Cephalometric evaluation of cranio-facial changes after orthopaedic therapy with the TCR appliance for class III correction: A Longitudinal Study

Aims: This study was aimed to investigate the Third Class Resolver (T.C.R.) (Dental World, Molfetta, Italy) in the class III correction. Material and Methods: The TCR© (Thirs Class Resolver, Dental World, Molfetta, BA, Italy, www.dental-world.it) is a new fixed orthopedic appliance. Through the mechanical principle of the inclined planes, the TCR© takes up one of the fundamental concepts of functional jaw orthopedics. The TCR© design reduces mandibular protrusion, thanks to the proprioceptive stimulus, due to the inclined planes. The result is that the TCR© provides a gentle continuous Class III force effective in correcting malocclusion. In this study, the authors compared cranio-facial changes produced in 20 Caucasian female children treated with the TCR using cephalometric tracings and comparing the tracings to 20 untreated Class III controls from the University of Chieti. Each patient in the study group was treated for exactly two years by the same operator using the TCR appliance and a standardized design and clinical technique, including fixed pre-adjusted orthodontics where indicated. The average starting age was 8.4 yrs. (SD±2.1). At the end of the therapy, the average age was 10.3 yrs. (SD±2.4). Two teleradiographs were made of each patient: the first one at the beginning of treatment and the second one after twelve months. The radiographs were taken with the subjects standing in the ortho-position with ear rods in the cephalostat. In order to detect errors due to landmark identification, duplicate measurements were made using ten radiographs, and the error variance was calculated using Dahlberg’s formula. Cranio-facial cephalometric variables were studied. Results: The SNA angle was significantly higher in the study group as compared to the control group (p<0.05) at the end of treatment, probably due to a significant maxilla repositioning in the treated group (p<0.001 and p<0.01) from pre- to posttreatment. There was a significant increase of the ANB angle and the Witts index from pre to post-treatment. Change was observed, also in the vertical angle. Infact the total vertical dimension was reduced for effect of the diminution of the maxilla-mandible angle. Also the total mandibular angle was reduced after the use of the SCR device. Other variables in the multiple regression were not significant. Conclusion: The findings suggested the efficacy of the TCR appliance in class III correction.