The effect of the dentin preparation with an ultrasonic abrasion on the microtensile bond strength of self-etch adhesive systems

Hiroyuki Takanashi, DDS,a Keiichi Hosaka, DDS, PhD,a Ryuzo Kishikawa, DDS, PhD,a Masayuki Otsuki, DDS, PhD,a and Junji Tagami, DDS, PhDa,b

aCariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, bGlobal Center of Excellence (GCOE) Program; International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: This study evaluated the effect of the dentin preparation with an ultrasonic abrasion on the microtensile bond strengths (μTBS) of two-step and one-step self-etch adhesive systems to dentin.
Materials and Methods: A two-step self-etch adhesive, Clearfil SE Bond (Kuraray Medical) and a one-step self-etch adhesive, Clearfil S3 Bond (Kuraray Medical) were applied on dentin prepared with a diamond-coated round working tip, Excavus (EX, Satelec) activated through ultrasonic frequency oscillations, with a regular grit diamond bur (DB) in a turbine handpiece, with a steel bur (SB) in a micromotor handpiece, or with a #600 grid silicon carbide abrasive paper (SiC). Then, a photo-cured composite was placed and polymerized. The μTBS was measured after storage in water for 24 hours at 37˚C. The data were statistically analyzed using a two-way ANOVA and Dunnett’s C test at 95% level of confidence. The prepared surfaces and their crosscut surfaces were observed using a scanning electron microscope (SEM).
Results: : For Clearfil SE Bond, the μTBS of EX was higher than that of DB and there were no differences among EX, SB, and SiC groups. For Clearfil S3 Bond, the μTBSs of EX and DB were lower than those of SB and SiC. The μTBS values of Clearfil SE Bond were significantly higher than Clearfil S3 Bond, irrespective of the dentin preparation methods. The two-way ANOVA analysis revealed that there was a significant interaction between the dentin preparation methods and the adhesive systems (p<0.05). Bond strength was influenced by the dentin preparation method (p<0.05) and by the adhesive systems (p<0.05). SEM observation of the dentin surfaces prepared with EX showed the thicker and uneven smear layers, compared with SB and SiC.
Conclusion: The μTBS to dentin prepared using an ultrasonic abrasion with EX, when Clearfil SE Bond was applied, was similar to SB and SiC groups and higher than DB group. However, when Clearfil S3 Bond was applied, the μTBS to dentin prepared with EX was statistically lower than SB and SiC groups and were similar to DB group. The mean μTBSs of Clearfil SE Bond were higher than those of Clearfil S3 when using the same dentin surface preparation.(Int Chin J Dent 2010; 10: 7-15.)

Key Words: cavity preparation, microtensile bond strength, self-etch adhesive system, smear layer