Problem: Despite previous studies, the exact architec-ture of the human lateral pterygoid (LP) muscle and itsrole in disc displacement seen in temporomandibularjoint disorders still remains controversial. Unlike archi-tectural studies that included 2-dimensional data, a studywas conducted to provide a detailed account of theanatomy and architecture of the lateral pterygoid musclethroughout its entire volume using directly acquiredindividual fibre bundle data and transfer it to a 3-dimen-sional computer model.

Materials and Methods: Following a unique approachfor optimal access and visualization, 19 adult cadavericspecimens were dissected and the lateral pterygoid mus-cle identified. For the entire LP muscle volume, all indi-vidual fibre bundles were serially dissected and thensubsequently digitized using a MicroScribe 3-DX digi-tizer. DANCE software, developed in our laboratory,allowed 3-D visualization and quantification of the digi-tized muscle architecture and attachment sites.

Results: Two separate heads of the LP muscle wereseen in 58% of the specimens, whereas 42% demon-strated 2 heads laterally that eventually blended into onemedially. Muscle insertion into the temporomandibularjoint (TMJ) disc-capsule complex comprised a mean of23% of all digitized muscle fibres of the entire LP. Of themuscles with 2 distinct bellies, insertions into the disc-capsule complex and condyle accounted for an averageof 61% and 39% of the superior head fibre bundles,respectively. Mean TMJ disc dimensions were 18.4 mmanteroposteriorly and 23.4 mm mediolingually. Disc thick-ness in the anterior, intermediate, and posterior regionsmeasured an average of 2.5, 1.8, and 3.3 mm, respectively.An abnormal disc-condyle relationship was seen in 21% ofthe specimens without a statistically different muscle inser-tion pattern. In contrast to reported literature, the origin ofthe superior head of the LP in all specimens was limited tothe superomedial margin of the inferior orbital fissure (in-fratemporal aspect).

Conclusions: The origin of the superior head of thelateral pterygoid muscle is different from that reported inprevious literature. The muscle shows significant varia-tion in architecture both in terms of arrangement andinsertion. The degree of muscle insertion into the disc-capsule complex was not a predictor of anteromedialdisc displacement, however, larger samples of displaceddiscs should be analyzed in the future. Such detailedmuscle architectural studies may more precisely predictinteraction between muscle parts, the effect of musclefunction on the TMJ, and pathologic states.

References

Bertilsson O, Strom D: A literature survey of a hundred years ofanatomic and functional lateral pterygoid muscle research. J OrofacPain 9:17, 1995

Ng-Thow-Hing V, Agur A, McKee N: A muscle model that capturesexternal shape, internal fibre architecture, and permits simulation ofactive contraction with volume preservation. Proceedings of the Fifth

International Symposium of Computer Models in Biomechanics andBiomedical Engineering, 2001

POSTER 7Upregulation of Inhibitor of Apoptosis-2Gene Expression in Human Head andNeck CancerJeffrey Burke, BS, Harvard School of Dental Medicine,188 Longwood Avenue, Boston, MA 02115 (Kim Y;Donoff B; Todd R)

Aims: Dysregulation of factors regulating apoptosisin human cancers are emerging as promising diagnosticand therapeutic targets. The inhibitor of apoptosis-2(cIAP-2) protein is upregulated in many human malig-nancies but has not been previously described in thecontext of oropharyngeal cancers. Based on preliminarydata derived from global gene expression analysis ofhuman head and neck cancers, we hypothesize thatcIAP-2 is upregulated in malignant oral epithelium.

Methods: Using high throughput-gene expressionanalysis of laser capture microdissected tissues, c-IAP-2(GenBank accession number U37546) was identified asbeing greater than 3-fold upregulated in malignant versusnormal oral epithelium. Differential gene expression wasconfirmed using RT-PCR on total RNA isolated from 2normal (OKB2, OKF4) and 5 malignant (SCC13, SCC15,SCC25, SCC66, SCC105) oral keratinocyte cell lines. Pro-tein expression was confined using western blot analysison the same cell lines. Differential cIAP-2 gene expres-sion and protein production were further validated by insitu hybridization and immunohistochemistry using low-density tissue arrays of malignant (n � 60) and normal(n � 10) head and neck tissues. Tissue array data wereanalyzed using a Kruskal-Wallis test.

Results: Upregulation of the cIAP-2 gene in malignantoral epithelium was validated in 5/5 malignant oral ker-atinocyte cell lines using RT-PCR and western analysis. Inhead and neck cancer tissues, both c-IAP-2 gene expres-sion and protein production was significantly elevated inthe malignant epithelium (P �.001). Both c-IAP-2 mRNAand protein were localized primarily in the epithelium.

Conclusion: Global gene expression analysis has beenpreviously described as a means of sets of transcriptswith clinical phenotypes. However, whether these can-cer-associated transcripts have biologic significance withrespect to malignant progression are seldom pursued.Our findings support c-IAP-2, an important regulator ofapoptosis, that is upregulated in malignant head andneck epithelium in vitro and in vivo. Future studies willpursue the functional consequences of c-IAP-2 dysregu-lation and the feasibility of c-IAP-2 as a diagnostic andtherapeutic target.

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References

Todd R, Wong DTW: DNA hybridization arrays for gene expressionanalysis of human oral cancer. J Dent Res 81:89, 2002

Deveraux Q, Reed J: IAP family proteins–suppressors of apoptosis.Genes Dev 13:239, 1999

Funding Source: OMS Department. Supported by NIH grants R29DE11983 (R.T.), P01 DE12647(R.T.), K02 00456 (R.T.), and R01DE11430 (R.T.) as well as a Research Support Grant from the Oral andMaxillofacial Surgery Foundation (H.O./R.T.) and a Milton Grant fromHarvard University (R.T.).

POSTER 8Potential Complications During AlveolarDistraction OsteogenesisRenato Mazzonetto, DDS, PhD, Rua Padre JoseConceicao Meireles, #60, Piracicaba, Sao Paulo13418.405 Brazil (Torezan JF)

Statement of the Problem: Alveolar atrophy has been amajor problem in achieving successful rehabilitationwith dental implants. Distraction osteogenesis has beenclinically applied to augment the alveolar ridge verticallysince 1996.

Purpose: The aim of this study is to evaluate theclinical results of alveolar distraction technique and itspotential problems during the treatment.

Patients and Methods: The subjects comprised 50 pa-tients who underwent vertical bone augmentation usingan alveolar distraction device in anterior maxilla andatrophic mandible. The follow-up schedule for all pa-tients consisted of regular appointments at 1, 7, 14, 30,60, and 90 days after surgery. At 90 days, the device wasremoved and implants were placed. Clinical evaluationinvolved notation of any abnormal problem. The prob-lems were classified in 2 groups: Minor complicationsthat do not compromise the success overall (swelling,minor infection, dehiscence or exposure of device, tip-ping of transport segment, temporary lost of sensibility)and major complications with failure of technique (de-vice fracture, scar tissue formation, fracture or resorp-tion of transport disk, and permanent loss of sensibility).For radiographic evaluation, orthopantomograms weretaken at 7, 30, 60, and 90 days. The radiographs wereanalyzed for any visual changes in osteotomy fragments,resorptive changes in osteotomy fragments, and union ofthe osteotomy segments.

Results: Among minor complications we found 4 casesof exposure of device (8%), 4 cases of abnormal swellingin mandible (8%), 1 case of temporary loss of sensibility(2%), and 12 cases of tipping of the transport disk (24%),treated by local anesthesia and positioning the segmentmanually back to its ideal location. Major complicationswere found in 4 cases (8%), when we observed fractureor resorption of transport disk.

Conclusions: Alveolar distraction osteogenesis is a pre-

dictable technique with a success rate close to 92%.Vertical bone defects can be treated using osteodistrac-tion. Minor complications can occur without failure ofthe procedure and a close follow-up and opportuneintervention is necessary in those cases.

References

Chin M, Toth BA: Distraction osteogenesis in maxillofacial surgeryusing internal devices. J Oral Maxillofac Surg 54:45, 1996

Millesi-Schobel GA, et al: The L-shaped osteotomy for vertical callusdistraction in the molar region of the mandible: A technical note. JCraniomaxillofac Surg 28:176, 2000

Funding Source: Unicamp–Brazilian Government Grant.

POSTER 9Aquaporin Expression in Dental Follicleand Odontogenic KeratocystsRoger W. Moreira, DDS, PhD, 3501 Terrace Street,Suite G-32, Pittsburgh, PA 15261 (Costello BJ;Ochs MW; Hart P; Michalec M; Hart TC)

The aquaporins (AQP) are a family of membrane chan-nel proteins that function as selective pores throughwhich water crosses the plasma membranes of manytissues and cell types. Eleven members of this trans-porter family, designated AQP0 to AQP10, have beencloned in humans. To understand the etiology of OKCdevelopment, we studied AQP expression in dental fol-licles (DF) and odontogenic keratocysts (OKCs). Muta-tions of the PTCH gene that encode a transmembraneprotein have been identified in syndromic and isolatedcases of OKC, but the impetus for development of cysticlesions is not understood. Raised osmolalities may beimportant in cystic development. We evaluated AQPexpression by RT-PCR. RNA was isolated from 8 DF andfrom 3 OKCs using Purescript reagent and cDNA wassynthesized with the Advantage RT-for-PCR Kit. Oligonu-cleotide primers were designed to amplify specific AQPsand distinguish genomic and cDNA products. RT-PCRamplification products were purified and sequence ver-ified using Big Dye Terminator (ABI) chemistry. All ex-periments were performed in duplicate. Control tissueswere used to demonstrate that absence of RT-PCR prod-ucts in the OKC and DF samples were not simply due toamplification failure. Results of RT-PCR and sequenceverification demonstrate that AQPs are differentially ex-pressed in DF and OKCs. AQPs 1, 9, and 10 are ex-pressed in DF, while AQPs 1, 3, 9, and 10 are expressedin OKCs. Our evaluation of expression patterns of theaquaporin gene family was driven by the hypothesis thatcystic development involves cellular control of ion con-centrations in the epithelial lining and that this regula-tion is, in part, controlled by regulated water transport.The generality of AQP expression in skin from different

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