Effect of Bonding Protocols on the Performance of Luting Agents Applied to CAD–CAM Composites

Abstract

This in vitro study aimed to evaluate the effect of different bonding strategies on the micro-shear bond strength (μSBS) of luting agents to CAD–CAM composites. Surface scanning electron microscopy (SEM) and spectroscopy by energy-dispersive X-ray spectroscopy (EDS) were performed to analyze the surfaces of the composite before and after bonding treatment. Three CAD–CAM composites were evaluated: Lava Ultimate restorative (LU), Brava Blocks (BR), and Vita Enamic (VE). The LU and BR surfaces were sandblasted using aluminum oxide, while the VE surfaces were etched using a 5% hydrofluoric acid gel according to the manufacturers’ recommendations. All surfaces were subjected to the following bonding strategies (n = 15): adhesive with silane and MDP (ScotchBond Universal, 3M Oral Care, St Paul, MI, USA); adhesive with MDP (Ambar Universal, FGM, Joinville, Brazil); adhesive without silane or MDP (Prime&Bond Elect, Dentsply Sirona, Charlotte, NC, USA), pure silane without MDP (Angelus, Londrina, Brazil), and pure silane with MDP (Monobond N, Ivoclar Vivadent, Schaan, Liechtenstei). Afterwards, tygons were filled with RelyX Ultimate (3M Oral Care), AllCem (FGM), or Enforce (Dentsply Sirona), which were light-cured and subjected to the μSBS test. Data were analyzed using two-way ANOVA and Bonferroni’s post hoc test (α = 0.05). Additional blocks (n = 15) were subjected to scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) before and after the surface treatment. The μSBS values on VE surfaces were higher than those observed on LU and BR surfaces (p < 0.001). Silane without MDP (Allcem) promoted the highest μSBS values, while silane with MDP (RelyX Ultimate) provided the highest values among all bonding strategies (p < 0.001). Enforce promoted no significant difference in μSBS values. SEM and EDS analyses detected noticeable changes to the surface morphology and composition after the surface treatment. The effectiveness of the bonding strategy may vary according not only to the CAD–CAM composite but also to resin cement/bonding agent/silane used.

A Polymer-Infiltrated Ceramic as Base Adherent in an Experimental Specimen Model to Test the Shear Bond Strength of CAD-CAM Monolithic Ceramics Used in Resin-Bonded Dental Bridges

“…If the purpose is to manufacture an authentic restoration, this issue should be assessed carefully [53,54] and visual inspection with magnification before delivery should be encouraged. Nevertheless, it was not considered a real constraint for the experimental purpose, as the adherend was a homogeneous industrial material subjected to standardized surface treatment for every experimental condition, with an expected good adhesive if combined with Rely X Ultimate cement [46]. In contrast, the materials used in the cylinders were expected to differ according to the manufacturer's datasheets [25,55,56].…”

“…This aspect is pertinent because the release of these monomers must be added to that released from the restoration itself whenever a resinbased CAD-CAM material is used, except for Vita Enamic (ENA) [45], probably because of its particular structure. For these reasons, a dual-cured adhesive cement, RelyX Ultimate (RU) (3M ESPE, Seefeld, Germany) with a 3-steps adhesive strategy under photoactivated polymerization was used to assemble the experimental model [36,46,47]. Advances in adhesive dentistry and technology have expanded the possibility of using resin-bonded bridges (RBB) with alternative preparation designs and materials [48,49].…”