Technique sensitivity associated with air-drying of HEMA-free, single-bottle, one-step self-etch adhesives

This study examined the effect of air-drying on bond strength to dentin and nanoleakage in resin-dentin interfaces using HEMA-free one-step self-etch adhesives.

Twelve teeth had their occlusal dentin exposed and split in half. In the group of G-BOND (GB), the adhesive was dried gently or vigorously on each slit half tooth, and then light-cured. In the group of the experimental adhesive (EX), three coats of adhesive were dried using a single air-drying process prior to light-curing or dried after each of three coats of adhesive before light-curing. The split specimens were built-up with resin composite and then subjected to microtensile bond strength testing and TEM examination.

GB showed significantly higher bond strength after vigorous drying than after gentle drying. Three teeth of from EX group showed higher bond strength after triple drying than after single drying, while two teeth showed no significant difference. Droplets were revealed in the adhesive layer after gentle drying with GB, and silver deposits existed along the interfaces in all groups.

The bonding quality to dentin may be improved by using an accelerated air-drying technique; although it is impossible to remove intrinsic dentin moisture that is drawn upwards from dentin tubules.