Re: Periodontal Evaluation in Patients Undergoing Maxillary Expansion. (2001)

Re: Periodontal Evaluation in Patients Undergoing Max-illary Expansion. Carmen M, Marcella P, Giuseppe C, Roberto A. J Craniofac Surg 2000;11:491-494. The basis of contemporary craniofacial distraction principles and devices is based on their historic use in orthodontics, most notably in maxillary (palatal) expansion. The effects of distracted bone movement on the overlying/attached soft tissue has not been examined for most craniofacial applications with the exception of gingival recession with various palatal expansion techniques. From this perspective, the authors have prospectively examined the incidence of gingival recession between the techniques of surgically assisted versus nonsurgical orthodontic expansion of the midpalatine suture of the maxilla. This study's results have shown that less gingival recession occurs when palatal expansion is assisted by a midpalatal osteotomy. Similar results have been previously reported by numerous authors and it is generally accepted that osteotomy cuts expedite distraction of the midpalatal suture, particularly when significant width increases are required. I have no criticisms of the protocol of this study or the results as I am certain that the data is valid and reproducible. It would have been helpful to have had some more detail about the gingival recession, particularly its location (buccal or palatal) and the amount. Palatal expansion typically results in gingival recession on the buccal surfaces of the premolar and molar teeth. From a craniofacial perspective, however, what does this study imply for the larger bone movements of the midface and mandible that we typically do? No such similar findings of soft tissue retraction or recession have been reported from even large anterior movements of the maxilla and mandible. This is undoubtably due to the considerable distance of the osteotomy/distraction sites from the firm attachment of the soft tissues at the dentoalveolar level and the lack of any significant resistance at the osteotomy site from complete bony cuts and moderate mobilization of the distal segment. So there is probably no real correlation, from a soft tissue standpoint, between transverse and anterior maxillary movements. It may better correlate with alveolar distraction, although the majority of these cases involve edentulous bone segments. Interestingly, why does gingival recession occur with palatal expansion? Isn't one of the effects of distraction expansion of soft tissue as well as bone? While this is true, it does not account for the unique features of gingival tissue. This specialized tissue is firmly attached to alveolar crestal bone with a dense collagenous make-up. It has minimal stretch when detached from bone and is not easily “expanded.” As palatal expansion occurs perpendicular to the plane of gingival attachment and usually causes some lateral dentoalveolar tipping, no real gingival expansion occurs. As a result, some recession may occur around the posterior teeth where the greatest expansion forces are occurring. While no direct soft tissue correlation exists between palatal expansion and horizontal LeFort and mandibular distraction, this study does remind us that such effects may exist if they are closely examined.