Influence of enamel wetness on resin composite restorations using various dentine bonding agents: Part I—effects on marginal quality and enamel microcrack formation

Summary 

Objectives

To investigate the influence of enamel wetness on marginal quality and enamel microcrack formation using various dentine bonding adhesives; and to determine the changes of marginal quality and enamel microcracks over time.

Methods

Forty extracted molars were each prepared with a cylindrical cavity and divided into five groups. Groups 1–4 were acid-etched and treated separately with either an ethanol-based adhesive (Single Bond) or an acetone-based adhesive (Prime&Bond NT) on either dry or wet enamel. Teeth in Group 5 were treated with a self-etching adhesive (Clearfil SE Bond). Epoxy replicas of different stages were taken after cavity preparation, after restoration, after 24h storage, and after thermocycling test. These replicas were examined under a scanning electron microscope for their restorative marginal quality and enamel microcrack. Quantitative measurement was performed to measure the length ratio of different margin patterns, and enamel microcracks.

Results

There was no difference in the marginal quality when ethanol-base adhesive was applied on dry or wet dentin. The group using acetone-based adhesive on the dry enamel presented higher intact margin ratio than the group on wet enamel did only after restoration. Using self-etching primer led to higher open margin ratio at all stages. Enamel microcracks were found in all five groups and were higher in groups using acetone-based adhesives.

Conclusion

Enamel wetness did not show a significantly adverse effect on the marginal quality of the restorations using either acetone- or ethanol-based adhesive. Using self-etching adhesive may lead to high incidence of margin deterioration.

Keywords: Enamel, Marginal quality, Enamel microcrack, Dentine bonding adhesive, Thermocycling test, Scanning electron microscope