J Adhes Dent. 2010 Dec;12(6):477-85. doi: 10.3290/j.jad.a17856.
ABSTRACT
PURPOSE: the aim of this study was to evaluate the ability of bond strength tests to accurately measure the bond strength of fiber posts luted into root canals.
MATERIALS AND METHODS: the test methods studied were hourglass microtensile (HM), push-out (PS), modified pushout (MP), and pull-out (PL). The evaluated parameters were: bond strength values, reliability (using Weibull analysis), failure mode (using confocal microscopy), and stress distribution (using finite element analysis). Forty human intact single-rooted and endodontically treated teeth were divided into four groups. Each group was assigned one of the test methods. The samples in the HM and PS groups were 1.0 ± 0.1 mm thick; the HM samples were hourglass shaped and the PS samples were disk shaped. For the PL and MP groups, each 1-mm dentin slice was luted with a fiber post piece. Three-dimensional models of each group were made and stress was analyzed based on Von Mises criteria.
RESULTS: PL provided the highest values of bond strength, followed by MP, both of which also had greater amounts of adhesive failures. PS showed the highest frequency of cohesive failures. MP showed a more homogeneous stress distribution and a higher Weibull modulus.
CONCLUSION: the specimen design directly influences the biomechanical behavior of bond strength tests.
PMID:20157648 | DOI:10.3290/j.jad.a17856
