Copper ion as a new leakage tracer.

STATEMENT OF PROBLEM Most failures of root canal treatments are caused by bacteria. Studies showed that the most common cause of endodontic failures were the incomplete obturation of the root canal and the lack of adequate apical seal. Some in-vitro methods are used to estimate sealing quality, generally by measuring microleakage that allows the tracer agent to penetrate the filled canal. PURPOSE Conventional methods of evaluating the seal of endodontically treated teeth are complicated and have some drawbacks. We used copper ion diffusion method to assess the leakage and the results were compared to dye penetration method. MATERIALS AND METHOD The crowns of 21 extracted teeth were cut off at the CEJ level. After preparing the canals, the teeth were placed in tubes containing saline. They were divided randomly into 15 experimental cases; 3 positive and 3 negative controls. Positive controls were filled by single cone without sealer while the experimental and the negative control groups were filled by lateral technique. The coronal portion of gutta was removed and 9mm was left. The external surface of each tooth was coated with nail polish. Two millimeters of apical portion was immersed into 9ml of distilled water and 0.3ml of CuSO4 solution was injected into the coronal portion. After 2 days, copper sulfate was measured by an atomic absorption spectrophotometer. The teeth were then immersed in 2% methylene blue for 24 hours, sectioned and the extent of dye penetration was measured by a stereomicroscope. RESULTS The maximum and minimum recorded copper ion concentrations for the experimental group were 18.37 and 2.87ppm respectively. The maximum and minimum recorded dye penetrations for the experimental group were 8.5 and 3.5mm respectively. The statistical analysis, adopting paired samples test, showed poor correlation between average recorded results of two methods. CONCLUSION Based on our results, there was no significant correlation between the dye penetration and the copper ion diffusion methods

Comparison of Micro-Shear Bond Strength of Resin Cements to Root Dentin of Bovine Teeth

Introduction: Nowadays resin cements are commonly used in operative dentistry but the strength of micro- shear bonds of these cements was different in various studies. The aim of this study was to compare the micro-shear bond strength of three resin cements with different mechanisms consisting of maxcem, variolink II and panavia F2.0 to bovine tooth dentin. Methods: Thirty nine longitudinal slices of bovine root dentin were prepared. Specimens were randomly divided into three equal groups. In each group one resin cement was used in cylinders with 1×2mm diameters on each slice. After setting of the cement, micro-shear bond strength was evaluated by a micro-tester device with 0.5mm/min cross head speed. Data were analyzed by ANOVA, Tukey and Bonferroni tests. Results: Micro-shear bond strength of Panavia F2.0, Maxcem and Variolink II was 15.07, 7.33 and 4.97Mpa, respectively. There were significant differences between groups. Conclusion: Micro-shear bond strength of total-Etch resin cements was lower than self-Etch ones

Comparison of Diagnostic Accuracy of Two Coloring Solutions, Acid Red and Povidone Iodine, for Differentiation of Sound Dentin from Infectious Dentin

Introduction: In order to improve caries detection, invasive methods should not be used and caries detector is useful, and antibacterial solutions can be used as well as a biological method for caries detection. Aim of the present study was to differentiate sound dentin from infectious dentin by two coloring solutions: acid red and povidone iodine. Methods: In this experimental investigation, 140 carious molar teeth were collected. Teeth were kept in normal saline solution in room temperature and were divided into two groups, A and B (70 samples in each group). Teeth in group A were painted by acid red 1% solution and in group B by povidone iodine 10% and the painted points were recorded. After omission of the painted points, all samples of group A were painted by povidone iodine (group C) and all samples of group B by acid red (group D) and the painted points were recorded again. Data was analyzed using chi-square and Mc-Nemar tests. Results: Diagnostic accuracy of acid red for detection of dental caries was more than povidone iodine and the difference was statistically significant (P< 0.05). Conclusion: It was concluded that the coloring power and accuracy of acid red is more than povidone iodine

Antimicrobial Effect of Copper Oxide Nanoparticles on Some Oral Bacteria and Candida Species

Statement of Problem: Acid producing bacteria including Streptococcus mutans and lactobacilli cause tooth demineralization and lead to tooth decay. Also, oral colonization of the species of Candida has been reported in many studies that are resistant to antifungal agents. Objectives: In this study, antibacterial and antifungal effects of nano-CuO were studied against some oral bacteria and yeast fungi. Materials and Methods: The minimum inhibitory concentrations (MICs) of copper oxide nanoparticles (CuO NPs) for oral bacterial and fungal test strains were determined in 96-well microtiter plate technique. The agar diffusion test (ADT) was employed to assess the antifungal properties of nystatin. Results: The MIC50 value of CuO NPs was determined at the range of 1–10 µg/ml for S. mutans, < 1 µg/ml for L. acidophilus, and 10 µg/ml for L. casei. Higher concentrations of CuO NPs (100-1000 µg/ml) were effective on the bacterial cell growth, resulting in 100% reduction in the optical density in TSB medium. The cells of Candida albicans, C. krusei and C. glabrata were treated with CuO NPs and the results showed a decrease in fungal growth at a concentration of 1-1000 µg/ml in TSB medium. The MIC50 value of CuO NPs was determined 1000 µg/ml for three species of Candida. The diameter of growth inhibition zones of 1100 µg/ml nystatin was obtained 15-21 mm for clinical isolates of three species of Candida. Conclusions: With respect to the potential bactericidal activity of CuO NPs on various cariogenic bacteria examined in this study, these NPs could be introduce as a candidate control agent for preventing dental caries or dental infections. In our study, on the other hand, Nano copper oxide had a weak effect on the candida species