Efficacy of different surface treatments and universal adhesives on the microtensile bond strength of bulk-fill composite repair
Journal of Adhesion Science and Technology. 2020;34(10):1115-1127.
ABSTRACT
The purpose of this in vitro study was to evaluate the influence of different surface treatments and aging on the microtensile bond strength (µTBS) of bulk-fill composite resins. Bulk-fill composites (Filtek One; 3M ESPE) randomly received five different surface treatments: (1) no treatment, control, (2) 37% phosphoric acid etching (PA), (3) 9% hydrofluoric acid etching (HF), (4) air-borne particle abrasion with 50-µm alumina particles (Al2O3), (5) tribochemical silica coating (CoJet). Following, the specimens were divided into three subgroups according to universal adhesive applied: Clearfil Universal Bond (CU; Kuraray), Prime&Bond Universal (PBU; Dentsply Sirona), or Single Bond Universal (SBU; 3M ESPE). A nanofill composite (Filtek Ultimate; 3M ESPE) was employed as a repair. Bonded specimens were stored in water for 24 h at 37 °C or thermal aged, then subjected to the µTBS test. Additionally, specimens were analyzed with a contact profilometer and were evaluated with scanning electron microscopy. Control and PA treatments were showed the lowest µTBS (p < 0.05), and there was no significant difference between these two groups (p > 0.05). Al2O3 and CoJet treatments generally exhibited a similar influence on µTBS values. In addition, a correlation was found between surface roughness and bond strength (r = 0.831). CoJet resulted in significantly higher repair µTBS values when compared to the other surface treatments. In addition, the use of silane-containing universal adhesive was increased the cohesive failure rate and maintained the repair µTBS values after thermocycling.
KEYWORDS
Universal adhesives · bulk-fill composites · resin composites · durability · bond strength
STUDY SUMMARY
This in vitro study measured the microtensile bond strength of repairs to bulk-fill composite after five surface treatments combined with three universal adhesives, tested at 24 hours and after thermal ageing. The untreated control and phosphoric acid etching gave the lowest bond strength and did not differ from each other, while tribochemical silica coating gave significantly higher values than the other treatments and surface roughness correlated with bond strength. The silane-containing universal adhesive was associated with more cohesive failures and maintained repair bond strength after thermocycling.