Pre-orthodontic Orthognathic Surgery (POGS) Using TADs: Evidences and Applications
Conventional protocol for orthodontic treatment followed by orthognathic surgery for skeletal discrepancies is not readily justified, since both procedures cause significant reduction of the overall masticatory function. In order to facilitate the procedu
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Kee-Joon Lee
Abstract
Conventional protocol for orthodontic treatment followed by orthognathic surgery for skeletal discrepancies is not readily justified, since both procedures cause significant reduction of the overall masticatory function. In order to facilitate the procedure, a pre-orthodontic orthognathic surgery (POGS) has been suggested and practiced. One of the essential factors may be the predictability of postsurgical tooth movement. The miniscrew-type TADs enable not only individual tooth movement but also the movement of segment and total arch. Underlying biomechanical advantages of segmental movement also supports the new protocol. In case of narrow maxillary arch, a miniscrew-assisted rapid palatal expander can be effective for the preliminary transverse correction prior to surgery, which also contributes to the establishment of stable occlusion in short period of time. Therefore, the TADs are regarded indispensible for the POGS procedure.
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Rationale of Presurgical Orthodontics
Conventional wisdom of surgico-orthodontic approach provides one with well-established protocol for the dentofacial deformities that cannot be camouflaged. The presurgical orthodontic treatment followed by orthognathic surgery and postsurgical orthodontic treatment has been the gold standard in conducting
K.-J. Lee, DDS, PhD Department of Orthodontics, Yonsei University, Yonsei-ro 50, Seodaemon-gu, Seoul 120-752, South Korea e-mail: [email protected]
combined orthodontic-orthognathic surgery [1]. In order to restructure the dentition as well as the maxillomandibular basal bone, the teeth have to be decompensated prior to surgical jaw movement. Although it is inarguable that the dental decompensation is an essential procedure for the success of orthognathic surgery, it is not clear whether the decompensation has to be carried out before surgery. The presurgical orthodontic movement has been shown to cause transient depression of the masticatory function in such as the maximum bite force and the lateral excursion, mainly due to the abrupt change in the occlusal relationship [2]. Moreover, the orthognathic surgery induces a reversible atrophy of the major
K.B. Kim (ed.), Temporary Skeletal Anchorage Devices, DOI 10.1007/978-3-642-55052-2_11, © Springer-Verlag Berlin Heidelberg 2014
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masticatory muscles such as masseters for about a year, regardless of the surgery type [3, 4]. Therefore, in terms of rehabilitation and restoration of the orofacial muscle function, the presurgical orthodontic treatment followed by an orthognathic surgery may not be justified. As for the tooth movement, the presurgical orthodontic treatment nearly always requires tooth movement against the existing occlusal interdigitation and/or muscular surroundings. For example, in a typical Class III patient, retraction of upper incisor against the tongue muscle and flaring of the lower incisor against lip muscles can be challenging, since artificial reduction of muscle force or tension can hardly be performed [5]. Considering t
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