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This article has been peer reviewed.

Maximum Cl II Therapy with Minimum Appliances By Larry White

ntroduction The correction of sagittal orthodontic malocclusions, i.e., Class II and Class III disorders presents orthodontic clinicians the most difficult conditions with which they must contend. When a Class I malocclusion appears with maxillary and mandibular arch length discrepancies, space can be achieved by a number of methods, e.g., expansion, extraction or interproximal enamel reduction, and little thought or effort is expended correcting the posterior occlusion. Arch length discrepancies may also occur with a sagittal malocclusion, which only complicates an already difficult task, but the primary intention in treating Class II or Class III malocclusions resides in correcting the posterior occlusion. For many years the main therapy applied to both Class II and Class III malocclusions was with some type of cranialsupported force to the maxilla or mandible (Figure 1). It was not until Case1 and Baker developed the idea of using intermaxillary elastics late in the 19th century that clinicians had effective and easily applied forces for addressing sagittal discrepancies. When intermaxillary elastic pressure is used, teeth move, but the problem for modern orthodontic clinicians is the simple fact that fewer and fewer patients seem amenable to using them in a consistent manner. The reluctance of patients to use elastics has resulted in the development of several socalled noncompliant appliances, which are fixed and not easily removed from the mouth.

Figure 1: Cranial strap to limit mandibular growth. IJO

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Nevertheless, the common feature of Class II correction that prevents more consistent and predictable correction of these malocclusions is a failure to correct the posterior occlusion first. This is what Carriere2 has called establishing the Class I platform. Once clinicians achieve Class I molars, the remaining treatment turns into a routine matter. The main factor that prevents early correction of the Class II posterior occlusion is the banding and bonding of too many teeth at the first of treatment. Such early application of brackets, bands and arch wires causes clinicians to embark on a regime of aligning and leveling, which in many cases causes the mandible to move downwards and backwards, complicating the Class II correction. The Partial Maxillary Appliance Mulligan3 has treated Class II malocclusions for many years with a simple technique of bonding a 2 x 4 arrangement, i.e., two maxillary molars and four maxillary incisors (Figure 2). By applying slightly long round stainless steel maxillary arch wires with 45째 bends against the molars, he is able to retract the molars into a Class I arrangement in a short period of time without flaring the incisors or employing Class II elastics, headgear or noncompliant Class II correctors, e.g., Herbst, Mara, MPA, Forsus, etc. The partial appliance allows clinicians to develop a desired force system that maximizes the moments and forces that will correct Class II molars, crossbites and overbites simultaneously.

Figure 2: A typodont illustration of the 2 x 4 partial appliance with a long, round arch wire and circle tiebacks against the molars. 33

International Journal of Orthodontics  
International Journal of Orthodontics