Efeito da relação de sistemas adesivos e cimentos resinosos duais na adesão de uma cerâmica de dissilicato de lítio CAD-CAM em substratos dentinário e resinoso

Abstract

Despite advances in adhesive dentistry, there are still gaps in the understanding of the safest clinical protocols for combining adhesive systems and dual resin cements in the cementation of CAD-CAM lithium disilicate ceramics (LD) on dental and restorative substrates. The aim of this study was to evaluate in vitro the effect of different adhesive systems on the shear bond strength (SBS) of a LD cemented to dentin and composite resin using dual-cured resin cements, as well as on the degree of conversion (DC) of the cements. A total of 238 LD samples were made, distributed, and cemented onto 119 dentin (D) and 119 composite resin (CR) samples using RelyX ARC (RARC), RelyX Ultimate (RULT), and RelyX U200 (RU200) dual-cured resin cements, with or without the adhesive systems Adper Scotchbond Multipurpose (ASM), Adper Single Bond 2 (ASB2), Clearfil SE Bond (CSE), and Single Bond Universal (SBU), resulting in 11 experimental groups for each substrate (n = 10): 1 - RARC/CR; 2 - RARC/D; 3 - RARC/ASM/CR; 4 - RARC/ASM/D; 5 - RARC/ASB/CR; 6 - RARC/ASB/D; 7 - RARC/CSE/CR; 8 - RARC/CSE/D; 9 - RARC/SBU/CR; 10 - RARC/ SBU/D; 11 - RULT/CR; 12 - RULT/D; 13 - RULT/ASM/CR; 14 - RULT/ASM/D; 15 - RULT/ASB/CR; 16 - RULT/ASB/D; 17 - RULT/CSE/CR; 18 - RULT/CSE/D; 19 - RULT/SBU/CR; 20 - RULT/SBU/D; 21 - RU200/CR; 22 - RU200/D. After cementing, the SBS test was performed on 220 samples in a universal testing machine. The types of fractures were evaluated under an optical magnifying glass on all the samples. The DC was evaluated by micro-Raman spectroscopy on 18 samples cut into 3 slices (n = 3) after cementation, and on the central slice, the adhesive interface was analyzed by scanning electron microscopy (SEM). For each substrate, the groups were compared using 2-way ANOVA, followed by appropriate post-tests (α = 0.05). In the CR cemented groups, the SBS was influenced only by the adhesive used (p = 0.021) and was higher in the RARC/SBU group compared to its control group (p = 0.003). In general, the most frequent fractures were ceramic/cement adhesive and mixed failures. On the D substrate, SBS was influenced by the cement and adhesive used (p < 0.001). For conventional cements, there was no difference in SBS when varying the adhesive systems, and all were superior to their respective negative control groups (p < 0.001). For the same adhesive, SBS was similar in the RARC and RULT groups, and higher than RU200 (p < 0.001). With the exception of the negative control groups, mixed failures ranged from 40 % to 100 %. Cement/dentin adhesive failures were 60 % in the RULT/CSE and RU200 groups. Ceramic cohesive failures occurred in 30 % to 50 % of the RARC groups. For both substrates, the DC was only influenced by the type of cement used (p < 0.001), with the RARC groups showing higher DC values. RU200 had the lowest DC and was similar to the RULT groups when cemented on CR . In general, the adhesive systems evaluated did not influence the DC of the dual resin cements used to cement the DL to the two substrates, nor the SBS of the DL cemented to composite resin. When cementing on D, the adhesives promoted better adhesion of the ceramic. Additionally, RARC cement had the best DC among the cements tested.