Objective:To explore the data distribution characteristics of hydrogen and methane breath test (HMBT) in Chinese population and to evaluate its applicability for diagnosing small intestinal bacterial overgrowth (SIBO) in Chinese population.Methods:HMBT data of 18 634 individuals who underwent health check-up nationwide from March 2019 to september 2022 were retrospectively collected, which included the levels of hydrogen and methane at 0, 30, 60, and 90 min. After quality control and data cleaning, the final valid sample size was 12 654 cases, comprising 7 146 SIBO-negative cases and 5 508 SIBO-positive cases. In order to exclude confounding factors such as oral hygiene, the 12 654 cases were divided into D0 and D1 dataset, when the 0 min-value of hydrogen and methane were both lower than the 30 min-value, the 0 min-value was taken as the baseline, and induded into the D0 dataset (5 556 cases), and other situations were induded into the D1 dataset (7 098 cases). There were 2 879 SIBO-negative cases and 2 659 SIBO-positive cases in D0 dataset, and 4 249 SIBO-negative cases and 2 849 SIBO-positive cases in D1 dataset. The hydrogen and methane level at each testing time point in the SIBO-negative and SIBO-positive individuals, the difference between the peak gas level at 90 min and the baseline, and the distribution of time points at which peak level occurred were analyzed. Independent-sample t test and Mann-Whitney U test were used for statistical analysis. Results:The overall SIBO positive rate was 43.53% (5 508/12 654). In SIBO-positive cases the hydrogen level at 0, 30, 60, and 90 min were 9.41×10 -6 (5.01×10 -6, 21.90×10 -6), 11.34×10 -6 (6.13×10 -6, 22.94×10 -6), 18.16×10 -6 (11.03×10 -6, 29.37×10 -6) and 29.59×10 -6 (20.12×10 -6, 43.36×10 -6), respectively, and methane level were 9.13×10 -6 (7.12×10 -6, 12.03×10 -6), 9.23×10 -6 (8.07×10 -6, 12.03×10 -6), 10.21×10 -6 (9.02×10 -6, 13.01×10 -6), and 12.03×10 -6 (10.01×10 -6, 14.11×10 -6), respectively, which were higher than those of SIBO-negative cases (6.04×10 -6 (3.10×10 -6, 11.08×10 -6), 6.04×10 -6 (3.21×10 -6, 10.06×10 -6), 6.95×10 -6 (4.03×10 -6, 11.01×10 -6), 8.96×10 -6 (5.01×10 -6, 13.91×10 -6); 8.04×10 -6 (7.02×10 -6, 10.00×10 -6), 8.03×10 -6 (7.03×10 -6, 9.95×10 -6), 8.04×10 -6 (7.03×10 -6, 10.00×10 -6) 8.98×10 -6 (7.12×10 -6, 10.03×10 -6)], and the differences were statistically significant ( U=1.41×10 7, 1.09×10 7, 6.66×10 6, 4.14×10 6, 1.51×10 7, 1.23×10 7, 1.02×10 7, 8.86×10 6; all P<0.001). In both D0 and D1 datasets, the increase in hydrogen and methane of SIBO positive subgroup were higher than those of SIBO negative subgroup (22.39×10 -6(14.82×10 -6, 33.37×10 -6) vs. 4.82×10 -6(1.96×10 -6, 7.85×10 -6), 20.61×10 -6(7.87×10 -6, 31.44×10 -6) vs. 3.25×10 -6(0.79×10 -6, 7.88×10 -6); 3.98×10 -6(2.87×10 -6, 6.87×10 -6) vs. 1.95×10 -6(0.98×10 -6, 2.99×10 -6), 2.95×10 -6(0.98×10 -6, 4.93×10 -6) vs. 0.98×10 -6(0.00×10 -6, 1.99×10 -6)), and the differences were statistically significant( U=7.24×10 6, 9.72×10 6, 5.74×10 6, 8.27×10 6; all P<0.001). In both D0 and D1 datasets, hydrogen and methane concentrations peaked at 90 min. Conclusion:HMBT can be used for non-invasive diagnosis of SIBO in Chinese population, and the differences in hydrogen and methane concentrations at 90 min of the test have critical value for SIBO diagnosis.

Objective:To explore the data distribution characteristics of hydrogen and methane breath test (HMBT) in Chinese population and to evaluate its applicability for diagnosing small intestinal bacterial overgrowth (SIBO) in Chinese population.Methods:HMBT data of 18 634 individuals who underwent health check-up nationwide from March 2019 to september 2022 were retrospectively collected, which included the levels of hydrogen and methane at 0, 30, 60, and 90 min. After quality control and data cleaning, the final valid sample size was 12 654 cases, comprising 7 146 SIBO-negative cases and 5 508 SIBO-positive cases. In order to exclude confounding factors such as oral hygiene, the 12 654 cases were divided into D0 and D1 dataset, when the 0 min-value of hydrogen and methane were both lower than the 30 min-value, the 0 min-value was taken as the baseline, and induded into the D0 dataset (5 556 cases), and other situations were induded into the D1 dataset (7 098 cases). There were 2 879 SIBO-negative cases and 2 659 SIBO-positive cases in D0 dataset, and 4 249 SIBO-negative cases and 2 849 SIBO-positive cases in D1 dataset. The hydrogen and methane level at each testing time point in the SIBO-negative and SIBO-positive individuals, the difference between the peak gas level at 90 min and the baseline, and the distribution of time points at which peak level occurred were analyzed. Independent-sample t test and Mann-Whitney U test were used for statistical analysis. Results:The overall SIBO positive rate was 43.53% (5 508/12 654). In SIBO-positive cases the hydrogen level at 0, 30, 60, and 90 min were 9.41×10 -6 (5.01×10 -6, 21.90×10 -6), 11.34×10 -6 (6.13×10 -6, 22.94×10 -6), 18.16×10 -6 (11.03×10 -6, 29.37×10 -6) and 29.59×10 -6 (20.12×10 -6, 43.36×10 -6), respectively, and methane level were 9.13×10 -6 (7.12×10 -6, 12.03×10 -6), 9.23×10 -6 (8.07×10 -6, 12.03×10 -6), 10.21×10 -6 (9.02×10 -6, 13.01×10 -6), and 12.03×10 -6 (10.01×10 -6, 14.11×10 -6), respectively, which were higher than those of SIBO-negative cases (6.04×10 -6 (3.10×10 -6, 11.08×10 -6), 6.04×10 -6 (3.21×10 -6, 10.06×10 -6), 6.95×10 -6 (4.03×10 -6, 11.01×10 -6), 8.96×10 -6 (5.01×10 -6, 13.91×10 -6); 8.04×10 -6 (7.02×10 -6, 10.00×10 -6), 8.03×10 -6 (7.03×10 -6, 9.95×10 -6), 8.04×10 -6 (7.03×10 -6, 10.00×10 -6) 8.98×10 -6 (7.12×10 -6, 10.03×10 -6)], and the differences were statistically significant ( U=1.41×10 7, 1.09×10 7, 6.66×10 6, 4.14×10 6, 1.51×10 7, 1.23×10 7, 1.02×10 7, 8.86×10 6; all P<0.001). In both D0 and D1 datasets, the increase in hydrogen and methane of SIBO positive subgroup were higher than those of SIBO negative subgroup (22.39×10 -6(14.82×10 -6, 33.37×10 -6) vs. 4.82×10 -6(1.96×10 -6, 7.85×10 -6), 20.61×10 -6(7.87×10 -6, 31.44×10 -6) vs. 3.25×10 -6(0.79×10 -6, 7.88×10 -6); 3.98×10 -6(2.87×10 -6, 6.87×10 -6) vs. 1.95×10 -6(0.98×10 -6, 2.99×10 -6), 2.95×10 -6(0.98×10 -6, 4.93×10 -6) vs. 0.98×10 -6(0.00×10 -6, 1.99×10 -6)), and the differences were statistically significant( U=7.24×10 6, 9.72×10 6, 5.74×10 6, 8.27×10 6; all P<0.001). In both D0 and D1 datasets, hydrogen and methane concentrations peaked at 90 min. Conclusion:HMBT can be used for non-invasive diagnosis of SIBO in Chinese population, and the differences in hydrogen and methane concentrations at 90 min of the test have critical value for SIBO diagnosis.

Objective:To assess the accuracy of two-dimensional (2D) photographs in measuring esthetic parameters of the maxillary anterior teeth by comparing them with measurements obtained from three-dimensional (3D) dental models.Methods:A total of one hundred volunteers (49 males, 51 females, aged 18-23 years) were recruited from School and Hospital of Stomatology, Wuhan University from January to February 2024. 3D digital models of their dentitions were obtained using an intraoral scanner, and standardized frontal 2D intraoral photographs were captured with a digital camera. The lengths, widths and width/length ratio of the bilateral incisors, lateral incisors and canines were measured on both the 3D digital models and the 2D intraoral photographs. The width ratios of adjacent maxillary anterior were also calculated on the 2D intraoral photographs and the frontal view of 3D digital models.Results:The widths of lateral incisors [(5.85±0.60) mm] and canines [(4.73±0.71) mm] and the lengths of canines [(8.72±0.96) mm] in the 2D intraoral photographs were significantly lower than those in 3D digital models [(6.65±0.59), (7.76±0.60), (8.90±0.86) mm] ( t=-18.24, P<0.001; t=-54.43, P<0.001; t=-4.40, P<0.001), while there were no significant differences in the lengths and widths of the other teeth ( P>0.05). The width/length ratios measured from the 2D intraoral photographs for the lateral incisors and canines (0.74±0.08, 0.55±0.08) were significantly lower than those measured in the 3D digital models (0.84±0.09, 0.88±0.09) ( t=-19.68, P<0.001; t=-50.21, P<0.001), and the width/length ratio of the central incisors showed no significant difference between the two groups ( P>0.05). The width ratios of canines/lateral incisors and lateral incisors/central incisors measured on the 2D intraoral photographs (0.72±0.06, 0.85±0.11) were significantly smaller than those measured in the frontal view of 3D digital models (0.75±0.06, 0.89±0.11) ( t=-9.31, P<0.001; t=-6.58, P<0.001). Conclusions:There is a difference between 2D and 3D measurement results of teeth in the esthetic area and the magnitude of the difference varies with their position in the dental arch. When analyzing the measurement of the anterior teeth, it is necessary to choose the appropriate method according to the target tooth position.