RESUMEN
OBJECTIVES: This study aimed to propose a standardized protocol for the fabrication of three-dimensionally (3D)-printed curvature-adaptive splints (CASs) and assess the precision of CASs on dentitions with different depths of the curve of Spee (COS). METHODS: 76 lower dental resin models, each exhibiting one of the four types of COS (0-, 2-, 4-, and 6-mm deep), were selected and digitally scanned. CASs were designed, 3D printed, and grouped into C0, C2, C4, and C6, corresponding to the four types of COS depths. To assess precision, the CASs occluded with the resin model were scanned as a whole and compared with the originally designed ones. RESULTS: In terms of translational deviations observed in the CASs, the mean value of absolute sagittal deviation (0.136 mm) was significantly higher than those of vertical (0.091 mm) and transversal deviations (0.045 mm) (P < 0.01). Regarding rotational deviations of the CASs, the mean deviation in pitch (0.323°) was significantly higher than those in yaw (0.083°) and roll (0.110°) (P < 0.01). However, when comparing the accuracy of CASs across C0, C2, C4, and C6 groups, no statistically significant difference was found. Additionally, the translational deviations, rotational deviations, and RMSE of all groups were significantly lower than the clinically acceptable limits of 0.5 mm, 1°, and 0.25 mm, respectively (P < 0.01). CONCLUSIONS: The depth of the COS has no significant impact on the precision of CASs, as evidenced by the absence of statistically significant differences in translational, rotational deviations, and RMSE among all groups (C0, C2, C4, and C6). Moreover, despite relatively high deviations in the sagittal dimension and pitch, all dimensional deviations and RMSE remained statistically significantly lower than the corresponding clinically acceptable limits (CALs) in all groups. CLINICAL SIGNIFICANCE: This standardized protocol incorporating "curvature-adaptation" represents an optimized approach to fabricating diverse 3D-printed splints tailored to dentitions with different anatomical features in contemporary digital dentistry.
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Background: Anxiety and depression are common psychological problems in orthodontic patients whose diet habits and oral health status change frequently during treatment. However, relationships between anxiety and depression, digestive tract condition, and impaired oral health-related quality of life remain unknown. Materials and methods: In this study, clinical assessments, including anxiety, depression, digestive tract condition, and oral health-related quality of life, were collected from 769 outpatients in the orthodontic department using three self-reported questionnaires. Correlation analysis was used to investigate the relationships among different clinical assessments. A chained mediation analysis model was further conducted to explore the direct and indirect effects of these various clinical factors. Results: Changes in digestive tract conditions were positively correlated with the psychological status and oral health-related quality of life. Anxiety and depression partially mediated the relationship between them, and the indirect effect was 0.68 (30%), of which the mediation effect of anxiety accounted for 56%. Conclusion: Anxiety and depression mediate the relationship between gastrointestinal conditions and oral health. In particular, anxiety seems to play a significant mediating role. Our findings indicate that psychological status must be paid more attention to in future clinical practices and supervision for digestive tract symptoms of orthodontic patients.
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OBJECTIVES: To analyze the anatomical limitations and characteristics of maxillary and mandibular retromolar regions affecting molar distalization using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 120 qualifying patients were classified into equal groups of skeletal Class II and Class III and stratified by vertical growth pattern, age, sex, and third molar presence. The available distance along the axis of distalization and cortical bone thickness (CBT) were measured in the maxillary and mandibular retromolar regions of Class II and Class III patients, respectively. One-way analysis of variance was used to examine the effects of the factors on the measured data. RESULTS: The minimum available distance of the Class II maxilla was observed at a level 3 mm from the cementoenamel junction (CEJ), while that of the Class III mandible was at a level 9 mm from the CEJ. The average available distance at the limit level was 4.06 ± 1.93 mm in the Class II maxilla, and the average corresponding CBT was 1.00 mm. The average available distance at the limit level in the Class III mandible was 2.80 ± 1.96 mm, and the corresponding CBT was 2.24 mm. In both skeletal Class II and Class III patients, hyperdivergent groups had the least available distance for molar distalization. CONCLUSIONS: The limit for available distance in the Class II maxilla is closer to the coronal level, while that of the Class III mandible is closer to the apical level. A hyperdivergent growth pattern in a patient is indicative of less potential for molar distalization. Axial slices of CBCT images provide valuable evaluation for molar distalization regarding limit levels.
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A highly ordered interface between LiFePO(4) phase and FePO(4) phase with staging structure along the a axis and perpendicular to the b axis direction has been observed for the first time, in a partially chemically delithiated Li(0.90)Nb(0.02)FePO(4) by advanced aberration-corrected annular-bright-field (ABF) scanning transmission electron microscopy (STEM).
