Treatment Effects Of The Edgewise Mandibular Anterior Repositioning Appliance Mara In Patients With Class Ii Malocclusions PDF Download

AbstractIntroduction: Class II malocclusions represent one of the most prevalent forms of malocclusion encountered in routine orthodontic practice. In order to correct a Class II malocclusion, miscellaneous orthopedic functional appliances with a broad spectrum of diverse appliance designs have been continuously developed. While the Twin Block is known as one of the best researched functional appliances, only few studies have evaluated the treatment efficacy of the Mandibular Anterior Repositioning Appliance (MARA) since its development in 1991. Thus, the purpose of this retrospective study was to evaluate and compare the skeletal and dentoalveolar effects of the Twin-block and the Mandibular Anterior Repositioning Appliance (MARA) in the treatment of adolescent patients with Class II malocclusions compared to controls. Materials and Methods: The present retrospective study was carried out on three samples: a Twin Block sample, a MARA sample, and a control sample.^The study was based on the evaluation of the lateral cephalometric radiographs of a total of 96 cases at T1 (pre-functional treatment), as well as at T2 (post-functional treatment/ equivalent timeframe in controls). The Twin Block sample with 37 cases represented the largest sample, consisting of 24 females and 13 males. It was treated by the inventor Dr. Clark in his private practice in Fife, Scotland, UK. The average age for the Twin Block group at T1 is 11 years of age. The MARA group consisted of a total of 34 cases: 16 females and 18 males. The average age of the MARA sample at T1 was consistent with the Twin Block sample (11 years of age). The MARA sample was respectively treated by its inventor Dr. Toll, Bad Soden, Germany. The control group was based on 25 cases (12 female and 13 male) obtained from the Michigan growth study. The untreated control group was matched to the MARA sample.^Lateral cephalometric radiographs were taken at the beginning of treatment (T1) and post-functional treatment (T2). Cephalometric changes were evaluated using the Clark analysis including 27 measurements. The MARA, and the control sample were evaluated by an independent commercial company, Rocky Mountain Data Systems, using Joe Ceph by Rocky Mountain Orthodontics. The Twin-Block sample was analyzed by Dr. Clark using Quick CephTM. Results: The results showed that sagittal correction of Class II appeared to be mainly achieved by dental changes, being accompanied by skeletal adaptation. A positive influence of the position of point Pogonion could be achieved in both groups resulting in a considerable decrease of the facial convexity. Skeletal alterations that contributed to skeletal adapations mainly took place in the mandibular ramus, while these changes were significant different form the controls.^No significant alteration of the mandibular plane angle could be determined in all three groups. The current study showed a lower incisors flaring of 5. 47 degree with the MARA appliance and 2. 11 degree with the Twin Block. The effects on the upper incisors varied between the two functional appliances. Slight protrusion of the upper incisors took place with the MARA (+5. 06 degree) and a significant retroclination occurred with the Twin Block ( -12. 42 degree). Accordingly, the interincisal angle decreased in the Twin Block sample and increased on the other hand with the MARA. No significant change of the incisor position of the controls was present. Incisor overjet decreased of about 7. 03 mm in the Twin Block group and 2. 46 mm in the MARA sample. Incisor overbite decreased about 1. 34 mm with the Twin Block and 2. 92 mm with the MARA. Molar relation was corrected in both functional groups resulting in a Class I relation, while no change appeared in the control sample.^While a slight distalizing effect on the upper first molars could be seen in the Twin Block sample ( -0. 06 mm), no such effect could be determined for the MARA appliance (+0. 96 mm). Conclusion: Both appliances resulted in a Class I relationship. Skeletal changes were very similar in both appliances. Overall the Twin Block seemed to be slightly superior to the MARA appliance. Key words: Fixed functional appliance; Twin Block; MARA; Class II malocclusion; Clark analysis.