Adhesive sonic agitation improves bonding durability to class-II cavity preparation

The purpose of this study was to evaluate the effect of adhesive sonic agitation on resin-dentin micro-tensile bond strength (µTBS) and interfacial morphology at the gingival wall of class-II cavity preparation. Seventy-two molars with prepared class-II cavities were divided into six groups (n = 12) according to the bonding mode; etch-and-rinse (E&R) or self-etch (SE) and application protocol of the universal adhesive (UA) employed (Clearfil Universal Bond Quick, Kuraray Noritake); following the manufacturer instructions (MI), manual agitation for 20 s (20s), or sonic agitation for 20 s using a modified sonic micro-brush mounted on EndoActivator device, Dentsply Sirona, (sonic). Restored teeth were sectioned into resin-dentin beams and slaps and µTBS was evaluated at 1 week (1w) and after thermocycling (10k). µTBS data were analyzed using the linear mixed-effects modeling with specific contrast (p < 0.05). The resin-dentin interfacial morphology was evaluated using a scanning electron microscope. Adhesive sonic agitation resulted in significantly higher µTBS means in both E&R and SE modes, compared to MI group. The µTBS of MI group showed significant reduction upon aging when applied in SE mode. Sonic agitation was associated with enhanced adhesive infiltration into dentin specially in E&R mode. Sonic agitation of UA using modified sonic micro-brush attached to EndoActivator device significantly improved the resin-dentin µTBS and interfacial morphology at the gingival wall of class-II cavity preparation.