hz frequency) with an occlusal load increasing up to 1800 N and 131,000 cycles. The number of cycles was recorded when the machine stopped or at the completion of the test. Fatigue resistance was analyzed using the Kaplan‐Meier survival test (95% significance level, log‐rank post hoc pairwise comparisons). The samples were categorized according to failure mode. The CAD‐CAM materials were examined through scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDS). Results: No differences were found between the thicknesses, regardless of the type of the CAD‐CAM material. The thick LS OV outperformed the RC and control groups. The thin RC OV and control groups showed a higher percentage of repairable and possibly repairable failures than the other groups. LS was more homogeneous under SEM, and the EDS analysis detected Si and Zr, but not Li. Conclusions: A larger thickness did not improve the resistance of the CAD‐CAM materials. Thick LS showed a higher cumulative survival rate to fatigue than the RC and control groups. The direct composite alone (control) survived similarly to the experimental groups, except for the thick LS. [ABSTRACT FROM AUTHOR]

Biomimetic restorations must have the utmost respect for hard tissue integrity and provide superior clinical service. Composite resins play a major role in achieving these goals. Resin-based materials' minimally invasive nature and cost-effectiveness are also making them increasingly popular for use with CAD/CAM systems, particularly when direct techniques are challenging to apply (e.g., cervical margins in dentin, large shrinking volume, and costs for the indirect technique are prohibitive). In anterior teeth, the milled product can be esthetically improved by histo-anatomical reduction of the CAD/CAM dentin base (i.e., incisoproximal cutback) and freehand covering with a generic enamel layer. With both anterior and posterior semi-direct techniques, patients can be treated either semi-directly in a single clinical session or semi-indirectly in two clinical sessions. This article presents semi-(in)direct composite resin approaches--valuable new tools in the restorative armamentarium--as viable, predictable, time- and cost-effective alternatives that bridge the gap between direct and indirect techniques. [ABSTRACT FROM AUTHOR]

Photography is an essential tool in esthetic dentistry. In this visual essay, the author emphasizes how the art and science of photography have influenced his career, inspired his work, and given him valuable insights into visual perception and esthetic analysis. The dental camera serves as an objective "third eye" for the operator throughout diagnostics, color matching, laboratory and clinical documentation, as well as fine adjustments during the final delivery of esthetic restorations. However, photography is also a tool to more closely observe nature in dentistry and beyond, as well as to express our deepest emotions for a true artistic experience. It enables us to see beyond what is possible with ordinary vision alone. [ABSTRACT FROM AUTHOR]