Takako Yoshikawa, DDS, PhD (1), Alireza Sadr, DDS, PhD (1,2), and Junji Tagami, DDS, PhD (1)
(1) Department of Cariology and Operative Dentistry, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
(2) IB3T Laboratory, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, WA, USA
Purpose: To evaluate the effect of γ-ray irradiation on resin composite/dentin bond strength and the composite adaptation to the dentin cavity wall.
Materials and Methods: Half of bovine incisors were irradiated with 60 Gy γ-rays. Flat dentin surfaces were prepared on the labial side. Half of flat dentin surfaces were treated with Clearfil SE Bond. Clearfil AP-X composite was built up. After light curing and 24 h storage, the teeth were sectioned and trimmed (ca. 1 mm2) at the adhesive-dentin interface for microtensile bond strength test. The trimmed specimens were stressed to failure. Other flat dentin surfaces were prepared cylindrical cavities. The cavities were restored with Clearfil SE Bond adhesive followed by Clearfil AP-X composite. After light curing and 24 h storage, dye penetration tests around the cavities were performed. 60 Gy γ-ray irradiation significantly decreased resin composite adaptation to the cavity wall. Bond strength data were compared using the Bonferroni test. Dye penetration test scores were analyzed using the Kruskal-Wallis and Mann-Whitney U-tests.
Results: There was no significant difference between irradiated dentin and non-irradiated dentin of resin composite bond strength (p > 0.05). However, 60 Gy γ-ray irradiation significantly decreased resin composite adaptation to the cavity wall (p < 0.05).
Conclusion: Irradiation with 60 Gy γ-ray had no effect on resin-dentin bond strength. However, 60 Gy γ-ray irradiation significantly decreased resin composite adaptation to the cavity wall.
(Asian Pac J Dent 2017; 17: 49-53.)
Key Words: adaptation, bond strength, dye penetration, γ-ray irradiation, resin composite