Skeletal,Dental, and Nasal Airway Changes After Treatment with Quad-helix Appliance as Evaluated by CBCT

Abstract

Introduction: Transverse maxillary deficiency has been associated with a variety of malocclusions, occlusion instability, and breathing problems. Managing this condition at an early stage is recommended to ensure normal dental and skeletal relationships and to improve oral health and aesthetics. Slow maxillary expansion using Wilson quad-helix is one treatment modality for transverse maxillary deficiency. The purpose of this study was to evaluate skeletal, dental, and nasal airway changes after treatment with the Wilson quad-helix appliance through CBCT.Method: Pre- and post-treatment CBCT images for a group of patients who received maxillary expansion treatment with a Wilson quad-helix appliance were retrospectively collected. The Wilson group consisted of 12 patients (nine males and three females). The pre-treatment age range was 10 to 13 years with a mean age of 11.4 ± 1.2 years. The period between pre-treatment (T1) and post-treatment (T2) CBCTs ranged from 1 to 2 years with a mean of 1.6 ± 0.4 years. The comparison group included 12 patients (eight males and four females) with an age range at the study’s onset of 10 to 13 years (age mean of 11.7 ± 0.7 years). The period between T1 and T2 CBCTs ranged from 1 to 2 years with a mean of 1.6 ± 0.3 years. The patients in the comparison group did not have maxillary expansion treatment. They had Class II elastics and fixed orthodontic appliances (braces). AVIZO software was used to locate specific anatomical skeletal and dental landmarks to measure skeletal and dental distances. Mimics software was used to segment the nasal airway and to reconstruct 3D models. Nasal volume, surface area, and part analysis (point-based analysis) were used to analyze 3D nasal models. ICC was used to test intra-examiner reliability. One-way ANOVA was applied to the linear skeletal and dental distances to identify differences between groups. Independent t-tests were conducted to compare the mean difference of nasal volume, surface area, and part analysis between the Wilson group and the comparison group.Results: There was statistically significant difference in the maxillary inter-molar width change from T1 to T2 between the Wilson group and the comparison group. The distance between upper first molars significantly (difference between groups) increased (mean 3.6 mm) at the pulp chamber and at the root apex (mean 3.5 mm). The distance between upper first premolars significantly increased (mean 3 mm) at the pulp chambers. There was no statistically significant difference in the nasal volume, surface area, and part analysis between the Wilson group and the comparison group.Conclusion: Maxillary inter-molar and inter-premolar widths increased as a result of the Wilson quad-helix treatment. Buccal translation movement of upper first molars was observed after Wilson quad-helix treatment. Dental changes were greater than skeletal changes. There was no statistically significant difference in nasal airway volume or surface area between the Wilson group and the control groupIntroduction: Transverse maxillary deficiency has been associated with a variety of malocclusions, occlusion instability, and breathing problems. Managing this condition at an early stage is recommended to ensure normal dental and skeletal relationships and to improve oral health and aesthetics. Slow maxillary expansion using Wilson quad-helix is one treatment modality for transverse maxillary deficiency. The purpose of this study was to evaluate skeletal, dental, and nasal airway changes after treatment with the Wilson quad-helix appliance through CBCT.Method: Pre- and post-treatment CBCT images for a group of patients who received maxillary expansion treatment with a Wilson quad-helix appliance were retrospectively collected. The Wilson group consisted of 12 patients (nine males and three females). The pre-treatment age range was 10 to 13 years with a mean age of 11.4 ± 1.2 years. The period between pre-treatment (T1) and post-treatment (T2) CBCTs ranged from 1 to 2 years with a mean of 1.6 ± 0.4 years. The comparison group included 12 patients (eight males and four females) with an age range at the study’s onset of 10 to 13 years (age mean of 11.7 ± 0.7 years). The period between T1 and T2 CBCTs ranged from 1 to 2 years with a mean of 1.6 ± 0.3 years. The patients in the comparison group did not have maxillary expansion treatment. They had Class II elastics and fixed orthodontic appliances (braces). AVIZO software was used to locate specific anatomical skeletal and dental landmarks to measure skeletal and dental distances. Mimics software was used to segment the nasal airway and to reconstruct 3D models. Nasal volume, surface area, and part analysis (point-based analysis) were used to analyze 3D nasal models. ICC was used to test intra-examiner reliability. One-way ANOVA was applied to the linear skeletal and dental distances to identify differences between groups. Independent t-tests were conducted to compare the mean difference of nasal volume, surface area, and part analysis between the Wilson group and the comparison group.Results: There was statistically significant difference in the maxillary inter-molar width change from T1 to T2 between the Wilson group and the comparison group. The distance between upper first molars significantly (difference between groups) increased (mean 3.6 mm) at the pulp chamber and at the root apex (mean 3.5 mm). The distance between upper first premolars significantly increased (mean 3 mm) at the pulp chambers. There was no statistically significant difference in the nasal volume, surface area, and part analysis between the Wilson group and the comparison group.Conclusion: Maxillary inter-molar and inter-premolar widths increased as a result of the Wilson quad-helix treatment. Buccal translation movement of upper first molars was observed after Wilson quad-helix treatment. Dental changes were greater than skeletal changes. There was no statistically significant difference in nasal airway volume or surface area between the Wilson group and the control group.