Paired box gene 3 (PAX3) plays an important role in craniofacial development. Mutations in this gene are associated with Waardenburg syndrome, which is a condition characterized by facial anomalies such as widely spaced inner corners of the eyes. PAX3 gene polymorphisms are associated with the relative position of the nasal root (nasion), even among healthy individuals. Facial morphology has primarily been examined using three-dimensional (3D) facial scans of soft tissues, whereas studies focusing on hard tissues remain limited. Therefore, the present study aimed to analyze 3D craniofacial morphology in hard tissues using computed tomography imaging and investigate the influence of PAX3 polymorphisms on the 3D morphology of the nasal root. The analysis was conducted on three populations: 201 healthy Japanese, 74 healthy Korean, and 142 healthy Egyptian individuals. DNA was extracted from saliva samples, and the genotypes of two PAX3 single-nucleotide polymorphisms (SNPs; rs9288572 and rs7559271) were analyzed. A multiple regression analysis of the association between these SNPs and measurements related to nasal root morphology revealed a significant association between rs7559271 and the protrusion angle of the nasion. These findings suggest that PAX3 gene polymorphisms influence the morphological development of the nasal root within the normal range of hard tissues.

Objectives: This study aimed to explore the association between the ANB angle and mandibular bone thickness in individuals with skeletal malocclusion. Methods: We analyzed 224 adults, with a gender imbalance noted (68 men and 156 women), and an age range between 18.0 and 65.1 years. The thicknesses of the ramus (RT) and the body of the mandible (BT) were measured at 25 sites on each side (left and right) of the jaw, using CT images. The main focus was on the statistical associations between the ANB angle and the ratio (BT-RT)/volume of the mandible (V). Results: Results revealed a significant negative association between (BT-RT)/V and the ANB angle (p < 0.001), while a positive association was found for RT/V (p < 0.001). No significant association emerged for BT/V. Conclusions: The findings indicated that with increased mandibular protrusion, the ramus thickness decreased, whereas the body thickness remained unchanged. The differing relationships in mandibular thickness underscore the significance of CT imaging in predicting craniofacial growth patterns, particularly in observing discrepancies between the mandibular body and ramus as they relate to the anterior–posterior jaw relationship.

Aim Balanced function of the orofacial muscles is important for normal occlusion and dentition; however, patients with malocclusion often present with myofunctional disorder (MFD). Myofunctional therapy (MFT) has received much attention as a method for reducing MFD. Moreover, prefabricated functional appliances (PFAs) have been developed as a method to eliminate abnormal muscle pressure and guide the tongue into the correct position. However, PFAs have disadvantages, such as poor intraoral retention, limited usage time due to discomfort and poor patient compliance, and changes in the axis of the mandibular anterior teeth. Therefore, this study aimed to develop a new custom -made splint -type orthodontic appliance with CAD/CAM technology. Moreover, we evaluated the characteristics of the appliance and conducted functional tests to determine the effects of the appliance on the orofacial muscles and the discomfort associated with its use. Materials and methods Twenty-five volunteers (nine females and 16 males; mean age 28.4 +/- 3.4 years) with normal swallowing function were included in the study. Lip-closing strength (LCS), electromyogram during swallowing, oxygen saturation, and pulse rate were measured and compared when the appliance was not worn and when it was worn. In addition, tongue habits were evaluated, and the maximum tongue pressure was measured when the appliance was not worn. The subjects were asked to answer a questionnaire using a numerical rating scale (NRS) regarding discomfort when wearing the appliance. The evaluation items were swallowing difficulty, speaking difficulty, and breathlessness, which were rated on an 11 -point scale ranging from 0 to 10. Statistical tests were conducted using IBM SPSS version 28.0.1 (IBM, Armonk, NY, USA) with the ShapiroWilk and Levene's test, followed by the Wilcoxon signed rank sum test. The significance level was set at alpha = 0.05. The measurement error for each measurement item was evaluated using an intraclass correlation coefficient. Results A new custom -made splint -type orthodontic appliance was fabricated for each subject. The fit and retention of the appliance in the mouth were good when fitted, and a comparison of the functional test measurements of 25 subjects with and without the appliance showed that the LCS decreased significantly (p<0.05) before and after wearing the appliance. However, no statistically significant differences were found for the other items. The Mann -Whitney U test regarding the effects of sex, previous orthodontic treatment, or MFT, and oral habits did not statistically significantly influence the effects of wearing the device. In the NRS results, "difficulty swallowing" was observed in half of the subjects, "difficulty breathing" was rarely observed, and "difficulty speaking" was observed in all subjects. Conclusions A novel custom -made splint -type orthodontic appliance was designed and fabricated using digital workflow and 3D printing technology. This appliance was designed to correct oral habits and was made from a new material classified as a class II medical appliance according to the international harmonized classification.

Objectives: This study aimed to compare the fit accuracy between retainers fabricated using conventional cold-curing resin (hereinafter referred to as “conventional retainers”) and those fabricated using three-dimensional (3D) printing based on computer-aided design/computer-aided manufacturing (CAD/CAM) technology (hereinafter referred to as “CAD/CAM retainers”). Furthermore, the study aimed to compare two different methods to evaluate the fit accuracy: the impression replica technique and the 3D triple-scan protocol. Methods: For each of the 20 working models derived from a maxillary typodont, one conventional retainer and one CAD/CAM retainer were fabricated. The fit accuracy was evaluated using the impression replica technique and the 3D triple-scan protocol. Measurements were taken at 12 points on each model, and the differences in thickness (gap) were analyzed using Wilcoxon’s signed-rank test. Moreover, the correlation between thickness and measurement site was evaluated using Spearman’s rank correlation coefficient. Results: In both evaluation methods, the CAD/CAM retainers exhibited superior fit accuracy compared to the conventional retainers. Notably, the 3D triple-scan protocol clearly demonstrated that the fit accuracy differed depending on the measurement site. Conclusions: CAD/CAM retainers demonstrated superior fit accuracy compared to conventional retainers, possibly because digital design can account for polymerization shrinkage. In the impression replica technique, the median (interquartile range) thickness for the conventional retainers was 0.169 (0.120–0.260) mm, whereas that for the CAD/CAM retainers was 0.136 (0.096–0.198) mm. The CAD/CAM retainers showed significantly smaller gap values (p < 0.001). Within the limitations of this in vitro study, CAD/CAM retainers showed significantly smaller gap values than conventional retainers, indicating improved fit accuracy. In particular, the 3D triple-scan protocol accurately captured site-specific variations in fit accuracy among the anterior, canine, and molar regions.

Background/Objectives: The local mechanical properties of periodontal supporting tissues influence their responses to orthodontic forces. This exploratory study sought to evaluate site-specific nanoindentation hardness in human root cementum and adjacent alveolar cortical bone and examine its association with cone-beam computed tomography (CBCT)- and micro-computed tomography (micro-CT)-derived relative imaging indices. Methods: Specimens from seven human cadavers were analyzed. Indentation hardness (HIT) was measured in the central and apical regions of root cementum and adjacent alveolar cortical bone. CBCT gray values and micro-CT-derived relative imaging indices were obtained from anatomically matched regions without phantom-based mineral-density calibration. Nonparametric tests, multiple linear regression analyses, and Spearman’s rank correlation analyses were performed. Results: Root cementum exhibited significantly higher HIT in the central region than in the apical region (p < 0.001). The central region and mandibular location were independently associated with higher cementum HIT. No significant regional variation or associated factors were identified for alveolar cortical bone. Neither CBCT nor micro-CT-derived indices were significantly associated with local tissue hardness. Conclusions: Human root cementum exhibits site-specific variation in hardness, unlike the adjacent alveolar cortical bone. Uncalibrated CT-derived relative imaging indices may not be significantly associated with local tissue hardness.

Background/Objectives: Acceleration of orthodontic tooth movement remains a major challenge in clinical orthodontics. Evidence suggests that increased local blood flow around the alveolar bone is key to bone remodeling and potentially reflects early biological responses associated with accelerated orthodontics. This study aimed to investigate the effects of non-invasive physical stimuli on gingival microcirculation. Methods: Eight healthy adult male volunteers were included in the analysis. Gingival blood flow was assessed using laser Doppler flowmetry under the following conditions: no-stimulation condition (None) and four types of stimuli: thermal stimulation (THM), electric field stimulation (ELF), vibration stimulation (VIB), and far-infrared stimulation (FIR). Gingival blood flow was recorded before and after each stimulation, and the rate of change was calculated. Statistical analysis was performed using a linear mixed-effects model with Type III ANOVA (Satterthwaite approximation), followed by Dunnett-adjusted comparisons. Results: A statistically significant difference was observed between stimulation conditions (p = 0.0087). VIB significantly increased gingival blood flow compared with the no-stimulation condition (p = 0.0041), whereas ELF showed a trend toward increased blood flow (p = 0.0936); THM and FIR showed no statistically significant effects. Conclusions: The findings of this study suggest that non-invasive physical stimuli, particularly vibration stimulation, can enhance gingival microcirculation. Although tooth movement was not directly evaluated, the observed hemodynamic changes may represent short-term physiological responses to non-invasive physical stimulation.