Influence of Cavity Pretreatments on the Fracture Resistance of Premolars with Self-adhesive Cemented Composite Inlay

Abstract

The aim of this study is to investigate whether different cavity pretreatment approaches affect the strength of premolars restored with self-adhesive (SA) resin cemented-composite resin inlays after mechanical and water aging. A total of 120 intact maxillary premolars were divided into 10 groups (n = 12). Mesio-occluso-distal (MOD) cavities were prepared in the teeth of nine groups, except group I in which the teeth remained intact. In group II, cavities were unrestored. Following fabrication of composite resin inlays for groups III-X, in group III, the inlays were cemented using the etch-and-rinse (E and R) adhesive/conventional resin cement. In other groups, cementation was performed using a SA cement with or without cavity pretreatments as follows: group IV: SA cement alone, group V: acid etching of enamel and dentin, group VI: acid etching of enamel, group VII: universal adhesive in the selective enamel-etching mode, group VIII: universal adhesive in the E and R mode, group IX: ethylenediaminetetraacetic acid (EDTA) conditioning, and group X: 20% polyacrylic acid conditioning. After aging processes, static fracture resistance was tested. Data were analyzed using one-way ANOVA and Dunn tests (α = 0.05). Fracture resistance of the 10 groups yielded a significant difference (p < 0.001). The median fracture resistances in Newton were the following: Gr I = 1025A, Gr II = 311BC, Gr III = 785A, Gr IV = 500B, Gr V = 435B, Gr VI = 775A, Gr VII = 805A, Gr VIII = 411BC, Gr IX = 397BC, and Gr X = 312C. Unlike the conventional method, SA cementation could not restore the strength of inlay-cemented premolars. Selective enamel acid etching with or without universal adhesive significantly increased the fracture resistance. Selective enamel acid etching is recommended for increasing the fracture resistance of the SA cemented composite inlay to the level of intact teeth.