Does use of silane-containing universal adhesive eliminate the need for silane application in direct composite repair?

Abstract

This in vitro study aimed to evaluate the effect of a silane-containing universal adhesive used with or without a silane agent on the repair bond strength between aged and new composites. Forty nanohybrid composite resin blocks were stored in distilled water for 14 d and thermo-cycled. Sandpaper ground, etched, and rinsed speciments were randomly assigned into four experimental groups: silane + two-step etch-and-rinse adhesive system, two-step etch-and-rinse adhesive system, silane + silane-containing universal adhesive system, and silane-containing universal adhesive system. Blocks were repaired using the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile testing. Ten unaged, non-repaired composite blocks were used as a reference group to evaluate the cohesive strength of the composite. Two-way ANOVA and Tukey's tests were used to analyze average µTBS. One-way ANOVA and Dunnet post-hoc tests were used to compare the cohesive strength values and bond strength obtained in the repaired groups (α = 0.05). The µTBS values were higher for the silane-containing universal adhesive compared to the two-step etch-and-rinse adhesive system (p = 0.002). Silane application improved the repair bond strength (p = 0.03). The repair bond strength ranged from 39.3 to 65.8% of the cohesive strength of the reference group. Using universal silane-containing adhesive improved the repair bond strength of composite resin compared to two-step etch-and-rinse adhesive. However, it still required prior application of a silane agent for best direct composite resin repair outcomes.

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

“…However, it should be noted that silanes added to adhesive systems only have a positive influence on bond strength immediately after their addition, as they will be inactivated by a dehydration and condensation reaction after a very short time (Yao et al, 2018 ; Yoshihara et al, 2016 ). This is why a separate surface pretreatment with a silane is recommended when repairing glass ceramics, as any degradation processes at the interface can be prevented (Elsayed et al, 2017 ; Silva et al, 2020 ; Yao et al, 2018 ; Yoshihara et al, 2016 ). Concerning the intraoral repair of direct and indirect restorations, there have not been any consistent protocols to date, and the literature holds numerous and various approaches (Kanzow et al, 2019 ).…”

Silanizing Effectiveness on the Bond Strength of Aged Bulk-Fill Composite Repaired After Sandblasting or Bur Abrasion Treatments: An in vitro Study

“…In contrast, other researchers disagree with this result and recommend an additional silanization step before using a silane-containing universal adhesive to enhance the bond strength. 24 These conflicting findings may be due to methodological differences, as they used tensile SBS testing. Moreover, they used an additional phosphoric acid etching step before the adhesive, which can enhance the surface cleanliness of the substrate composite.…”

“…21 Previous studies have reported conflicting results on the need for an additional silanizing step before using silane-containing universal adhesives. [22][23][24] Bulk-fill resin composites are considered monoincremental resins that can be applied in layers up to a thickness of 4 mm with significantly low rates of polymerization shrinkage. 25,26 The utilization of bulk-fill resin composites has expanded due to their ease of application and satisfactory clinical performance.…”

Influence of Different Surface Treatments on the Bond Strength Between Composites and Resin Cement

“…The filling material composition can also affect the bond strength, since each composite class could respond differently after surface treatments (20). Studies have evaluated the repair bond strength in silorane based composites after surface treatments (11)(12)(13)(21)(22)(23) and the repair bond strength between resin composites (6,7,(10)(11)(12)(22)(23)(24)(25)(26). However, few studies approached surface treatments between composites and resin cements by luting analyses with composites blocks for indirect restorations (16,27) and not by direct analysis of bond strength between a resin cement and a resin composite (9).…”