Thai Journal of Orthodontics

Control of Maxillary First Molar Inclination during Intrusion Using TAD-Supported Fixed Appliances versus Clear Aligners in Anterior Open Bite Correction

Karnrawee Rangsitsathian, Chanchai Pattanaviriyapisan, Udom Thongudomporn — Thu, 11 Jun 2026 00:00:00 +0700

Background: Maxillary first molar intrusion is a key treatment goal for anterior open bite (AOB) patients. The effects of TAD-supported fixed appliances and clear aligners on vertical intrusion and molar inclination are not fully understood. Objective: To compare the effectiveness of TAD-supported fixed appliances and clear aligners in achieving vertical intrusion and controlling molar inclination in adult AOB patients. Materials and methods: Thirty-six adult patients with AOB were randomly assigned to two groups: 17 subjects treated with TAD-supported fixed appliances (TADs) and 19 with clear aligners (CA). Vertical and inclination changes of the maxillary first molars were measured using lateral cephalometric radiographs and CBCT. Spearman’s rank correlation analysis was performed to assess the relationship between vertical and inclination changes. Results: Both groups showed significant vertical intrusion, with the TAD-supported fixed appliance group achieving greater intrusion (1.91 ± 0.88 mm) than the clear aligner group (1.04 ± 0.77 mm). Molar inclination varied significantly between groups, with the TAD group experiencing more tipping and the clear aligner group showing better control of inclination. No significant correlation was found between vertical and inclination changes in either group (r = 0.17 for TADs, r = 0.15 for CA, P > 0.05). Conclusion: TAD-supported fixed appliances offer superior vertical intrusion compared to clear aligners, while clear aligners provide better control of molar inclination. Tailored treatment based on biomechanical demands, using skeletal anchorage for vertical control and precise aligner design for inclination stability, is recommended. Further long-term studies are needed to refine treatment protocols for AOB.

Comparison of Convolutional Neural Networks Architectures for Screening Mandibular-Plane-to-Hyoid Distance as a Risk Indicator of Obstructive Sleep Apnea on Lateral Cephalograms

Nichakorn Songsang, Udom Thongudomporn, Witsarut Upalananda — Thu, 11 Jun 2026 00:00:00 +0700

Background: Lateral cephalometric radiographs can aid in screening obstructive sleep apnea (OSA) through the mandibular-plane-to-hyoid (MP-H) distance. An automated tool based on this measure could support OSA screening. However, the accuracy of such tools depends on the performance of AI-assisted models, making it essential to evaluate and compare their effectiveness in detecting MP-H distance for reliable clinical application. Objective: To evaluate the performance of different convolutional neural network (CNN) architectures in classifying patients into short and long MP-H groups. Materials and methods: A total of 304 pre-orthodontic lateral cephalometric radiographs from adults (age 18-56 years) were classified into short MP-H (< 18 mm) and long MP-H (≥ 18 mm) groups. Four CNN architectures (DenseNet-121, ResNet-50, EfficientNet-B0, and MobileNetV3) were trained to classify short and long MP-H groups. To address class imbalance, weighted binary cross entropy loss functions (weights ranging from 1 to 5) were applied, assigning greater penalties to misclassification of the minority class. Results: In the scenario without application of weighted cross entropy loss, DenseNet-121 achieved the overall high screening performance, with sensitivity = 0.87, specificity = 0.95, precision = 0.79, F1-score = 0.82, accuracy = 0.93, AUROC = 0.91, and AUPRC = 0.83. MobileNetV3 consistently demonstrated the lowest performance. Weighted loss functions provided inconsistent benefits across architectures. DenseNet-121 showed consistent performance among all weights. Conclusion: DenseNet-121 shows potential of screening long MP-H distance from lateral cephalograms. Weighted loss functions may provide improvements, but model selection remains the more critical factor.

Mechanical Indicators of Primary Stability of Orthodontic Miniscrews: Effects of Pilot-Hole Diameter Across Three Commercial Systems with Different Thread External Diameters and Designs: An In Vitro Study

Thu, 11 Jun 2026 00:00:00 +0700

Background: Pre-drilling of pilot holes has been suggested to facilitate miniscrew placement in dense palatal bone. Objective: To compare mechanical indicators of primary stability (maximal insertion torque and pull-out strength) of miniscrew systems with different thread external diameters under varying pre-drilled pilot-hole diameters. Materials and methods: This study included 120 titanium alloy miniscrew implants with a thread length of 6.0 mm. The implants were classified into three groups according to thread external diameter (1.8, 1.9, and 2.0 mm). Each group was subdivided into four pilot-hole conditions: 0.0 mm (control), 1.1 mm, 1.2 mm, and 1.3 mm. All implants were inserted into synthetic composite palatal bone. Primary stability was evaluated by maximum insertion torque and vertical pull-out strength. Results: Both miniscrew system group and pre-drilled pilot-hole diameter significantly affected maximal insertion torque and pull-out strength (P < 0.001). A significant interaction between miniscrew system/design group and pilot-hole diameter was observed (P < 0.001). Maximal insertion torque decreased as pilot-hole diameter increased across all systems. The 2.0-mm system/design group consistently demonstrated the highest insertion torque under all drilling conditions. Pull-out strength remained relatively stable at 1.1-1.2 mm pilot-holes in the 1.8 mm system, whereas larger pilot-hole diameters resulted in significant reductions in some systems/designs. Conclusion: Both miniscrew implant design and pre-drilled pilot-hole diameter influence primary stability. Pilot-hole diameters of 1.1–1.2 mm provide an optimal balance between insertion torque and pull-out strength for 1.8–2.0 mm diameter miniscrews; however, the ideal pilot-hole size should be determined according to the specific miniscrew implant design.

Direction-Dependent Soft Tissue Thickness in Facial Asymmetry: A Three-Dimensional Analysis Using Facial Scanning and Cone Beam Computed Tomography

Tanapat Jearanai , Bancha Samruajbenjakun — Thu, 11 Jun 2026 00:00:00 +0700

Background: Facial asymmetry is a common craniofacial condition affecting facial aesthetics and function. Although skeletal discrepancies are the primary determinant, the role of direction-dependent soft tissue thickness in shaping facial morphology remains unclear. Objective: To investigate directiondependent patterns of soft tissue thickness in patients with facial asymmetry using integrated three-dimensional facial scanning and cone beam computed tomography. Materials and methods: This cross-sectional study included 60 adults aged 18–35 years undergoing orthodontic and orthognathic evaluation. Cone beam computed tomography and three-dimensional facial scan datasets were fused to construct composite craniofacial models. Bilateral skeletal landmarks were identified, and soft tissue thickness was measured relative to the midsagittal plane in transverse and sagittal directions. Paired statistical tests compared measurements between deviated and contralateral sides. Results: Significant skeletal asymmetry was observed at multiple craniofacial landmarks, particularly at the antegonial notch (2.09 ± 4.40 mm), orbitale (1.66 ± 3.16 mm), and anterior ramus notch (1.34 ± 1.94 mm), among others (P < 0.01). Direction-dependent patterns of soft tissue thickness was identified. In the transverse, soft tissue was generally thinner on the deviated side at the anterior ramus notch, canini, antegonial notch, and gonion (P < 0.01). In contrast, sagittal measurements showed greater soft tissue thickness on the deviated side at the condylion, antegonial notch, and gonion (P < 0.01). Conclusion: Soft tissue thickness in facial asymmetry demonstrates direction-dependent patterns and only partially reflects skeletal deviations. Integrated three-dimensional imaging may improve evaluation of skeletal–soft tissue relationships and assist orthodontic and orthognathic treatment planning.

Dentoalveolar Effects of Miniscrew-Assisted Transpalatal Arch versus Clear Aligner in Anterior Open Bite: A Prospective Cephalometric Study

Suthinun Suksutthiphan, Angkana Thearnmontree, Chidchanok Leethanakul — Thu, 11 Jun 2026 00:00:00 +0700

Background: Treatment of anterior open bite commonly involves anterior extrusion, posterior intrusion, or both. Miniscrew-assisted transpalatal arch (MT) mechanics have been used for maxillary posterior intrusion, whereas clear aligner (CA) therapy has become popular because of its esthetic advantages. However, the mechanics of open-bite correction with clear aligners remain controversial. Objective: To compare dentoalveolar changes following anterior open bite treatment with MT mechanics versus CA therapy using lateral cephalometric analysis. Materials and methods: In this single-center prospective cohort study, 34 adults with anterior open bite (0–4 mm) were treated and evaluated: 15 in the MT group and 19 in the CA group. Lateral cephalograms were obtained at pretreatment (T0) and after 6 months (T1). Within- and between-group dentoalveolar changes were analyzed using paired and independent t-tests (P < 0.05). Results: Both treatments significantly reduced the anterior open bite, with no significant between group difference in overbite change (MT = 3.17 mm, CA = 3.11 mm). MT produced greater maxillary first molar intrusion than CA (U6-PP: MT = 2.01 mm, CA = 0.82 mm). Only the CA group showed a significant increase in anterior dental height (ADH: CA = +1.93 mm). CA showed greater decreases in U1-NA angulation (CA = -5.87°, MT = +2.67°) and U1-NA distance (CA = -1.98 mm, MT = +0.76 mm). Overjet decreased more with CA (P < 0.05). Conclusion: MT with partial fixed anterior archwire primarily produced posterior intrusion and minimal incisor changes, whereas CA predominantly produced maxillary incisor extrusion and retroclination with limited molar intrusion.

Correction of Class II Malocclusion Using a Resin Block Build up with Class II Elastic in an Adult Patient: A Case Report

Nicha Kukongviriyapan, Pornpimon Kamchai, Bancha Samruajbenjakun — Thu, 11 Jun 2026 00:00:00 +0700

Class II malocclusion is one of the most prevalent orthodontic problems that is commonly associated with mandibular retrognathia. Treatment in adults poses a challenge because growth modification is no longer possible, and most corrections rely on camouflage mechanics or orthognathic surgery. This report presents a 23-year-old female with a skeletal Class II normodivergent pattern, retrognathic mandible, and proclined maxillary incisors. A modified fixed twin block appliance was combined with fixed orthodontics as a non-extraction camouflage strategy. After 18 months, the patient achieved improved facial balance, normalized overjet and overbite, and Class I molar relationships. Skeletal change was minimal, while the effects were largely dentoalveolar; however, vertical control and occlusal stability were favorable. This case highlights the limited but valuable role of fixed twin block appliances in adults as a cost-effective camouflage option where surgery or extraction is not preferred.