Correlation Analysis between Three-Dimensional Changes in Pharyngeal Airway Space and Skeletal Changes in Patients with Skeletal Class II Malocclusion following Orthognathic Surgery

Introduction. Studies on the pharyngeal airway space (PAS) changes using three-dimensional computed tomography (CT) have shed more light on patients with Class III than Class II malocclusion. This paper focuses on analyzing the long-term changes in the PAS and evaluating the postoperative association between these PAS and skeletal changes in patients with skeletal Class II malocclusion who have undergone orthognathic surgery. Methods. The records of 21 patients with skeletal Class II malocclusion who had undergone orthognathic surgery were included. The anatomical modifications in both jaws, changes in volume, sectional area (SA), minimum sectional area (MSA), and anterior-posterior (AP) and transverse (TV) width in the airway at one month before surgery ( T 0 ), and one month ( T 1 ) and one year ( T 2 ) after surgery were analyzed using CT images. The association between the skeletal and airway changes was evaluated between T 0 , T 1 , and T 2 . Results. After surgery, the ANS, A point, and PNS demonstrated significant posterior and superior movement. The B point and the pogonion exhibited substantial anterior and superior movement. The total and inferior oropharyngeal volumes (vol 3, vol 4) notably increased, while the nasopharyngeal volume (vol 1) decreased. The anterior-posterior movement at the ANS and PNS after surgery was significantly associated with the total volume, vol 2, vol 3, SA 1, MSA, and TV width 1, while substantial association with the total volume was found at the pogonion. Conclusion. Thus, an ideal treatment plan can be formulated for patients with skeletal Class II malocclusion by considering the postoperative PAS changes.

Evaluation of Postsurgical Stability And Condylar Morphology In Skeletal Class II Patients With Condylar Resorption Following Orthognathic Surgery

Background: To retrospectively evaluate postsurgical stability and condylar morphology for skeletal class II malocclusion patients with condylar resorption (CR) treated with orthognathic surgery.Methods: Thirty-five patients treated with combined orthodontic and orthognathic surgery between 2014 and 2018 were enrolled in this retrospective study. CT scans were acquired preoperatively (T0), 2–7 days after surgery (T1), and 1 year postoperatively (T2). The amount of mandibular advancement, postsurgical relapse, condylar morphology and joint spaces were analysed respectively. Statistical analysis was performed using R, version 3.4.3 (R Development Core Team 2010).Results: The average mandibular advancement and counter-clockwise rotation were 5.51 mm and -2.82 degrees respectively. The average relapse was 1.08 mm (19.6% of the advancement) and 1.13 degrees. The condylar volume showed a postoperative reduction of 161.86 mm3(13.7% of initial condylar volume). AJS increased after surgery and gradually returned to its original state, while SJS and PJS decreased and remained stable. Surgical advancement of B point was significantly correlated with skeletal relapse. The optimal cut-off values were as follows: MP-FH (40.75°); ramus height (51.125 mm); SJS (1.63 mm); surgical displacement (4.72 mm); CCR (-4.3°); AJSC (1.07 mm).Conclusions: Skeletal class II patients with CR have a high risk of postsurgical condylar resorption, which was most related to nonsurgical risk factors such as gender(female) and condylar angle. Condylar had moved posteriorly to the concentric position after surgery and remained quite stable through the 1-year follow-up. Preoperative skeletal patterns such as lower ramus height and surgical procedures such as larger advancement of the mandible were closely associated with sagittal relapse of the mandible.

Association between Crowding and the Effective Maxillary and Mandibular Length among Orthodontic Patients of Kathmandu, Nepal.

Background: During orthodontic consultation, the most frequent major complaint of the patients is dental crowding, which is caused by a disparity between the arch length and tooth size. Objective: The purpose of this study was to evaluate the association between crowding and the effective maxillary and mandibular length in Nepalese orthodontic patients.Methods: The orthodontic records of 390 people (from January 2018 to December 2020) were randomly selected and classified into three skeletal malocclusions based on the ANB angle (Angle formed by point A and point B at the nasion). Subjects with skeletal malocclusions were subdivided into two groups depending on the degree of crowding in the mandibular arch: Group 1 had crowding of < 3mm, and Group 2 had crowding of >3mm. On pretreatment casts, digital vernier calipers (Digimatic, Precise, India) were used to assess dental arch crowding, whereas, on a pretreatment lateral cephalogram, digital cephalometric analysis (Vistadent OC 1.1, USA) was done to quantify effective maxillary and mandibular length. Inter-group comparisons were assessed using a one-way analysis of variance. The correlation was assessed by Pearson’s correlation coefficient (p≤0.05).Results: There was a statistically significant difference in effective maxillary and mandibular length among skeletal malocclusions (p<0.05). Skeletal Class II malocclusion had the greatest mandibular crowding, while skeletal Class III malocclusion had the least. The effective maxillary and mandibular lengths and dental crowding had a significant but weak inverse correlation, whereas a strong but moderate positive correlation existed between the maxillary and mandibular effective lengths (r=0.674) and also between maxillary and mandibular crowding (r=0.631).Conclusion: Effective maxillary length was highest in skeletal class II malocclusion whereas effective mandibular length was highest in skeletal class III malocclusion. The shorter effective maxillary and mandibular lengths showed a weak association with dental crowding.

Runx2 rs59983488 polymorphism in class II malocclusion in the Indonesian subpopulation

Background: Class II malocclusion is one of the main orthodontic issues for patients in seeking treatment. The prevalence of class II malocclusion varies in different populations. Variation in skeletal profile is mainly controlled internally by a regulatory gene. Runt-related transcription factor-2 (Runx2) plays a role in osteoblast differentiation and is highly expressed during development. Purpose: This study aimed to evaluate the relation of regulatory gene variation in the Runx2 promoter with class II malocclusion. Methods: DNA samples were acquired from 95 orthodontic patients in Jakarta, Indonesia, who were divided into two groups: class I skeletal malocclusion (control group) and class II malocclusion. A single nucleotide polymorphism was investigated using the polymerase chain reaction and restriction fragment length polymorphism techniques. The distribution of alleles was assessed using the Hardy-Weinberg test. The relationship between polymorphism and skeletal variation was assessed with the Chi-Square test and logistic regression. Results: The frequency distributions of genotypes and alleles were tested for Hardy-Weinberg equilibrium and found to be slightly deviated. There was an equal distribution of G and T alleles throughout class II and class I skeletal malocclusions and the Chi-Square test showed that this relationship was not significant (p=0.5). Conclusion: Runx2 rs59983488 polymorphism was found in the Indonesian subpopulation; however, an association between Runx2 rs59983488 polymorphism and class II skeletal malocclusion was not found.

Comparison of AdvanSync2® and Twin Block Appliances in Treatment of Class II Malocclusion With Retrognathic Mandible—An Observational Retrospective Study

Objectives: To evaluate the treatment outcomes between Twin Block and AdvanSync2® appliances by comparing the skeletal, dentoalveolar, and soft tissue changes. Materials and Methods: Radiographic data of 20 patients were retrospectively analyzed. Data were selected from patients in their skeletal growth spurt as evaluated by the cervical vertebral maturation method (CVMI 2, 3, and 4), with class II malocclusion characterized with retrognathic mandible (ANB > 4°, SNB < 77°, FMA = 25 ± 5°, overjet > 5 mm). There were 10 patients in each group that underwent orthodontic correction for class II malocclusion: either using Twin Block or AdvanSync2®. Independent t test and Paired t test and chi-square tests were used for the data analysis. The level of statistical significance was set at P value ≤.05. Results: The chronological and skeletal age were similar in both the groups. Records were taken for the functional treatment with mean treatment span of 8 ± 1 month. Changes in SNB (group I = 1.59°, group II = 3.11°) ( P < .01), Co-Gn (group I = 2.89 mm, group II = 5.34 mm), and U1-L1° (group I = −1.51°, group II = 2.97°) showed statistically different outcome between the groups, when the pre-post data were studied. Rest of the variables—cranial base, maxillary skeletal, mandibular skeletal, intermaxillary, vertical skeletal, maxillary dentoalveolar, mandibular dentoalveolar, and soft tissue—showed similar outcome ( P > .05). Conclusion: Both appliances lead to desirable outcomes in the correction of class II malocclusion. AdvanSync2® resulted in inducing more of changes in SNB and effective mandibular length as compared to Twin Block. Overjet and molar relation improved significantly with both the appliances. Both the appliances resulted in similar skeletal, dentoalveolar, and soft tissue changes.