Desensitizing bioactive agents improves bond strength of indirect resin-cemented restorations: preliminary results

Abstract

Objective: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material.

Materials and method: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5): Group I: acid etching + Prime & Bond NT (Dentsply); Group II: application of a bioactive glass (Biosilicato) + acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita); Group IV: Biosilicato + One-up Bond F. Indirect composite resin (Artglass, Kulzer) cylinders (6 x 10 mm) were fabricated and cemented to the teeth with a dual-cure resin-based cement (Enforce, Dentsply). After cementation, the specimens were stored in artificial saliva at 37 degrees C for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC) with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence).

Results: Groups I, II and III had statistically similar results (p>0.05). Group IV had statistically significant higher bond strength means (p<0.05) than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups.

Conclusion: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems.

FIGURE 1. Matrix used for fabrication of the composite resin specimens. A) disassembled; B) attached; and C) assembled

FIGURE 2. Specimens subjected to bond strength (loop) testing in a universal testing machine

FIGURE 3. Failure modes (%) for the studied groups

FIGURE 4. SEM micrograph of adhesive failure (G-IV – 2000x)

FIGURE 5. SEM micrograph of cohesive failure (G-IV – 2000x)

FIGURE 6. SEM micrograph of mixed failure (G-IV – 2000x)