Effect of pretest storage conditions of extracted teeth on their dentin bond strengths

Abstract

It is becoming increasingly difficult to obtain sufficient freshly extracted human teeth to utilize in in vitro studies, particularly for bonding investigations. The purpose of this study was to investigate the effect of different storage conditions for human extracted teeth prior to their use in microtensile bond strength (microTBS) testing. Thirty incisors were divided into groups according to their storage time and condition. The first group consisted of freshly extracted teeth. Teeth of the second group were stored in chloramine-T at 4 degrees C for 2 years +/-1 month. The last group was stored dry for up to 2 years +/-2 months, after which teeth were rehydrated in distilled water for 2 weeks before use. All teeth were disinfected using 0.5% chloramine-T. Dentin surfaces were exposed and then bonded using Scotchbond Multi-Purpose or Clearfil SE Bond to composite resin foundations (Esthet-X). Following 24-hour storage, bonded teeth (n=30) were sectioned into beams with a cross-section of 0.9 +/-0.1 mm(2) and subjected to microTBS testing using a microtensile testing machine (Micro Tensile Tester). Data were calculated and statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (alpha=.05). Failure modes were determined using a stereomicroscope at x40 magnification. Statistical analysis revealed no significant difference between the different storage conditions nor between the 2 adhesive systems for each storage condition (P>.05). Modes of failure for all tested groups were predominantly adhesive followed by mixed. Within the limitations of this study, it was concluded that aging of teeth and storage conditions had no significant effect on dentin microtensile bond strength to composite resin.