Evaluation of the effects of different CAD/CAM materials, anterior tooth morphology and tooth preparation on stress distribution in laminate veneer restorations: Finite element analysis

In this finite element analysis (FEA) study, the distribution of von Mises stresses was evaluated on different anterior tooth morphologies under two directions of static forces, by applying different preparation designs and various CAD/CAM restorative block materials to porcelain laminate veneers (PLVs), which are widely preferred in modern aesthetic dental treatments. Additionally, the structural fracture resistance of the restorative materials under simulated biting stresses was analyzed using three-dimensional finite element analysis (3D FEA). For PLVs commonly used in the anterior region, central, lateral, and canine teeth were modeled in both non-prep and minimally prepared forms. The preparation design included a chamfer finish line at the gingival level, and in prepared teeth, the incisal edge was shaped with an incisal bevel. For the non-prep and 0.5 mm depth preparations, restorations were virtually designed with 0.5 mm thickness using the properties of IPS e.max CAD (Ivoclar Vivadent), LAVA Ultimate (3M ESPE), and Vita Enamic (Vita Zahnfabrik) CAD/CAM materials, in accordance with the manufacturers' instructions. Considering clinical application, a 100 μm thick light-cured RelyX Veneer (3M ESPE) resin cement layer was simulated between the restoration and the tooth surface. To simulate biting force, in the planned 3D FEA, a 100 N force was applied at an angle of 60° and 125° to a point located 1 cm from the incisal edge along the long axis of the tooth. The effects of this force on stress distribution in the models were analyzed both with color-coded mapping and numerical data. According to the study findings, whether preparation was performed affected the stress distribution on both the restorations and the tooth surfaces. It was observed that restorations in non-prep groups were exposed to lower stress levels. As the functional force angle increased, stress increased in restorations on central incisors, while it decreased in lateral and canine teeth. As the material hardness increased, the stress observed on the PLVs increased, while the stress transferred to the tooth structure decreased. Among the anterior teeth, the highest stress value was observed on the lateral tooth due to its morphological structure. No significant differences were found between materials in terms of structural fracture resistance. KEYWORDS: Laminate veneer, Non-Prep, Finite Element Analysis, CAD/CAM