Bonding Reactions of Dental Self-Adhesive Cements with Synthetic Hydroxyapatite as a Function of the Polymerization Protocol

Three Self-Adhesive Resin Cements and Their Influence on the Marginal Adaptation of Zirconia-Reinforced Lithium Silicate Single Crowns: An In Vitro Scanning Electron Microscope Evaluation

Background: In everyday dentistry, monolithic single crowns can be cemented with self-adhesive resin cements. The aim of this in vitro study was to evaluate how the marginal adaptation of full monolithic zirconia-reinforced lithium silicate (ZLS) single crowns is influenced by three different self-adhesive resin cements. Methods: Forty-five typodont teeth fully prepared for full monolithic crowns were divided into three groups (fifteen each) for the use of three different self-adhesive resin cements. A fourth control group (Temp-bond) was created by taking five teeth from each group before cementation with self-adhesive resin cements. All forty-five abutments were scanned using a Primescan intra-oral scanner (IOS), followed by computer-aided design (CAD) and computer-aided manufacturing (CAM) of zirconia-reinforced lithium silicate (ZLS) full crowns using a four-axis machine. Initially, the crowns of the control group were fixed to the abutments using Temp-bond, and the marginal gap was evaluated using a scanning electron microscope (SEM). After removing the control group crowns from the abutments, fifteen crowns in each group were cemented using a different self-adhesive resin cement and observed under SEM for evaluation of the marginal gap. A Kolmogorov-Smirnov test was performed, indicating no normal distribution (p < 0.05), followed by Mann-Whitney tests (α = 0.05). Results: The total mean marginal gap of the temp-bond control group was significantly lower compared to all three groups of self-adhesive resin cement (p < 0.0005). The total mean marginal gap of the G-cem ONE group was significantly lower compared to the TheraCem group (p < 0.026) and RelyX U200 group (p < 0.008). The total mean marginal gap of the TheraCem group was significantly higher than the G-cem ONE group (p < 0.026) but showed no significant difference with the RelyX U200 group (p > 0.110). Conclusions: All four groups showed a clinically acceptable marginal gap (<120 microns). Although all three groups of self-adhesive resin cement showed a significant increase in the marginal gap compared to the temp-bond control group, they were within the limits of clinical acceptability. Regarding the marginal gap, in everyday dentistry, it is acceptable to use all three self-adhesive resin cements, although the G-cem ONE group exhibited the lowest marginal gap for ZLS single crowns.

Formulations of NaOCl-based in liquid, gel form or with surfactants on dentin deproteinization before fiber post cementation

The objective of the study was to evaluate the effects of dentin deproteinization protocols for post space using different formulations containing sodium hypochlorite before fiber post cementation with self-adhesive resinous cement. The groups were divided according to the irrigation protocol (DWC, SHS, SHT and SHG). The residue cleanliness, bond strength, adhesive failure pattern, and tag formation at the adhesive interface between the self-adhesive cement and the dentin were evaluated. For this, analysis in scanning electron microscope, push-out test and confocal laser scanning microscopy were performed. The SHT protocol showed the highest residue cleanliness on the dentin surface of the post space (p<0.05). In addition, SHT protocol showed highest bond strength and tag formation in the cervical and middle thirds (p<0.05). Dentin deproteinization with sodium hypochlorite with surfactant provided the best dentin cleaning of residues, bond strength and tag formation after cementation of the fiber post with self-adhesive cement.