Influence of aging on direct resin composite repair bond

Atia Anjum, BDS,(a) Khairul Matin, BDS, PhD,(a,b) Ryoichiro Uchida, DDS,(a,b) and Junji Tagami, DDS, PhD,(a,b,c)

(a)Cariology and Operative Dentistry, Department of Restorative Sciences, (b)Support Program for Improving Graduate School Education, and (c)Global Center of Excellence (GCOE) Program; International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: The objective of this study was to evaluate the effect of aging on repair bond strength of direct resin composites.
Materials and Methods: Total of 45 (D: 9 mm and L: 4 mm) composite specimens were prepared (Clearfil AP-X). Forty-two specimens were kept for storage in Milli-Q water and in human saliva at 37oC for 2, 4, and 12 weeks. Rest three non-aged specimens (L: 8 mm and D: 9 mm) were used as control. Each aged specimen was roughened by a an abrasive point, washed with water jet and air dried. Then, silane was applied followed by the application of Clearfil SE bond. After surface treatment, fresh composite of same resin: SR (Clearfil AP-X) and different resin: DR (Estelite S) was added and light cured in each group. After 24 hours of storage in water at 37°C, all the repaired and non repaired control specimens were cut into 1 mm sticks with a cross-sectional area of 0.7 mm2 at the bonding interface and microtesile bond strength test was performed. The fracture modes and surface alterations were inspected by using a scanning electron microscope. Data were analyzed by two-way and one-way ANOVA.
Results: Post-hoc comparison showed significantly reduced bond strength between 2 weeks saliva SR (43.97) and 12 weeks Milli-Q water DR (35.11) groups. When compared to control, Dunnett T3 test revealed significantly decreased bond strength in all groups of 12 weeks.
Conclusion: The composite repair bond strengths were influenced by the different types of storage solutions and resin composition.(Int Chin J Dent 2008; 8: 53-61.)
Key Words: aging, composite resin, human saliva, repair bond strength.