J Korean Acad Conserv Dent JKACD Journal of Korean Academy of Conservative Dentistry 1225-0864 2093-8179 The Korean Academy of Conservative Dentistry 10.5395/JKACD.2011.36.5.409 Basic Research Effect of Er:YAG lasing on the dentin bonding strength of two-step adhesives Song Byeong-Choon DDS PhD Graduate student 1 Cho Young-Gon DDS MSD PhD Professor 1 Lee Myung-Seon RDH Full Time Lecturer 2 Department of Conservative Dentistry, Chosun University School of Dentistry, Gwangju, Korea. Department of Dental Hygiene, SeoYeong University, Gwangju, Korea. Correspondence to Young-Gon Cho, DDS, MSD, PhD. Professor, Department of Conservative Dentistry, Chosun University School of Dentistry, 421 Seosuk-dong Dong-gu, Gwangju, Korea 501-825. TEL, +82-62-220-3845; FAX, +82-62-223-9064; ygcho@mail.chosun.ac.kr 09 2011 30 09 2011 36 5 409 418 29 07 2011 29 08 2011 29 08 2011 Copyright © 2011 Korean Academy of Conservative Dentistry 2011 Objectives

The purpose of this study was to compare the microshear bond strength (µSBS) and bonding interfaces of two-step total-etching and self-etching adhesive systems to three etch types of dentin either the acid etched, laser etched or laser and acid etched.

 Materials and Methods

The occlusal dentinal surfaces of thirty human molars were used. They were divided into six groups: group 1, 37% H3PO4 + Single Bond 2 (3M ESPE); group 2, Er:YAG laser (KEY Laser 3, KaVo) + Single Bond 2; group 3, Er:YAG laser + 37% H3PO4 + Single Bond 2; group 4, Clearfil SE Primer + Bond (Kuraray); group 5, Er:YAG laser + Clearfil SE Bond; group 6, Er:YAG laser + Clearfil SE Primer + Bond. The samples were subjected to µSBS testing 24 hr after bonding. Also scanning microscopic evaluations were made on the resin-dentin interfaces of six specimens.

 Results

The µSBS of group 2 was significantly lower than that of groups 1 and 3 in Single Bond 2 (p < 0.05). There were significant differences among the uSBS of groups 4, 5, and 6 in Clearfil SE Bond (p < 0.05). Very short and slender resin tags were observed in groups 2 and 5. Long and slender resin tags and lateral branches of tags were observed in groups 3 and 6.

 Conclusions

Treatment of dentin surface using phosphoric acid or self-etching primer improved the adhesion of Er:YAG lased dentin.

 Bonding interfaces Er:YAG lasing Microshear bond strength Two-step adhesives

Conflict of Interest: No potential conflict of interest relevant to this article was reported.

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Scanning electron microscophic photograph showing the hybrid layer (H) and many taper resin tags with lateral branches (LB) in Group 1.

Scanning electron microscophic photograph showing the wide gap (G) and few short and slender resin tags in Group 2.

Scanning electron microscophic photograph showing the hybrid layer (H), slender and long rod shaped resin tags with lateral branches (LB) in Group 3.

Scanning electron microscophic photograph showing the hybrid layer (H) and many long rod shaped resin tags with lateral branches (LB) in Group 4.

Scanning electron microscophic photograph showing the small gap (G) at the resin-dentin interface and short and slender resin tags in Group 5.

Scanning electron microscophic photograph showingthe hybrid layer (H) and few slender and long resin tags in Group 6.

Adhesive systems and resin composite

Group classification by adhesive systems and etch types of dentin

Mean microshear bond strength (MPa) to dentin and failure mode

G1, G4, Acid etch; G2, G5, Laser etch; G3, G6, Laser etch + acid etch.

G1, G2 and G3 used Single Bond 2. G4, G5 and G6 used Clearfil SE Bond.

Different superscripts indicate values of statistically significant difference by Kruskal-Wallis test, median test and Mann-Whitney test.