Effect of placement agitation and drying time on dentin shear bond strength: an in vivo study

The current study measured the bond strength of a self-etch system to dentin with and without agitation and with varying drying times of primer in vital dentin. The null hypotheses tested were that primer agitation and primer drying time did not affect the dentin shear bond strength. Sixty human maxillary and mandibular premolars scheduled to be extracted for orthodontic reasons were selected. The adhesive/resin combination used was Clearfil SE (Kuraray, Osaka, Japan)/TPH Spectrum (Dentsply DeTrey, Konstanz, Germany). The occlusal surfaces of the teeth were flattened using straight fissure diamond abrasive points ISO-012. Samples were divided into six groups of 10 teeth each. Primer was applied following the manufacturer's instructions with and without agitation followed by air-drying time of 0 (without air drying), five and 10 seconds. Clearfil SE Bond was applied and cured for 10 seconds. TPH Spectrum composite, shade A2 (Dentsply DeTrey), was placed over cured adhesive and was cured for 40 seconds. The teeth were restored to their original anatomy. The teeth were extracted after one week and the samples were kept in distilled water until testing at room temperature. The samples were tested in shear at a 1 mm/minute crosshead speed using an LR100 Universal Testing Machine. The data was analyzed using ANOVA and Tukey post-hoc tests (p < 0.05). Varying the drying time of the primer from zero (0) to 10 seconds did not significantly affect the bond strength values in vivo. At five seconds drying time, agitation significantly improved the shear bond strength to dentin. Agitation showed no effect when primer was not dried or it was dried for 10 seconds.