Evaluation of the effect of different attachment configurations on molar teeth in maxillary expansion with clear aligners - a finite element analysis.

OBJECTIVE: To evaluate the effects of different attachment configurations with and without buccal root torque on expansion movements achieved with aligners through finite element analysis (FEA). METHODS: FEA modelling was done with 0.25 mm buccal expansion force application to the maxillary molars with different attachment configurations: Eight models were tested (1) no attachment (NA), (2) horizontal attachment (HA), (3) gingivally beveled horizontal attachment (GHA), and (4) occlusally beveled horizontal attachment (OHA), as well as models with 6obuccal root torque, (5) no attachment (TNA), (6) horizontal attachment (THA), (7) gingivally beveled horizontal attachment (TGHA), and (8) occlusally beveled horizontal attachment (TOHA). RESULTS: The first and second molars exhibited buccal tipping in all models. The highest amount of buccal tipping for the molars was observed in the NA (6CMB, 0.232 mm; 6CMP, 0.246 mm; 7CMB, 0.281 mm; 7CMP, 0.312 mm) and GHA (6CMB, 0.230; 6CMP, 0.245; 7CMB, 0.279 mm; 7CMP, 0.311 mm) models, respectively, while the least tipping was observed in the TOHA model (6CMB, 0.155 mm; 6CMP, 0.168 mm; 7CMB, 0.216 mm; 7CMP, 0.240 mm). In all groups, the buccal tipping of the second molars was higher than that of the first molars. CONCLUSION: This FEA study showed that expansion with aligners tip maxillary molars buccally and the use of occlusally beveled attachments and addition of buccal root torque reduces uncontrolled buccal tipping.

Evaluating anchorage loss in upper incisors during distalization of maxillary posterior teeth using clear aligners in adult patients: A prospective randomized study.

Objective: : To evaluate the effect of clear aligner treatment and differential sequence distalization of maxillary posterior teeth on anchorage loss in the upper incisors (U1s). Methods: : This study used lateral cephalometries and digital models of 12 patients treated with 33% sequential distalization (group 1, mean age: 22.9 ± 0.7 years, five males, seven females) and 12 treated with 50% sequential distalization (group 2, mean age: 25.83 ± 0.5 years, three males, nine females) acquired before and after distalization of upper second premolars (U5) and upper first molars (U6) and upper second molars (U7). The amount of distalization was determined as 2.5 mm in both the groups. Independent Samples t test was used to compare normally distributed parameters. Mann-Whitney U and Wilcoxon tests were used to compare parameters that were not normally distributed. Results: : In both groups, the posterior teeth significantly moved by tipping distally and the U1s were displaced anteriorly. Increase in maxillary posterior transverse width (P < 0.001) and distopalatal rotation were observed in U5, U6, and U7 after distalization. It was also observed that U1 was significantly more proclined (1.82°; P < 0.001) and protruded (0.62 mm; P < 0.001), and the overjet (0.45 mm; P < 0.001) increased more in group 1 than in group 2. Conclusions: : After sequential distalization of maxillary posterior teeth, more anchorage loss was observed in the anterior region in group 1 than in group 2.

Effect of body mass index on soft tissues in adolescents with skeletal class I and normal facial height.

Background: The evaluation of soft tissues in patients undergoing orthodontic treatment plays a critical role in diagnosis and treatment planning. This study aims to evaluate the effect of body mass index (BMI) on facial soft tissues in skeletal Class I patients with normal vertical growth. Methods: The study included 72 patients with a normal vertical growth pattern (SN-GoGn 26-38°) and skeletal Class I (ANB 2‒4°) malocclusion. According to their BMI (kg/m2) values, the patients were divided into three groups of 24 individuals each: underweight (>5th percentile) (13 females, 11 males; mean age, 11.58 ± 1.95 years), normal weight (5‒85th percentile) (12 females, 12 males; mean age, 11.54 ± 1.95 years), overweight (85‒95th percentile) (12 females, 12 males; mean age, 11.62 ± 2.01 years). Soft tissue thickness and height measurements were made on lateral cephalometric radiographs. Results: In all soft tissue thickness measurements, except for the nasion, the overweight weight group had higher values. In comparing the underweight and normal weight groups, statistically significant differences were found in the thickness measurements at the nasion and gnathion (p < 0.05). The differences in thickness measurements at the glabella, labiale superius, stomion, labiale inferius, pogonion, gnathion, and menton are statistically significant between the underweight and overweight groups (p < 0.005). Comparing the normal and overweight groups revealed statistically significant differences the thickness measurements at the glabella, labiale superius, stomion, pogonion and menton (p < 0.05).

Relationship between vertical facial morphology and dental arch measurements in class II malocclusion: a retrospective study.

Background: To evaluate the relationship between dental arch measurements and the vertical facial pattern determined in skeletal Class II untreated patients. Methods: Lateral cephalograms and plaster models were obtained from 124 untreated female adults (average age: 17.6 ± 3.8 years). Class I (CI), Class II Division 1 (CII/1) and Class II Division 2 (CII/2) malocclusions were divided into three subgroups according to their vertical morphology as hypodivergent, normodivergent and hyperdivergent. The multivariate variance analysis (MANOVA) method was used in the comparison of measurement values according to vertical and sagittal morphology. The relationship between both A point-Nasion-B point (ANB) and Frankfurt-mandibular plane (FMA) angles and dental arch measurements was examined by Pearson correlation analysis. The significance level was received as p < 0.05. Results: While vertical morphology has a statistically significant effect on mandibular arch length, sagittal morphology affects maxillary arch depth. The parameters influenced by both morphologies are maxillary and mandibular arch length, as well as maxillary intermolar width. The mandibular arch length was significantly shorter in hyperdivergent-CII-2 malocclusion (50.5 ± 7.4 mm). Larger values were obtained in both mandibular arch length and maxillary arch depth measurements in CII-1 malocclusion compared to CII-2 malocclusion. The maxillary intermolar width was significantly shorter in hypodivergent-CII-1 malocclusion (46.8 ± 3.4 mm), while it was higher in hypodivergent-CI malocclusion (51.1 ± 3.4 mm). The maxillary arch length was the lowest in hyperdivergent-CI malocclusion (63.1 ± 13.3 mm) and the highest in hypodivergent-CI malocclusion (72.8 ± 7.6 mm). Additionally, a positive but weak correlation was found between ANB and FMA angles. Conclusion: Dental arch measurements have been found to be affected by both vertical facial morphology and skeletal sagittal relationship. A positive correlation was found between ANB and FMA angles.

Evaluation of patient satisfaction with pharyngeal airway changes after orthognathic surgery in patients with Class III skeletal anomalies.

Purpose: The aims of our study were to determine the changes in the pharyngeal airway after treating patients with Class III malocclusion who received double jaw surgery, to determine the hard tissue and soft tissue parameters and the hyoid bone and tongue positions after surgery, to determine the changes to compare the pretreatment and post-treatment measurements of the patients in the double jaw group with the measurements of the control group patients, and to evaluate postoperative patient satisfaction. Materials and methods: The study included thirty-two Class III adult patients that received double jaw surgery and twenty-five Class I patients. Cephalometric records were taken before treatment (T1) and after treatment (T2). Results: After double jaw orthognathic surgery, there were statistically significant changes in all pharyngeal airway linear and areal parameters (p<0.001). There were significant superior and posterior movements of the tongue and hyoid bone post-surgery. The post-treatment analysis of the double jaw surgery group and control group were compared, with statistically significant differences in the mandibular dental parameters and pharyngeal airway measurements in patients in the double jaw surgery group. Conclusion: Despite the narrowings detected, high satisfaction scores were observed in the patient satisfaction questionnaire and the patients did not experience respiratory problems.

Patient perceptions and attitudes regarding post-orthodontic treatment changes.

OBJECTIVES: To determine patient perceptions and attitudes regarding posttreatment changes at least 2 years after completion of orthodontic treatment. MATERIALS AND METHODS: A total of 125 patients (75 females, 50 males, aged 22.93 ± 2.98 years) were enrolled at least 2 years after debonding. Participants had either vacuum-formed retainers (VFRs) or bonded retainers (BRs). Posttreatment changes were evaluated digitally by comparing tooth positions at debonding and at least 2 years after debonding. A questionnaire was used to assess patient attitudes. Retainer usage, awareness of relapse, satisfaction with their current occlusion, and whether posttreatment changes were severe enough for them to consider retreatment were investigated. RESULTS: All patients showed some posttreatment changes in irregularity. Only 74% of patients wearing VFRs and 47.1% of patients wearing BRs were aware of posttreatment changes. Patients were more likely to notice posttreatment changes if there was an increase in mandibular irregularity of 1-3 mm. Awareness of posttreatment changes in the upper arch was higher in both groups. The majority of participants were satisfied with the results even if they noticed some minor posttreatment changes (VFR, 69.4%; BR, 76.5%). Dissatisfaction with posttreatment changes did not necessarily mean that a patient wanted retreatment. CONCLUSIONS: A total of 26% of patients wearing VFRs and 52.9% of patients wearing BRs were unaware of posttreatment changes. Approximately half of the patients who noticed posttreatment changes were still satisfied with the result 2 years after debonding. Even patients dissatisfied with the effect of posttreatment changes do not necessarily want retreatment.