The dental, skeletal and soft tissue changes induced by Sabbagh Universal Spring (SUS²) appliance used in Class II mandibular retrusion patients

The purpose of this study is to evaluate the dental, skeletal and soft tissue changes induced by the SUS² appliance.The study sample consisted of 27 subjects (15 treated and 12 control) with skeletal and dental Class II malocclusion. Our study was carried out on 54 lateral cephalometric radiographs which were taken before placement and after removal of the SUS² appliance in the treatment group and at the beginning and six months after in the control group. The patient selection criteria were as follows: skeletal and dental Class II malocclusion due to retrognatic mandible, normal or low-angle growth pattern, post-peak growth period and no extracted or congenitally missing permanent teeth.In order to evaluate the changes that took place in the treatment and control groups, 24 cephalometric points and 36 cephalometric measurements were analyzed. Non-parametric ?Wilcoxon and Mann-Whitney U tests? were used for statistics. In order to detect any method errors, 20 cephalometric radiographs were digitized again by the same researcher after 20 days and correlation coefficients of all parameters were controlled.The statistical assesment of the data suggested the following conclusions: Changes in the sagittal growth potential of the maxilla were statistically insignificant and maxilla was not affected by the device. Sagittal growth potential of the mandibula proved to be statistically insignificant. The changes that took place in the mandibula were dentoalveolar. There were no statistically significant changes in the vertical parameters. The slight retrusion and extrusion of the maxillary incisors as well as the distinct protrusion and intrusion of mandibular incisors were found to be statistically significant. The occlusal plane was rotated in the clockwise direction as a result of these dentoalveolar changes. Overbite and overjet were reduced significantly in all patients. Soft tissue profile improved limitedly.As a result, correction of Class II malocclusion by the SUS² appliance in post peak growth period was achieved by only dentoalveolar changes. Thus, this appliance can be an acceptable substitute to Class II elastics for patients who appear to be noncompliant. Also, since no vertical changes were observed, the appliance can be used in high angle patients without gummy smile. It would be useful to investigate the effects of the SUS² appliance on the temporomandibular joint in future clinical studies.