Abstract: PURPOSE: To explore the effect of different depth and width of meiso-occlusal (Class Ⅱ) cavity type on the tooth tissue resistance stress after restoration with composite resin inlays. METHODS: The 3-D finite element model of mandibular first molar with meiso-occlusal (ClassⅡ) cavity restored with composite resin inlay was established by using CBCT scanning and reverse engineering software Mimics, Geomagic Studio, and finite element analysis software ANSYS. Comparative analysis of restoration with different depth and width meiso-occlusal (ClassⅡ) cavity under the same load of perpendicular and 45° deviation was explored, and finally the main stress and Von-mises stress changed as well as stress distribution were analyzed. RESULTS: The main stress was located in the gingival wall opposite to the inlay, while the major stress concentration area of the tooth was distributed near the canal at the bottom of the cavity. With the increase of the depth and width, the main stress and Von-mises stress distribution areas of tooth were getting larger. The Von-mises stress of tooth was influenced by the width variation of the cavity, while that depth change of cavity was affected by Von Mises stress of the inlay. CONCLUSIONS: With the increase of the depth and width of the cavity as well as lateral loading force, the peak stress of tooth with inlays increased and the distribution of stress concentration is modified after meiso-occlusal (ClassⅡ) cavity being inlayed with composite resin.

Key words: Meiso-occlusal (ClassⅡ) cavity, Composite resin inlay, Stress, Finite element analysis