Objective: To evaluate the pharyngeal airway volume following treatment of skeletal Class II mandibular retrusion with miniplate-anchored Herbst appliance by Cone Beam Computed Tomography (CBCT).
Materials and Methods: Fourteen female Class II post-pubertal patients with mandibular retrusion were randomly selected with mean age was 16.7 1.56 years. As a first orthodontic phase, they were treated by type IV Herbst functional appliance that anchored by two reconstructive plates located bilaterally in the mandible between the canine and first premolar teeth, while attached to the maxilla through dental splints utilizing orthodontic bands. The CBCTscans were obtained before treatment (T1) and immediately after removal of Herbst appliance (T2) for volumetric pharyngeal airway evaluation. In addition, sagittal cephalometric parameters were analyzed.
Results:Paired sample t-testshowed a non-statistically significant (p>0.05) increase (585 mm3) in nasopharyngeal airway volume with treatment, whereas velopharyngeal airway, glossopharyngeal airway and total airway volume showed statistically significant (p < 0.01) increases after Herbst appliance treatment by 2448mm3, 1107mm3, 2607mm3, respectively. Moreover, an improvement in mandibular retrognathism was evident as demonstrated by significant increase in SNB angle and significant decrease in ANB angle (p < 0.05).
Conclusions: Pharyngeal airway volume considerably enhanced subsequent to mandibular advancement through miniplate- anchored Herbst appliance which could be a helpful treatment opportunity for post-pubertal patients who have skeletal Class II malocclusion with mandibular retusion and suffering breathing disorders.