title: Influence of cavity design on the biomechanics of direct composite resin restorations in Class IV preparations.
abstract: This study evaluated the effect of cavity design on stress distribution and fracture resistance of direct composite resin restorations in Class IV preparations. A finite element analysis (FEA) model of the maxillary central incisor with a Class IV cavity was established. Five model variations were studied: (i) a 1-mm bevel (ii) a 2-mm bevel, (iii) a plain chamfer, (iv) a stair-step chamfer, and (v) butt joints (a control configuration). All FEA variations modeled a tooth restored with composite resin loaded under 100 N at an angle of 45° to the longitudinal axis. The interfacial von Mises stress was evaluated. The FEA was complemented with an in vitro assessment. Fracture resistance of direct composite resin restorations was tested with a universal testing machine and fracture patterns were observed. Finite element analysis showed that stress in chamfer and stair-step chamfer models was more homogenously distributed, while stress in bevel models was relatively concentrated at lingual regions. Fracture resistance of a 1-mm bevel preparation was lower than for the 2-mm bevel, plain chamfer, and stair-step chamfer preparations, but was higher than for butt joints. The stair-step chamfer group presented the most favorable failure pattern. Considering biomechanics and esthetics, the present study indicates that the stair-step chamfer and 2-mm bevel should be recommended for clinical restoration.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Haiping
authors.initials: H
authors.lastname: Xu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Jiang
authors.forename: Ximei
authors.initials: X
authors.lastname: Xiao
authors.forename: Jing
authors.initials: J
authors.lastname: Fu
authors.forename: Qin
authors.initials: Q
authors.lastname: Su
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D003188:Composite Resins; D003198:Computer Simulation; D003737:Dental Cavity Preparation / Q000145:classification* / Q000379:methods*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000502:physiology; D008422:Materials Testing
chemical_list: D003188:Composite Resins