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

Aims: This study was aimed to investigate the Second Class Resolver (S.C.R.) (Dental World, Molfetta, Italy) in the class II correction. Material and Methods: The SCR© (Second 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 SCR© takes up one of the fundamental concepts of functional jaw orthopedics. The SCR© design reduces orthopedic protrusion, thanks to the proprioceptive stimulus, due to the inclined planes. The result is that the SCR© provides a gentle continuous Class II force effective in correcting malocclusion. The rationale is similar to the functional treatment philosophies advocated by Sanders and Clark. The main components of the SCR© appliance are the guide lower plane (named Blockrun©), and the inclined upper bar (named Skibar©), which are buccally positioned on both sides. The Skibar© of the SCR© is a cylindric piece, mounted at an angle approximately 70° to the horizontal. It produces active guidance of the mandible to a more anterior position when the jaw is closed and the Skibar© is clasped by the Blockrun©. The Blockrun© is a three-cornered prism, which includes two inclined planes and a threaded pin to allow the sliding to stop along the sagittal bar or the orthodontic archwire. In fact, the Blockrun© slides along the sagittal wire to activate the appliance. In this study, the authors compared cranio-facial changes produced in 40 Caucasian female children treated with the SCR using cephalometric tracings and comparing the tracings to 40 untreated Class II controls from the University of Chieti. Each patient in the study group was treated for exactly two years by the same operator using the SCR 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 SNB angle was significantly higher in the study group as compared to the control group at the end of treatment, probably due to a significant mandibular repositioning in the treated group from pre- to posttreatment. There was a significant reduction of the ANB angle and 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. Moreover, the cephalometric results showed that 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 SCR appliance in class II correction.