Comparison of stepwise vs single-step advancement with the Functional Mandibular Advancer in Class II division 1 treatment

• Published in: The Angle orthodontist Vol. 87; no. 1; pp. 82 - 87
• Main Authors: Aras, Isil, Pasaoglu, Aylin, Olmez, Sultan, Unal, Idil, Tuncer, Ali Vehbi, Aras, Aynur
• Format: Journal Article
• Language: English
• Published: United States Edward H. Angle Society of Orthodontists 01-01-2017
• Subjects: Adolescent; Cephalometry; Child; Dental Occlusion; Dentistry; Female; Humans; Male; Malocclusion, Angle Class II - therapy; Mandible - diagnostic imaging; Mandible - growth & development; Mandibular Advancement - instrumentation; Mandibular Advancement - methods; Maxillofacial Development; Original; Orthodontic Appliances, Functional; Overbite - therapy; Functional orthodontic appliance; Angle Class II
• ISSN: 0003-3219; 1945-7103
• DOI: 10.2319/032416-241.1

To compare two groups of subjects at the peak of the pubertal growth period treated with the Functional Mandibular Advancer (FMA; Forestadent, Pforzheim, Germany) appliance using either single-step or stepwise mandibular advancement.
This study was conducted on 34 Class II division 1 malocclusion subjects at or just before the peak phase of pubertal growth as assessed by hand-wrist radiographs. Subjects were assigned to two groups of mandibular advancement, using matched randomization. Both groups were treated with the FMA. While the mandible was advanced to a super Class I molar relation in the single-step advancement group (SSG), patients in the stepwise mandibular advancement group (SWG) had a 4-mm initial bite advancement and subsequent 2-mm advancements at bimonthly intervals. The material consisted of lateral cephalograms taken before treatment and after 10 months of FMA treatment. Data were analyzed by means paired t-tests and an independent t-test.
There were statistically significant changes in SNB, Pg horizontal, ANB, Co-Gn, and Co-Go measurements in both groups (P < .001); these changes were greater in the SWG with the exception of Co-Go (P < .05). While significant differences were found in U1-SN, IMPA, L6 horizontal, overjet, and overbite appraisals in each group (P < .001), these changes were comparable (P > .05).
Because of the higher rates of sagittal mandibular skeletal changes, FMA using stepwise advancement of the mandible might be the appliance of choice for treating Class II division 1 malocclusions.