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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. [ABSTRACT FROM AUTHOR]

The clinical survival of different types of post-and-core systems requires assessment. The purpose of this retrospective clinical study was to evaluate the clinical survival rate (CSR) of custom-fabricated cast metal and prefabricated (both metal- and fiber-reinforced composite resin post) post-and-cores as a function of patient- and restoration-related variables. A retrospective analysis was conducted on electronic charts indicating that these patients had received some type of post-and-core between January 2003 and January 2018. A total of 754 records were included in the analysis based on the inclusion criteria. Data were analyzed by using the Kaplan-Meier and Cox proportional hazards analysis. Kaplan-Meier analysis demonstrated the mean survival time for each group to be 12.0 years for fiber-reinforced composite resin posts, 11.8 years for cast metal post-and-cores, and 10.2 years for prefabricated metal posts. Although the mean survival time differed by 1.8 years among groups, with prefabricated metal posts having a slightly higher risk of failure, this effect was not statistically significant (P =.067). The effect of post type also failed to reach significance when controlling for patient demographics and post position in a Cox proportional hazards analysis (P =.106). However, the Cox model did show that survival was associated with tooth position (P =.003), cement (P =.021), and type of restoration (P <.001). Analysis showed no evidence that post-and-core survival was significantly associated with 3 types of post-and-cores (custom-fabricated metal, prefabricated metal, and prefabricated fiber-reinforced composite resin). The percentage of root in the bone, tooth position, cement, and type of restoration, however, were significantly associated with survival. [ABSTRACT FROM AUTHOR]

Abstract Statement of problem Whether tooth whitening alters the surface topography of enamel causing an increase in surface roughness that could increase susceptibility to restaining is unclear. Purpose The purpose of this in vitro study was to evaluate whether immersing enamel in common solutions produces a color change of ΔE greater than 2; whether the highest concentration carbamide peroxide bleaching agent produces the greatest ΔE; whether bleaching increases the susceptibility to further staining by common solutions; and whether morphologic changes to the enamel surface are observed after staining and bleaching as evidenced by scanning electron microscopy (SEM) analysis and energy-dispersive X-ray spectroscopy (EDS). Material and methods Forty-five extracted human teeth were immersed in 5 solutions (wine, coffee, tea, soda, and water) for 15 days at 80°C, and the change in ΔE was assessed with a colorimeter. The teeth were bleached using different concentrations of carbamide peroxide (20%, 35%, and 44%) and ΔE was measured at different time intervals. The teeth were then restained with the same solutions. The ΔE after initial staining was compared with the ΔE after bleaching and restaining of the same teeth. SEM was performed at baseline, after staining, bleaching, and restaining to evaluate the changes in the enamel surface topography. EDS was used to determine the elemental composition of tooth surfaces after restaining. Results All liquids caused a ΔE greater than 2 after 15 days. The concentration of bleaching agent was not significantly associated with ΔE for any stain types. No significant difference was found in the rate of staining between initial staining and restaining after bleaching. However, a significant effect of time was found for the staining, where the overall ΔE increased by 0.34 for each day in the solution (P <.001). SEM images showed no major changes to enamel topography after bleaching. However, a coating was noted on teeth stained with wine and tea, which had different elemental compositions when compared with the tooth surface. Conclusions Based on SEM observation, bleaching teeth with carbamide peroxide does not increase the susceptibility of enamel to staining and does not alter the topography of the enamel. Using higher bleaching concentrations did not increase tooth whitening as a function of time. [ABSTRACT FROM AUTHOR]