The influence of various adhesive applicators on the bond strength to dentin: an in vitro experimental study

The aim of this in vitro study was to evaluate the influence of various adhesive applicators on the microshear bond strength (µSBS) of flowable resin composite to dentin.

Forty-two extracted molars were prepared as disks and divided into two groups. In the first group, GLUMA Bond Universal (Heraeus Kulzer GmbH) was applied to the tooth surface for 20 seconds using a bristle brush, while in the second group, the same adhesive was applied by the same operator using a microbrush. Photopolymerization was performed for 10 seconds using a Valo light-curing unit (Ultradent Products Inc.). Microcylindrical silicone tubes (2 mm long, 0.8 mm inner diameter) were used as molds on the bonded dentin surfaces, and Charisma Bulk Flow ONE resin composite (Heraeus Kulzer GmbH) was injected and cured for 20 seconds. Both groups underwent a µSBS test, and the failure modes were examined microscopically. Student t-test compared the failure stress between the groups (p < 0.05).

The bristle brush group had the highest mean stress at failure (49.09 ± 8.76 MPa) compared to the microbrush group (37.20 ± 6.77 MPa), which also had the highest percentage of adhesive failure (95.24%).

The choice of adhesive applicator plays a significant role in determining the µSBS of flowable resin composite to dentin. It is advisable to use a bristle brush applicator when applying adhesive.