Effect of different restoration techniques and cavity designs on cuspal deflection of posterior teeth restored with resin composite inlays

Objectives: The aim of this study was to evaluate the influence of different restoration techniques (immediate dentin sealing (IDS) restoration techniques) and cavity designs on the cuspal deflection of posterior teeth that were restored with resin composite inlays. Methods: Sixty caries-free extracted maxillary premolars were selected and equally divided into two experimental groups. Group D1: MOD cavities were prepared. Group D2: MOD cavity with gingival steps. Each group was subdivided to three subgroups (n = 10) and restored as follows: inlay without IDS; inlay with IDS and adhesive system; inlay with IDS and adhesive system and low-viscosity resin. Cuspal deflection was measured with a micrometer. One-Way Analysis of Variance ANOVA was used to analyze the results. Results: Cavity design D1 showed the lowest cuspal deflection compared to cavity design D2. In group D1; Inaly without IDS showed the highest significant cuspal deflection (9.85 μm) followed by Inaly + IDS + Low viscosity resin (7.16 μm). The lowest value was obtained for Inaly + IDS group (4.76 μm) with significant difference between all tested restoration techniques. In group D2; Inaly without IDS showed the highest significant cuspal deflection (14.7 μm) followed by Inaly + IDS + Low viscosity resin (11.69 μm). The lowest value was obtained for Inaly + IDS (9.59 μm) with a significant difference between all tested restoration techniques. Conclusion: IDS and Protect Liner F allowed less cuspal deflection comparable with traditional technique. However, IDS restoration techniques did not decrease the cuspal deflection in case of more extensive loss of dental structure in the premolar teeth. Keywords: Cuspal deflection, Inlay, Cavity design, Restoration techniques