Objective:To digitally measure the three-dimensional (3D) size of primary tooth crowns and the dimensions of the dental arch in children with individual normal primary dentition, preliminarily obtaining baseline data on the 3D size of primary tooth crowns as well as the length and width of the dental arch, and their influence factors. This study aims to provide a data foundation for the design of reference models for primary dentition.Methods:From May to June 2021, 122 caries-free children aged 3.5-4.5 years with individual normal occlusion were selected from five kindergartens in Haidian District, Beijing. Impressions were taken and plaster models were cast. After preliminary screening, 67 eligible models were scanned to obtain digital dental models. Digital measurement software was used for landmark-based measurements. Parameters included 3D crown dimensions (mesiodistal diameter, buccolingual diameter, and occlusogingival height), dental arch dimensions (length and width at specific regions), and occlusal measurements (overjet and overbite at the primary central incisors, and Bolton index for anterior and full dentition). Gender differences in crown dimensions and bilateral symmetry of homologous teeth, as well as the correlations between arch dimensions and gender, height, weight, and body mass index (BMI) were analyzed.Results:The homonymous teeth of 67 children exhibited strong bilateral symmetry in all 3D dimensions ( P>0.05). Gender differences were observed in the buccolingual dimension for all deciduous molars except for the right mandibular first deciduous molar ( P<0.05). For the occlusogingival dimension, gender differences were found in the right maxillary first and second deciduous molars, left maxillary first deciduous molar, and left mandibular first and second deciduous molars ( P<0.05). For the mesiodistal dimension, only the left mandibular second deciduous molar and right mandibular deciduous canine showed gender differences ( P<0.05). All significant differences above indicated larger dimensions in boys compared to girls. In both maxillary and mandibular arches, the lengths and widths at various locations were significantly larger in boys than in girls ( P<0.05). Univariate correlation analysis revealed that body weight was positively correlated with the width of the terminal plane in both the maxilla and mandible and the total length of the mandibular dental arch, while BMI was positively correlated with the width of the maxillary terminal plane and the widths at all measured sites in the mandible ( P<0.05). Multiple regression analysis demonstrated that, after controlling for relevant variables, BMI was a significant positive predictor for the lengths and widths at various sites of the dental arch ( P<0.05), and height was a positive predictor for dental arch length ( P<0.05), as well as body weight was a positive predictor for the width in the molar region ( P<0.05). Overjet at the primary central incisors was 2.28 (1.57, 2.66) mm, and overbite was 1.13 (0.75, 1.92) mm. The anterior Bolton index was 0.79±0.03, and the overall Bolton index was 0.94±0.03. Conclusions:Primary tooth crowns of individual normal occlusion children demonstrate strong bilateral symmetry in homologous teeth. Most primary molars exhibit gender differences in buccolingual and occlusogingival dimensions, with larger values in boys. Arch dimensions (length and width) are consistently larger in boys.

Objective:To digitally measure the three-dimensional (3D) size of primary tooth crowns and the dimensions of the dental arch in children with individual normal primary dentition, preliminarily obtaining baseline data on the 3D size of primary tooth crowns as well as the length and width of the dental arch, and their influence factors. This study aims to provide a data foundation for the design of reference models for primary dentition.Methods:From May to June 2021, 122 caries-free children aged 3.5-4.5 years with individual normal occlusion were selected from five kindergartens in Haidian District, Beijing. Impressions were taken and plaster models were cast. After preliminary screening, 67 eligible models were scanned to obtain digital dental models. Digital measurement software was used for landmark-based measurements. Parameters included 3D crown dimensions (mesiodistal diameter, buccolingual diameter, and occlusogingival height), dental arch dimensions (length and width at specific regions), and occlusal measurements (overjet and overbite at the primary central incisors, and Bolton index for anterior and full dentition). Gender differences in crown dimensions and bilateral symmetry of homologous teeth, as well as the correlations between arch dimensions and gender, height, weight, and body mass index (BMI) were analyzed.Results:The homonymous teeth of 67 children exhibited strong bilateral symmetry in all 3D dimensions ( P>0.05). Gender differences were observed in the buccolingual dimension for all deciduous molars except for the right mandibular first deciduous molar ( P<0.05). For the occlusogingival dimension, gender differences were found in the right maxillary first and second deciduous molars, left maxillary first deciduous molar, and left mandibular first and second deciduous molars ( P<0.05). For the mesiodistal dimension, only the left mandibular second deciduous molar and right mandibular deciduous canine showed gender differences ( P<0.05). All significant differences above indicated larger dimensions in boys compared to girls. In both maxillary and mandibular arches, the lengths and widths at various locations were significantly larger in boys than in girls ( P<0.05). Univariate correlation analysis revealed that body weight was positively correlated with the width of the terminal plane in both the maxilla and mandible and the total length of the mandibular dental arch, while BMI was positively correlated with the width of the maxillary terminal plane and the widths at all measured sites in the mandible ( P<0.05). Multiple regression analysis demonstrated that, after controlling for relevant variables, BMI was a significant positive predictor for the lengths and widths at various sites of the dental arch ( P<0.05), and height was a positive predictor for dental arch length ( P<0.05), as well as body weight was a positive predictor for the width in the molar region ( P<0.05). Overjet at the primary central incisors was 2.28 (1.57, 2.66) mm, and overbite was 1.13 (0.75, 1.92) mm. The anterior Bolton index was 0.79±0.03, and the overall Bolton index was 0.94±0.03. Conclusions:Primary tooth crowns of individual normal occlusion children demonstrate strong bilateral symmetry in homologous teeth. Most primary molars exhibit gender differences in buccolingual and occlusogingival dimensions, with larger values in boys. Arch dimensions (length and width) are consistently larger in boys.

OBJECTIVETo investigate the influence of digit-sucking habit on palatal features in pre-school children by using a laser scanning system.

METHODSForty pre-school children were chosen according to the results of questionnaires, among which 20 with digit-sucking habit(digit-sucking group) and 20 without any oral habits(control group). Impression of the upper jaw was taken from each child. After laser scanning the plaster casts, and three-dimensional reconstruction by the computer, parameters of anterior and posterior palatal length, width and height were measured, ratios of height/width, length/width and width ratio of anterior and posterior palatal were analyzed. The differences of palatal features between two groups were analyzed by t test.

RESULTSThere was statistical significance between digit-sucking group and control group in posterior palatal width, anterior palatal length and anterior palatal height. The ratios of height/width and length/width in both posterior and anterior areas were statistically significant (P < 0.05). Compared to the control group, the results indicated that palatal features were relatively deeper, narrower and more protrusive in digit-sucking group.

CONCLUSIONThe digit-sucking habit may have some deleterious impacts on the palatal features in pre-school children with primary dentition. And it is practical to measure the spacial palatal features by using laser scanning system to some extent.

Child ; Child, Preschool ; Fingersucking ; Habits ; Humans ; Lasers ; Malocclusion ; Maxilla ; Tooth, Deciduous

OBJECTIVE: To discuss the types of control groups in randomized controlled trials (RCTs) of Chinese herbal medicine (CHM), and to provide suggestions for improving the design of control group in future clinical studies in this therapeutic area. METHODS: A search of the Cochrane Library was conducted in July 2005 to identify RCTs of CHM, and 66 RCTs with CHM for type 2 diabetes mellitus were obtained as the basis for further analysis. RESULTS: Of 66 RCTs with CHM for type 2 diabetes mellitus, 61 (92.4%) trials had both a treatment group and a control group. Twenty-seven (40.9%) RCTs compared CHM plus conventional drug vs conventional drug, 24 (36.4%) compared CHM vs conventional drug, 5 (7.6%) compared CHM vs placebo, 3 (4.5%) compared CHM plus conventional drug vs conventional drug plus placebo, 3 (4.5%) compared CHM plus conventional drug vs other CHM, 1 (1.5%) compared CHM vs no treatment, 1 (1.5%) compared CHM plus placebo vs conventional drug plus placebo, 1 (1.5%) compared CHM vs CHM plus conventional drug vs conventional drug vs placebo, and 1 (1.5%) compared CHM vs conventional drug vs CHM plus conventional drug. CONCLUSION: A variety of control groups were used in RCTs of CHM for type 2 diabetes mellitus, including placebo, active, and no treatment control groups. Justification for selecting particular types of control groups were not provided in the trials reviewed in this study. Different control groups may be appropriate according to the study objectives, and several factors should be considered prior to selecting control groups in future RCTs of CHM. RECOMMENDATIONS: (1) Investigators of CHM who design clinical trials should understand the rationale for selecting different types of control groups; (2) Control groups for RCTs should be selected according to study objectives; (3) Active control groups should select interventions for comparisons that have the strongest evidence of efficacy and prescribe them as recommended; (4) Placebo control groups should select a placebo that mimics the physical characteristics of test intervention as closely as possible and is completely inert; (5) No treatment control groups should only be used when withholding treatment is ethical and objectives outcomes will not be subject to bias due to absent blinding; (6) Crossover control groups may be appropriate in chronic and stable conditions.

OBJECTIVE: To discuss the quality of reporting in randomized controlled trials (RCTs) of Chinese herbal medicine (CHM), and to provide suggestions for improving the reporting of future clinical studies in this therapeutic area. METHODS: A search of the Cochrane Library was conducted to identify RCTs of CHM. A revised CONSORT checklist designed for CHM clinical studies was implemented. The revised CONSORT checklist contained 63 items, including the following new items added specifically for CHM: (1) "syndrome of disease" based on Chinese medicine theories; (2) rationale of CHM formula; (3) formula composition; (4) preparation form of CHM; (5) quality control of CHM. RESULTS: The overall reporting quality of the RCTs as assessed with the revised CONSORT checklist varied between 19% and 44%, with a median score of 32% (standard deviation 8%). CONCLUSION: The overall quality of reporting of RCTs of CHM evaluated with a revised CONSORT checklist was poor, reflecting the need for improvements in reporting future clinical trials in this area. RECOMMENDATIONS: To improve the quality of reporting of RCTs of CHM, we recommend adopting a revised CONSORT checklist that includes items specific to CHM. We also recommend that editors of CHM journals require authors to use a structured approach to presenting their trials as a condition of publication.