Clinical observation of the tooth surface during air-drying of self-etching primer under 3D video microscope

To clarify the optimal amount of air-drying time, this study measured the time taken to remove residual excess solvent from self-etching primer under observation with a 3D video microscope. One hundred teeth were restored with direct resin composite restorations (16 upper anterior teeth, three lower anterior teeth, 14 upper premolars, 13 lower premolars, 16 upper molars, and 38 lower molars) under observation with a 3D video microscope. In all restorations, Clearfil SE Protect was used for bonding of the resin composite under controlled environmental conditions (intra-oral temperature and humidity) using an intra-oral vacuum device. The duration of air-drying needed to evaporate the residual solvent from the self-etching primer solution was simultaneously measured. The data obtained were statistically evaluated by one-way ANOVA and Tukey’s HSD multiple comparisons (p?<?0.05). The duration for complete air-drying of the 100 cases was 40.9?±?18.7?s. The air-drying durations in lower molar and upper anterior restorations were 48.1?±?21.7 and 27.3?±?14.6?s, respectively, with a statistically significant difference (p?=?0.002). This study revealed that a greater air-drying duration was needed to evaporate solvent from the self-etching primer than routine air-drying in the clinical situation. It also indicated that a greater air-drying duration was required for posterior cavities than for anterior cavities.