Avaliação laboratorial e clínica de protocolos restauradores de Lesões Cervicais Não Cariosas

Abstract

Noncarious cervical lesions (NCCLs) are characterized by loss of mineralized tissue at the cementum-enamel junction and presents multifactorial etiology, involving stress, friction and corrosion agents. Although there is no consensus regarding clinical management, the control of NCCL is the evaluation and management of etiological factors and restoration mainly with composite resin. Considering this, the general propose were to evaluate the clinical and biomechanical behavior of NCCL’s restorative protocols, divided into four specific objectives: 1- to evaluate the effect of occlusal pattern, restorative procedure and morphology of NCCL on the biomechanical behavior of maxillary premolar; 2- to analyze the influence of the NCCL restorative technique on the residual shrinkage stress and degree of conversion of composite resins; 3- to evaluate the stress-strain pattern of intact maxillary premolar submitted to mechanical fatigue; and 4- to analyze the clinical success rate of NCCL restorative protocols, divided into two study factors: gingival displacement (with and without gingival retraction cord); and method of applying the universal adhesive system. For this study, 3D finite element analyze, in vivo strain gauge test, 2D finite element analyze, ex vivo strain gauge test, fourier transform infrared spectrophotometer and randomized clinical trial were performed. As a result, occlusal contact outside the long axis of the tooth and the mechanical fatigue process have been shown to increase the concentration of stress and strain in the buccal cervical region, especially when the contact is in the grinder slope of the buccal cusp. The presence of NCCL increase the stress and strain values, however, its morphology does not significantly interfere on the biomechanical behavior. The restorative procedure dissipates more homogeneously the stress generated by the occlusal forces, resulting in a mechanical behavior closer to the intact tooth. The technique of insertion of one increment, either of conventional or low shrinkage composite resin, is the most indicated for NCCL of up to 2mm of depth, because it presents lower residual shrinkage stress and adequate degree of conversion. When analyzing the longevity of the restorations, the mean success rate was 92.8% in 180 days. Therefore, it were concluded that the occlusal arrangement should be periodically evaluated to identify possible premature contacts or occlusal interference; the restoration is a fundamental step for the control of NCCLs; the technique with single or bulk-fill increment is indicated to restore these cavities; the gingival displacement with retracting cord and the method of applying the universal adhesive system did not influence the longevity of the NCCL restorations in up to 180 days.