The effect of treatment with the Bass appliance on skeletal Class II malocclusions: a cephalometric investigation

Abstract

The purpose of this investigation was to study the short-term effects of treatment with the Bass appliance by comparative evaluation of treated and untreated skeletal Class II malocclusions. The subjects consisted of forty-seven Class II, division 1 malocclusion cases. Twenty-seven (14 girls, 13 boys) were treated with the Bass appliance for an average of 6 months. The remaining 20 cases (6 girls, 14 boys) served as a control. At the end of the 6 month treatment period the statistically significant treatment changes could be summarized as follows: the sagittal skeletal relationship was improved as a result of favourable growth responses in both the maxilla and the mandible. The overjet was reduced and the molar relationship was corrected as a result of the extended skeletal changes. Distal movement of the upper dentition was evident, with unchanged inclination of the maxillary incisors. Both anterior and posterior facial heights were increased without changes in the inclinations of the palatal and mandibular planes. No significant dental movement was observed in the mandible.

The effects of torque control spurs in twin‐block appliances

“…The upper incisors still retroclined an average of 7°. This value was smaller and less variable than the average of 11°reported by Lund and Sandler (2) who used a labial bow, but more than the insignificant tipping (average 1.5°) found with the Bass appliance (in the first 6 months of treatment) by Cura and Sarac (8) or the average of 4.1°over 9 months found by Illing et al (9) The more efficient inclination control with Bass-type incisor springs is probably due to their greater contact with the gingival undercut area. Bass-type springs on each central incisor were used to good effect by the current authors on a number of cases, but discontinued because of the large median diastemas associated with concurrent use of the upper arch expansion screw.…”

Facial profile and dental changes before, during and after treatment with Hansaplate/Headgear

“…Our study shows a 5-mm reduction of overjet on average, which is in accordance with the results reported for the effect of different functional appliances [4,7,8,12,18,20,35]. …”

“…Unsere Studie zeigt eine Verringerung der sagittalen Frontzahnstufe um durchschnittlich 5 mm, was mit den beschriebenen Ergebnissen ~iber die Effekte verschiedener funktionskiefer-orthop~idischer Ger~ite t~bereinstimmt [4,7,8,12,18,20,35].…”

“…Die Inklination der oberen Schneidez~ihne zeigte unter der Behandlung eine nur kleine Retroinklination, vermutlich infolge der Anwendung yon Torquefedern nach Bass [1,4,26,29].…”

“…The upper incisor inclination underwent only minor retroclination during treatment, probably due to the use of torque springs according to Bass [1,4,26,29].…”