Association of gonial angle with morphology and bone mineral content of the body of the adult human mandible with complete permanent dentition.

We investigated the differences between 2 gonial angle (GA) size groups with respect to the morphometry and quantitative bone mineral content (QBMC) of mandibles with all teeth erupted and normal occlusion. We used 19 dried mandibles that were obtained from an Indian population and stored in our department. These mandibles were at Hellman's developmental dental stage VA and were divided into low gonial angle (LGA) (GA ≤ 120°; 8 specimens; 16 sides) and high gonial angle (HGA) (GA ≥ 125°; 11 specimens; 22 sides) groups. After lateral radiography of the mandibles using a titanium step wedge, linear measurements and the QBMC were determined, on hard copies and digital images, respectively. The age and sex of the cadavers to which the specimens belonged were unknown. The mandibular cortical width (MCW) and the antegonial notch depth of the LGA group were significantly larger than those of the HGA group. No significant difference was found in the distribution of the 3 categories of mandibular cortical index (MCI) or in cortical and trabecular bone mineral contents (CBMC and TBMC). The GA size was negatively and moderately associated with the MCW and the mandibular cortical width on the point AG (MCWAG), but was not significantly associated with either variable for CBMC and TBMC. These results suggested that the GA size of these stage-VA mandibles influenced changes in the width of inferior cortex and morphology of antegonial notch. The GA size did not influence QBMC under the mental foramen of the mandible and had negative associations with the MCW and MCWAG.

Differences in 5 anatomic parameters of mandibular body morphology by gonial angle size in dentulous Japanese subjects.

This study aimed to determine the differences in 5 anatomical parameters of the mandibular body on dental panoramic radiographs (DPRs) of 234 dentulous Japanese subjects (21-78years; mean, 25.76; median, 27 teeth) according to gender and gonial angle (GA) size, and to analyse the correlations between GA size and each variable by gender. The subjects were divided into low (LGA≤120°) and high gonial angle (HGA≥125°) groups. Linear, angular, and morphological measurements were obtained using the DPRs. Statically significant differences were determined using the Mann-Whitney U and χ(2) tests and simple regression analysis. Mandibular cortical width - MCW, antegonial notch depth - AD and angle - AA, and panoramic mandibular index - PMI in the LGA group were significantly larger than those of the HGA group. In men, a significant difference was observed in the distribution of the 3 mandibular cortical index categories between both GAs. Sexual dimorphism for MCW and AD was significantly greater in men than in women. There were significantly negative low correlations between the GA and variables of the MCW, AD, and PMI. These results suggest that the MCW and AD can show significantly different morphology according to gender and GA size.

Environmental monitoring and bactericidal efficacy of chlorine dioxide gas in a dental office.

We monitored the quantity of airborne microorganisms at 11 points (points A to K) in a dental office on a routine day of use, and tested the bactericidal efficacy of chlorine dioxide (ClO2) gas in the dental operatory after consulting hours. Fallen airborne microorganisms were collected under air-conditioning (AC) in the dental office, and under four conditions in the operatory. Specimens of the microbes were cultivated on nutrient and Sabouraud agar media (NAM and SAM). Many colonies were observed at the entrance hall and on the cabinet in a disinfection room in the NAM and SAM tests, respectively, while no colony was observed at the foot position of the operating table and treatment bed, and above the head position of the operating room in the NAM and SAM tests, respectively. In the bactericidal efficacy test using ClO2 gas, the dental operatory could be kept clean by the use of 4 mg/L-ClO2 gas in addition to the use of an AC with a plasma filter and the HEPA filter.