Journal of Dental Medicine

Background and Aim: Extracted teeth used in preclinic should be disinfected. The aim of this study was to evaluate the effects of some disinfectants on microorganisms cultured from pulp chamber of extracted teeth.
Materials and Methods: In this experimental study 54 intact human teeth were collected. After access cavity preparation, 10 8 B. streothermophillus endospors were inoculated into pulp chamber. Then cavities were sealed with a temporary restorative material. Teeth were divided into 5 groups of 10 each. The teeth were then stored in these disinfectants: 5.25% hypochlorite sodium, 5% Microten, 5% Deconex, 2% Glutaraldehyd, and 10% Formalin for 48 hours. Two teeth were autoclaved as negative controls and two were stored in normal saline as positive controls. The teeth were then sectioned in cervical area and cultured in Trypticase Soy Broth. After three days turbidity in tubes was evaluated. Statistical analysis was done by Fisher's exact test.
Results: None of these solutions were able to prevent microorganism growth in all samples however, Formalin was better in six cases than that of other disinfectants. Differences between these five groups were not statistically significant (P=0.384).
Conclusion: Sterilization of the teeth with autoclave is the only absolute method for disinfecting the root canals of extracted teeth and disinfectants are not reliable for this purpose.

Background and Aims: The purpose of this experimental study was to investigate the shear bond strength of three new adhesive systems to enamel and dentin of permanent human teeth using three new etch and rinse and self-etch adhesive systems.
Materials and Methods: Sixty intact caries-free third molars were selected and randomly divided into 6 groups. Flat buccal and lingual enamel and dentin surfaces were prepared and mounted in the acrylic resin perpendicular to the plan of the horizon. Adhesives used in this study were Tetric N-Bond, AdheSE and AdheSE-One F (Ivoclar/Vivadent, Schaan, Liechtenstein). The adhesives were applied on the surfaces and cured with quartz tungsten halogen curing unit (600 mW/cm² intensity) for 20 s. After attaching composite to the surfaces and thermocycling (500 cycles, 5-55ºC), shear bond strength was measured using a universal testing machine at a crosshead speed of 0.5 mm/min. The failure modes were examined under a stereomicroscope. The data were statistically analyzed using T-test, one-way ANOVA, Tukey and Fisher's exact tests.
Results: In enamel, Tetric N-Bond (28.57±4.58 MPa) and AdheSE (21.97±7.6 MPa) had significantly higher bond strength than AdheSE-One F (7.16±2.09 MPa) (P<0.0001). Tetric N-Bond had higher bond strength than AdheSE but there was not any significant difference between them (P=0.093). In dentin, there were significantly differences among all adhesives (P<0.001). Tetric N-Bond (20.62±3.03 MPa) showed the highest and AdheSE-One F (6.54±1.13 MPa) had the lowest value. The bond strength in enamel was higher than that observed in dentin and the difference was significant in Tetric N-Bond (P=0.044) and AdheSE (P=0.000) groups. There were no significant differences in the mode of failures among groups (P>0.05).
Conclusion: Shear bond strength to dentin in Tetric N-Bond (etch and rinse system( was higher than self-etch adhesives (AdheSE and AdheSE-One F). The bond strength to enamel and dentin in two-step self-etch (AdheSE) was higher than one-step self-etch (AdheSE-One F).