RESUMO
STATEMENT OF PROBLEM: Marginal integrity and internal adaptation are key to the long-term success of porcelain laminate veneers. Evidence for their marginal and internal fit is unclear, and the factors affecting such fit have not been identified. PURPOSE: The purpose of this systematic review and meta-analysis was to summarize the scientific literature assessing the effects of various parameters on the marginal and internal fit of porcelain laminate veneers. MATERIAL AND METHODS: An electronic search was conducted to identify all relevant published articles on the fit accuracy of ceramic veneers between January 2000 and June 2021 in the PubMed-MEDLINE, Scopus, Embase, Google Scholar, and Web of Science databases. Information, including the study outcomes, in terms of the mean marginal gap, internal gap, and absolute marginal discrepancies of porcelain laminate veneers, was extracted from the selected studies. The inverse-variance random effects model was used to analyze the pooled results and estimate the overall effect based on the heterogeneity of studies (α=.05). RESULTS: Twenty-one studies were selected for analysis, 2 clinical and 19 in vitro. The risk of bias was "medium" for most studies (19 of 21), and only 2 studies were classified as "high risk." A mean difference of -4.53 µm (95% CI: -21.46 to 12.41) was found, with no statistically significant difference in marginal gap between the pressed and milled fabrication modes (P=.600). As for the internal gap, significant differences were found (mean difference=-40.56 µm; 95% CI: -76.54 to -4.58), with pressed veneers performing better (P=.030). Butt joint preparation design produced significantly (P=.002) lower marginal gaps than the palatal chamfer (mean difference=-14.02 µm; 95% CI: -23.07 to -4.98). CONCLUSIONS: No significant differences were found between the pressed and milled porcelain laminate veneers for marginal gap, but for the internal gap, the differences were significantly in favor of the pressed type. The butt joint veneer preparation design was significantly better than the palatal chamfer design in terms of marginal fit.
RESUMO
This study sought to evaluate the effects of different staining solutions on the colour stability of nanocomposites compared with microhybrid resin and to evaluate the degree of conversion of these two materials. Two different shades of two different composites were cured in polytetraflouroethylene disk rings. Coffee, tea and cola drinks were used as staining solutions, and distilled water was used as a control. Data were statistically analysed using a paired T-test with a significance level of 5%. Nano composite showed the highest degree of conversion (DC) values based on calculation of the bonded and free carbonyl peak intensities in the spectrum. The colour analysis showed that nanohybrid had the highest ΔE values when exposed to coffee solutions; they showed less color stability despite having a higher degree of conversion. Nano resin composite showed significantly higher discoloration than microhybrid composite.
