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Background This study aimed to determine if individuals with skeletal Class II and skeletal Class III malocclusions had different levels of masticatory muscle activity. Materials and methods This cross-sectional study, conducted at the University of Damascus, investigated the myoelectric activity of perioral muscles in patients with Class II and III malocclusions. The sample size of 60 patients was determined according to a prior sample size calculation. Patients were selected based on specific inclusion and exclusion criteria and divided into Class II and III groups. Electromyography was used to monitor the activity of various muscles, including the temporalis, masseter, orbicularis oris, buccinator, mentalis, and digastric muscles. Results The study found similar muscle activity within the same group in the temporalis, masseter, buccinator, digastric, and orbicularis oris muscles. No significant differences were observed between the Class II and III groups for several oral and perioral muscles (P > 0.05). However, the mean activity of the digastric muscle was significantly greater in the Class II group (P < 0.05), whereas the mean activity of the mentalis muscle was smaller in the Class II group (P < 0.05). Conclusions Perioral muscles influence facial complex development and jaw relationship, affecting orthodontic treatment. Digastric muscle activity is greater in Class II patients, while mental muscle activity is smaller in Class III patients. Further studies are needed for older age groups and other skeletal malocclusion types., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Saker et al.)

To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion. The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests. The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P <.001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P <.001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups. The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment. [ABSTRACT FROM AUTHOR]

Crowding of teeth is one of the most common malocclusion. Determination of etiology of crowding could have significant effects on treatment planning and prognosis of class II malocclusion. Growth pattern might affect the amount of crowding in class II malocclusion. Aim of this study was to evaluate the relationship between lower dental arch crowding and various growth patterns in class II subjects. Pretreatment lateral cephalograms and dental occlusal view mandibular arch photographs for class II subjects were collected for the study. Lateral cephalograms were traced and the subjects were divided into different growth patterns (n=60) (horizontal =20, vertical = 20, average = 20) on the basis of gonial angle. Crowding in each growth pattern was assessed from the records of patients visiting the dental hospital. From the results,15% of the vertical growers showed very severe crowding, 20% of the vertical growers showed severe crowding, 40% showed moderate crowding, 5% had mild crowding. 10 % of the horizontal growers showed severe crowding, 25% had moderate crowding, 40% showed mild crowding. 35 % of the average growers had moderate crowding, 30% had mild crowding. Results were statistically significant.(p<0.05). Significant association was found between vertical growth patterns and severity of the mandibular arch crowding as compared to horizontal or average growth patterns. No association between crowding and gender. Hence, it can be concluded that the Class II subjects with Vertical growth patterns have severe lower dental arch crowding as compared to the subjects with horizontal and average growth patterns. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate the relation between mandibular advancement, the three-dimensional extent of the posterior airway space (PAS), and the position of the hyoid bone, using cone-beam computed tomography (CT). Twenty-eight Class II patients (21 women (mean (SD) age 29 (9) years) and seven men (mean (SD) age 23 (6) years)), who had had mandibular-only advancement surgery (Obwegeser-Dal Pont) were included in the study. In each case, cone-beam CT scans were taken one week before and six months after operation, and a retrospective analysis made of the alterations of several airway variables (volume, mean cross-sectional area, and diameter) and the three-dimensional extent of mandibular and hyoid movement, by using IPlan® cranial software. A linear regression was also done to correlate mandibular advancement, the movement of the hyoid bone, and airway variables. There were significant postoperative increases in all volumetric PAS variables, and in most diametric and spherical variables (p < 0.05). There was also a significant linear relation between forward displacement of the mandible and the movement of the hyoid bone (p < 0.05). These results show that mandible-only advancement surgery causes an increase in most dimensions of the PAS. This intervention can be assumed to reduce airway resistance and therefore might be a suitable treatment option for patients with obstructive sleep apnoea syndrome. [ABSTRACT FROM AUTHOR]

Objective: Improving the effectiveness of complex treatment in patients with distal occlusion of the dentition during the period of active skeletal growth., Material and Methods: 202 patients with skeletal distal occlusion were examined and treated. Patients are divided into three subgroups depending on the position/size of the jaw bones and the main link of pathogenesis. The parameters of TRG and CBCT sections were measured before and after treatment. Various parameters were used for the analysis: skeletal (SNA, SNB, ANB, etc.), dental (II/SN, II/ii, APog-I, APog-i, etc.), skeletal profile and soft tissue parameters., Results: Various orthodontic techniques have been applied, including FNTA, the Damon bracket system, the Biederman apparatus and others. In the retention period, non-removable retainers in the frontal section and removable night retention devices of various structures were used. Patients were monitored for up to 15 years after the completion of the active orthodontic treatment stage. The analysis of the X-ray examination data indicates the normalization of the mutual position of the jaw bones in relation to the base of the skull, optimization of the ratios of the bone elements of the TMJ. An algorithm has been developed for the treatment of patients with dental anomalies in the sagittal plane, with narrowing of the upper jaw during the bite of permanent teeth., Conclusion: Comprehensive treatment of patients with distal occlusion during the period of active skeletal growth makes it possible to achieve significant improvements in dentition, position and closure of teeth, as well as skeletal parameters of X-ray examinations. The results indicate the importance of early intervention using modern orthodontic techniques. Long-term follow-up in the retention period shows the stability of the results and the effectiveness of the treatment.

Introduction: Cone Beam Computed Tomography (CBCT) imaging recently has become a very common diagnostic tool in the orthodontic literature. Recent research work has shown that CBCT imaging would give additional information regarding the volumetric assessment of the craniofacial structures. However, the previous published work has not considered the impact of the anterior-posterior skeletal classification and the vertical skeletal pattern on the volumetric assessment of the maxillary and mandibular bones. Aim: To evaluate maxillary and mandibular volumes (MxV and MdV, respectively) in hyper-divergent skeletal Class II (CII) and normo-divergent skeletal Class I (CI) patients and to investigate any possible correlation between CBCT derived lateral cephalometric variables and the calculated volumes. Materials and Methods: CBCT images of 60 patients (30 patients: CI, 30 patients: CII) were obtained and processed with Mimics® 17 software (Materialise, NV, Belgium). The threedimensional models of both jaws were reconstructed and the related volumes were calculated using a novel approach. CBCT based cephalograms were also derived and linear and angular measurements of the craniofacial complex were obtained. Significance tests were based on t-tests (alpha set at 5%) and Pearson’s correlation coefficients were calculated. Results: No significant differences were detected between the two groups in the MxV (p=0.435) and the MdV (p=0.507). In the CI group, no or weak correlations were found between the volumetric measurements and the 2D variables. In the CII group, there was a strong correlation between both MxV and MdV and both the posterior facial height (r=0.60, 0.78 respectively) and the facial height index (r=0.62, 0.72 respectively). A negative moderate correlation was found between both MxV and MdV and the mandibular plane angle (r=-0.48, -0.44 respectively) and Bjork's sum (r=-0.48, -0.44 respectively). Conclusion: There were no significant differences in the MxV and MdV between CI and CII skeletal patterns. Some cephalometric variables had moderate to strong correlation with the MxV and MdV in the CII group.

Objectives: To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion., Materials and Methods: The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests., Results: The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups., Conclusions: The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment., (© 0000 by The EH Angle Education and Research Foundation, Inc.)

Background: Lateral Cephalometric Radiographs (LCR) are a common decision-making aid in orthodontic treatment planning and are routinely used in clinical practice. The aim of this present study was to test the null hypothesis that LCR evaluation does not alter specific components of orthodontic treatment planning in Class II patients., Materials and Methods: Records of 75 patients, who had been treated at the Department of Orthodontics, Centre of Dental Medicine, University of Zurich comprised the study material. Inclusion criteria were: (1) adolescents between the age of 12-15, (2) permanent dentition with Class II buccal segment relationship (3) absence of craniofacial and dento-alveolar malformations. Fifteen orthodontists from the dental faculties of Istanbul University, Istanbul and Ege University, Izmir filled out Likert-type linear scale questionnaires without knowing that they would repeat the same procedure with and without LCRs at two different time points. Equivalence and clinical relevance were assessed using (%95 CI) Wilcoxon signed rank tests., Results: Extraction decision did not differ between groups ( p =0.68). Preference of functional appliance use ( p =0.006) and inter-maxillary fixed functional appliance (p=0.043) was different among groups., Conclusion: LCR evaluation has minor influence on treatment planning procedure of Class II patients. It might be beneficial to consider its prescription not in a routine manner but as a supplementary tool considering possible reduction of radiation exposure.