Influência dos protocolos de finalização de preparos protéticos em dentina na adesão à compósito vitrocerâmico

Abstract

This study aimed to evaluate the influence of different post-prosthetic preparation dentin finishing protocols on the bond strength of the glass-ceramic composite for CAD-CAM - Brava Block (FGM Dental Group, Joinville, SC, Brazil). 126 sound human third molars were used, in which the occlusal surface was sectioned and the exposed dentin surface was standardized with a silicon carbide sandpaper disc (#600) and prepared with a cylindrical diamond bur (#3145, KG Sorensen, Cotia, SP, Brazil). The specimens were divided into 7 groups (n=18) with different finishing instruments: FB (F and FF diamond burs), MB (multilaminated burs), UT (ultrasonic diamond tips), MS (mounted stones of aluminum oxide and silicon carbide), SB (sintered diamond burs), APA (airborne-particle abrasion), RC (resin coating). Representative specimens were analyzed by scanning electron microscopy (SEM) and confocal laser microscopy - LEXT to evaluate the surface roughness and characteristics of the deposited smear layer. Glass-ceramic composite blocks for CAD-CAM - Brava Block (FGM Dental Group, Joinville, SC, Brazil) (14x14x5 mm) were prepared and cemented with conventional dual resin cement (Panavia V5, Kuraray Noritake Dental, Tokyo, Japan) under control of pressure. The resulting specimens were stored under absolute humidity for 24 h and then serially sectioned perpendicularly to the adhesive surface, obtaining rectangular sticks of approximately 1 mm² of adhesive area. These sticks were fixed in a specific microtensile device and subjected to a tensile stress at a speed of 0.7 mm/min until the specimens failed. The results of analysis of variance revealed statistically significant differences in bond strength between different substrate finishing methods. The RC group showed the highest bond strength, followed by the MS, APA and FB groups. There was no statistically significant difference between the APA and FB groups. The group with the lowest bond strength was the MB group, followed by the SB and UT groups. Roughness analysis showed statistically significant differences between groups. The FB, APA and RC groups showed greater roughness and statistically differed from the others. However, there were no statistically significant differences between these three groups. The analysis of the smear layer thickness showed statistically significant differences between the groups. The FB group had the highest 11 thickness of the smear layer deposited on the dentin surface, followed by the APA and MB groups. The UT, MS and SB groups had lower smear layer thickness and did not present significant differences between themselves, but differed from the other groups. In conclusion, the methods of finishing and finalizing the dentin substrate after prosthetic preparation influenced the bond strength, surface roughness and formation of the smear layer.