Effectiveness of a universal adhesive for repair bonding to composite and amalgam

The Effect of Mechanical Alteration on Repair Bond Strength of S-PRG-Filler-Based Resin Composite Materials

This study investigates the impact of mechanical alteration on resin composite surfaces and its subsequent effect on repair bond strength. A total of 100 resin composite disks were prepared and were allocated for 24 h or 1 year of artificial aging. Specimens were embedded in epoxy resin, and the composite surfaces were mechanically altered using either diamond burs or air abrasion with aluminum oxide or glass beads. A universal bonding material was applied and a 2 mm circular and 3 mm high repair composite cylinder were prepared using a Teflon mold. Then, the specimens were tested for their shear bond strength, and the de-bonded specimens were observed under a scanning electron microscope to determine the failure pattern. SPSS 26.0 statistical software was used to analyze the data. Two-way ANOVA showed a statistically significant effect of mechanical alteration and aging on the shear bond strength of S-PRG-filler-based resin composite (p < 0.05). Surface modification with a fine diamond bur showed a significantly higher bond strength in both 24-h- and 1-year-aged specimens. Surface modification with alumina significantly increased the bond strength of 1-year-aged specimens; however, it was statistically insignificant for 24 h-aged specimens. Mechanical alteration with a fine diamond bur and 50-micron alumina can improve the repair bond strength of the composite.

Scoping review: Effect of surface treatments on bond strength of resin composite repair

OBJECTIVE

to evaluate the existing evidence on surface treatment techniques employed in resin composite repair and their effect on the repair short- and long-term bond strength.

DATA AND SOURCE

This scoping review was performed under the PRISMA-ScR guidelines for scoping reviews and registered on the Open Science Framework platform.

STUDY SELECTION

A systematic search was conducted in PubMed, Embase, and Scopus and grey literature up to September 2022 without language or date restriction. In vitro studies comparing mechanical surface and/or chemical treatments on repair bond strength of resin composite were included. Studies evaluating experimental adhesive systems or resin composites were excluded. Selection of studies and data extraction were performed. Data from selected studies was qualitatively analyzed.

RESULTS

A total of 76 studies were included in the qualitative analysis. Among the mechanical treatments, alumina blasting was the most frequently used, followed by silica coating and diamond bur. As for chemical treatments, dentin bonding systems were the most frequently evaluated, followed by universal adhesive systems and silane/ceramic primer. The combination of mechanical and chemical pre-treatments increased the repair bond strength of resin composite in both short- and long-term simulated aging scenarios. The evidence obtained from the included studies was classified as moderate quality, mainly due to the medium risk of bias observed across most of the studies.

CONCLUSION

The techniques used to treat the surface of resin composites for repair are diverse. Incorporating a combination of mechanical and chemical pre-treatments resulted in superior repair bond strength of resin composite materials under both short- and long-term simulated aging conditions.

CLINICAL SIGNIFICANCE

The analysis of evidence revealed significant variability among protocols for repairing resin composites. Utilizing both mechanical and chemical pre-treatment methods is important for enhancing the bond strength of resin composites during both short- and long-term simulated aging situations.

Effect of Different Surface Treatments on the Long-Term Repair Bond Strength of Aged Methacrylate-Based Resin Composite Restorations: A Systematic Review and Network Meta-analysis

This systematic review and network meta-analysis is aimed at investigating the effect of common surface treatments on the long-term repair bond strength of aged resin composite restorations and to rank and compare these surface treatments. In vitro studies evaluating the methacrylate-based resin composites subjected to rigorous aging protocols before and after being repaired with a new composite were included. A frequentist network meta-analysis was carried out using a random effects model. P scores were used to rank the efficacy of the surface treatments. Also, the global and node-split inconsistencies were evaluated. Web of Science, PubMed/Medline, Scopus, and Embase databases were searched until July 07, 2022. Twenty-six studies were included in the meta-analysis. The results showed that the application of silane and a total-etch (shear MD 32.35 MPa, 95% CI: 18.25 to 46.40, P score 0.95; tensile MD 33.25 MPa, 95% CI: 25.07 to 41.44; P score 0.77) or a self-etch (shear MD 38.87 MPa, 95% CI: 21.60 to 56.14, P score 0.99; tensile MD 32.52 MPa, 95% CI: 23.74 to 41.29; P score 0.73) adhesion protocol subsequent to the roughening with diamond bur produced the highest (micro)tensile and (micro)shear bond strengths compared to diamond bur alone as the control group. There was no difference between self- and total-etch adhesive protocols. Mechanical surface treatments yielded greater bond strength when used alongside the chemical adhesive agents. Further, it is possible to achieve acceptable repair bond strength using common dental clinic equipment. Therefore, clinicians could consider repairing old resin composites rather than replacing them.

Dentin contamination during repair procedures: A threat to universal adhesives?

Objective

This study examined the influence of surface contamination during repair procedures with hydrofluoric acid, silane, or ammonium polyfluoride on the bond strength of universal adhesives to dentin using different etching modes before and after thermocycling.

Materials and Methods

Dentin surfaces of human molars were contaminated in different ways (silane, hydrofluoric acid, ammonium polyfluoride, and no pretreatment as control) followed by application of a universal adhesive (etch & rinse or self‐etch mode). After a composite build‐up was placed onto each tooth, sticks for the microtensile bond strength (MTBS) test were sectioned. Half of the sticks were tested after water storage for 24 h, the other half after thermocycling (15,000 cycles, 5/55°C). The MTBS data were analyzed statistically by using the Kolmogorov–Smirnov test, one‐way analysis of variance, and Tukey HSD test (p < 0.05). The fracture patterns of all specimens were evaluated and analyzed using a χ² test.

Results

Dentin contamination with a multifunctional silane does not influence microtensile bond strength irrespective of aging. Contamination with hydrofluoric acid or an ammonium polyfluoride primer leads to a significantly lower bond strength after aging, irrespective of the etch mode.

Conclusion

Dentin contamination with hydrofluoric acid or ammonium polyfluorides during repair procedures should be avoided, as they appear to decrease the bond strength of universal adhesives.