Stress Distribution Pattern in Class I Cavities Restored by Different Techniques According to the Stress Reducing Direct Composite Concept: A Finite Element Analysis.

This study aimed to compare stress distribution in Class I cavities restored by different techniques according to the stress reducing direct composite (SRDC) concept using finite element analysis (FEA). In this FEA, a model of a three-rooted maxillary molar tooth with a Class I cavity was designed using Mimics 21, Geomagic Design X, and ANSYS software programs. The cavity was restored with a conventional micro-hybrid composite in Group A, bulk-fill composite in Group B, polyethylene fiber beneath the micro-hybrid composite in Group C, and self-cure composite beneath the micro-hybrid composite in Group D. Stress distribution in tooth during resin polymerization and following the application of 600 N load was evaluated in the four groups by FEA. The maximum von Mises stress and total deformation were reported. Almost equal maximum stress values were detected in the enamel close to the dentinoenamel junction and particularly at the marginal ridges in all groups. The maximum stress applied to the hybrid and adhesive layers was greater in Group A, compared with other groups. More uniform stress distribution in the cavity floor was detected in Groups B and C. Stress distribution in the restorative material was less uniform in Group D. Maximum deformation was noted in Group A, followed by Groups C, B, and D. In Class I cavities, application of polyethylene fiber beneath the micro-hybrid composite decreased the maximum stress applied to the adhesive and hybrid layers and total deformation, compared to the use of micro-hybrid composite alone; application of bulk-fill composite and self-cure composite beneath the micro-hybrid composite ranked next. Stress distribution in the cavity floor was more uniform in use of polyethylene fiber beneath the micro-hybrid composite and application of bulk-fill composite.