Purpose: The current in-vitro investigation analyzed the impact of speed sintering and different finish line width on marginal adaptation, internal fit and microleakage of translucent monolithic zirconia crowns.
Materials and Methods: Sixty maxillary premolars were reduced based on basic guidelines of tooth preparation for a zirconia crown with either 0.5, 0.8 and 1.2 mm chamfer width (n=20̸each finish line width). After digital scanning and milling of zirconia crowns, the sintering procedure was performed in special furnace for two different sintering programs (n =10 per group) following either standard or speed sintering procedure. Each crown was cemented to its corresponding prepared tooth utilizing self-adhesive-resin cement. After 15000 thermal cycles between 5°C and 55°C, specimens were submersed in methylene blue for 12 hours. After sectioning bucco-lingually, marginal gap and cement film thickness values were recorded at nine sites using a digital microscope followed by microleakage scores examination.
Results: Tested groups with 0.5 mm chamfer widths had the greatest mean marginal gap values of 47.9±5.4 and 50.1±5.6 µm for both conventional and speed sintering respectively, while groups with 1.2 chamfer widths had the lowest mean gap values of 42.3±5.6 and 44.5±5 µm for both standard and speed sintering, respectively. Two-way ANOVA revealed statically insignificant impact of sintering procedure on crown adaptation (p=.08). The greatest mean microleakage score (3±088 µm) was obtained from the 0.5 mm chamfer width group, while the smallest (2±0.78 µm) score was obtained from the 1.2 mm chamfer width group.
Conclusions: Marginal adaptation and internal fit of translucent monolithic zirconia crowns are affected by width of the preparation margin while sintering protocol has little impact on adaptation.