• Mayurach Pipatphatsakorn D.D.S., Ph.D.

Objective The purpose of this study was to evaluate the impact of etching time on the microtensile
bond strength (μTBS) of Vertise^® Flow^TM on sound enamel, artificial initial caries-like enamel and
remineralized artificial initial caries-like enamel.

Materials and Methods One hundred and twenty extracted human molars were ground to create a
flat surface of enamel. Samples were randomly divided into 15 groups according to enamel substrates
(S: sound enamel, D: artificial initial caries-like enamel, or R: remineralized artificial initial
caries-like enamel), materials (C: Concise^TM or V: Vertise^® FlowTM) and ethching time (0: Etching
time 0 sec, 10: Etching time 10 sec, 15: Etching time 15 sec, 20: Etching time 20 sec). Enamel samples
were bonded with either Vertise^® Flow^TM or Concise^TM according manufacturerûs instruction and
trimmed into an hourglass shape. The μTBS test was performed and the failure modes were assessed
by scanning electron microscope.

Results The highest μTBS was found in group ^VR15 (32.01 ± 4.63 MPa) and the lowest μTBS was
found in group VS0 (8.04 ± 2.96 MPa). The μTBS values of Concise^TM groups were significantly lower
(p<0.05) compared to the Vertise^® Flow^TM groups and the bond strength were not significantly different
regardless of the enamel substrates. Etching on enamel substrates in Vertise^® FlowTM groups gave
significantly higher μTBS than the groups without etching (p<0.05). The μTBS obtained from Vertise^®
FlowTM on sound enamel had a significantly lower bond strength compared to Vertise^® Flow^TM on
artificial initial caries-like enamel and remineralized artificial initial caries-like enamel for all groups
with 10-seconds, 15- seconds and 20-seconds etching time (p<0.05). Considering the effect of etching
time on Vertise^® Flow^TM groups with 15-seconds and 20-seconds etching time gave significantly
higher μTBS than the 10-seconds etching time groups for all the three different enamel substrates
(p<0.05). The majority of samples presented an adhesive failure between the material and enamel.

Conclusion From this study, it can be concluded that the bonding effectiveness of self-adhesive
flowable resin composite on different enamel substrates are better when conditioned by phosphoric
acid. The μTBS was significantly influenced by different enamel substrates, where remineralized
caries-like enamel and artificial initial caries-like enamel demonstrated the higher μTBS values comparing
with sound enamel.

(CU Dent J. 2015;38(Suppl):83-96)