Prevalence of C-shaped Canals and Three-rooted Mandibular Molars Using CBCT in a Selected Thai Population.

Introduction: C-shaped canals and three rooted mandibular molars are challenging to treat. These anatomies are commonly found in mandibular molars, especially in the Mongoloid population. However, there is no report on these anatomies using cone-beam computed tomography on all three mandibular molars in Thais. The objectives of this study were to determine the prevalence of C-shaped canals and three-rooted mandibular molars in Thais and investigate whether there is a relationship between these morphology and gender. Methods and Materials: Three pre-calibrated observers independently determined the presence of each anatomy using a specific protocol in 753 molars from cone-beam computed tomographic images. The three observers randomly re-evaluated 20% of the samples to determine inter- and intra-observer agreement using Cohen's Kappa statistic. The relationship of these root canal anatomy with sex was analysed by the Chi-square test. Results: The prevalence of C-shaped canals and three-rooted molars was 0.39% and 12.1%, 42.4% and 3.9%, and 16.6% and 9.1% in first, second, and third mandibular molars respectively. The inter-/intra-observer reliability of the results was extremely high. Conclusion: This cross-sectional study showed the prevalence of C-shaped canals in mandibular second molars was relatively high and should be considered normal root canal anatomy in Thais. The prevalence of three-rooted molars was highest in first molars and frequently found in third molars. Cone-beam computed tomography was a reliable technique to determine root canal anatomy.

Activity of chitosan antifungal denture adhesive against common Candida species and Candida albicans adherence on denture base acrylic resin.

STATEMENT OF PROBLEM: Candida adherence to the denture base is an important cause of denture stomatitis. In addition, infections with drug-resistant Candida have become more prevalent, especially among elderly and immunocompromised patients. Thus, alternative safe antifungal agents for oral applications are needed. PURPOSE: The purpose of this in vitro study was to investigate the activity of chitosan, a natural biopolymer, against common oral Candida species and its efficacy in inhibiting C albicans adherence to denture-base acrylic resin. MATERIAL AND METHODS: The minimum fungicidal concentrations (MFCs) of 5 types of chitosan against 6 species of Candida and 10 C albicans clinical isolates were determined by broth and agar dilution, respectively. N-succinyl chitosan (NSC), low- and high-molecular-weight water-soluble chitosan (LMWC and HMWC), and oligomer and polymer shrimp-chitosan were examined. NSC and HMWC, as pure gel and as a mixture with carboxymethylcellulose (CMC), were applied to acrylic resin disks, incubated with C albicans for 24 hours, and washed, and adherent cells were collected for colony count. The effects of HMWC on human gingival fibroblasts after 1 and 24 hours of treatment were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The retention force of HMWC gel was measured by using a universal testing machine. The Kruskal-Wallis and Mann-Whitney U tests were used to compare the antiadherence activity (α=.05). RESULTS: HMWC had the highest antifungal activity against most Candida species tested and C albicans clinical isolates. HMWC gel completely inhibited C albicans adherence to denture base acrylic resin (P<.001). CMC denture adhesive significantly increased C albicans adherence (P<.001), but adding 2×MFC HMWC into CMC reduced the adherence, although this was not statistically significant (P=.06). HMWC at 1×MFC and 2×MFC showed no toxic effect on gingival fibroblast viability and proliferation. Moreover, the retention force provided by HMWC gel was sufficient for use as a denture adhesive (>5000 Pa). CONCLUSIONS: High-molecular-weight, water-soluble chitosan is a biocompatible biopolymer that could inhibit C albicans adherence and that showed properties suitable for development into an antifungal denture adhesive.

Age estimation methods using hand and wrist radiographs in a group of contemporary Thais.

OBJECTIVES: The aim of this study was to evaluate the accuracy and reliability of three commonly used age estimation methods in Thailand: Greulich-Pyle, Tanner-Whitehouse and Fishman. MATERIALS AND METHODS: Three hundred and sixty-five hand and wrist radiographs of 8-20 years old Thai patients were retrospectively collected. The radiographs were taken between 2011-2016. Greulich-Pyle, Tanner-Whitehouse 3 radius, ulna and selected short bones (RUS), and Fishman method were applied for each radiograph. Comparisons between the estimated age from each method and the chronological age were done using Wilcoxon signed ranks test with Bonferroni correction. Sensitivity, specificity and accuracy tests were performed on the important legal age thresholds in Thailand (10, 13, 15 and 18years old). Intra- and inter-observer reliability were evaluated by weighted kappa analysis. RESULTS: The estimated ages from the three methods were significantly different from the chronological age, except for Tanner-Whitehouse 3 RUS in males. Regarding the legal age thresholds, Greulich-Pyle showed the best accuracy (83.2% for females and 79.63% for males) for legal age threshold of 10years old. Fishman method showed the best accuracy for legal age threshold of 13 (77.5% for females and 74.31% for males) and 15years old (83.08% for females and 73.77% for males). For age threshold of 18years old, Greulich-Pyle showed an accuracy of 53.85% for females and 54.44% for males. The reliability tests showed substantial to almost perfect agreement. CONCLUSIONS: This study showed no significant difference between Tanner-Whitehouse 3 RUS age and chronological age for male subjects of contemporary Thai children and adolescents. However, Greulich-Pyle and Fishman method were superior regarding the accuracy of prediction based on Thai legal age thresholds. Due to the possible effects from ethnical difference and secular changes, adaptation of age estimation methods specifically for contemporary Thai population should be further studied.