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The aim of this study was to determine the effects of age and sex on the difference between chronological age (CA) and dental age (DA) predicted using the Demirjian and Willems methods in Taiwanese children. A total of 232 periapical X-ray images were obtained from children aged 5–12 years in Taiwan. Among them, 119 were boys, and 113 were girls. DA was calculated on the basis of the X-ray images of permanent teeth by using the aforementioned methods. The children were stratified by age (5–9 years [early mixed dentition period] vs. 10–12 years [late mixed dentition period]) and sex (boys vs. girls). Statistical analyses were performed to investigate potential age- and sex-based differences in the correlation between CA and DA. No significant difference was observed between the mean CA and DA predicted using the Willems method in children with late mixed dentition and in girls. However, the correlation between CA and DA was stronger in children with early mixed dentition than in those with late mixed dentition and also stronger in boys than in girls. For children in mid-Taiwan, age and sex influence the development of permanent teeth. In addition, the correlation between DA and CA is relatively strong for boys in the early mixed dentition period. [ABSTRACT FROM AUTHOR]

Clear aligners are popular orthodontic tools because of their relatively aesthetic appearance and convenience of use. Nevertheless, bodily tooth movements still present challenges. This study evaluated various configurations of attachments placed on the mandibular canine in terms of the efficiency of canine bodily movement and correction of tipping. A finite element model of the mandible was constructed to investigate the effects of various attachment configurations on the overall bodily movement and undesirable tipping of a mandibular canine. Canine movements were categorized into four types, namely tipping and bodily movements in the mesial and distal directions. The size and shape of the attachments were fixed, but their placement and orientation were varied. Five and seven attachment configurations were evaluated for their influence on tipping and bodily movements, respectively. Attachment configuration significantly influenced mandibular canine tipping. The mesial occlusal–distal cervical and mesial occlusal–mesial cervical configurations had notable effects on mesial tipping, and the mesial occlusal–mesial cervical configuration excelled in distal tipping by increasing strain by 33.1%. The mesial occlusal–mesial cervical attachment configuration consistently had superior efficiency in facilitating both mesial and distal bodily movements of the canine. The mesial occlusal–mesial cervical attachment configuration excelled in all four types of canine movement. Irrespective of the attachment configuration, canines tend to move overall with slight tipping due to skeletal resistance and their center of rotation. The attachment configuration is crucial to the success of clear aligner treatment and must be carefully considered in clinical practice. [ABSTRACT FROM AUTHOR]

Background: Dental cone beam computed tomography (CBCT) is commonly used to evaluate cancellous bone density before dental implant surgery. However, to our knowledge, no measurement approach has been standardized yet. This study aimed to evaluate the relationship between three different regions of interest (ROI) methods on cancellous bone density at the dental implant site using dental CBCT images. Methods: Patients' dental CBCT images (n = 300) obtained before dental implant surgery were processed using Mimics (Materialise, Leuven, Belgium). At the potential implant sites, the rectangle, cylinder, and surrounding cylinder ROI methods were used to measure bone density. Repeated measures one-way analysis of variance was performed to compare the three ROI methods in terms of measurement results. Pearson correlation analysis was performed to identify the likely pair-wise correlations between the three ROI methods. Results: The density value obtained using the surrounding cylinder approach (grayscale value [GV],523.56 ± 228.03) was significantly higher than the values obtained using the rectangle (GV, 497.04 ± 236.69) and cylinder (GV,493 ± 231.19) ROI methods in terms of results. Furthermore, significant correlations were noted between the ROI methods (r > 0.965; p < 0.001). Conclusions: The density measured using the surrounding cylinder method was the highest. The choice of method may not influence the trends of measurement results. Trial registration: This study was approved by the Institutional Review Board of China Medical University Hospital, No. CMUH111-REC3-205. Informed consent was waived by the Institutional Review Board of China Medical University Hospital, CMUH111-REC3-205, owing to the retrospective nature of the study. [ABSTRACT FROM AUTHOR]