American Journal of Orthodontics and Dentofacial Orthopedics最新文献

Introduction: Orthodontic-aided closed eruption of impacted second premolars often fails in patients with cleidocranial dysplasia (CCD). This study aims to evaluate the 3-dimensional position and root morphology of impacted second premolars and identify factors affecting the success of orthodontic-guided closed eruption in CCD patients.

Methods: Cone-beam computed tomography images from CCD patients with impacted second premolars were selected and evaluated. The original cone-beam computed tomography data were reconstructed using Dolphin Imaging software (Dolphin Imaging and Management Solutions, Chatsworth, Calif), and the 3-dimensional position, root morphology of impacted second premolars, along with factors associated with closed-eruption success, were analyzed.

Results: Eleven patients (37 impacted second premolars) with CCD, comprising 7 males and 4 females, were included. The average duration of the closed-eruption treatment was 29.00 ± 6.84 months, yielding a success rate of 89.29%. In the 37 impacted second premolars, vertical impaction was the most common (23 [62.16%]), followed by palatal (10 [27.03%]) and buccal (4 [10.81%]). Moreover, 9 of the 37 impacted second premolars failed to erupt, of which 6 were in the low palatal position with a completed root apex. Chi-square tests revealed that the impacted second premolars in the coronal and axial positions, and Nolla's stages were significantly associated with closed-eruption failure (P <0.05).

Conclusions: Most impacted second premolars with failed eruption were at the mandibular palatal side and in Nolla's stages 9 and 10. Closed-eruption treatment in patients with CCD is primarily influenced by coronal and axial positions and Nolla's stage.

Introduction: This study aimed to investigate the factors influencing the pterygomaxillary suture split (PMSS) after miniscrew-assisted rapid palatal expansion (MARPE) in late adolescents and young adults using cone-beam computed tomography.

Methods: Preexpansion (T0) and postexpansion (T1) cone-beam computed tomography images of 82 MARPE patients (mean age, 20.7 ± 3.7 years; range, 15.2-32.4 years) were analyzed. Vertical (SN-GoGn angle) and horizontal (ANB angle) skeletal relationships were assessed at T0. Associations between PMSS incidence and variables including age, sex, midpalatal suture maturation (MPSM) stage, palate length (PL), expansion magnitude, and midpalatal suture opening pattern were evaluated. Statistical analyses included Spearman's correlation test and the Wilcoxon signed rank test.

Results: PMSS was observed in half of the subjects after MARPE. Inferior PMSS demonstrated a moderate positive correlation with posterior palatal expansion (ρ = 0.561, P <0.001). Conversely, inferior PMSS showed significant negative correlations with MPSM stage (ρ = -0.555, P <0.001), age (ρ = -0.286, P <0.05), and the ANB angle (ρ = -0.316, P <0.05). No significant correlations were observed between PMSS and the posterior palatal expansion to anterior palatal expansion ratio, sex, PL, or SN-GoGn angle. The magnitude of inferior PMSS was significantly greater than that of superior PMSS (P <0.001), whereas left and right PMSS magnitudes were symmetrical (P >0.05).

Conclusions: Among late adolescents and young adults treated with MARPE, posttreatment PMSS magnitude showed a moderate positive correlation with posterior palatal expansion magnitude, a moderate negative correlation with MPSM stage, and weak negative correlations with both age and ANB angle. The bilateral PMSS magnitudes were symmetrical, with significantly greater magnitudes inferiorly than superiorly. Sex, PL, vertical skeletal pattern, and midpalatal suture opening pattern were not significantly associated with PMSS magnitude.

Introduction: A limited amount of maxillary molar distalization can be achieved with sequential molar distalization with clear aligner therapy (CAT), accompanied by significant distal crown tipping. Thus, combining CAT with temporary skeletal anchorage devices (TSADs) has been proposed, but a detailed evaluation is lacking.

Methods: This retrospective study evaluated pretreatment and postanterior retraction cone-beam computed tomography (CBCT) images and intraoral scans of adult patients treated with CAT + infrazygomatic TSADs with at least 1 mm of programmed maxillary first molar distalization. Achieved tooth movement shown on the CBCT and intraoral scan was compared with the prescribed ClinCheck tooth movement.

Results: This study included 38 sides from 21 patients (17 females and 4 males; aged 28.71 ± 4.16 years at pretreatment). At the crown level, approximately 1 mm of molar distalization was achieved (maxillary first molar, 1.05 mm [-0.8, 3.6] based on intraoral scans, 0.80 mm [-1.1, 3.4] based on CBCTs; maxillary second molar, 0.95 mm [-1.8, 4.4] based on intraoral scans, 1.25 mm [-1.9, 3.7] based on CBCTs), which is significantly lower than the prescribed movement (maxillary first molar, 3.05 mm [1.0, 5.6]; maxillary second molar: 3.05 mm [0.9, 6.1]). Limited crown distal tipping and mesial-out rotation, but significant buccal expansion and intrusion of the maxillary molars were also observed. In addition, a negative correlation was detected between the amount of prescribed molar distal movement and the distalization efficacy.

Conclusions: TSADs did not significantly improve the efficacy of maxillary molar distalization with CAT but provided more bodily movement and intrusion of the molars.

Introduction: This retrospective study aimed to evaluate the morphology of the alveolar bone and to assess the incidence of fenestration and dehiscence during presurgical orthodontic decompensation in patients with skeletal Class III malocclusion.

Methods: The study included 60 patients with skeletal Class III high-angle malocclusion who had completed presurgical orthodontic treatment. Lateral cephalograms and cone-beam computed tomography images were obtained before (T0) and after (T1) the presurgical orthodontics. The labial inclination angles of the mandibular central incisors were measured using lateral cephalograms. Cone-beam computed tomography images evaluated alveolar bone thickness and height along the roots of the target teeth and assessed the incidence of fenestration and dehiscence. Statistical analyses were conducted using paired t tests, chi-square tests, and binary logistic regression.

Results: From T0 to T1, decompensatory movements of the mandibular central incisors resulted in a reduction in alveolar bone thickness and vertical height. Most teeth exhibited bone loss of 2 mm apical to the cementoenamel junction. The prevalence of labial bone defects increased significantly, rising from 51.7% to 73.3% in the mandibular left central incisor and from 51.7% to 76.7% in the mandibular right central incisor. Greater decompensation angles were linked to higher risks of fenestration and dehiscence at T1. When the probability of bone defect occurrence was set at 50%, the thresholds for changes in the IMPA and L1-NB were found to be 5.47° and 5.91°, respectively.

Conclusions: The threshold for decompensation of the mandibular central incisors is relatively low in patients with skeletal Class III high-angle because of the anatomically thin alveolar bone. Exceeding this threshold increases the risk of bone defects. Therefore, careful evaluation of the periodontal condition is essential when establishing treatment objectives to prevent adverse periodontal outcomes.

Introduction: This study analyzed the influence of the 3-dimensional (3D) root apex position on the traction duration of unilateral impacted maxillary canines, compared with the cusp tip position.

Methods: Thirty-one cone-beam computed tomography scans were analyzed. Each normally erupted canine was mirrored across the midsagittal plane to create an image of its enantiomorph. The distances were measured between the root apices of the impacted canine and the enantiomorphic contralateral normally erupted canine, as well as between their cusp tips and tooth angulations. Each distance variable was further subdivided into vertical displacement, horizontal displacement, mesiodistal (MD) displacement, and labiopalatal displacement, whereas the angulation variable was divided into MD tip difference and torque difference. The correlation between each measurement and the traction duration was analyzed.

Results: The position of the root apex showed no significant correlation with traction duration. However, the 3D displacement, horizontal displacement, and labiopalatal displacement of the cusp tip (P <0.001), vertical displacement of the cusp tip (P <0.01), and the 3D angulation difference and MD tip difference between tooth axes (P <0.05) showed a significantly positive correlation with traction duration. Multiple regression analysis showed that the 3D displacement of the cusp tip explains approximately 55.4% of the variance in traction duration, increasing by 1.2 months per 1 mm.

Conclusions: Although root apex position does not affect traction duration in unilateral impacted maxillary canines, the 3D displacement of the cusp tip is a key determinant, with more significant palatal displacement and a higher vertical position associated with longer traction duration.