An in vitro study of mesiobuccal root thickness of maxillary first molars

Introduction: 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. Materials and Methods: 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. Results: 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. Conclusion: 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

Role of Fas Ligand in Apical Periodontitis upon Infection with Oral Anaerobes (Fusobacterium nucleatum )

Role of Fas Ligand in Apical Periodontitis upon Infection with Oral Anaerobes (Fusobacterium nucleatum )By Yasaman Ravandoust, DDSFusobacterium nucleatum (Fn) is one of the most prevalent anaerobes found in endodontic infections. Our group has shown that Fn aggregates immune cells, upregulates the death-ligand FasL,and induces apoptosis (Jewett 2000, Fraser 2010, Huynh 2011). In this study, we investigated the role of FasL in regulating bone resorption upon murine pulp exposure and infection with Fn and Prevotella intermedia (Pi). Mandibular first molar pulps from Wild-type, and FasL- deficient mice were exposed and infected with Fn and Pi. Mice with no pulp exposures were the control group. Animals were euthanized after 21 days. Hemi-mandibles were fixed in 10% phosphate-buffered-formalin, and subjected to micro-computed-tomography. The volumetric measurements of the periapical lesions on the mesial and distal roots were calculated and statistically analyzed with ANOVA and Post-hoc Tukey's test. Mesial and distal root periapical lesion sizes were significantly larger in Wild-type mice than in FasL deficient mice respectively (p<0.05). a) Wild type mouse mesial root: 0.17±0.007; b) FasL-deficient mouse mesial root: 0.12±0.007; c) Wild type mouse distal root: 0.15±0.008; d) FasL-deficient mouse distal root: 0.11±0.001 In conclusion, FasL plays an important role in the induction of periapical bone resorption induced by co-infection with Fusobacterium nucleatum & Prevotella intermedia

An in vitro study of mesiobuccal root thickness of maxillary first molars

Introduction: 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. Materials and Methods: 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. Results: 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. Conclusion: 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