Clinical effects of twin-block combined with maxillary expansion on the upper airway in adolescents with Class II malocclusion.

BACKGROUND: Class II malocclusion, particularly class II division 1, poses a significant orthodontic challenge with implications for both aesthetics and health. This study aimed to explore the impact of twin-block (TB) combined with maxillary expansion treatment (TB-ME) on upper airway dimensions and inflammatory profiles in adolescents with skeletal Class II Division 1 malocclusion in adolescent. METHODS: Ninety-two eligible patients were randomly assigned to two groups: TB-ME treatment and traditional McLaughlin Bennett Trevisi (MBT) straight-wire orthodontic treatment (Control). Cephalometric lateral X-ray scans were conducted before and after treatment to assess skeletal changes, including SNA, ANB, and SNB angles, which are essential to assess the anteroposterior relationships of the maxilla and mandible to the cranial base. We also measured the upper airway volumes and areas. Concentrations of inflammatory factors including intercellular adhesion molecule 1 (ICAM-1), matrix metallopeptidase 2 (MMP2), and interleukin 8 (IL-8) of gingival crevicular fluid analysis (GCF) were detected by enzyme-linked immunosorbent assay. RESULTS: TB-ME treatment induced significant improvement in cephalometric parameters, including a decrease in SNA and ANB angles and an increase in SNB angle. Upper airway volumes and areas increased significantly in both groups, with TB-ME showing greater improvements. GCF analysis revealed a reduction in ICAM-1, MMP2, and IL-8 concentrations in the TB-ME group compared to the Control group. CONCLUSIONS: TB-ME treatment demonstrates multifaceted improvements in skeletal malocclusion, upper airway dimensions, and inflammatory profiles in adolescents with class II division 1 malocclusion, showing the promise of TB-ME in addressing the complexities associated with class II malocclusion.

Combined Periodontal-Orthodontic Treatment with Periodontal Corticotomy Regenerative Surgery in an Adult Patient Suffering from Periodontitis and Skeletal Class II Malocclusion: A Case Report with 5-Year Longitudinal Observation.

A thick periodontal phenotype with thick gingiva and alveolar bone volume is required for safe orthodontic tooth movement and long-term stability. A high incidence of dehiscence and fenestration in the labial aspect of mandibular anterior teeth may limit the correction of deformity and orthodontic treatment, especially when the lower anterior teeth are needed to have a large range of movement. This study reports a combination of periodontal therapy and orthodontic therapy with periodontal corticotomy regenerative surgery (PCRS) in a 25-year-old patient suffering from skeletal Class II malocclusion and periodontitis. The patient received periodontal therapy 5 years ago and commenced orthodontic treatment 4.5 years ago. During the 4 years of follow-up for PCRS, the clinical and radiographic evaluations revealed significant improvements in the periodontal phenotype of the mandibular anterior region. The periodontal phenotypes in the mandibular incisors region were all modified from thin to thick. Supplementing orthodontic treatment with labial PCRS could be a promising treatment strategy to maintain long-term periodontal health in adult patients with alveolar deficiency and thin gingiva tissue.

Effect of Early Orthodontic Treatment on Long-Term Stability of Class II Malocclusions.

Background: Class II malocclusions are a common orthodontic problem, often requiring comprehensive treatment to achieve proper occlusion and facial harmony. Early orthodontic intervention in the mixed dentition phase has been advocated to address these issues. Materials and Methods: A retrospective analysis was conducted on a cohort of 150 patients with class II malocclusions who underwent early orthodontic treatment between the ages of 7 and 10 years. The treatment included fixed or removable appliances, headgear, and functional appliances, depending on individual needs. Records of their initial malocclusion severity, treatment modalities, and long-term follow-up data (mean follow-up duration of 10 years) were collected and analyzed. Stability was assessed by evaluating overjet and overbite changes from post-treatment to the long-term follow-up. Results: The initial mean overjet and overbite values were 8.5 mm and 4.0 mm, respectively. Following early orthodontic intervention, these values were significantly reduced to 3.0 mm and 1.5 mm, respectively (P < 0.001). At the long-term follow-up, the mean overjet and overbite remained stable at 3.2 mm and 1.6 mm, respectively. Analysis revealed that 85% of patients maintained their corrected class II occlusion within clinically acceptable limits, while 15% experienced minor relapse requiring minimal additional treatment. Conclusion: Early orthodontic treatment in class II malocclusions can lead to significant improvements in overjet and overbite, and these corrections tend to remain stable over the long term.

Accuracy of patient-specific implants versus CAD/CAM splints with the mandible-first approach in bimaxillary orthognathic surgery for skeletal Class II malocclusion.

This retrospective study aimed to compare the accuracy of patient-specific implants (PSI) versus mandible-first computer-aided design and manufacturing (CAD/CAM) splints for maxilla repositioning in orthognathic surgery of skeletal Class II malocclusion patients. The main predictor was the surgical method (PSI vs. splints), with the primary outcome being the discrepancy in maxilla centroid position, and secondary outcomes being translation and orientation discrepancies. A total of 82 patients were enrolled (70 female, 12 male; mean age 25.5 years), 41 in each group. The PSI group exhibited a median maxillary position discrepancy of 1.25 mm (interquartile range (IQR) 1.03 mm), significantly lower than the splint group's 1.98 mm (IQR 1.64 mm) (P < 0.001). In the PSI group, the largest median translation discrepancy was 0.74 mm (IQR 1.17 mm) in the anteroposterior direction, while the largest orientation discrepancy was 1.83° (IQR 1.63°) in pitch. In the splint group, the largest median translation discrepancy was 1.14 mm (IQR 1.37 mm) in the anteroposterior direction, while the largest orientation discrepancy was 3.03° (IQR 2.11°) in pitch. In conclusion, among patients with skeletal Class II malocclusion, the application of PSI in orthognathic surgery yielded increased precision in maxillary positioning compared to mandible-first CAD/CAM splints.

Evaluating the Effects of Carriere Motion Appliance and Twin Block Appliances in Class II Correction-A Retrospective Study.

This retrospective study compared Class II orthodontic non-extraction treatment using Carriere Motion Appliance (CMA) and Twin Block (TB) appliances. METHODS: The treatment of 38 patients was assessed. Pre- and post-treatment cephalometric radiographs were analyzed to evaluate skeletal, dental, and soft tissue treatment outcomes and efficacy. RESULTS: Both appliances effectively corrected the Class II molar relationship. When measured at the distal aspect of the first molar, TB achieved 4.22 mm, while CMA had a 2.55 mm correction. When measured in the mesial aspect, the CMA achieved a 3.9 mm correction. The changes in SNB and ANB were statistically significant only in the TB group. The CMA appliance demonstrated statistically significantly less protrusion of the mandibular incisors and less upper incisor retrusion without vertical changes compared to the TB appliance. The TB demonstrated statistically significant lower lip protrusion compared to the CMA. CONCLUSION: The CMA corrects Class II malocclusions only by exerting a dentoalveolar influence and does not demonstrate the added effects associated with TB, such as elongation of lower facial height (LFH) and less loss of lower anchorage. Nonetheless, the correction in the TB group comprised both dentoalveolar and skeletal components. The CMA promotes a multidirectional upper and lower molar movement, and despite our 2D cephalometric analysis, we were able to estimate the extent of upper molar derotation.

Evaluation of modified clear Twin Block aligner in treating adolescents with skeletal class II malocclusion: A two-centre cephalometric study.

INTRODUCTION: The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. METHODS: A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre-treatment (T1) and post-treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent-sample t-test, paired-sample t-test, ANOVA test and Scheffe's Post Hoc test. RESULTS: Seventy-five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms-S Vert/Mi in the CTB group (P < .01) and the TB group (P < .001), as well as deep overjet through significant different in S Vert/Is-S Vert/Ii in the CTB group (P < .001) and the TB group (P < .001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. CONCLUSIONS: For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance.

Clear Aligners in the Growing Patient: A Systematic Review.

Mixed dentition represents a critical phase in the oral development of pediatric patients, characterized by the simultaneous presence of primary and permanent teeth. This article proposes a comprehensive systematic review of the application of aligners as an innovative methodology in managing mixed dentition. The primary objective is to explore the efficacy, safety, and acceptability of this emerging orthodontic technology in the evolving age group. This systematic review focuses on randomized controlled trials, cohorts, and observational studies investigating the use of aligners in patients with mixed dentition. Clinical, radiographic, and psychosocial parameters will be considered to assess the overall impact of aligner therapy in this critical phase of dental development. An in-depth analysis of such data aims to provide a comprehensive overview of the potential of this technology in pediatric orthodontics. Expected outcomes may contribute to outlining practical guidelines and targeted therapeutic strategies for orthodontists involved in managing mixed dentition. Furthermore, this article aims to identify gaps in the current research and suggest future directions for studies exploring the use of transparent aligners in patients with mixed dentition, thereby contributing to the ongoing evolution of evidence-based orthodontic practices.

Long-term skeletodental changes with early and late treatment using modified C-palatal plates in hyperdivergent Class II adolescents.

OBJECTIVES: To compare skeletodental changes between early and late treatment groups using modified C-palatal plates (MCPP) and long-term retention outcomes in hyperdivergent Class II adolescents. MATERIALS AND METHODS: Seventy-one hyperdivergent Class II patients were divided into four groups according to treatment modality and treatment timing: group 1, early treatment with MCPP (n = 16; 9.9 ± 0.9 years); group 2, late treatment with MCPP (n = 19; 12.3 ± 0.8 years); group 3, early treatment with headgear (HG; n = 18; 9.6 ± 0.8 years); and group 4, late treatment with HG (n = 18; 12.1 ± 1.2 years). Lateral cephalograms were taken and skeletal and dental variables were measured. For statistical analysis, paired t-tests, independent t-tests, and multiple regression were performed. RESULTS: The early MCPP group showed a more significant decrease in mandibular plane angle than the late MCPP group did, and vertical control was more efficient in the early group than in the late group. In the MCPP groups, both FMA and SN-GoGn were increased with late treatment but decreased with early treatment, and the difference was statistically significant (P < .01). The early-treatment MCPP group had a significant decrease in SN-GoGn of 0.6° compared with an increase of 1.7° in the early treatment HG group (P < .01). Posttreatment stability of both the early and late MCPP groups was maintained in long-term retention. CONCLUSIONS: Early MCPP showed more significant vertical control than late MCPP. However, there was no difference in long-term stability between early and late groups.

Assessment of maximal inspiratory and expiratory pressures in skeletal Class II patients with different growth patterns.

OBJECTIVES: To evaluate maximal inspiratory (MIP) and expiratory (MEP) pressures, which are reflective of respiratory muscle strength, in skeletal Class II patients with different growth patterns (horizontal, average, and vertical) and to correlate those with airway dimension. MATERIALS AND METHODS: Patients with a Class II skeletal base seeking orthodontic treatment were assigned to the following groups: average, horizontal, and vertical growth pattern. The control group (n = 14) comprised patients with a Class I skeletal base and average growth pattern. Airway dimensions were obtained using cone-beam computed tomography scans, and a spirometer with a pressure transducer was used for assessment of MIP and MEP. Routine spirometry for assessment of lung function was also performed. RESULTS: No significant differences were found in maximal inspiratory and expiratory pressures for the study groups in comparison with the control group. Class I patients had significantly greater oropharyngeal and nasopharyngeal airway volumes compared with the study groups. No significant difference in minimal cross-section area of the airway was observed among groups. A weak positive correlation between maximal inspiratory pressure and airway volume was observed. CONCLUSIONS: Although Class I patients displayed significantly greater oropharyngeal and nasopharyngeal airway volumes, there was no significant difference in respiratory muscle strength or airway function between Class II patients with different growth patterns and the Class I control group. The findings underscore the significance of exploring factors beyond craniofacial growth patterns that may contribute to sleep-related breathing disorders.

Headgear therapy in children with Class II malocclusion and the role of compliance on treatment outcome: A nine-month randomized controlled trial.

OBJECTIVES: To evaluate three-dimensional movements of maxillary teeth during headgear treatment in Class II growing children, using digital analytical tools, and to determine the effects of compliance on these movements. MATERIALS AND METHODS: A 9-month parallel-group randomized controlled trial was carried out on 40 children with Class II malocclusion, aged 8-12 years, half assigned to receive a cervical headgear and half to a no-treatment group, using block randomization. Subjects in the treatment group were instructed to wear the headgear for 12 hours daily and monitored using an electronic module. After 9 months, the following dental outcomes were measured: first maxillary molar distalisation, rotation, tip and torque, arch depth, and interpremolar and intermolar distances. Caregivers and participants were not blinded to group assignments, but those assessing outcomes were. Linear regression models were used to detect differences between groups and correlation coefficients to find correlations between compliance and dental outcomes. RESULTS: All 40 included patients were analysed. A significant difference in molar distalisation was observed between the treatment (1.2 mm) and control groups (-0.2 mm). Arch depth change was also increased to a larger extent in the treatment groups (1.3 mm vs 0.1 mm), as was the interpremolar distance (1.9 mm vs 0.4 mm). In contrast, no significant differences in molar rotation or torque change were observed. With regard to compliance, average compliance was 55%. A significant correlation was found between molar distalisation and compliance in the treatment group. CONCLUSIONS: Headgear therapy has significant effects on molar distalisation, arch depth, and arch width. Compliance has a significant positive effect on molar distalisation.

The Effect of Early Orthodontic Treatment on Long-Term Stability of Class II Malocclusions.

Background: Class II malocclusions are a common dental issue characterized by the misalignment of the upper and lower teeth. Early orthodontic treatment is often considered to correct these malocclusions, but its long-term effectiveness remains unclear. Materials and Methods: In this study, we examined the impact of early orthodontic treatment on the long-term stability of Class II malocclusions. We conducted a retrospective analysis of dental records from a sample of 150 patients who had received early orthodontic treatment for Class II malocclusions. The treatment involved braces and other orthodontic appliances. We compared their dental measurements before and after treatment, with a follow-up period of 5 years. Results: Our analysis revealed that the early orthodontic treatment led to a significant improvement in the alignment of upper and lower teeth, as indicated by a reduction in the overjet (the horizontal distance between upper and lower incisors). The mean overjet reduction was 3.2 millimeters. Furthermore, the Angle's Class II molar relationship was corrected in 80% of the cases. Conclusion: Early orthodontic treatment for Class II malocclusions demonstrated positive long-term stability, as evidenced by a reduction in overjet and improvement in molar relationships.

Evaluation of Glenoid Fossa Position in Class II Malocclusion Associated with Mandibular Retrusion and Class III Malocclusion Associated with Mandibular Protrusion.

Objective: This study examined the glenoid fossa in Class II and Class III malocclusions with mandibular retrusion and protrusion. Materials and Methods: A retrospective investigation examined 60 Class II and 60 Class III cephalometric radiographs. Cephalometric landmarks and glenoid fossa measurements were taken. Statistical analysis contrasted the two malocclusion groups' glenoid fossas. Results: Class II malocclusion had a much lower mean Sella-Nasion-Condylion (SNCd) angle (glenoid fossa sagittal position) than Class III (14.6° ± 1.9). Class II malocclusion had a lower mean Sella-Nasion-Gonion (SNGo) angle (32.5° ± 4.3) than Class III (36.2° ± 3.9). The SNCd angle and SNGo angle in both groups demonstrated a negative correlation, demonstrating a relationship between the glenoid fossa and the mandibular sagittal axis. Conclusion: The glenoid fossa location differs significantly between Class II malocclusion with mandibular retrusion and Class III with protrusion. Class II malocclusion has a posterior glenoid fossa, while Class III has a less posterior one. Understanding these links may help patients receive more personalized treatment.

Pain Intensity of Skeletally Anchored Maxillary Molar Distalization in Conjunction with Micro-osteoperforations: A Randomized Clinical Trial.

Objective To assess pain intensity levels during orthodontic therapy of Class II malocclusion patients undergoing skeletally anchored maxillary molar distalization assisted with different micro-osteoperforation (MOP) approaches. Methods Twenty-seven patients (12 males and 18 females) with a mean age of 16.1 ± 0.3 years were randomized into three equal groups (n=9): Group 1 comprised MOPs on buccal surface, Group 2 comprised MOPs on buccal and palatal surface, and Group 3 comprised the control or no-MOP group. The patients underwent maxillary molar distalization using skeletally anchored distal jet appliance assisted with or without MOPs. The MOPs were applied repeatedly on the buccal and buccal and palatal sides, or no MOP (control). Pain intensity was assessed using a 10 cm visual analog scale after each device activation at 24, 48, 72 hours, and at seven days. Data were analyzed using one-way ANOVA and repeated measures ANOVA for non-paired and paired means. Results Both approaches of buccal and buccal and palatal application of MOPs showed statistically significant (p< 0.01) higher levels of pain intensity after the first activation at 24 hours. Nevertheless, pain intensity levels decreased significantly in both MOP groups and between the two activations. Conclusion The repeated application of MOPs on either the buccal side only or on both buccal and palatal sides during maxillary molar distalization did not affect the levels of pain experienced; however, these levels were reported to be higher than that obtained in the control group. Moreover, it is observed that these pain levels tend to gradually reduce to mild levels over the subsequent days.

Evaluation of mandibular motion in adolescents with skeletal class II division 1 malocclusion during mandibular advancement using clear functional aligners: a prospective study.

BACKGROUND: This study aimed to evaluate the characteristics of mandibular protrusive condylar trajectory in adolescents with skeletal Class II Division 1 malocclusion and the changes of condylar trajectory during mandibular advancement (MA) treatment using clear functional aligners. METHODS: This prospective study consisted of a cross-sectional study and a longitudinal study. In cross-sectional study, sixty-one adolescents were divided into two groups: Class I (n = 30) and Class II Division 1 (n = 31). The condylar trajectory was measured and compared using the Mann-Whitney U test. The longitudinal study was the MA treatment group using clear functional aligner and consisted of 16 participants from Class II Division 1group. The condylar trajectory was collected at three-time points: pre-treatment (T1), during MA treatment at approximately 3 months (T2, 105.6 days average), and at the end of MA treatment (T3, 237.6 days average). The changes at T1, T2, and T3, as well as the symmetry between the left and right condyles across all groups, were examined using the Wilcoxon paired test. RESULTS: A greater increase in the anteroposterior displacement and space displacement during protrusive movements was observed in the Class II Division 1 group compared with that in the Class I group, with a large difference being observed in the left and right condylar movements. The condylar anteroposterior displacement and space displacement decreased significantly at T2 and increased significantly at T3; however, no significant difference was observed between T1 and T3. A significant difference was observed between the condylar movement on the left and right sides at T1; however, no significant difference was observed at T2 and T3. CONCLUSIONS: Adolescents with Class II Division 1 malocclusion had higher protrusive capacity than those with Class I. Moreover, their left and right condylar motion was more asymmetric. The range of condyle motion decreased first and then increased during MA therapy, and the left and right condyle movement became more symmetrical, which may be the adaptive response of neuromuscular function to the changes in jaw position.

Comparative assessment of two-phase class II treatment with Activator or Bionator followed by fixed appliances: A retrospective controlled before-and-after study.

AIM: Two-phase treatment for children with Class II malocclusion with several functional appliances is still performed by many orthodontists, while the Activator and the Bionator appliances are two of the most popular ones. Aim of this study was to compare the skeletal and dentoalveolar effects of treatment with these two appliances. METHODS: Class II children treated with Activator or Bionator in the first phase, followed by a phase of fixed appliances were included. Skeletal and dentoalveolar parameters were assessed from lateral cephalograms and analysed with linear regressions at 5%. RESULTS: A total of 89 patients (mean age 10.0 years; 47% female) were included. During the first phase, Bionator increased less the SNB (difference in mean treatment-induced changes [MD] -0.7°; 95% confidence interval [CI] -1.3 to -0.2°; P=0.01) and decreased less the ANB angle (MD 0.6°; 95% CI 0 to 1.1°; P=0.03) compared to Activator. Activator slightly increased the facial axis and Bionator reduced it (MD -1.6°; 95% CI -2.3 to -0.8°; P<0.001). Compared to Activator, the Bionator retroclined more the upper incisors (MD -2.4°; 95% CI -4.6 to -0.2°; P=0.03) and increased more the interincisal angle (MD 2.9°; 95% CI 0.5 to 5.4°; P=0.02). After the second phase (6.2 years after baseline), the only differences were a reduced facial axis (MD -1.3°; 95% CI -2.2 to -0.3°; P=0.008) and an increased maxillary rotation (MD 0.9°; 95% CI 0 to 1.8°; P=0.04) with Bionator compared to Activator. CONCLUSION: Similar dentoalveolar effects were seen overall with two-phase treatment with either appliance, with Bionator being associated with more vertical increase compared to Activator.

Comparison of Twin Block appliance and Herbst appliance in the treatment of Class II malocclusion among children: a meta-analysis.

BACKGROUND: Our meta-analysis aimed to evaluate the efficacy of applying Herbst and Twin Block appliances in the treatment of Class II malocclusion among children. METHODS: Databases, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), China VIP Database (VIP), and Wanfang were thoroughly searched from inception to August 9, 2023. The outcomes included skeletal, dental, and soft tissue changes. The weighted mean difference (WMD) was used as the effect indicator, and the effect size was expressed with a 95% confidence interval (CI). The heterogeneity of each outcome effect size was tested, and the heterogeneity statistic I2 ≥ 50% was analyzed by the random-effect model, otherwise, the fixed-effect model was conducted. Sensitivity analysis was performed. RESULTS: A total of 12 studies involving 574 patients were included in this meta-analysis. Herbst appliance had a statistically significant increase in mandibular body length (WMD: 1.44, 95% CI: 0.93 to 1.96, P < 0.001) compared with the Twin Block appliance. More increases in angle and distance of L1 to mandibular plane (MP) were found in the Herbst appliance compared with the Twin Block appliance. Significant and greater improvements in molar relationship (WMD: 0.79, 95% CI: 0.28 to 1.29, P = 0.002), posterior facial height (WMD: -1.23, 95% CI: -2.08 to -0.38, P = 0.005), convexity angle (WMD: -1.89, 95% CI: -3.12 to -0.66, P = 0.003), and Sella-Nasion plane angle (U1 to SN) (WMD: 3.34, 95% CI: 2.25 to 4.43, P < 0.001) were achieved in the Twin Block appliance. Herbst and Twin Block appliances produced similar effects in the skeletal and dentoalveolar changes including Sella-Nasion-point A (SNA), Sella-Nasion-point B, point A-Nasion-point B (ANB), overjet, and overbite. CONCLUSION: As the findings revealed both Herbst and Twin Block appliances contributed successfully to the correction of Class II malocclusion. Compared with the Twin Block appliance, the Herbst appliance may have more advantages in mandibular bone movement. Twin Block therapy resulted in more improvement in the aesthetics of the face.

A Comparative Electromyographic Analysis of Masticatory Muscles Between Skeletal Class II and Skeletal Class I Malocclusion: A Cross-Sectional Study on a Syrian Population.

OBJECTIVES: This study aimed to investigate whether there was a difference in the muscular activity of the masticatory muscles between patients with skeletal Class II and skeletal Class I malocclusion. MATERIALS AND METHODS: A cross-sectional study was conducted using a sample of 56 selected patients referred to the Department of Orthodontics and Dentofacial Orthodontics, Faculty of Dentistry at the University of Damascus, Damascus, Syria. An electromyographic device measured the myoelectric activity of the perioral muscles on patients in the two created groups: the skeletal Class I malocclusion group (n=28 patients) and the skeletal Class II malocclusion group (n=28 patients). RESULTS: The study found a similarity in the muscular activity between the right and left sides within the same group, without significant differences between both sides for each muscle (P>0.05). The Class II group had significantly greater activity in the buccinator and digastric muscles than the Class I group (p<0.05). On the other hand, the Class I group had significantly greater activity in the orbicularis and mentalis muscles than the Class II group (P<0.05). CONCLUSION: Patients with skeletal Class II malocclusion and skeletal Class I showed differences in muscular activity. The buccinator and digastric muscles were more active in skeletal Class II patients, while orbicularis oris and mentalis were less active. The temporalis and masseter muscles showed similar activity in both groups.

Three-dimensional computed tomography analysis of airway volume in growing class II patients treated with Frankel II appliance.

OBJECTIVE: The purpose of this retrospective study was to assess the airway volume changes associated with the use of Frankel appliance (FR II) in Class II malocclusion patients using three-dimensional cone beam computed tomography (3D CBCT) imaging. MATERIALS AND METHODS: The sample consisted of 31 Class II malocclusion patients (mean age 9.24 ± 1.93 years old, 17 males (54.8%) and 14 females (45.2%)) treated with FR II appliance by the same orthodontist for an average of 9 months ± 20 days. CBCT images were taken before and after treatment and upper airway volume changes were measured using Dolphin 3D software version11.0 (Dolphin Imaging, Chatsworth, CA) and statistically compared. RESULTS: Airway volume of nasal cavity, nasopharynx, oropharynx, hypopharynx and the total airway volume significantly increased after the use of FR II appliance. In addition, significant increase was reported in maxillary base, inter-molar, inter-premolar and inter-canine width. Significant increase in soft tissue thickness was only recorded opposite to CV2. CONCLUSION: The use of the FR II appliance in growing subjects with Class II malocclusion led to a significant increase in the upper airway volume in addition to the anticipated dental and skeletal transverse expansion effects.

New insights into the genetics of mandibular retrognathism: novel candidate genes.

PURPOSE: Mandibular retrognathism (MR) is a common skeletal malocclusion in humans with a strong genetic component. Single nucleotide polymorphisms (SNPs) in genes encoding epidermal growth factor (EGF) and EGF receptor (EGFR) could be involved in the etiology of mandibular retrognathism. Therefore, in this study, we investigated whether SNPs in the genes encoding for EGF and EGFR are associated with MR in German teenagers. METHODS: This nested case-control study evaluated German orthodontic patients, aged 10-18 years. DNA, which was isolated from buccal epithelial cells using two cytobrushes, was used for genotyping analysis and digital pretreatment lateral cephalograms were examined to calculate SNB and ANB. Patients with a retrognathic mandible (SNB < 78°) were included as cases, while patients with an orthognathic mandible (SNB = 78-82°) were included as controls. Four SNPs in the genes encoding for EGF and EGFR were chosen and genotyped using real-time PCR. Allele, genotype, and haplotype frequency were compared across groups (α = 5%). RESULTS: Finally, 119 patients were included in this study (45 orthognathic mandible, 74 retrognathic mandible). The minor allele G in rs4444903 (EGF) was statistically more frequent in individuals with an orthognathic mandible (p = 0.008). The haplotype formed by the mutant alleles for rs4444903|rs2237051 (EGF; G|A) was statistically more frequent in the orthognathic mandible group (p = 0.007). The SNPs rs4444903 and rs2237051 in EGF, and rs2227983 in EGFR were statistically associated with a decreasing risk of developing a retrognathic mandible according to univariate and multivariate statistical analysis (p < 0.05). CONCLUSION: SNPs in EGF (rs4444903 and rs2237051) and EGFR (rs2227983) were associated with MR in our German sample and could be genetic biomarkers for early and individualized diagnostic identification of retrognathic mandibular development by means of genetic screening tests.

Cephalometric and digital model analysis of dentoskeletal effects of infrazygomatic miniscrew vs. Essix- anchored Carriere Motion appliance for distalization of maxillary buccal segment: a randomized clinical trial.

TRIAL DESIGN: Parallel. OBJECTIVE: To compare skeletally anchored Carriere Motion appliance (CMA) for distalization of the maxillary buccal segment vs. Essix anchored CMA. METHODS: Thirty-two class II malocclusion patients were randomly allocated into two equal groups. One group was treated with infrazygomatic (IZC) miniscrew- anchored CMA (IZCG) and the other group treated with Essix retainer- anchored CMA (EXG). Two lateral cephalograms and two digital models for upper and lower arches were taken for each patient: immediately before intervention and after distalization had been completed. RESULTS: Distalization period was not significantly different between the two groups. In contrast to EXG, IZCG showed insignificant difference in ANB, lower incisor proclination, and mesial movement of the lower first molar. There was significant rotation with distal movement of maxillary canine and first molar in both groups. CONCLUSION: IZC anchored CMA could eliminate the side effects of class II elastics regarding lower incisor proclination, mesial movement lower molars with a more significant amount of distalization of the maxillary buccal segment but with significant molar rotation. TRIAL REGISTRATION: The ClinicalTrials.gov Protocol Registration and Results System (PRS) has this RCT registered as (NCT05499221) on 12/08/2022.