Effects of sterilization/disinfection of teeth on composite shear bond strength

Introduction: Extracted teeth used in bond strength study are a potential source of infection. The investigators are potentially exposed to a wide variety of microorganisms during various laboratory procedures. Objective: To compare the shear/peel bond strength of orthodontic composite bonded on extracted teeth that were subjected to different infection control procedure. Methods: Four groups of thirty extracted premolar teeth had been prepared and subjected to the following disinfection or sterilization procedures prior to bonding. Group 1 (control group) was stored in distilled water. Group 2 was disinfected using 1% sodium hypochloride solution at room temperature for 24 hours. Group 3 was disinfected using Peform solution containing oxidising agent at room temperature for 10 minutes. Group 4 was sterilized using autoclave with a sterilization cycle of 134ºC for 15 minutes at 207kPa. Each tooth had brackets attached in a standardized manner using Transbond XT (3M Unitek). The debonding force was measured using Instron Universal Testing Machine. ANOVA and Pairwise comparison were performed to detect significant differences among the groups (p<0.05). Results: The results showed that there was no significant difference among group 1 (mean 3.38±2.60 N/mm²), 2 (mean 3.71±2.26) and 4 (mean 3.39±1.68). There was a significant difference between group 3 (mean 7.95±4.57) and the rest of the groups. Conclusions: The results indicated that there was no difference in bond strength among the group 1 (control), 2 and 4. Based on this finding it could be recommended that in any laboratory bond strength study, extracted teeth could either be stored in 1% sodium hypochloride solution at room temperature for 24 hours or sterilized using autoclave with a sterilization cycle of 134ºC for 15 minutes at 207kPa as an infection control procedure. Further study is required to confirm the findings.