Remoção seletiva de dentina cariada e selamento pulpar com ionômero de vidro reduz tensões de contração em restaurações de resina composta bulk-fill em molares

Abstract

Dental caries in young molars progress rapidly, generating the need for restorative interventions in cavities involving dentin degradation. The removal of infected and caries-affected tissue is still controversial in the most appropriate strategy to be used. According to this context, the purpose of this study was to evaluate the effect of selective or total caries removal on molars affected by deep caries restored using bulk fill composite resin (Tetric N Ceram, Ivoclar Vivadent) with or without the use of a protective layer of the complex dentino-pulp with resin-modified glass ionomer cement, RMGIC (Vitrebond, 3M Oral Care) in the distribution of tension in the pulp chamber roof as a possible cause of pulp sensitivity. Finite element models were created from digital X-ray of the lower first molar characterizing the experimental groups: I. healthy tooth; II. tooth with deep caries; III. selective removal of infected dentin using a glass ionomer liner; IV. selective removal of infected dentin and without using a glass ionomer liner; V. non-selective removal of decayed dentin and using a glass ionomer liner; and VI. non-selective removal of decayed dentin and without using a glass ionomer liner. The dentin healthy elasticity module, affected and infected tooth decay was calculated using dynamic nanoindentation. The post-gel contraction of the bulk fill and RMGIC composite resin were determined using the extensometry method. The modified Von Mises tension (MPa) was extracted at the nodes of the inner wall of the pulp ceiling chamber after a restorative procedure and with a 100N occlusal load simulation. The data were analyzed qualitatively by images of stress distribution patterns and quantitatively by stress peaks along the pulp chamber roof. Both factors of the study influenced the stress concentration during the restorative procedure. The tension generated during the restorative procedure was higher for non-selective caries removal without using RMGIC (25.9 MPa) and lower for selective caries removal using RMGIC (13.5 MPa). Molar with deep caries showed high tension in the pulp roof (89.6 MPa) and in the weakened coronal structure. During the bite force simulation, the group with non-selective caries removal without using RMGIC presented higher modified von Mises tension values than the selective caries removal associated with the use of RMGIC. The selective removal of caries followed by the use of RMGIC reduced the sensibility on the pulp chamber roof after restoration and during the bite force. The pulp sensitivity observed in molar teeth affected by caries during the chewing process can also be explained by the high concentration of stresses in the roof of the pulp chamber. The selective removal of caries in molar teeth with deep caries, in addition to avoiding accidental pulp exposure, can also minimize the occurrence of pulp sensitivity after restoration with bulk fill composite resin, especially when associated with RMGIC.