in vitro study of mesiobuccal root thickness of maxillary first molars

Understanding the internal anatomy of root canal system can significantly influence outcomes of root canal treatment. The aim of this in vitro study was to measure the thickness of mesiobuccal root at different levels in maxillary first molars. In this cross-sectional study, forty extracted human maxillary first molars were radiographed; accordingly, the mesial and distal root thicknesses of mesiobuccal [MB] roots were measured at four parallel horizontal levels. The samples were sectioned at the measured levels and then sections were scanned and saved in the computer. Buccal [B], Palatal [P], Mesial [M] and Distal [D] aspects of root thicknesses in single-canalled roots were measured. In two-canalled mesiobuccal roots, Distobuccal [DB] and Distopalatal [DP] aspects were evaluated alongside other measurements. Average radicular thickness in each aspect and each level was compared using ANOVA and t-test. A total of 25 had two canals and 15 had one canal in MB root. In single-canalled roots M and D aspects were the thinnest whereas in two-canalled samples, the thicknesses of DP and DB aspects were significantly less than others [P<0.001]. The B and P had the greatest thicknesses in all the samples. The results showed that special attention should be paid to "danger zone" areas of mesiobuccal maxillary first molar roots in order to avoid technical mishaps

Frequency of hepatitis C in patients with rheumatoid arthritis

Hepatitis C virus [HCV] infection has been explained as a disease that sometimes present with rheumatic manifestations indistinguishable from rheumatoid arthritis. This study has been performed to evaluate the frequency of hepatitis C virus infection in a group of patients with rheumatoid arthritis. In this study, during one year, serum samples collected from two hundred consecutive patients with rheumatoid arthritis in all affiliated hospitals of Shaheed Beheshti University, MC., were examined for anti-HCV antibody and HCV-RNA by ELISA and RT-PCR method, respectively. Using a questionnaire, the frequency of HCV infection, age and sex distribution, duration of rheumatoid arthritis, associated immune mediated disorders and risk factors for hepatitis C virus infection were assessed. A total of 200 patients [M/F=26/174] who were mainly aged 51-70 years were studied. The frequency of HCV was found to be 2% [95%CI: 0.6-7%]. All of the infected persons have had a low risk occupation in terms of exposure to the virus and none of them had HCV risk factors. No associated immune mediated disorder was found in HCV infected patients. Our results did not support any contribution of HCV infection in the pathogenesis of rheumatoid arthriti

Technical quality of root canal treatment performed by undergraduate dental students

This study was carried out to evaluate the technical quality of root canal treatment [RCT] performed by undergraduate dental students at the Islamic Azad University in Tehran, Iran. Four-hundred records of patients who had received RCT at faculty of dentistry, between the years 2004-2006 were evaluated. For each treated tooth at least three periapical x-rays were assessed: preoperative, working length measurement, and postoperative. Evaluation of root canal filling was based on two variables: length and density. The filling length was recorded as adequate, under- or overfilled. Density of filling was recorded as poor or adequate. Fillings with adequate length and density were recorded as acceptable. Detected iatrogenic errors were: ledge formations, root perforations, furcation perforations, strip perforations and presence of fractured instruments. Results were evaluated statistically using one-way ANOVA and Chi-square analysis. Out of the 400 teeth, 50.5% had at least one of the mentioned errors. Acceptable filling was observed in 32.5% of all studied teeth. Ledge was found in 17.5% of the teeth. Canal curvature was the most important factor associated with ledge formation [P<0.05]. The technical quality of RCT performed by undergraduate dental students using step-back preparation and cold lateral condensation was classified as acceptable in 32.5% of the cases