American Journal of Orthodontics and Dentofacial Orthopedics最新文献

Introduction: Previous studies assessed the palatal bone thickness in adult patients or cadavers to identify ideal insertion sites for orthodontic mini-implants. These findings might not be transferable to children and adolescent patients, whose jawbones are still growing. This retrospective cross-sectional pilot study aimed to assess the median and paramedian palatal bone thickness in growing patients using cone-beam computed tomography.

Methods: Cone-beam computed tomography scans from 20 patients, aged 6-18 years, were included, and a grid of 13 × 8 measurement points was defined. At each reference point, the bone thickness was assessed orthogonally to the occlusion plane.

Results: In the sagittal direction, bone thickness decreased from the anterior to posterior positions (P <0.001). In the transversal direction, a V-shaped pattern of bone thickness was observed, with significantly lower values at the suture and increasing values at the paramedian aspects (P <0.001). Older patients (13-18 years) showed higher bone thickness values in the more posterior regions (P <0.001), whereas male patients exhibited greater bone thickness values both anteriorly and posteriorly (P <0.001).

Conclusions: Within the limitations of the present pilot study, including only 20 3D radiographs, paramedian insertion at the connection line of the first premolars showed comparatively greater bone thickness in this pilot sample. Further research is warranted to better understand how palatal bone thickness matures in relation to sex and age during the growth period.

Introduction: This study aimed to assess whether sagittal maxillary-mandibular skeletal relationships influence perceived facial esthetics in patients with varying sagittal skeletal discrepancies.

Methods: We analyzed 3-dimensional facial models from cone-beam computed tomography scans of 40 patients (17 males and 23 females aged 14-48 years; ANB = 0°-10°), lacking skin color or hair, to isolate shape. A total of 100 laypeople rated these for esthetics and sexual dimorphism using visual analogue scales. Procrustes-based 3-dimensional geometric morphometrics quantified shape, and multivariate linear regression estimated vectors for visual analogue scales ratings. Linear regression tested correlations between shapes linked to the ANB angle and esthetics.

Results: Perceived attractiveness was unrelated to age, asymmetry, or deviation from the population average shape. Esthetics correlated with lower facial third shape (r² = 0.473, P = 0.058, 4.5% variation), particularly with anterior or inferior gnathion and pogonion displacement, with consistent patterns across sexes (r_v = 69.2°, P <0.0001). Shapes associated with higher ANB angles (indicating convexity) showed a negative association with attractiveness (r² = 0.494, P <0.001). Sexual dimorphism was linked to cheek placement, facial roundness, and nasal tip position (r² = 0.558, P = 0.001, 9.0% variation).

Conclusions: Sagittal maxillary-mandibular relationships, as measured by the ANB angle and sagittal skeletal discrepancy, modestly influence facial esthetics, with straighter profiles and prominent chins rated more attractive. These findings suggest a partial biological basis for esthetic preferences, though individual and cultural factors, including smile esthetics and dental symmetry, also play a role. The study informs orthodontic treatment planning by highlighting the esthetic impact of jaw alignment.

Introduction: The objective of this study was to systematically evaluate cortical bone remodeling and mandibular incisor movement during presurgical orthodontic decompensation in patients with severe skeletal Class III malocclusion and explore more suitable indicators for determining the decompensation range.

Methods: Cone-beam computed tomography images of 46 patients with severe skeletal Class III malocclusion who underwent presurgical orthodontic treatment were analyzed. Vertical bone loss (sagittal view) was measured, and cortical bone remodeling and mandibular tooth movement (coronal view) were assessed at the crestal, midroot, and apical levels. Patients were grouped by their degree of alveolar bone deterioration. Mandibular incisor inclination angle (the angle between the long axis of the mandibular central incisor [MCI] and the long axis of the mandibular symphysis) and incisor mandibular plane angle (the angle between the long axis of the MCI and the mandibular plane) were compared between groups using t tests.

Results: MCIs exhibited tipping movement, with prominently increased lingual alveolar bone defects after decompensation. The mean mandibular incisor inclination angles were as follows: (1) pretreatment was 4.45° for group 1 (with better alveolar bone conditions) and 2.99° for group 2 (with worse alveolar bone conditions) (P = 0.252), and (2) posttreatment (after decompensation) was 10.91° for group 1 and 19.31° for group 2 (P <0.001). The mean incisor mandibular plane angles were as follows: (1) pretreatment was 77.63° for group 1 and 71.64° for group 2 (P <0.05), and (2) posttreatment was 85.95° for group 1 and 84.84° for group 2 (P = 0.624).

Conclusions: Instead of decompensating until the mandibular incisors are nearly upright relative to the mandibular plane, the relationship with the mandibular symphysis should be prioritized for healthier considerations.

Introduction: Miniscrew-assisted rapid palatal expansion (MARPE) is a predictable option for nongrowing patients with maxillary transverse deficiency manifesting as posterior crossbite. However, recent evidence suggests a high frequency of asymmetrical expansion as a complication of MARPE.

Methods: Retrospective analysis of 9 patients (mean age: 21.7 years; 65% female; average Yonsei Transverse Index: -4.6 mm) included superimposition of pre (T1) and posttreatment (T2) cone-beam computed tomographies using a voxel-based technique on the anterior cranial base. T1 and T2 cone-beam computed tomographies were digitized in a common Cartesian plane, enabling linear and angular measurements using T1 landmarks as the reference to compare T2 landmarks. Geometric analyses included linear Euclidean left vs right and transverse distances, 3-dimensional (3D) angulation, and 3D matrix rotations to quantify asymmetry. Asymmetry thresholds were set at 2 mm or 2°. Stepwise regression was used to determine the association between potential explanatory variables and asymmetry.

Results: There was no statistically or clinically significant asymmetry of the ANS-PNS vector. Linear, angular, or zygomaticomaxillary roll of jugale, keyridge, or zygomaticofrontal suture around the ANS-PNS vector was found (P >0.05). Statistically but not clinically significant linear asymmetry of keyridge (0.9 ± 0.9 mm; P = 0.02) and first molar furcation (0.7 ± 0.8 mm; P = 0.02) was found. Stepwise regression did not find any potential explanatory variables explaining the keyridge and the first molar furcation linear asymmetry.

Conclusions: Under the conditions of this study and 3D analyses, MARPE resulted in statistically significant linear asymmetry of the keyridge and the first molar furcation. Statistical significance does not equate clinical significance or relevance.

Introduction: Improvement in facial and dental esthetics is a motivator for orthodontic treatment. An update in the preferences of clinicians and patients is necessary because beauty standards are constantly evolving and extraction and nonextraction decisions impact soft tissue and incisor position. This study aimed to update facial profile and incisor inclination preferences among orthodontists (ORs), general dentists (GPs), and laypeople (LPs) and correlate these preferences with objective soft tissue and incisor changes.

Methods: This retrospective study used discriminant analysis to identify 30 borderline patients with Class I and mild Class II treated with extractions and 30 treated with nonextraction. Assessment of profile and incisor inclination was performed by 90 LPs, 40 ORs, and 40 GPs using a 200 mm visual analog scale and rankings on a web-based survey. The degree of preference between the profile esthetics and incisor inclination was compared using the Cohen d value for standardized mean difference.

Results: Survey results indicated ORs' preference for extraction profiles (mean difference = 5.52 mm; 95% confidence interval = 1.64-9.40), GPs' preference for nonextraction profiles (mean difference = 3.67 mm; 95% confidence interval = 0.43-6.92), and all groups showing a stronger preference for more upright incisors. LPs' preferences are more aligned with GPs.

Conclusions: GPs preferred protrusive lips and acute nasolabial angles (typical in nonextraction treatment), while strongly preferring upright incisors (typical in extraction treatment). These discrepancies in preferences highlight the importance of communication of treatment objectives and expectations among ORs, LPs, and GPs.