A survey of dental airlines and an examination of tooth-drying techniques

The aims of this study were: 1. To assess the prevalence and severity of water and oil contamination in 20 dental airlines in clinical use, using a commercial test kit, LP Aerotest. 2. To determine the effect, in vitro, of such contamination on the shear bond strengths to etched bovine enamel, of composite resin and a dedicated bonding agent. The enamel was dried using either an oil-and-water-contaminated 3-in-1 syringe, a warm-air tooth-dryer, silica gel-dried air or blotting paper, prior to bonding. A total of 11 (5 mm diameter) composite discs were bonded in each group. The samples were shear tested 72 hours later at a cross-head speed of 50 mm/min. All airlines had > 100 mg/m3 water and traces of oil (< 0.5 mg/m3) were present in 50% of samples. The mean shear bond strengths (MPa) for the 3-in-1 syringe, tooth-dryer, dried air and blotting paper-dried teeth were 14.5 +/- 3.8, 19.0 +/- 2.6, 19.6 +/- 4.2 and 19.7 +/- 1.9 respectively. The differences between the values for the tooth dryer, dry air and blotting paper were not significant (P > 0.01) but a significant difference (P < 0.01) was observed between these and the 3-in-1 syringe.