Restauração de resina composta em dentes posteriores: avaliação de uma técnica simplificada

Abstract

Studies have shown good clinical performance for composite resin restorations with results over 22 years showing relatively low annual failure. However, some techniques still result in undesirable consequences for patients such as postoperative sensitivity, broken dental structure, and marginal restoration management. The present study aimed to evaluate the performance of composite resin restorations used with a simplified restorative technique for posterior teeth (Natural Enamel and Dentin Substitution - NE&DS). In this technique, the material was applied in layers, simulating the structurally drawing of the enamel and dentin substrates, as applicable in the distribution of the sigmoid curve (convex enamel / concave dentin). Also, the influence of the type of composite resin used to make restorations on teeth with the different restoration techniques was evaluated. An incremental fill technique (IFT), a natural dentin and enamel substitution technique (NE&DS), a total bulk fill technique and a simplified incremental fill technique (IST) were evaluated for biomechanical behavior. As physicochemical properties of X-tra Fill composite resins, Filtek Z350 XT was evaluated by (i) kinetics and polymerization rate evaluation, (ii) polymerization depth, (iii) post-gel shrinkage evaluation. composite resins, (iv) diametral tensile strength and (v) compressive strength. Restorations performance was evaluated by: (i) cuspal strain, (ii) transillumination to detect enamel crown cracking, (iii) mechanical cycling, (iv) radiodensity, (v) finite element methodology and (vi) microtensile bond strength. The degree of conversion of compound X-tra Fill was 35.2% ± 5.4 and Filtek Z350 XT 29% ± 4.1; cure depth X-tra Fill 9.2 ± 0.2; a diametral tensile strength (MPa) was 45.9 ± 5.3, a compressive strength (MPa) of 266.3 ± 24.9 and a modulus of elasticity (GPa) of 5.6 ± 0.2. In the performance of restorations, technical simplification does not interfere with biomechanical properties. The cusp strain test showed statistical difference between the groups, the IFT technique obtained a high value of 339.0 (75.2) during the restorative technique compared to the other groups. The 100N load test according to NE&DS 29.2 (5.0) was smaller compared to other groups, while IST 839.6 (133.2) showed less deformation compared to other techniques during fracture resistance. As restorative filler techniques, NE&DS and IST were able to decrease stress without impairing the mechanical strength of the restorations.