Influence of preparation design on fracture strength of ceramic veneers

Abstract

Purpose: The aim of this study was to access the influence of preparation design on fracture strength of CAD/CAM ceramic veneers in lower incisors. Methods and materials: 30 human lower incisors were selected after approval of Ethics Committee of Federal University of Santa Catarina and randomly divided into 3 groups: 1(DH): sound incisors, 2 (SRI): preparation without incisal reduction+ ceramic veneer and, 3 (CRI): preparation with incisal reduction (1.5mm)+ceramic veneer. The preparations were made with diamond burs (1011, 4138, 4138F and 4138FF, Microdont, Sao Paulo, SP, Brazil), silicone guides and amillimeter probe were use to measure the wear. All ceramic veneers (IPS e.max CAD LT BL1/C14) were design using CERED 3D (Software V.3.80) and subsequently machined in CEREC MC XL (Sirona Dental Systems, Bensheim, Germany). The specimens were embedded in a 65◦ angulation. After storage in distilled water at 37 ◦C for 7d, the specimens were subjected to compression test and the then, fracture analysis patterns. Results: Statistical analysis showed significant difference between the groups DH e CRI, e SRI e CRI (p>0.05). The 1.5mm incisal reduction decreased fracture strength of tooth/restoration under compression forces. 19 specimens (63.33%) showed tooth fracture; 5 (16.66%) exhibited ceramic fracture and13 (43.33%) showed toothand restoration fracture. Conclusion: It was concluded that incisal reduction design for ceramic veneers in lower incisors decreases tooth/restoration fracture strength.