942 Int. J. Odontostomat., 15(4):942-947, 2021. Table-Top Lithium Disilicate Ceramic Restoration Thickness Effect on the Stress Distribution in Upper Premolars: 3D Finite Element Analysis Efecto del Espesor de la Restauración de Cerámica de Disilicato de Litio de Sobremesa en la Distribución de Tensiones en los Premolares Superiores: Análisis de Elementos Finitos 3D Alexandre Luiz Souto Borges 1 ; Roberta dos Santos Rangel Silva 1 ; Jefferson David Melo de Matos 1 ; Amanda Maria de Oliveira Dal Piva 1 ; Oswaldo Daniel Andreatta Filho 1 ; Guilherme da Rocha Scalzer Lopes 1 & João Paulo Mendes Tribst 2 BORGES, A. L. S.; SILVA, R. S. R.; DE MATOS, J. D. M.; DAL PIVA, A M. O.; FILHO, O. D. A.; LOPES, G. R. S. & TRIBST, J. P. M. Table-top lithium disilicate ceramic restoration thickness effect on the stress distribution in upper premolars: 3D finite element analysis. Int. J. Odontostomat., 15(4):942-947, 2021. ABSTRACT: To evaluate the stresses generated in upper premolars rehabilitated with ceramic fragments (table-top) of lithium disilicate on the occlusal surface. An upper premolar was modeled following its anatomical references using computer aided design software (Rhinoceros version 5.0 SR8, USA). The dental tissues were individually designed containing enamel, dentin and periodontal ligament. The main anatomical points were used as parameters for model creation. Ceramic fragments were modeled varying their maximum thicknesses as: 0.5 mm, 1.0 mm and 1.5 mm. Solid geometries were exported to the analysis software (ANSYS 17.2, USA) in STEP format. The materials were considered isotropic, homogeneous and linear, and the values of the elastic modulus of the materials and structures were used to perform a static structural mechanical analysis. The set was submitted to 200 N load. The system fixation was defined on the basis of the three- dimensional model, and the results were obtained in MPa according to the failure criteria of the analyzed materials (tensile stress). Occlusal restoration was not detrimental to mechanical behavior. Stress distribution in the internal region of the restoration was similar between the groups. Thicker fragments presented a lower concentration of tensile stress, therefore suggesting better prognosis in attenuating tensile stresses in the tooth region. More conservative occlusal ceramic fragments presented worse prognosis. However, all evaluated thickness for table-tops support the occlusal rehabilitation of upper premolars when submitted to 200 N loading. KEY WORDS: ceramics; finite element analysis; fixed prosthesis. INTRODUCTION Considering the stressful routine faced by many patients, bruxism or briquism is constantly present in dental offices. Bruxism can be defined as a parafunctional habit or non-functional contact that manifests eccentrically (teeth grinding) or centrically (teeth tightening) (Wigdorowicz-Makowerowa et al., 1979). This habit has a multifactorial nature such as of emotional or stress origin. The treatment of bruxism is still debatable. However, among the most accomplished methods are the preparation of an occlusal splint, pharmacological therapy and psychological support therapy (Attanasio, 1997). As a sign of this parafunctional habit, there is the presence of wear on the incisal surface of anterior teeth and occlusal surface of posterior teeth (Calderon et al., 2006), which reduces the vertical dimension of occlusion (VDO). The VDO consists of the jaw’s ver- tical position in relation to the maxilla, measured between two points when the upper and lower teeth are in intercuspid contact in the position of maximum closure (Dawson, 1985). Its decrease does not lead to great discomfort, but it influences the opening and 1 Department of Dental Materials and Prosthodontics, São Paulo State University (Unesp), Institute of Science and Technology, São José dos Campos - SP, Brazil. 2 Department of Dentistry, University of Taubaté (UNITAU), São Taubaté - SP, Brazil - SP, Brazil. Received: 2021-04-23 Accepted: 2021-08-28