A Radiographic Comparison of the Root Length and Area After Class II Treatment with Two Different Functional Appliances.

Objective: The purpose of this study was to compare the changes in root lengths and root surface areas that occur after treatment with two functional appliances the Twin Block (TWB) and Crown Herbst appliances. Methods: Forty patients (12 boys, 28 girls) were included in this study. Half of them were treated with the stainless steel Crown Herbst appliance (with crowns placed on the first molars and the first and second premolars), and the other half were treated with the TWB appliance. Panoramic and cephalometric films were obtained before treatment (T1) and after the functional treatment (T2). All upper and lower teeth except second and third molars were analysed with the ImageJ software (version 1.37, National Institutes of Health, Bethesda) on panoramic films. Root length and area values were compared using t-tests. Results: The intragroup comparison showed that root length values were significantly decreased in right and left mandibular incisors and canines in the Crown Herbst group (12 years 7 months ± 9 months). However, significantly increased root length was observed in right and left maxillary second premolars and right maxillary first premolar in the TWB group (11 years 1 month ± 4 months). The intergroup comparison indicated that root length values were significantly decreased in right maxillary premolars, right and left mandibular laterals and left mandibular canine in the Crown Herbst group when compared with those in the TWB group. Conclusion: It was concluded that the Crown Herbst group showed a greater tendency for decreased root length than the TWB group. In orthopaedic correction of Class II malocclusions, in the absence of any contraindications, TWB appliance may be preferred for the promotion of root development. [ABSTRACT FROM AUTHOR]