Shear bond strengths of molar tubes bonded with different adhesives

Aims: This study determined which molar base retentive designs produced the greatest shear bond strength (SBS) to human molars when using different adhesives. Methods: One hundred and fifty extracted human molars were divided into 15 groups of 10. The tested molar tube bases included two stainless steel experimental base designs, a titanium single mesh 80 gauge base, a stainless steel double mesh 150 gauge under 80 gauge base and a stainless steel single mesh 80 gauge base. Each base was bonded with Transbond XT, Pad Lock and Light Bond. One primer, Assure, was used for all specimens. Bonded specimens were stored in water for 7 days and SBS was measured on an Instron testing machine with a crosshead speed of 1 mm/minute. Two-way ANOVA were performed with post-hoc comparisons of the means to determine any statistical differences in SBS. The significance level was set at 5 per cent. Results: The brackets, adhesives and combinations of brackets and adhesives used had a significant effect on SBS (Bracket: p < 0.001; Adhesive: p = 0.020; Interaction: p = 0.005). Mean SBS differed significantly for the adhesives: Light Bond, Pad Lock and Transbond (p < 0.001, p = 0.001 and p < 0.001, respectively). In general, the stainless steel single mesh 80 gauge base and Light Bond adhesive produced the greatest SBS. Conclusion: The clinician's choice of bracket and adhesive affect the SBS of bonded molar attachments.