STATEMENT OF PROBLEM: The bonding of light-activated adhesives to root canal dentin with an additional touch-polymerization activator has been insufficiently examined. PURPOSE: The purpose of this in vitro study was to investigate the effect of touch-polymerization activators and extended light-irradiation time on the microtensile bond strength (μTBS) of light-activated adhesives. MATERIAL AND METHODS: Post cavities were prepared in 50 extracted mandibular premolars and bonded using Prime&Bond Universal (PBU); PBU+Self Cure Activator (SCA); Clearfil SE Bond 2 (SEB); SEB+Clearfil DC Activator (DCA); or Clearfil Universal Bond Quick ER (UBQ). After light-irradiation for 10 or 20 seconds, the post cavities were filled with dual-activated resin core materials. Eight beams were prepared per specimen and subjected to the μTBS test. The μTBS data were analyzed by using 3-way ANOVAs with the Bonferroni correction (α=.05). RESULTS: The 3-way ANOVAs indicated that the use of touch-polymerization activators (SCA and DCA) significantly increased the μTBS of PBU and SEB in both the coronal (P=.015) and apical (P=.001) regions. The extension of light-irradiation time to 20 seconds significantly improved their μTBS in the apical region (P<.001), but not in the coronal region (P=.09). Light-irradiation for 20 seconds increased the μTBS of UBQ significantly in the coronal region (P=.014). CONCLUSIONS: Touch-polymerization activators improved the bond strength of light-activated adhesives to root canal dentin, especially when combined with an extended light-irradiation time.

Assistant Professor Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan

Clinical Fellow Operative Dentistry Clinic Tokyo Medical and Dental University Dental Hospital Tokyo Japan

Graduate student Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan; Graduate student Institute of Dental Medicine 1st Faculty of Medicine of the Charles University and General University Hospital Prague Prague Czech Republic

Graduate student Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan; Lecturer Biomaterials Department Faculty of Oral and Dental Medicine Modern University for Technology and Information Mokatam Cairo Egypt

Graduate student Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan; Lecturer Department of Conservative Dentistry Faculty of Dentistry Hasanuddin University Makassar South Sulawesi Indonesia

Junior Associate Professor Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan

Professor Department of Cariology and Operative Dentistry Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan

Senior Lecturer Department of Oral Prosthetic Engineering Graduate School of Medical and Dental Sciences Tokyo Medical and Dental University Tokyo Japan

References provided by Crossref.org