N. Nakabayashi et al., A TENSILE TEST TO FACILITATE IDENTIFICATION OF DEFECTS IN DENTIN BONDED SPECIMENS, Journal of dentistry, 26(4), 1998, pp. 379-385
Objectives: To determine the efficacy of a miniaturized dumbbell test
procedure designed to more easily identify defect(s) in bonded dentine
test specimens.Methods: Extracted human dentine substrates were pre-c
onditioned with 10-3 solution for 10, 30 or 60 s prior to dentine bond
ing with 4-META/MMA-TBB resin. Miniaturized dumbbell-shaped test speci
mens were prepared from the resin bonded samples. After 24 h storage i
n 37 degrees C water, the specimens were tensile-loaded to failure. Fr
actured surfaces and cross-sections were examined and compared under s
canning electron microscopy (SEM) and transmission electron microscopy
(TEM). Results: Cohesive failure within the bonding resin was observe
d in specimens pre-conditioned for 10 s. The tensile bond strength of
these was excellent. Bond strengths of specimens that were pre-conditi
oned for 30 and 60 s were significantly lower, and defects in these sp
ecimens, formerly difficult or impossible to identify, were readily id
entified under SEM and TEM microscopy. Conclusion: The proposed method
of tensile stressing to failure and microscopically examining fractur
ed miniaturized dumbbell-shaped test specimens is a simple and reprodu
cible test procedure. The protocol is capable of clearly elucidating d
efective resin infiltration of demineralized dentine in bonded interfa
ces. These defects are difficult to visualize by conventional and/or I
SO recommended methods. (C) 1998 Elsevier Science Ltd. All rights rese
rved.