The evaluation of stress patterns in porcelain laminate veneers with different restoration designs and loading angles induced by functional loads: A three-dimensional finite element analysis study.

BACKGROUND: Fractures in porcelain laminate veneers (PLVs) are a significant clinical problem. Preparation designs can affect stress distribution, which leads to fractures in PLVs. Therefore, identification of the most favorable preparation design in terms of stress distribution is required. OBJECTIVE: The purpose of this study is to examine the functional stress patterns of PLVs with featheredge, incisal bevel, and overlapped preparation designs under 0 degrees , 60 degrees , and 120 degrees functional loads using finite element analysis. MATERIALS AND METHODS: Porcelain veneers with three different preparation designs (incisal overlap, incisal bevel, and featheredge) were modeled. A cement layer of 100 mum of luting composite resin was assumed, and a thickness of 0.5 mm of porcelain veneers was used. All models were loaded at 0 degrees , 60 degrees , and 120 degrees to the long axis of the tooth to determine the stresses that may occur during mastication under different load angulations. A total force of 200 N was applied from the incisal edge of the models. RESULTS: Maximum stresses were recorded in the incisal overlapped design (53.3 MPa) under 120 degrees of functional load. Minimum stresses were recorded in the incisal bevel preparation design (22.37 MPa) under 0 degrees of functional load. CONCLUSION: Both the preparation design and load angle affected the stress distribution on the PLVs. The incisal bevel preparation design provided a more appropriate geometry for stress distribution compared with the other techniques. Lateral forces produced more stress on the tooth and laminate material than vertical forces.