Treatment effects of the Bimler functional appliance on Class II division 2 malocclusion
Bolton, Robert P.
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Correction of Class II malocclusion has led clinicians to look at many factors when considering appliance design and its effect on the maxilla, mandible and respective dentoalveolar complex. When considering the armamentarium of orthopedic functional appliances most studies are in agreement concerning their effects on the facial structures while a few are in contradiction. Only few clinicians have utilized functional appliances to successfully correct Class II division 2 malocclusion. The aim of this investigation was thus to provide information on the treatment effects of the Bimler Type B functional appliance on correcting Class II division 2 malocclusions and, specifically, if the resultant treatment effects are different than the effects observed using functional appliances to correct Class II division 1 malocclusions. The sample in this study consisted of twenty-six (26) Class II division 2 patients (9 males, 17 females) treated with the Bimler Type B functional appliance at the practice of Dr. Hans Peter Bimler in Weisbaden, Germany. The records were graciously donated to the orthodontic department at the State University of New York at Buffalo by the daughter of the late Dr. Bimler. For each of the 26 subjects, two lateral cephalograms, one at the time of appliance delivery (T1) and a second at least two years after initiation of treatment (T2) were analyzed using a custom analysis with the following linear and angular measurements: A-NaPerp, Co-A, Co-Gn, Ar-Gn, Pg-NaPerp, ANS-Me, Op-Sn, FMA,U1-SN, IMPA, Wits, OJ, L1-APo. It was determined following statistical analysis and comparison to an untreated control group that the Bimler Type B functional appliance, used specifically for correction of Class II division 2 malocclusions, proclines maxillary incisors (U1-SN) (p>0.05), an effect not seen when using functional appliances for Class II division 1 correction, and potentially inhibits maxillary forward growth (Co-A). However, the results of this study indicate that the appliance does not significantly increase mandibular length (Co-Gn) relative to normal growth, or procline mandibular incisors; the antithesis of the effects seen when treating Class II division 1 malocclusions with functional appliances. Due to the relatively small sample size of this study the true effects of the Bimler functional appliance cannot be fully appreciated. Only with an investigation utilizing a larger sample size, a Class II control population, and a means to measure change in maxillary and mandibular molar sagittal position can one evaluate the true effects of the Bimler Type B appliance in correcting Class II division 2 malocclusions and how these effects differ from those observed when correcting Class II division 1 malocclusions using functional appliances.