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TREATMENT EFFECTS OF R-APPLIANCE IN VERTICAL GROWING PATIENTS-CASE SERIES division I malocclusion. An electronic search in literature will reveal copious researches about functional appliances and their effects on mandible (14, 16, 18, 19). During treatment with functional appliances, it has been claimed that forward growth of the maxilla may be inhibited (5, 22, 23). Some studies have reported that the mandibular incisors procline or advance significantly during functional appliance treatment (24, 25, 29, 30, 31). In the R-appliance group the mandible was positioned anteriorly for construction bite. The lingual shield of R-appliance was fabricated with less undercut relief. The undercut relief should be reduced to the extent that it does not irritate the patient (32); however, it should be reduced enough to cause mild trauma. To avoid this trauma all patients were recurrently instructed to posture the mandible forward. This posturing became habitual as patients naturally adopted a comfortable position. In addition, the discomfort caused by reduced relief changed patient’s compliance into an unconscious one in the long run. Since the patient moves the mandible forward the protractor muscles are activated and retractor muscles are deactivated. The activation of protractor muscles would keep mandible forward while the retractor muscles wouldn’t have any significant role to pull it back. This active protrusion has a favorable effect on the growth and remodeling of the mandible (33). In addition, this activation prevents headgear effect on maxillary complex and flaring of the lower incisors. Lack of reflex of retractor muscles on the mandible would cause a slight uprighting of the lower incisors. In this study, the increase of Jarabak index is indicative of the efficacy of R-appliance in treatment of vertical growth pattern patients suffering from Class II malocclusion division 1. This was achieved by increasing the thickness of the connection between lingual and buccal shields which would act as a posterior bit plate. Conclusion: The following conclusions can be drawn on the basis of this study’s findings: 1- R-appliance resulted in forward positioning of the mandible in Class II division I patients with vertical growth pattern. 2- R-appliance did not cause any proclination of lower incisor; moreover, it even reduced their flaring. Bibliography 1. Tausche E, Luck O, Harzer W. Prevalence of malocclusions in the early mixed dentition and orthodontic treatment need. Eur J Orthod. 2004;26(3):237-244. 2. Perillo L, Masucci C, Ferro F, Apicella D, Baccetti T. Prevalence of orthodontic treatment need in southern Italian schoolchildren. Eur J Orthod. 2010;32(1):49-53. 3. McNamara JA, Jr. Components of class II malocclusion in children 8-10 years of age. Angle Orthod. 1981;51(3):177-202. 4. Perillo L, Padricelli G, Isola G, Femiano F, Chiodini P, Matarese G. Class II malocclusion division 1: a new classification method by cephalometric analysis. Eur J Paediatr Dent. 2012;13(3):192-196. 5. Ghafari J, Shofer FS, Jacobsson-Hunt U, Markowitz DL, Laster LL. Headgear versus function regulator in the early treatment of Class II, division 1 malocclusion: a randomized clinical trial. Amer J Orthod Dentofacial Orthop. 1998;113(1):51-61. 6. Tulloch JF, Proffit WR, Phillips C. Influences on the outcome of early treatment for Class II malocclusion. Am J Orthod Dentofacial Orthop. 1997;111(5):533-542. 7. Ehmer U, Tulloch CJ, Proffit WR, Phillips C. An international comparison of early treatment of angle Class-II/1 cases. Skeletal effects of the first phase of a prospective clinical trial. J Orofac Orthop. 1999;60(6):392-408. STOMA.EDUJ (2014) 1 (2) 8. Wheeler TT, McGorray SP, Dolce C, Taylor MG, King GJ. Effectiveness of early treatment of Class II malocclusion. Am J Orthod Dentofacial Orthop. 2002;121(1):9-17. 9. O’Brien K, Wright J, Conboy F, Sanjie Y, Mandall N, Chadwick S, Connolly I, Cook P, Birnie D, Hammond M, Harradine N, Lewis D, McDade C, Mitchell L, Murray A, O’Neill J, Read M, Robinson S, Roberts-Harry D, Sandler J, Shaw I. Effectiveness of treatment for Class II malocclusion with the Herbst or twin-block appliances: a randomized, controlled trial. Am J Orthod Dentofacial Orthop. 2003;124(2):128-137. 10. Jamilian A, Showkatbakhsh R, Kamali Z. R-appliance: a different design in functional \