Abstract
Background: Functional appliances such as Bionator have been used to treat Class II malocclusion. The purpose of this study was to compare the skeletal, dental and soft tissue effects of Bionator appliances with Multi-P (a newly developed appliance) in the treatment of Class II malocclusion.
 Subjects and methods: 45 class II children were chosen and randomly assigned to either the Bionator or Multi-P treatment group. After excluding 13 patients from the study, 21 patients in Bionator and 11 patients in Multi-P group have participated in the study. Lateral cephalograms were analyzed at the beginning (To) and at the end of treatment (T1) to evaluate the changes in both groups. The paired t.test and Leven’s test were enrolled for statistical analysis.
 Results: Reduction of ANB angle was detected in both treatment groups. The Bionator group underwent insignificant greater mandibular advancement as measured by the SNB angle. (p= 0.737) The mandibular plane angle increased insignificantly in both groups. (p> 0.05) The inclination of upper incisors decreased significantly in Multi-P group. (p= 0.042)
 Conclusion: Both appliances are effective therapeutic means for class II treatment associated with mandibular deficiency and may lead to normalization of the dentoskeletal parameters at the end of the treatment.
Highlights
Class II malocclusions can be displayed in various skeletal and dental patterns
The duration of treatment with Multi-P was significantly longer than that of Bionator. (P= 0.02) The Bionator group and the Multi-P group were almost similar at the start of treatment, with the exception of overjet and upper incisor inclination values which were greater in the Multi-P group. (P< 0.05)
Skeletal changes: Reduction in the anteroposterior apical base discrepancy via an angular assessment of ANB angle was observed in both treatment groups (Bionator = 0.857o and Multi-P = 1.727o)
Summary
Class II malocclusions can be displayed in various skeletal and dental patterns. Most Class II patients have a discrepancy in the anteroposterior position of both jaws which can be caused either by maxillary prognathism, mandibular retrognathism or both conditions.[1]. No skeletal modification has been found for the maxilla, a notable increase in the total mandibular length has been depicted consistently in patients treated with Bionator.[12] The skeletal changes associated with functional appliances have significant effects on the soft tissues, predominantly on vertical dimensions of the face and position of the lips.[4,13] While the effect of Bionator on soft tissue profile is still questionable 14,15 general cephalometric signs demonstrate the effectiveness of Bionator functional treatment on skeletal Class II disharmony These include increase in ramus height, increase in total mandibular length, opening of the gonial angle, posterior rotation of the condylar line in relation to the mandidbular line and backward displacement of the condylar head in relation to the reference system.[10,12,16] According to Rodrigues De Almeida et al study, treatment with Bionator and Frankel (FR-2) appliances showed statistically significant increases in mandibular growth and mandibular protrusion. The Bionator group underwent insignificant greater mandibular advancement as measured by the SNB angle. (P= 0.73) The mandibular plane angle increased insignificantly in both groups. (P> 0.05) The inclination of upper incisors decreased significantly in Multi-P group. (P= 0.04) Conclusion: Both appliances are effective therapeutic means for Class II treatment associated with mandibular deficiency and may lead to normalization of the dentoskeletal parameters at the end of the treatment. [GMJ. 2013;2(1):1-11]
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