CHAPTER 23 - An effective and precise method for rapid molar derotation: Keles TPA

Abstract

Distal molar relationships can arise due to the mesiopalatal rotation of maxillary molars. In some cases, an ideal Class I intercuspation can be achieved with the opposing molar and a Class II relationship can be corrected by molar derotation. Maxillary molars consist of three roots and, due to the early loss of the deciduous second molars, the palatal root acts as a hinge for mesial rotation of molars. Lemons and Holmes1 reported that a gain of 1 to 2 mm of arch length per side may be achieved following derotations. The transpalatal arch (TPA) for molar derotation was introduced to the orthodontic literature by Goshgarian2 in 1972. Cetlin and Ten Hoeve3 showed that the TPA is an effective device to stabilize, rotate, and distalize the molars. According to Ricketts,4 a line drawn from the distobuccal and mesiopalatal cusp tips of the first molars should pass through the cusp tip of the canines on the opposite side. Investigators have assessed the shape of maxillary first molars and examined the arch length gain with derotation.5–7 According to Braun et al,8 2.1 mm of arch length can be gained with the application of a TPA and a distal force equivalent at the level of the maxillary first molar center of resistance. The TPA can be removable or fixed, depending on the clinician’s preference. The aim of this study was to develop an easy method to rapidly and precisely rotate the maxillary molars.