Abstract
Objectives The aim of this study was to evaluate the influence of inlays/onlays with or without
pulp extension from different materials on stress distribution in endodontically treated
molars by three-dimensional finite element analysis (3D FEA).
Materials and Methods We used 3D mandibular molar models in this study. The models represented mesio-occluso-distal
(MOD) cavities restored by inlays, onlays that covered buccal cusps, and onlays that
covered all cusps with pulp extension (modified inlay/onlay) or without pulp extension
(conventional inlay/onlay). Three materials (L: lithium disilicate glass-ceramic,
P: polymer-infiltrated ceramic network [PICN], and C: nanofilled composite resin)
were utilized. A force of 600 N was applied vertically and obliquely. Stress distribution
in FEA models was analyzed using the von Mises theory.
Results The results revealed that an oblique load generated higher stresses than vertical
load. Composite resin restorations transmitted almost all the stress to the neighboring
tooth structures, while lithium disilicate ceramic restorations absorbed most of the
stresses. Moreover, modified inlays and onlays with pulp extension proved better than
conventional inlays/onlays in terms of stress redistribution in dental structures.
Onlays showed a better pattern of stress distribution than inlays within the restoration
and the restored tooth.
Conclusions According to stress distribution in dental structures, modified lithium disilicate
ceramic onlays with pulp extension have been found to be the best choice to restore
endodontically treated molars among the studied restorations.
Keywords
inlay - onlay - restoration materials - restoration design - finite element analysis
