Centrex: uma proposta de sistema de forças ortodônticas para atuação no centro de resistência

Abstract

OBJETIVO: este trabalho propõe um novo sistema de forças ortodônticas que visa eliminar ou diminuir alguns efeitos secundários da mecânica ortodôntica, como as inclinações, extrusões e perdas de ancoragem. Por meio de uma revisão crítica da literatura sobre a biomecânica, e de ilustrações detalhadas dos mecanismos, procura-se apresentar didaticamente o seu conceito e sua proposta de funcionamento. CONCLUSÕES: embora já existam outras tentativas de diminuir efeitos indesejados da mecânica ortodôntica, como o Power-arm de Andrews e a mecânica com arcos segmentados, ainda assim, sua utilização tem se mostrado muito distante de uma unanimidade na prática clínica ortodôntica. O Centrex talvez se mostre como uma forma de melhorar a mecânica ortodôntica pela diminuição de alguns efeitos indesejados.

Optimization of orthodontic treatment using the Centrex System to retract anterior teeth

“…The incorporation of root lingual torque is often required to avoid excessive retroclination extrusion of the crowns of anterior teeth. 19 Additionally, a compensatory bend can be incorporated to the wire to compensate the extrusive effect of anterior teeth, 20 however, this adds friction to the process, which may result in a delay during movement of such teeth.…”

“…24 The lack of adequate torque control during UAR tends to produce an out of control inclination movement of anterior teeth, buccally protruding the apical third of these teeth in an area of low osseous availability (Fig 1). 19 This becomes even more relevant in cases of adult patients with horizontal bone loss, since the applied force in the crown is transferred to the apices with greater magnitude, since the center of resistance of teeth, in such situations, are more apically located.…”

“…7,17,19 Eventually if loss of inclination control occurs during retraction, in addition to the possibility of root resorption there is a tendency of excessive uprighting of the anterior teeth. Such a fact is perceived mainly, in cases of great retractions.…”

“…In a previous article 19 a proposal of orthodontic movement was presented with appliances capable of moving apically the force action line to the desired position, according to previous planning. In this paper clinical applications of these concepts discussed before will be presented.…”

“…In individuals presenting bone loss in the anterior region, torque control is even more critical, since the center of resistance of the teeth is further away from the crown, where the force is applied. 19 In these cases, torque magnitude should be increased to interpose the force generated by the retraction. In some situations, it is appropriate to modify the force line of action to make it closer to or even coincide, in height, to the center of resistance of teeth to be moved.…”