Korean Journal of Orthodontics最新文献

Objective: To determine the correlation between dentoskeletal parameters related to craniofacial morphology and the upper airway (UA) volume.

Methods: Cone-beam computed tomography images of 106 randomly selected orthodontic patients were analyzed using NemoFab Ortho software. The dentoskeletal variables assessed were anterior facial height (AFH), posterior facial height (PFH), PFH/AFH ratio, hyoid position, maxillary width (MW), and palatal depth. The UA volume (evaluation in anatomical regions and as a whole) was also assessed using the same software. We also evaluated potential differences in UA variables between age and sex groups. The correlation between the dentoskeletal parameters and UA volume was calculated using the Pearson correlation coefficient (R). Analysis of variance and Student's t test were performed to assess differences between age and sex for UA variables. Statistical analyses were performed using SPSS software (version 26 for Windows).

Results: This study found that PFH, AFH, and MW were the dentoskeletal parameters most strongly correlated with UA volume. However, the ANB angle did not show any significant correlation with UA volume. Additionally, differences in UA volumes were observed between age groups. Sex differences were found in both the "8-12" and "≥ 16" age groups for oropharyngeal and pharyngeal volumes.

Conclusions: In conclusion, our findings indicate a significant correlation between UA volume and dentoskeletal parameters, particularly those related to facial height and MW.

Objective: To evaluate tooth displacement and periodontal stress generated by the dual action vertical intra-arch technique (DAVIT) for open-bite correction using three-dimensional finite element analysis.

Methods: A three-dimensional model of the maxilla was created by modeling the cortical bone, cancellous bone, periodontal ligament, and teeth from the second molar to the central incisor of a hemiarch. All orthodontic devices were designed using specific software to reproduce their morpho-dimensional characteristics, and their physical properties were determined using Young's modulus and Poisson's coefficient of each material. A linear static simulation was performed to analyze the tooth displacements (mm) and maximum stresses (Mpa) induced in the periodontal ligament by the posterior intrusion and anterior extrusion forces generated by the DAVIT.

Results: The first and second molars showed the greatest intrusion, whereas the canines and lateral incisors showed the greatest extrusion displacement. A neutral zone of displacement corresponding to the fulcrum of occlusal plane rotation was observed in the premolar region. Buccal tipping of the molars and lingual tipping of the anterior teeth occurred with intrusion and extrusion, respectively. Posterior intrusion generated compressive stress at the apex of the buccal roots and furcation of the molars, while anterior extrusion generated tensile stress at the apex and apical third of the palatal root surface of the incisors and canines.

Conclusions: DAVIT mechanics produced a set of beneficial effects for open-bite correction, including molar intrusion, extrusion and palatal tipping of the anterior teeth, and occlusal plane rotation with posterior teeth uprighting.

Objective: This study aimed to investigate the effects of archwire form and power arm positions on maxillary incisors during lingual en masse retraction supported by miniscrew implants, using the finite element analysis method.

Methods: Sliding mechanics for lingual en masse retraction were simulated using the finite element method. Power arms were placed mesial and distal to the maxillary canine with straight and mushroom-shaped archwires. Miniscrews provided absolute anchorage for retraction force.

Results: When power arms were positioned mesial to the canine teeth, an increase in the intercanine distance was observed, while a decrease was noted when the power arms were distal to the canine tooth. Lateral incisors exhibited a greater torque loss, particularly when the power arm was mesial to the canine tooth. In the central incisors, the mushroom archwire resulted in intrusion, while the straight archwire showed an extrusion tendency. Movements in groups using the straight archwire were less controlled compared to those in groups using the mushroom archwire.

Conclusions: The archwire form and the position of the power arm affected the torque loss and vertical position of incisors during lingual en masse retraction supported by miniscrew implants. The most controlled movement was achieved with the combination of a power arm positioned distal to the canine tooth and a mushroom archform.

Objective: To assess the effectiveness of leukocyte-platelet-rich fibrin (L-PRF) compared with conventional treatment on canine retraction, rotation, pain, and soft tissue healing.

Methods: Sixteen adult patients aged 18-25 years (10 females, and 6 males; mean age 22.25 ± 2.26 years) with Class I bimaxillary protrusion and Class II div 1 malocclusion participated in this single-center, split-mouth randomized controlled trial at the Orthodontics Department of a single hospital in SCB Dental College and Hospital, Cuttack, India. Randomization was performed using a computer-assisted function with a 1:1 allocation ratio. The intervention included the placement of L-PRF on the experimental side and follow-up for 90 days. The primary outcome measures were canine retraction, rotation, pain, and soft tissue healing. The range of tooth movement was evaluated at 15-day intervals: 0th day (T0), 15th day (T1), 30th day (T2), 45th day (T3), 60th day (T4), 75th day (T5), and 90th day (T6). Canine rotation was assessed at T0 and T6, and pain and soft tissue healing were evaluated on the 3rd, 7th, and 15th days of the treatment.

Results: Cumulatively, the L-PRF group demonstrated a significantly greater tooth movement as compared to conventional treatment group (P < 0.001). Overall, canine retraction was 1.5 times greater on the L-PRF side than on the control side. Canine rotation showed no significant relationship, whereas pain and soft tissue healing were significantly better on the L-PRF side than on the control side.

Conclusions: Local administration of L-PRF amplifies canine retraction while improving pain and soft tissue repair.

Objective: Understanding the orofacial characteristics and growth patterns in children is essential for both orthodontics and research on children with orofacial abnormalities. However, a concise resource of normative data on the size and relative position of these structures in different populations is not available. Our objective was to aggregate normative data to assess the growth of the orofacial skeletal structures in children with a well-balanced face and normal occlusion.

Methods: The MEDLINE, Embase, and Scopus databases were searched. Inclusion criteria included longitudinal and cross-sectional studies on cephalometric measurement of skeletal tissues and a study population ≤ 18 years with a well-balanced face and normal occlusion. Key study parameters were extracted, and knowledge was synthesized. A quality appraisal was performed using a 10-point scale.

Results: The final selection comprised of 12 longitudinal and 33 cross-sectional studies, the quality of which ranged from good to excellent. Our results showed that from childhood to adulthood, the length of the cranial base increased significantly while the cranial base angle remained constant; both the maxilla and mandible moved forward and downward. The profile becomes straighter with age.

Conclusions: Growth patterns in children with a well-balanced face and normal occlusion follow accepted theories of growth.

The clinical application of aligners is accompanied by the ageing of the polymer appliances and the attachments used, which may result in inefficiency in reaching the predicted range of tooth movement, and release of compounds and microplastics in the oral cavity as a result of the friction, wear and attrition of the aligner and composite attachment. The purpose of this review is to present the mechanism and effects of in vivo ageing; describe the hydrolytic degradation of aligners and enzymatic degradation of composite attachments; examine the ageing pattern of aligners in vivo, under actual clinical scenarios; and identify a link to the discrepancy between predicted and actual clinical outcome. Lastly, strategies to deal with three potentially critical issues associated with the use of aligners, namely the necessity of weekly renewal, the dissimilar mechanical properties of aligner and attachment resulting in wear and plastic deformation of the aligner, and the development of integuments and biofilms with microbial colonization of the appliance, are discussed.

Objective: The study aimed to assess the prevalence of dental malocclusion, orthodontic parameters, and parafunctional habits in children with developmental dyslexia (DD).

Methods: Forty pediatric patients (67.5% boys and 32.5% girls, mean age: 11.02 ± 2.53 years, range: 6-15 years) with DD were compared with 40 age- and sex-matched healthy participants for prevalence of dental malocclusion, orthodontic parameters, and parafunctional habits. Dental examinations were performed by an orthodontist.

Results: Pediatric patients with DD exhibited a significantly higher prevalence of Angle Class III malocclusion (22.5% vs. 5.0%, P = 0.024), deep bite (27.5% vs. 7.5%, P = 0.019), midline deviation (55.0% vs. 7.5%, P < 0.0001), midline diastemas (32.5% vs. 7.5%, P = 0.010), wear facets (92.5% vs. 15.0%, P < 0.0001), self-reported nocturnal teeth grinding (82.5% vs. 7.5%, P < 0.0001), nail biting (35.0% vs. 0.0%, P < 0.0001), and atypical swallowing (85.0% vs. 17.5%, P < 0.0001) compared to that in healthy controls.

Conclusions: Pediatric patients with DD showed a higher prevalence of Class III malocclusion, greater orthodontic vertical and transverse discrepancies, and incidence of parafunctional activities. Clinicians and dentists should be aware of the vulnerability of children with dyslexia for exhibiting malocclusion and encourage early assessment and multidisciplinary intervention.

Objective: This retrospective study evaluated the mandibular condyle position before and after bimaxillary orthognathic surgery performed with the mandibular condyle positioned manually in patients with mandibular prognathism using cone-beam computed tomography.

Methods: Overall, 88 mandibular condyles from 44 adult patients (20 female and 24 male) diagnosed with mandibular prognathism due to skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (BSSRO) and Le Fort I performed using the manual condyle positioning method were included. Cone-beam computed tomography images obtained 1-2 weeks before (T0) and approximately 6 months after (T1) surgery were analyzed in three planes using 3D Slicer software. Statistical significance was set at P < 0.05 level.

Results: Significant inward rotation of the left mandibular condyle and significant outward rotation of the right mandibular condyle were observed in the axial and coronal planes (P < 0.05). The positions of the right and left condyles in the sagittal plane and the distance between the most medial points of the condyles in the coronal plane did not differ significantly (P > 0.05).

Conclusions: While the change in the sagittal plane can be maintained as before surgery with manual positioning during the BSSRO procedure, significant inward and outward rotation was observed in the axial and coronal planes, respectively, even in the absence of concomitant temporomandibular joint disorder before or after the operation. Further long-term studies are needed to correlate these findings with possible clinical consequences.

Objective: Lingual fixed retainers, made from 0.0175-inch 3-strand twisted stainless steel wire (TW) and 0.016 × 0.022-inch straight rectangular wire (RW), are generally used in clinical practice. This study aimed to calculate their accuracy by comparing the discrepancy between computer-aided customized retainers made from these two types of wires.

Methods: Eleven orthodontic patients were selected, resulting in 22 maxillary and mandibular three-dimensional printing dental models. Two types of lingual fixed retainers were bonded from canine to canine. To determine the accuracy, five points were chosen for each model, resulting in 110 selected points. The absolute values of the distances on the x-, y-, and z-axes were measured to compare the accuracy of the two types of computer-aided retainers.

Results: The accuracy of the two types of retainers did not differ significantly in the x- and z-axes, but only in the y-axis (P < 0.01), where RW-fixed retainers exhibited a slightly but significantly increased distance compared to the TW.

Conclusions: Both types of retainers showed high accuracy; however, RW had a slight but statistically significant difference along the y-axis compared with TW. This type of computer-aided design/computer-aided manufacturing bending machine is limited to two dimensions, and the dental arch is curved. Therefore, RW may require slight manual adjustment by the practitioner after manufacturing.

Objective: This study aims to employ finite element method (FEM) analysis to compare the differences between bicortical and tricortical anchorage of the posterior miniscrews in a single-screw miniscrew-assisted rapid palatal expansion (MARPE) and a double-screw tandem skeletal expander (TSE) under open and closed suture conditions.

Methods: A cone beam computed tomography of the human skull of a 21.5-year-old female was utilized as a model for creating a FEM analysis. Simulations involved the insertion of four palatal miniscrews: two anterior ones with bicortical anchorage and two posterior ones (one with bicortical and another with tricortical anchorage), under open and closed suture conditions in a single-screw MARPE and double-screw TSE, resulting in a total of eight different simulation configurations. Evaluation parameters include total deformation (mm), Von Mises stress (MPa), and strain for each miniscrew body.

Results: Tricortical anchorage of the posterior miniscrews provides greater anchorage, higher stress, and deformation on the anterior miniscrews in single-screw MARPE. Tricortical anchorage combined with a double-screw TSE promotes a more even distribution of force and stress on miniscrews under open suture conditions, leading to a parallel midpalatal suture opening along its entire length and height.

Conclusions: FEM analysis revealed favorable midpalatal suture opening with equal force distribution and less stress when posterior tricortical anchorage in conjunction with double-screw TSE is applied.