Comparison of various adhesive systems using Weibull reliability analysis

Objectives: The scatter of bond strengths can be used to characterize reliability of adhesive systems. This hypothesis was tested using Weibull reliability analysis with eight adhesive systems of different generations on the human dentin. Methods: Total-etch OptiBond FL/Gel Etchant (SDS-Kerr), Gluma Comfort Bond/Gluma Etch 20 Gel (Heraeus-Kulzer), Prime&Bond NT/Conditioner 36 (Dentsply-DeTrey) and self-etching Clearfil SE Bond (Kuraray), OptiBond Solo Plus SE (SDS-Kerr), Adper Prompt L-Pop (3M-ESPE) and iBond (Heraeus-Kulzer) adhesives combined with a microhybrid composite Charisma (Heraeus Kulzer) were tested on the human dentin. The samples (each adhesive system n=18-23) were exposed for 24 hours at 37oC in distilled water and then subjected to a shear load. Mean bond strength and parameters of Weibull distribution were determined using statistical software Statistica 7. Results: A one-way ANOVA and post-hoc Fisher‘s LSD homogenous group test (a = 0.05) revealed significant differences (p<0.001) among the adhesives tested. The mean bond strengths were 20.9-22.4 MPa for OptiBond FL, Gluma Comfort Bond, Clearfil SE Bond, OptiBond Solo Plus SE (Group A), 15.8-16.0 MPa for Xeno III and iBond (Group B) and 12.0-11.7 MPa for Prime&Bond NT and Adper Prompt L-Pop (Group C). The Weibull modulus characterizing “variability” of bond strength ranged from 4.6-8.3 (Group A) to 4.2-6.4 (Group B) and 2.2-4.3 (group C). Conclusion: Pronounced differences in the bond strength and in the Weibull modulus suggest variations in the reliability of adhesive systems tested, which results rather from their individual chemical composition than the generation they belong to.

Supported by the Grant Agency of the Czech Ministry of Health, grant No. NR 8278-3.