Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin

Abstract

Background: The purpose of this study was to evaluate the influence of three different luting

protocols on shear bond strength of computer aided design/computer aided manufacturing

(CAD/CAM) resin nanoceramic (RNC) material to dentin.

Materials and Methods: In this in vitro study, 30 disks were milled from RNC blocks

(Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to

the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens

were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using

a total‑etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal

Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a

self‑etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in

Group 3, disks were cemented using a self‑adhesive protocol (RelyX™ Unicem 2 Automix self‑adhesive

resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing

Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between

the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min.

Data were analyzed with analysis of variance and post‑hoc Tukey’s test at a level of significance of 0.05.

Results: Post‑hoc Tukey testing showed that the highest shear strength values (P < 0.001) were

reported in Group 2. The lowest data (P < 0.001) were recorded in Group 3.

Conclusion: Within the limitations of this in vitro study, conventional resin cements (coupled with

etch and rinse or self‑etch adhesives) showed better shear strength values compared to self‑adhesive

resin cements. Furthermore, conventional resin cements used together with a self‑etch adhesive

reported the highest values of adhesion.

Key Words: Adhesive cements, computer aided design/computer aided manufacturing ceramic, shear bond strength