Poster 12: Venous Anastomoses Coupler With Implantable Doppler in Head and Neck Microvascular Reconstruction: A Preliminary Cohort

Anesthesia metastasize. In OSCC, upregulation of integrin ␣v␤6 expression is recognized as a hallmark for metastases and poor prognosis. Integrins are a large family of ␣␤ heterodimeric transmembrane receptors that link the cellular cytoskeleton to the extracellular matrix (ECM). Integrin expression dysregulation has been implicated in tumor formation and metastasis since successful invasion requires continuous remodeling of the ECM by integrins. Previous work from our lab suggests there might be an inverse relationship between ␣␤1 and ␣v␤6 expression in epithelial tumors; however, correlation between expression levels of these integrins and malignant phenotypes remains to be elucidated. Three OSCC cell lines, SCC9, SCC9␤6 and SCC9␤6␤1, were used to study the effects of increased expression of ␣v␤6 in oral cancer. SCC9␤6 cells were generated by co-culturing SCC9 cells with retroviral producer cell lines that expressed fulllength ␤6. The SCC9␤6 cells were then infected with ␤1-myc lentiviruses to generate the SCC9␤6␤1 cell line. Flow cytometry and Western blot analysis were used to evaluate levels of ␤6. SCC9␤6 and SCC9␤6␤1 cells were FACS sorted to obtain cell populations with high ␤6 and high ␤6/␤1 expression, respectively. The effect of differential integrin expression on growth of OSCC cells was evaluated using cell proliferation assays and scratch wound assays were used to access migratory abilities of the cells. Furthermore, the various cell lines were grown on coverslips coated with fibronectin (FN) and immunofluoresence was used to assess the ability of these cells to organize an FN matrix in vitro. Proliferation assays were also utilized to evaluate whether 0.01 mM zoledronate influenced the growth of SCC9␤6 cells. Finally, FACS analysis was used to assess surface expression of ␣v␤6 in SCC9␤6 cells and SCC9␤6 cells grown in 0.01 mM zoledronate. Flow cytometry and Western blot analysis indicated there was a 10-fold increase in the expression of ␤6 in SCC9␤6 compared to SCC9 cells. Cell proliferation assays demonstrated that SCC9␤6 cells were more proliferative than the SCC9 cells, which showed more growth than the SCC9␤6␤1 cells. Scratch wound assays indicated that SCC9␤6 cells were the most migratory, followed by SCC9␤6␤1 and finally by SCC9 cells. The SCC9 and SCC9␤6␤1 cells were able to organize the FN into a fibrillar pattern in association with peripheral focal adhesion whereas the SCC9␤6 cells were not able to do so. Proliferation of SCC9␤6 cells in the presence of zoledronate was greatly decreased compared to SCC9␤6 cells grown in isolation and these cells showed a decrease in surface expression of ␣v␤6 by approximately 40%. This data suggest upregulation of integrin ␤6 increases the proliferative and migratory capacities of SCC9 cells while decreasing the matrix organizing ability of these cells. Furthermore, increased expression of ␤1 in SCC9␤6 cells appears to reverse these malignant phenotypes. Therefore, the tipping of the balance of these integrins, upregulation of ␣v␤6 and downregulation of AAOMS • 2011

␣␤1, may contribute to cell invasion and migration in OSCC. The ability of zoledronate to inhibit proliferation of SCC9␤6 cells is of great interest since OSCC cells with increased ␣v␤6 expression are associated with a poor prognosis and there is currently no tumor cell specific therapy for the treatment of OSCC. Downregulation of ␣v␤6 in SCC9␤6 cells grown in the presence of zoledronate suggests a possible mechanism by which zoledronate inhibits cell proliferation. References: Bagutti C, et al: Comparison of integrin, cadherin, and catenin expression in squamous cell carcinomas of the oral cavity. J Pathol,1998.186(1): p.8-16. Thomas GJ, et al: AlphaVbeta6 integrin promotes invasion of squamous carcinoma cells through up-regulation of MMP-9. Int J Cancer,2001.92(5):p.641-50.

POSTER 12 Venous Anastomoses Coupler With Implantable Doppler in Head and Neck Microvascular Reconstruction: A Preliminary Cohort S. P. Best: Nova Southeastern Universtiy/Broward General Medical Center, R. Movahed, J. Kaltman, S. McClure Statement of the Problem: Microvascular free tissue transfer has grown over the past few decades and in most institutions has become the standard in head and neck reconstruction. Success rates have been reported between 91-99%. Post-operative monitoring is essential for the success of free tissue transfer. Monitoring techniques using pen Dopplers, buoy flaps, pin pricks, micro dialysis and spectrophotometry to have been employed to monitor free flaps. The most common cause of flap failure is venous thrombosis. Veins are thin walled, contain low pressure flow, and are easily disrupted by twisting or bending vessels within the neck. Traditional monitoring techniques become difficult with buried flaps. Overlying tissues impede direct inspection of the flap and pen Doppler has decreased specificity as nearby vessels can provide a false positive. Successful salvage is time dependent. Rapid detection of venous flow cessation decreases time between venous thrombotic event and salvage surgery. Materials and Methods: Synovis (Birmingham, AL) obtained FDA 510(k) approval for the GEMTM Flow Coupler in February 2010. This device is a combination of their microvascular coupler and a 20-mHz ultrasonic Doppler for providing constant monitoring of venous flow. In this abstract we discuss our experience with the GEMTM Flow Coupler® for observation of buried flaps. The Synovis® GEMTM Flow Coupler® was used for venous anastomosis in two cases. Patient 1 underwent an osteoe-59

Anesthesia myofascial free fibula flap (FFF) to reconstruct an ablative defect in the mandible. Patient 2 had a radial forearm free flap (RFFF) utilized for reconstruction of a pharyngectomy defect. A total of 3 couplers were used and continuous monitoring was performed intraoperatively and postoperatively. Probes were removed at bedside without complication on postoperative day 8. Results of Investigation: No postoperative flap complications were experienced. Patient 2 had a Doppler implanted at each of 2 venous anastomoses. Intraoperatively one of the flow couplers identified loss of flow in an end-to-end anastomosed vein. Upon examination, the vein was found to be twisted. Doppler signal resumed after venous re-anastomosis. During closure one of the two signals ceased. Direct pen Doppler was used to confirm venous flow. A new probe was exchanged into the existing coupler; however, flow signal was not recaptured. Conclusion: The use of an implantable Doppler allows for real time evaluation and immediate intervention of buried flaps. Recognition of venous thrombosis may be delayed with traditional monitoring techniques possibly leading to a decreased salvage rate. References: Chen KT, Mardini S, Chuang DC, et al. Timing of Presentation of the First Signs of Vascular Compromise Dictates the Salvage Outcome of Free Flap Transfers. Plast Reconstr Surg 2007;120:187-195. Brown JS, Devine JC, Magennis P, et al. Factors that influence the outcome of salvage in free tissue transfers. Brit J Oral Max Surg 2003;41:16-20.

POSTER 13 Treatment and Reconstruction of Ameloblastoma in an Urban Hospital Setting D. Hirsch: New York University, P. Franco, J. Levine Statement of the Problem: Ameloblastomas account for 1% of all oral tumors and 10% of all tumors from odontogenic origin. For large or recurrent tumors, resection of the involved bone is the treatment of choice. For small defects, local resection, curettage, cryotherapy and bone grafting may be performed. When resection is indicated, reconstruction of the defect often involves replacement of bone and, in some instances, soft tissue. Because of the cosmetic and functional importance of this area, the reconstructive demands are considerable. In this paper we discuss our recent experience with the treatment and reconstruction of ameloblastoma. Materials and Methods: A retrospective review was performed of case records at Bellevue Hospital Center during a 6-year period from February 2005 to February 2011. Once identified, specific information regarding this group of patients was obtained. In addition to pae-60

tient demographics, the charts were reviewed for type of resection, tumor pathology, tumor size, location of tumor, type and timing of reconstruction, and dental prosthetic rehabilitation. Methods of Data Analysis: This was a retrospective chart review from February 2005 to February 2011. Records with surgical intervention for ameloblastoma, patient demographics, and case variables were analyzed. Results of Investigation: Of the 30 patients diagnosed with ameloblastoma at our institution, 18 were men and 12 were women. The average age at the time of surgical intervention was 32 years of life. African American patients made up the slight majority of the patients in our study at 17 of 30 cases, 7 patients were Latin American, 4 patients were Asian, and 2 were Middle Eastern. Twenty-seven of the 30 tumors were located in the mandible (19 in the posterior mandible and 8 in the anterior mandible); the other 3 tumors were located in the maxilla. The size of ameloblastomas ranged from just under 3 cm to approximately 15 cm. Just over 50% of the cases were the solid also known as multicystic or conventional (16 of 30) subtype; 11 cases were unicystic also known as cystic. There was 1 case of a peripheral ameloblastoma also known as extraosseous ameloblastoma, and 2 cases of ameloblastic carcinoma. Also of note there was 1 recurrence in 2011 from a solid ameloblastoma surgically treated in 1999. Segmental resection and reconstruction with microvascularized free fibular flap (MVFFF) was performed in 50% of the 30 cases, and immediate placement of endosseous dental implants in neomandible/neomaxilla was performed in the most recent 7 cases utilitzing free tissue transfer. One case was treated with mandibulectomy, MVFFF, placement of 6 endosseous dental implants and an immediate loaded dental prosthesis. Other methods of excision included: enucleation with peripheral ostectomy and cryotherapy, marginal resection. Other methods of reconstruction included: radial forearm free flap (RFFF), bone morphogenic protein-2, tibia bone grafts, and anterior and posterior iliac crest bone grafts. To date the longest follow-up has been 6 years and there have been no recurrences during that time. Conclusion: Ameloblastoma is a benign, locally invasive and highly recurrent epithelial odontogenic tumor with a variable clinical course, ranging from nonaggressive to locally destructive with distant metastasis. The type of surgical excision and reconstruction of ameloblastoma should be based on the histopathological type, size and location of the tumor. At our institution, resection and reconstruction with a microvascularized free flap with immediate placement of endosseous dental implants has become the standard for ameloblastomas larger than 6 cm. References: Olaitan A, et al, Recurrent Ameloblastoma of the Jaws: A Follow Up Study, Internal Journal of Oral Maxillofacial Surgery. 27;456, 1998

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