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Oral Abstract Session 2 on Maxillofacial Reconstruction
Oral Abstract Session 2 MAXILLOFACIAL RECONSTRUCTION Thursday, September 13, 2001, 8:00 am - 10:00 am
The Use of Pericranial Flap for Frontal Sinus Obliteration in the Treatment of Frontal Sinus Fractures Daniel P. Brunner, DDS, MD, LAC/USC Medical Center, 1175 N Cummings St, OPD 1P51, Los Angeles, CA 90033 (Bach T. Le, DDS, MD; Eric J. Dierks, DMD, MD; Dennis-Duke R. Yamashita, DDS) Purpose: Frontal sinus obliteration has been well described for the treatment of selected fractures. Suitable materials used for sinus obliteration have included autogenous fat, bone, fascia, and calcium phosphate cements. We report on the use of a laterally based pericranial flap for frontal sinus obliteration. Patients and Methods: Eight patients underwent frontal sinus obliteration using laterally based pericranial flaps for the treatment of frontal sinus fractures. The patients’ postoperative course was followed clinically and by radiographic exams to ascertain any signs or symptoms of adverse effects. Results: Eight patients were included in the study. The follow-up range was between 1 and 3 years, with the average follow-up time of 13 months. No adverse effects were detected in any patients in whom the procedure was performed. Conclusion: Preliminary data on the use of the laterally based pericranial flap suggest that it is a suitable alternative for frontal sinus obliteration when indicated in the treatment of frontal sinus fractures. It provides for a vascularized graft without separate donor site morbidity. References Ducic Y, Stone T: Frontal sinus obliteration using a laterally based pedicled pericranial flap. Laryngoscope 109:541, 1999 Thaller SR, Donald P: The use of pericranial flaps in frontal sinus fractures. Ann Plast Surg 32:284, 1994
An Extended Mandibular Coronoid Graft for the Correction of Complex Nasal Deformities Erik J. Nuveen, DMD, MD, PO Box 276, Buckingham, PA 18912 (Robert J. Relle, DDS; Rhonda Lubka, MD) Introduction: Comprehensive management of complex nasal deformities requires meticulous attention to both functional and cosmetic deficiencies. Numerous articles have previously addressed either functional or cosmetic alterations independently. We describe an effective method for the simultaneous correction of func22
tional airway impairment and cosmetic deformity used successfully in 6 patients. This technique incorporates an extended mandibular coronoid bone graft to simultaneously re-establish internal support, nasal projection, and improve cosmesis. Materials and Methods: All 6 patients presented with subjective difficulty with nasal respiration and cosmetic deformity. Three patients reported past histories of traumatic nasal injury, 2 had multiple elective rhinoplasties, and 1 had an unknown etiology. All risks, complications, and alternatives were discussed and the patients elected the option of nasal reconstruction with the mandibular coronoid bone graft. Preoperative and postoperative frontal, lateral, and submental vertex photographs of 1 representative patient will be included. Discussion: Acquired deformity of the nose may result in the loss of multiple structures of nasal support. Subsequent collapse of the internal or external nasal valve often results in a compromise in airway resistance. Numerous surgical options for the correction of nasal vault collapse have been described. Cosmetic deformity may also result from any reduction or loss of the supporting structures. Corrections of cosmetic nasal deformities have focused on either dorsal augmentation grafts or lateral batten grafts. Materials used in these techniques have included autogenous tissue, allografts, and alloplastic materials. Minor defects may be restored with cartilage which provides similar material of variable flexibility and tone. Major defects require larger quantities of more rigid material and can be achieved with autogenous bone. Resorptive advantages of membranous bone grafts have been revealed elsewhere. Membranous graft sources have included the calvarium, lingual mandible, symphysis of the mandible, and coronoid grafts. Advocates for the use of alloplastic materials have cited unpredictable resorption of autogenous bone but are not without their own disadvantages. Surgeons familiar with sagittal mandibular ramus osteotomy techniques will readily master this modification for graft harvest. In this series, this graft consistently provided an adequate source of membranous bone for correction. All patients treated have had significant subjective improvement in airway resistance and cosmesis. Conclusion: The reconstructive goals of nasal surgery in patients with complex deformities are to re-establish nasal support to correct nasal valve restriction and improve cosmetic appearance. Focus of reconstruction of acquired nasal deformity was placed independently on either the correction of regional functional nasal valve AAOMS • 2001
Oral Abstract Session 2: Maxillofacial Reconstruction deformities or cosmetic camouflage. This report describes an alternative regional autogenous grafting technique for definitive correction of deficient internal nasal valve support and simultaneous cosmetic improvement. References Constantian M: The incompetent external nasal valve: Pathophysiology and treatment in primary and secondary rhinoplasty. Plast Reconstr Surg 95:919, 1994 Wheeler E, Kawamoto H, Zarem H: Bone grafts for nasal reconstruction. Plast Reconstr Surg 69:9, 1982
Total Rehabilitation of Children After Resection for Treatment of Primary Jaw Tumors W. Bradford Williams, Massachusetts General Hospital, 55 Fruit St, Warren 1201, Boston, MA 02114 (Maria J. Troulis, DDS, MSc; Leonard B. Kaban, DMD, MD) Purpose: The purpose of this study was to evaluate a series of growing children who were treated for a primary tumor of the maxillofacial region using a staged protocol: 1) en bloc resection and mandibular rigid plate fixation, 2) delayed bone graft, 3) implant placement, and 4) implant loading. Patients and Methods: This is an evaluation of 10 consecutive pediatric patients. The charts were reviewed and the data obtained included age at tumor presentation and resection, type of tumor, adjuvant therapy, type of bone graft, and number of implants placed. Outcomes assessed included postoperative infection, tumor margins, tumor recurrence, plate fractures, number of bone grafts required for implant placement, number of unsuccessful implants, and number of implants successfully restored prosthodontically. Results: There were 10 children (age 3.5 to 16 years) treated for maxillary (n ⫽ 3) or mandibular (n ⫽ 7) tumors. The tumor types included giant cell lesion (n ⫽ 4), osteosarcoma (n ⫽ 2), myofibroma (n ⫽ 1), ossifying or desmoplastic fibroma (n ⫽ 2), and ameloblastoma (n ⫽ 1). Eight of the patients presented for initial treatment and 2 presented with recurrent giant cell lesions (previously enucleated). No patients experienced postoperative infection, wound dehiscence, or significant facial deformity after en bloc resection. In 1 case of osteosarcoma, positive margins required further resection. Both osteosarcoma cases received pre- and postoperative chemotherapy. One patient experienced recurrence of the giant cell lesion after en bloc resection and was treated with interferon. To date (mean ⫽ 59 months), no recurrences have occurred. In one case, the fixation plate fractured and was replaced with an iliac bone graft 21 months postresection. In the second stage of this protocol, an iliac bone graft was placed in 9 patients to re-establish continuity of the jaw. One patient
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spontaneously regenerated the mandible and none of the patients experienced infection of the bone graft or wound dehiscence. Before or during implant placement, 3 patients required additional bone grafts to support the endosseus implants. A total of 18 implants were placed in 6 patients. No patients had infection or pain during the osseointegration period and all 18 implants went to second-stage implant surgery. Only 1 implant failed to osseointegrate and was removed. Five patients who had implants placed had a fixed prosthesis. The prosthetic restorations were loaded for a mean of 19 months (range of 1 to 47 months). Of the remaining 5 patients, 1 is scheduled to have the prosthesis placed, and 4 patients are scheduled to have implants placed. Conclusion: Preliminary results of this ongoing study indicate that maxillofacial tumors in the pediatric population can be successfully treated and the patients can be totally rehabilitated using a delayed reconstruction protocol such as en bloc resection and rigid reconstruction plate, autogenous bone graft, endosseous implants, and fixed prosthodontic restoration. References Chuong R, Kaban LB, Kozakewich H, et al: Central giant cell lesions of the jaws. A clinicopathologic study. J Oral Maxillofac Surg 44:708, 1986 Kaban LB, Mulliken JB, Ezekowitz A, et al: Antiangiogenic therapy of a recurrent giant cell tumor of the mandible. Pediatrics 103:1145, 1999 Funding Source: Department of Oral and Maxillofacial Research Fund.
Clinical Application of a TissueEngineered Ex Vivo–Produced Oral Mucosa Equivalent: A Preliminary Report Kenji Izumi, DDS, PhD, Division of Oral & Maxillofacial Surgery, Niigata University Graduate School for Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata City, Niigata 951-8514 Japan (Akihiko Iida, DDS, PhD; Michiko Yoshizawa, DDS, PhD; Ichiro Suzuki, DDS, PhD; Ritsuo Takagi, DDS, PhD; Stephen E. Feinberg, DDS, MS, PhD) Preprosthetic and reconstructive procedures open wounds in the oral mucosa. A graft should prevent microbial infection, excessive fluid loss, and foreign material contamination or relapse secondary to wound contracture and assist in prosthetic reconstruction and wound healing. Oral mucosa or skin grafts require a second surgical procedure and have disadvantages. Oral mucosa is limited in supply whereas split-thickness skin grafts are available in ample supply, but contain adnexal structures and express a pattern of surface keratinization that interferes with function. The elective nature of oral
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Oral Abstract Session 2: Maxillofacial Reconstruction and maxillofacial surgical procedures allows flexibility and timing to develop a tissue-engineered ex vivo–produced oral mucosa equivalent (EVPOME). Objective: Clinical evaluation of use of EVPOME for intraoral grafting. Materials and Methods: The study included 6 patients, 49 to 74 years old, diagnosed with epithelial dysplasia to squamous cell carcinoma of lateral portion of the tongue. Four weeks before surgery, a 5 ⫻ 5 mm2 punch biopsy was taken. Oral keratinocytes were dissociated and expanded in a serum-free culture system. Harvested keratinocytes were seeded onto AlloDerm to fabricate an EVPOME (cultured 4 days submerged and 7 days at an air-liquid interface). EVPOME was placed on the open wound and stabilized by a gauze bolster. Day 6 postoperatively, the bolster was removed and surface of the transplanted EVPOME was scraped for cytologic examination. Patients were transnasally fed until postoperative day 8 and then placed on a soft diet. Grafted sites were evaluated by direct observation and photography. A punch biopsy was performed 4 weeks postoperatively. Results: AlloDerm without epithelium and EVPOME were successfully grafted in all cases. Gross appearance of grafted EVPOME at postoperative day 6 showed a darker red color indicating an increase in vascularity. This was not seen in AlloDerm. EVPOME also showed less contraction and induration of wound than grafted AlloDerm without an epithelial layer. Cytologic results showed the presence of small, round-shaped cells suggestive of the presence of basal cells on the EVPOME but not the AlloDerm. Histopathologic examination showed both EVPOME and AlloDerm’s surface were covered by a thick, regenerative epithelial layer at 4 weeks postgrafting. Vascular ingrowth composed of thin endothelial cells was seen in the underlying submucosal layer of EVPOMEs, whereas blood vessels lined with endothelial cells were present in AlloDerm. Grafted EVPOME and AlloDerm both remodeled and formed a neodermis more rapidly than in our in vivo animal studies. However, the more uniform reorganization of the dermis of the EVPOME seems to indicate a more natural regenerative response with less inflammation within the neodermis. Conclusion: Marked vascular ingrowth into the dermal component of EVPOME was consistent with less of an inflammatory reaction and granulation tissue formation than seen with AlloDerm alone, resulting in a more favorable wound healing response after intraoral grafting. References Izumi K, Terashi H, Marcelo CL, et al: Development and characterization of a tissue engineered human oral mucosa equivalent produced In a serum-free culture system. J Dent Res 79:798, 2000 Izumi K, Marcelo CL, Feinberg SE: Evaluation of ex vivo produced oral mucosal equivalent grafts transplanted to SCID mice. J Oral Maxillofac Surg 57:30, 1999 (suppl 1)
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Funding Source: NIH DE13417 (S.E.F.) and Grant-in-Aid for Scientific Research (No. 12771216) from the Ministry of Education, Science and Culture, Japan (K.I.)
Formation of Ramus/Condyle Unit by Tissue-Engineering H. Abukawa, DDS, PhD, Massachusetts General Hospital, OMFS-WRN 1201, 55 Fruit St, Boston, MA 02114 (H. Terai, MD; L.B. Kaban, DMD, MD; D. Hannouche, MD; S. Tevoda, MD) Purpose: Minimally invasive techniques for reconstruction of the mandibular ramus/condyle unit have been reported. However, when bone grafts are required, the harvest procedure produces significant morbidity and prolonged hospital stay. The marriage of minimally invasive surgical techniques and tissue-engineered bone may potentially decrease morbidity, cost, and hospital stay. The purpose of this study was to tissue-engineer a bony construct in the shape of a mandibular condyle. Material and Methods: In the isolation and expansion of porcine mesenchymal stem cells (pMSCs), pMSC were isolated from marrow of the iliac crest of Yucatan minipig (age 6 months, n ⫽ 3). The cells were incubated using standard cell culture conditions. When culture flasks became near-confluent (approximately 14 days), cells were detached and replated on new flasks and osteogenic supplements (dexamethasone, ascorbic acid, and -glycerophosphate) were provided. In the preparation of the 3-dimensional scaffolds, a model of a porcine condyle porous polymer scaffolds was fabricated from biodegradable polymer of PLGA, poly (DL-lactic-co-glycolic acid) using silicone rubber impression materials of a cadaver mandible (n ⫽ 3). The scaffolds were treated 100 ⫻ vitrogen for 24 hours. In the culture method of tissue-engineered construct, 3 days after the cells were replated and differentiated, osteoblasts were transferred to the PLGA scaffold and cultured for 4 weeks in an original gas-permeable rotating bioreactor system. Osteogenic differentiation of stem cells was assessed by osteoblastic morphology, expression of alkaline phosphatase, and formation of mineralized extracellular matrix using the von Kossa staining method. Four weeks later, the cultured scaffolds were examined grossly and histologically. Scaffolds (n ⫽ 2) were used as a control. Results: Gross examination revealed a hard, white structure with a shape that closely resembled the model condyle. Histologically, bone was observed at the surface of PLGA scaffolds. Bone lamella with osteocytes in lacunae surrounded by bone matrix was observed. The control scaffolds lacked evidence of bone formation. Conclusions: In this pilot study, tissue-engineered bone constructs were successfully made by combining biodegradable synthetic polymers and mesenchymal
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Oral Abstract Session 2: Maxillofacial Reconstruction stem cells (n ⫽ 3). This technique has great potential for skeletal reconstruction. References Troulis MJ, Kaban LB: Endoscopic approach to the ramus/condyle unit: Clinical applications. J Oral Maxillofacial Surg May 2001 Langer R, Vacanti JP: Science 1993, p 260
Funding Source: Hanson Foundation: Boston, MA.
A Tissue-Engineered Human Oral Mucosa: A New Approach Toward Clinical Application Xue Tao Xie, DDS, PhD, MD, 5679 Kresge I, Box 0592, 200 Zina Pitcher Dr, Ann Arbor, MI 48109-0592 (Cynthia Zuccaro, BS, CTBS; Cynthia L. Marcelo, PhD; Stephen E. Feinberg, DDS, MS, PhD) Objective: Lack of a sufficient source of mucosa for reconstruction is a major problem. Although mucosa or skin grafts and flaps have been widely used for intraoral reconstruction, they have disadvantages of availability or functional impairment due to different keratinization patterns and textures and donor site morbidity. Numerous investigators have been working on a tissue-engineered oral mucosa. Problems that have impeded their clinical use include the use of potentially virus-containing bovine pituitary extract, use of serum in fabrication, and the limitation in fabrication of large constructs of tissue-engineered oral mucosa. This study addresses a modified approach that concerns these issues. Materials and Methods: Human oral keratinocytes, were cultured in serum ⫹ BPE-free Epilife™ medium with EDGS (Epilife define growth supplement; from Cascade Biologics Inc, Portland, OR), and passaged until the desired number of cells was reached. The dermal equivalent, AlloDerm威 (LifeCell Corporation, Branchburg, NJ), was cut into the required size and shape; rehydrated in phosphate-buffered saline without Ca⫹⫹ and Mg⫹⫹ for 1 hour. One group of AlloDerm威 was precoated with collagen type IV (Life Technologies, Gaithersburg, MD) and a second group was left uncoated. The keratinocytes were seeded onto the basement side of the AlloDerm威 in a medium containing a high concentration of calcium (1.8 mmol/L). After keeping submerged in the medium for 4 days, oral mucosa equivalents then were allowed to float on the surface of the medium. The medium was changed every 2 days. Oral mucosa equivalents were removed from cultures at 4, 11, and 18 days postseeding, and evaluated histologically. Results: Epithelial cells cultured in defined Epilife™ medium had normal morphology, were able to be subcultured serially, and were highly proliferative after the second passage. The successful rate for primary cultivation was 94.4% (34 of 36); the oral mucosa equivalents in AAOMS • 2001
the noncollagen type IV-coated group had a normal appearance at different time points. On day 4, the monolayer of the epithelial sheet integrated with the underlying AlloDerm威, day 11 showed continuous stratified epithelium with characteristic 4 layers, and day 18 showed more fully differentiated and stratified epithelium. In contrast, those in the collagen type IV-coated showed epithelium peeling off from the AlloDerm威 in most cases. Conclusion: Human oral mucosa equivalents can be developed without the risk of introducing exogenous DNA and viruses in the subsequent grafting procedure using the Epilife™ define medium. Type IV collagen precoating does not enhance the binding of the epithelial cells on the AlloDerm威 and should be excluded from the procedure because the basement membrane of the AlloDerm威 contains type IV collagen and laminin. Instead of using costly, size-limited organotypic tissue culture flasks, floating the mucosa equivalents in ordinary cultureware is not only a far simpler, more cost-effective method, but also a good solution for fabrication of large constructs of different sizes and shapes. References Izumi K, Takacs G, Terashi H, et al: Ex vivo development of a composite human oral mucosal equivalent. J Oral Maxillofac Surg 57:571, 1999 Izumi K, Terashi H, Marcelo CL, et al: Development and characterization of a tissue-engineered human oral mucosa equivalent produced in a serum-free culture system. J Dent Res 79:798, 2000 Parenteau NL, Nolte CM, Bilbo P, et al: Epidermis generated in vitro: Practical considerations and applications. J Cell Biochem 45:245, 1991 Funding Source: NIH DE13417 (S.E.F.).
Bioengineering of Hydroxyapatite Composites to Optimizing Bone Ingrowth in Cranial Defects Liansheng Song, DDS, MS, 601 Elmwood Ave, Division of Oral and Maxillofacial Surgery, Eastman Department of Dentistry, University of Rochester, Rochester, NY 14642 (Mark Moss, DDS, PhD; Ross H. Tallents, DDS; Han S. Malmstrom, DDS; Lee D. Pollan, DMD; Brian L. McIntyre, MS; Arun K. Gosain, MD) The present study investigated hydroxyapatite (HA) biomaterials implanted in critical size defects (CSD) in the calvaria of adult sheep to determine the optimal bioengineering of HA composites to facilitate bone ingrowth into these materials. Methods: Five calvarial defects 16.8 mm in diameter were made in each of 10 adult sheep. Three defects were filled with cement paste (CP) composites of HA and -tricalcium phosphate (TCP) as follows: 1) 100% HACP, 2) 60% HA-CP, and 3) 20% HA-CP. One defect was filled with a ceramic (CER) composite containing 60% 25
Oral Abstract Session 2: Maxillofacial Reconstruction HA-CER, and the fifth defect remained unfilled. One year postimplantation, the volume of all biomaterials was determined from CT scan, and porosity and bone ingrowth were determined using backscatter electron microscopy. Results: Volumetric: None of the unfilled cranial defects closed over 1 year, confirming these to be CSDs. There was a significant increase in volume in both the CP and CER implants containing 60% HA (P ⬍ .01). There was no significant change in volume of the remaining CP biomaterials. Bone Ingrowth: Mean bone ingrowth was 4.8 ⫾ 1.4% in 100% HA-CP, 11.2 ⫾ 2.3% in 60% HA-CP, and 28.5 ⫾ 4.5% in 20% HA-CP. There was an inverse correlation between the concentration of HA and the amount of bone ingrowth in the CP for each composite tested (P ⬍ .01). Bone ingrowth in 60% HA-CER (13.6 ⫾ 2.0%) was not significantly different from that in 60% HA-CP. Porosity: The CER composite contained macropores (200 -300 ) which did not change in size over 1 year. All CP composites initially contained micropores (3 nm-5 nm), which remained unchanged in 100% HA-CP. CP implants containing increased TCP showed a corresponding increase in macropores after resorption of the TCP component. Conclusions: There was no significant bone ingrowth into pure HA-CP (bone source) in the present study. The introduction of macropores in a biomaterial can optimize bone ingrowth for reconstruction of CSDs in calvaria. This was shown in CER composites of HA, and in CP composites by increasing the composition of a rapidly resorbing component such as -TCP. References Gosain AK, Song L, Riordan P, et al: A one-year study of osteoinduction in hydroxyapatite-derived biomaterials in an adult sheep model. Plast Reconstr Surg (in press) Ripamonti U, Schnitzler CM, Cleaton-Jones PE: Bone induction in a composite allogeneic bone/alloplastic implant. J Oral Maxillofac Surg 47:963, 1989
as the resorption of the polymer when such plating is used. We have previously used a finite element model to study the effects of plating system material properties on maxillary stress after a simulated Le Fort I procedure. Depending on the plating deployment layout, the distribution of the maxillary stress can be different for a given mechanical load. In this study, we applied the model to study the effects of plating deployment layouts on maxillary stress after a simulated Le Fort I procedure. Materials and Methods: We performed CT scan (Philips, AV-E1) on a dry adult at an axial thickness of 1 mm from the level of maxillary dentition to the vertex. CT images were processed and 3D surface rendering was obtained. Based on these image data, we developed a 3D finite element model for the skull with anatomic details of the nasal cavity and the maxillary sinus. Using the computer model, we studied the effect of plating deployment layouts on the maxillary stress after a simulated Le Fort I procedure. Two L-shaped plates were applied to the right maxilla to close the simulated surgical cuts. We simulated 3 different deployment layouts: 1) L and L, 2) backward-L and L, as well as 3) inverted-L and L. We compared plating systems made of Lactosorb biodegradable and titanium with a respective Young’s modulus of 78 and 1.2 ⫻ 104 kg/mm2. A Young’s modulus of 1,370 kg/mm2 was used for the skull. A 1-kg compressive load was applied to the central incisor in the anterior-posterior direction. Mechanical stresses in terms of von Mises stresses developed in the maxilla at the immediate vicinity of the bone screws were compared for cases with different materials and plating systems deployment layouts. Results: Values of von Mises stress are summarized in the following table: Maximum Maxillary Stress in the Vicinity of Bone Screws (kg/mm2) Plating Deployment Layout
Funding Source: Faculty Fellowship of American College of Surgeons to A.K.G.
Plating System Deployment and Maxillary Stress After a Simulated Le Fort I Procedure Cheng-Jen Chuong, PhD, c/o Douglas P. Sinn, DDS, 5323 Harry Hines Blvd, Dallas, TX 75390-9109 (Douglas P. Sinn, DDS) Statement of the Problem: It is difficult to measure the distribution of stress in the craniofacial skeleton when the skeleton is under mechanical load. The difficulty is compounded for patients after maxillofacial skeletal surgery in whom the distribution of stress and deformation could affect wound healing through bone growth as well 26
Lactosorb Titanium
L and L
Backward-L and L
Inverted-L and L
0.008 0.030
0.011 0.041
0.005 0.019
Comparing the effect of plating materials, Lactosorb biodegradable is much more compliant; it absorbs part of the external loads through its elastic deformation leading to lower maxillary stress. Titanium has a higher mechanical stiffness. It transmits the external load to the maxilla through bone screws with only a small fraction of the work converted into its elastic energy associated with its deformation, hence higher maxillary stress. Among the 3 plating deployment layouts, the “inverted-L and L” layout lead to the lowest maxillary stress, whereas the “backward-L and L” layout offers the highest values. We found the same trend for both Lactosorb and titanium materiAAOMS • 2001
Oral Abstract Session 2: Maxillofacial Reconstruction als. All 3 layouts are stable in transmitting the external load. They lead to different maxillary stress because they undergo different degrees of elastic deformation—with the “inverted-L and L” plating undergoing highest elastic deformation followed by “L and L” and “backward-L and L” layout. Conclusions: Using a computer model, we studied the effects of plating deployment layout on the maxillary stress after a simulated Le Fort I procedure. The modeling reveals that the use of “inverted-L and L” plating
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layout leads to the lowest maxillary stress, followed by “L and L” and “backward-L and L” design. Our studies suggest that differences in the plating system layout can result in different maxillary stresses after a Le Fort I procedure. It is important to identify an optimal plating deployment layout so that a mechanical environment in the maxilla can be obtained after surgery for optimal wound healing. Funding Source: Walter Lorenz Surgical.
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The Use of Pericranial Flap for Frontal Sinus Obliteration in the Treatment of Frontal Sinus Fractures Daniel P. Brunner, DDS, MD, LAC/USC Medical Center, 1175 N Cummings St, OPD 1P51, Los Angeles, CA 90033 (Bach T. Le, DDS, MD; Eric J. Dierks, DMD, MD; Dennis-Duke R. Yamashita, DDS) Purpose: Frontal sinus obliteration has been well described for the treatment of selected fractures. Suitable materials used for sinus obliteration have included autogenous fat, bone, fascia, and calcium phosphate cements. We report on the use of a laterally based pericranial flap for frontal sinus obliteration. Patients and Methods: Eight patients underwent frontal sinus obliteration using laterally based pericranial flaps for the treatment of frontal sinus fractures. The patients’ postoperative course was followed clinically and by radiographic exams to ascertain any signs or symptoms of adverse effects. Results: Eight patients were included in the study. The follow-up range was between 1 and 3 years, with the average follow-up time of 13 months. No adverse effects were detected in any patients in whom the procedure was performed. Conclusion: Preliminary data on the use of the laterally based pericranial flap suggest that it is a suitable alternative for frontal sinus obliteration when indicated in the treatment of frontal sinus fractures. It provides for a vascularized graft without separate donor site morbidity. References Ducic Y, Stone T: Frontal sinus obliteration using a laterally based pedicled pericranial flap. Laryngoscope 109:541, 1999 Thaller SR, Donald P: The use of pericranial flaps in frontal sinus fractures. Ann Plast Surg 32:284, 1994
An Extended Mandibular Coronoid Graft for the Correction of Complex Nasal Deformities Erik J. Nuveen, DMD, MD, PO Box 276, Buckingham, PA 18912 (Robert J. Relle, DDS; Rhonda Lubka, MD) Introduction: Comprehensive management of complex nasal deformities requires meticulous attention to both functional and cosmetic deficiencies. Numerous articles have previously addressed either functional or cosmetic alterations independently. We describe an effective method for the simultaneous correction of func22
tional airway impairment and cosmetic deformity used successfully in 6 patients. This technique incorporates an extended mandibular coronoid bone graft to simultaneously re-establish internal support, nasal projection, and improve cosmesis. Materials and Methods: All 6 patients presented with subjective difficulty with nasal respiration and cosmetic deformity. Three patients reported past histories of traumatic nasal injury, 2 had multiple elective rhinoplasties, and 1 had an unknown etiology. All risks, complications, and alternatives were discussed and the patients elected the option of nasal reconstruction with the mandibular coronoid bone graft. Preoperative and postoperative frontal, lateral, and submental vertex photographs of 1 representative patient will be included. Discussion: Acquired deformity of the nose may result in the loss of multiple structures of nasal support. Subsequent collapse of the internal or external nasal valve often results in a compromise in airway resistance. Numerous surgical options for the correction of nasal vault collapse have been described. Cosmetic deformity may also result from any reduction or loss of the supporting structures. Corrections of cosmetic nasal deformities have focused on either dorsal augmentation grafts or lateral batten grafts. Materials used in these techniques have included autogenous tissue, allografts, and alloplastic materials. Minor defects may be restored with cartilage which provides similar material of variable flexibility and tone. Major defects require larger quantities of more rigid material and can be achieved with autogenous bone. Resorptive advantages of membranous bone grafts have been revealed elsewhere. Membranous graft sources have included the calvarium, lingual mandible, symphysis of the mandible, and coronoid grafts. Advocates for the use of alloplastic materials have cited unpredictable resorption of autogenous bone but are not without their own disadvantages. Surgeons familiar with sagittal mandibular ramus osteotomy techniques will readily master this modification for graft harvest. In this series, this graft consistently provided an adequate source of membranous bone for correction. All patients treated have had significant subjective improvement in airway resistance and cosmesis. Conclusion: The reconstructive goals of nasal surgery in patients with complex deformities are to re-establish nasal support to correct nasal valve restriction and improve cosmetic appearance. Focus of reconstruction of acquired nasal deformity was placed independently on either the correction of regional functional nasal valve AAOMS • 2001
Oral Abstract Session 2: Maxillofacial Reconstruction deformities or cosmetic camouflage. This report describes an alternative regional autogenous grafting technique for definitive correction of deficient internal nasal valve support and simultaneous cosmetic improvement. References Constantian M: The incompetent external nasal valve: Pathophysiology and treatment in primary and secondary rhinoplasty. Plast Reconstr Surg 95:919, 1994 Wheeler E, Kawamoto H, Zarem H: Bone grafts for nasal reconstruction. Plast Reconstr Surg 69:9, 1982
Total Rehabilitation of Children After Resection for Treatment of Primary Jaw Tumors W. Bradford Williams, Massachusetts General Hospital, 55 Fruit St, Warren 1201, Boston, MA 02114 (Maria J. Troulis, DDS, MSc; Leonard B. Kaban, DMD, MD) Purpose: The purpose of this study was to evaluate a series of growing children who were treated for a primary tumor of the maxillofacial region using a staged protocol: 1) en bloc resection and mandibular rigid plate fixation, 2) delayed bone graft, 3) implant placement, and 4) implant loading. Patients and Methods: This is an evaluation of 10 consecutive pediatric patients. The charts were reviewed and the data obtained included age at tumor presentation and resection, type of tumor, adjuvant therapy, type of bone graft, and number of implants placed. Outcomes assessed included postoperative infection, tumor margins, tumor recurrence, plate fractures, number of bone grafts required for implant placement, number of unsuccessful implants, and number of implants successfully restored prosthodontically. Results: There were 10 children (age 3.5 to 16 years) treated for maxillary (n ⫽ 3) or mandibular (n ⫽ 7) tumors. The tumor types included giant cell lesion (n ⫽ 4), osteosarcoma (n ⫽ 2), myofibroma (n ⫽ 1), ossifying or desmoplastic fibroma (n ⫽ 2), and ameloblastoma (n ⫽ 1). Eight of the patients presented for initial treatment and 2 presented with recurrent giant cell lesions (previously enucleated). No patients experienced postoperative infection, wound dehiscence, or significant facial deformity after en bloc resection. In 1 case of osteosarcoma, positive margins required further resection. Both osteosarcoma cases received pre- and postoperative chemotherapy. One patient experienced recurrence of the giant cell lesion after en bloc resection and was treated with interferon. To date (mean ⫽ 59 months), no recurrences have occurred. In one case, the fixation plate fractured and was replaced with an iliac bone graft 21 months postresection. In the second stage of this protocol, an iliac bone graft was placed in 9 patients to re-establish continuity of the jaw. One patient
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spontaneously regenerated the mandible and none of the patients experienced infection of the bone graft or wound dehiscence. Before or during implant placement, 3 patients required additional bone grafts to support the endosseus implants. A total of 18 implants were placed in 6 patients. No patients had infection or pain during the osseointegration period and all 18 implants went to second-stage implant surgery. Only 1 implant failed to osseointegrate and was removed. Five patients who had implants placed had a fixed prosthesis. The prosthetic restorations were loaded for a mean of 19 months (range of 1 to 47 months). Of the remaining 5 patients, 1 is scheduled to have the prosthesis placed, and 4 patients are scheduled to have implants placed. Conclusion: Preliminary results of this ongoing study indicate that maxillofacial tumors in the pediatric population can be successfully treated and the patients can be totally rehabilitated using a delayed reconstruction protocol such as en bloc resection and rigid reconstruction plate, autogenous bone graft, endosseous implants, and fixed prosthodontic restoration. References Chuong R, Kaban LB, Kozakewich H, et al: Central giant cell lesions of the jaws. A clinicopathologic study. J Oral Maxillofac Surg 44:708, 1986 Kaban LB, Mulliken JB, Ezekowitz A, et al: Antiangiogenic therapy of a recurrent giant cell tumor of the mandible. Pediatrics 103:1145, 1999 Funding Source: Department of Oral and Maxillofacial Research Fund.
Clinical Application of a TissueEngineered Ex Vivo–Produced Oral Mucosa Equivalent: A Preliminary Report Kenji Izumi, DDS, PhD, Division of Oral & Maxillofacial Surgery, Niigata University Graduate School for Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata City, Niigata 951-8514 Japan (Akihiko Iida, DDS, PhD; Michiko Yoshizawa, DDS, PhD; Ichiro Suzuki, DDS, PhD; Ritsuo Takagi, DDS, PhD; Stephen E. Feinberg, DDS, MS, PhD) Preprosthetic and reconstructive procedures open wounds in the oral mucosa. A graft should prevent microbial infection, excessive fluid loss, and foreign material contamination or relapse secondary to wound contracture and assist in prosthetic reconstruction and wound healing. Oral mucosa or skin grafts require a second surgical procedure and have disadvantages. Oral mucosa is limited in supply whereas split-thickness skin grafts are available in ample supply, but contain adnexal structures and express a pattern of surface keratinization that interferes with function. The elective nature of oral
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Oral Abstract Session 2: Maxillofacial Reconstruction and maxillofacial surgical procedures allows flexibility and timing to develop a tissue-engineered ex vivo–produced oral mucosa equivalent (EVPOME). Objective: Clinical evaluation of use of EVPOME for intraoral grafting. Materials and Methods: The study included 6 patients, 49 to 74 years old, diagnosed with epithelial dysplasia to squamous cell carcinoma of lateral portion of the tongue. Four weeks before surgery, a 5 ⫻ 5 mm2 punch biopsy was taken. Oral keratinocytes were dissociated and expanded in a serum-free culture system. Harvested keratinocytes were seeded onto AlloDerm to fabricate an EVPOME (cultured 4 days submerged and 7 days at an air-liquid interface). EVPOME was placed on the open wound and stabilized by a gauze bolster. Day 6 postoperatively, the bolster was removed and surface of the transplanted EVPOME was scraped for cytologic examination. Patients were transnasally fed until postoperative day 8 and then placed on a soft diet. Grafted sites were evaluated by direct observation and photography. A punch biopsy was performed 4 weeks postoperatively. Results: AlloDerm without epithelium and EVPOME were successfully grafted in all cases. Gross appearance of grafted EVPOME at postoperative day 6 showed a darker red color indicating an increase in vascularity. This was not seen in AlloDerm. EVPOME also showed less contraction and induration of wound than grafted AlloDerm without an epithelial layer. Cytologic results showed the presence of small, round-shaped cells suggestive of the presence of basal cells on the EVPOME but not the AlloDerm. Histopathologic examination showed both EVPOME and AlloDerm’s surface were covered by a thick, regenerative epithelial layer at 4 weeks postgrafting. Vascular ingrowth composed of thin endothelial cells was seen in the underlying submucosal layer of EVPOMEs, whereas blood vessels lined with endothelial cells were present in AlloDerm. Grafted EVPOME and AlloDerm both remodeled and formed a neodermis more rapidly than in our in vivo animal studies. However, the more uniform reorganization of the dermis of the EVPOME seems to indicate a more natural regenerative response with less inflammation within the neodermis. Conclusion: Marked vascular ingrowth into the dermal component of EVPOME was consistent with less of an inflammatory reaction and granulation tissue formation than seen with AlloDerm alone, resulting in a more favorable wound healing response after intraoral grafting. References Izumi K, Terashi H, Marcelo CL, et al: Development and characterization of a tissue engineered human oral mucosa equivalent produced In a serum-free culture system. J Dent Res 79:798, 2000 Izumi K, Marcelo CL, Feinberg SE: Evaluation of ex vivo produced oral mucosal equivalent grafts transplanted to SCID mice. J Oral Maxillofac Surg 57:30, 1999 (suppl 1)
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Funding Source: NIH DE13417 (S.E.F.) and Grant-in-Aid for Scientific Research (No. 12771216) from the Ministry of Education, Science and Culture, Japan (K.I.)
Formation of Ramus/Condyle Unit by Tissue-Engineering H. Abukawa, DDS, PhD, Massachusetts General Hospital, OMFS-WRN 1201, 55 Fruit St, Boston, MA 02114 (H. Terai, MD; L.B. Kaban, DMD, MD; D. Hannouche, MD; S. Tevoda, MD) Purpose: Minimally invasive techniques for reconstruction of the mandibular ramus/condyle unit have been reported. However, when bone grafts are required, the harvest procedure produces significant morbidity and prolonged hospital stay. The marriage of minimally invasive surgical techniques and tissue-engineered bone may potentially decrease morbidity, cost, and hospital stay. The purpose of this study was to tissue-engineer a bony construct in the shape of a mandibular condyle. Material and Methods: In the isolation and expansion of porcine mesenchymal stem cells (pMSCs), pMSC were isolated from marrow of the iliac crest of Yucatan minipig (age 6 months, n ⫽ 3). The cells were incubated using standard cell culture conditions. When culture flasks became near-confluent (approximately 14 days), cells were detached and replated on new flasks and osteogenic supplements (dexamethasone, ascorbic acid, and -glycerophosphate) were provided. In the preparation of the 3-dimensional scaffolds, a model of a porcine condyle porous polymer scaffolds was fabricated from biodegradable polymer of PLGA, poly (DL-lactic-co-glycolic acid) using silicone rubber impression materials of a cadaver mandible (n ⫽ 3). The scaffolds were treated 100 ⫻ vitrogen for 24 hours. In the culture method of tissue-engineered construct, 3 days after the cells were replated and differentiated, osteoblasts were transferred to the PLGA scaffold and cultured for 4 weeks in an original gas-permeable rotating bioreactor system. Osteogenic differentiation of stem cells was assessed by osteoblastic morphology, expression of alkaline phosphatase, and formation of mineralized extracellular matrix using the von Kossa staining method. Four weeks later, the cultured scaffolds were examined grossly and histologically. Scaffolds (n ⫽ 2) were used as a control. Results: Gross examination revealed a hard, white structure with a shape that closely resembled the model condyle. Histologically, bone was observed at the surface of PLGA scaffolds. Bone lamella with osteocytes in lacunae surrounded by bone matrix was observed. The control scaffolds lacked evidence of bone formation. Conclusions: In this pilot study, tissue-engineered bone constructs were successfully made by combining biodegradable synthetic polymers and mesenchymal
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Oral Abstract Session 2: Maxillofacial Reconstruction stem cells (n ⫽ 3). This technique has great potential for skeletal reconstruction. References Troulis MJ, Kaban LB: Endoscopic approach to the ramus/condyle unit: Clinical applications. J Oral Maxillofacial Surg May 2001 Langer R, Vacanti JP: Science 1993, p 260
Funding Source: Hanson Foundation: Boston, MA.
A Tissue-Engineered Human Oral Mucosa: A New Approach Toward Clinical Application Xue Tao Xie, DDS, PhD, MD, 5679 Kresge I, Box 0592, 200 Zina Pitcher Dr, Ann Arbor, MI 48109-0592 (Cynthia Zuccaro, BS, CTBS; Cynthia L. Marcelo, PhD; Stephen E. Feinberg, DDS, MS, PhD) Objective: Lack of a sufficient source of mucosa for reconstruction is a major problem. Although mucosa or skin grafts and flaps have been widely used for intraoral reconstruction, they have disadvantages of availability or functional impairment due to different keratinization patterns and textures and donor site morbidity. Numerous investigators have been working on a tissue-engineered oral mucosa. Problems that have impeded their clinical use include the use of potentially virus-containing bovine pituitary extract, use of serum in fabrication, and the limitation in fabrication of large constructs of tissue-engineered oral mucosa. This study addresses a modified approach that concerns these issues. Materials and Methods: Human oral keratinocytes, were cultured in serum ⫹ BPE-free Epilife™ medium with EDGS (Epilife define growth supplement; from Cascade Biologics Inc, Portland, OR), and passaged until the desired number of cells was reached. The dermal equivalent, AlloDerm威 (LifeCell Corporation, Branchburg, NJ), was cut into the required size and shape; rehydrated in phosphate-buffered saline without Ca⫹⫹ and Mg⫹⫹ for 1 hour. One group of AlloDerm威 was precoated with collagen type IV (Life Technologies, Gaithersburg, MD) and a second group was left uncoated. The keratinocytes were seeded onto the basement side of the AlloDerm威 in a medium containing a high concentration of calcium (1.8 mmol/L). After keeping submerged in the medium for 4 days, oral mucosa equivalents then were allowed to float on the surface of the medium. The medium was changed every 2 days. Oral mucosa equivalents were removed from cultures at 4, 11, and 18 days postseeding, and evaluated histologically. Results: Epithelial cells cultured in defined Epilife™ medium had normal morphology, were able to be subcultured serially, and were highly proliferative after the second passage. The successful rate for primary cultivation was 94.4% (34 of 36); the oral mucosa equivalents in AAOMS • 2001
the noncollagen type IV-coated group had a normal appearance at different time points. On day 4, the monolayer of the epithelial sheet integrated with the underlying AlloDerm威, day 11 showed continuous stratified epithelium with characteristic 4 layers, and day 18 showed more fully differentiated and stratified epithelium. In contrast, those in the collagen type IV-coated showed epithelium peeling off from the AlloDerm威 in most cases. Conclusion: Human oral mucosa equivalents can be developed without the risk of introducing exogenous DNA and viruses in the subsequent grafting procedure using the Epilife™ define medium. Type IV collagen precoating does not enhance the binding of the epithelial cells on the AlloDerm威 and should be excluded from the procedure because the basement membrane of the AlloDerm威 contains type IV collagen and laminin. Instead of using costly, size-limited organotypic tissue culture flasks, floating the mucosa equivalents in ordinary cultureware is not only a far simpler, more cost-effective method, but also a good solution for fabrication of large constructs of different sizes and shapes. References Izumi K, Takacs G, Terashi H, et al: Ex vivo development of a composite human oral mucosal equivalent. J Oral Maxillofac Surg 57:571, 1999 Izumi K, Terashi H, Marcelo CL, et al: Development and characterization of a tissue-engineered human oral mucosa equivalent produced in a serum-free culture system. J Dent Res 79:798, 2000 Parenteau NL, Nolte CM, Bilbo P, et al: Epidermis generated in vitro: Practical considerations and applications. J Cell Biochem 45:245, 1991 Funding Source: NIH DE13417 (S.E.F.).
Bioengineering of Hydroxyapatite Composites to Optimizing Bone Ingrowth in Cranial Defects Liansheng Song, DDS, MS, 601 Elmwood Ave, Division of Oral and Maxillofacial Surgery, Eastman Department of Dentistry, University of Rochester, Rochester, NY 14642 (Mark Moss, DDS, PhD; Ross H. Tallents, DDS; Han S. Malmstrom, DDS; Lee D. Pollan, DMD; Brian L. McIntyre, MS; Arun K. Gosain, MD) The present study investigated hydroxyapatite (HA) biomaterials implanted in critical size defects (CSD) in the calvaria of adult sheep to determine the optimal bioengineering of HA composites to facilitate bone ingrowth into these materials. Methods: Five calvarial defects 16.8 mm in diameter were made in each of 10 adult sheep. Three defects were filled with cement paste (CP) composites of HA and -tricalcium phosphate (TCP) as follows: 1) 100% HACP, 2) 60% HA-CP, and 3) 20% HA-CP. One defect was filled with a ceramic (CER) composite containing 60% 25
Oral Abstract Session 2: Maxillofacial Reconstruction HA-CER, and the fifth defect remained unfilled. One year postimplantation, the volume of all biomaterials was determined from CT scan, and porosity and bone ingrowth were determined using backscatter electron microscopy. Results: Volumetric: None of the unfilled cranial defects closed over 1 year, confirming these to be CSDs. There was a significant increase in volume in both the CP and CER implants containing 60% HA (P ⬍ .01). There was no significant change in volume of the remaining CP biomaterials. Bone Ingrowth: Mean bone ingrowth was 4.8 ⫾ 1.4% in 100% HA-CP, 11.2 ⫾ 2.3% in 60% HA-CP, and 28.5 ⫾ 4.5% in 20% HA-CP. There was an inverse correlation between the concentration of HA and the amount of bone ingrowth in the CP for each composite tested (P ⬍ .01). Bone ingrowth in 60% HA-CER (13.6 ⫾ 2.0%) was not significantly different from that in 60% HA-CP. Porosity: The CER composite contained macropores (200 -300 ) which did not change in size over 1 year. All CP composites initially contained micropores (3 nm-5 nm), which remained unchanged in 100% HA-CP. CP implants containing increased TCP showed a corresponding increase in macropores after resorption of the TCP component. Conclusions: There was no significant bone ingrowth into pure HA-CP (bone source) in the present study. The introduction of macropores in a biomaterial can optimize bone ingrowth for reconstruction of CSDs in calvaria. This was shown in CER composites of HA, and in CP composites by increasing the composition of a rapidly resorbing component such as -TCP. References Gosain AK, Song L, Riordan P, et al: A one-year study of osteoinduction in hydroxyapatite-derived biomaterials in an adult sheep model. Plast Reconstr Surg (in press) Ripamonti U, Schnitzler CM, Cleaton-Jones PE: Bone induction in a composite allogeneic bone/alloplastic implant. J Oral Maxillofac Surg 47:963, 1989
as the resorption of the polymer when such plating is used. We have previously used a finite element model to study the effects of plating system material properties on maxillary stress after a simulated Le Fort I procedure. Depending on the plating deployment layout, the distribution of the maxillary stress can be different for a given mechanical load. In this study, we applied the model to study the effects of plating deployment layouts on maxillary stress after a simulated Le Fort I procedure. Materials and Methods: We performed CT scan (Philips, AV-E1) on a dry adult at an axial thickness of 1 mm from the level of maxillary dentition to the vertex. CT images were processed and 3D surface rendering was obtained. Based on these image data, we developed a 3D finite element model for the skull with anatomic details of the nasal cavity and the maxillary sinus. Using the computer model, we studied the effect of plating deployment layouts on the maxillary stress after a simulated Le Fort I procedure. Two L-shaped plates were applied to the right maxilla to close the simulated surgical cuts. We simulated 3 different deployment layouts: 1) L and L, 2) backward-L and L, as well as 3) inverted-L and L. We compared plating systems made of Lactosorb biodegradable and titanium with a respective Young’s modulus of 78 and 1.2 ⫻ 104 kg/mm2. A Young’s modulus of 1,370 kg/mm2 was used for the skull. A 1-kg compressive load was applied to the central incisor in the anterior-posterior direction. Mechanical stresses in terms of von Mises stresses developed in the maxilla at the immediate vicinity of the bone screws were compared for cases with different materials and plating systems deployment layouts. Results: Values of von Mises stress are summarized in the following table: Maximum Maxillary Stress in the Vicinity of Bone Screws (kg/mm2) Plating Deployment Layout
Funding Source: Faculty Fellowship of American College of Surgeons to A.K.G.
Plating System Deployment and Maxillary Stress After a Simulated Le Fort I Procedure Cheng-Jen Chuong, PhD, c/o Douglas P. Sinn, DDS, 5323 Harry Hines Blvd, Dallas, TX 75390-9109 (Douglas P. Sinn, DDS) Statement of the Problem: It is difficult to measure the distribution of stress in the craniofacial skeleton when the skeleton is under mechanical load. The difficulty is compounded for patients after maxillofacial skeletal surgery in whom the distribution of stress and deformation could affect wound healing through bone growth as well 26
Lactosorb Titanium
L and L
Backward-L and L
Inverted-L and L
0.008 0.030
0.011 0.041
0.005 0.019
Comparing the effect of plating materials, Lactosorb biodegradable is much more compliant; it absorbs part of the external loads through its elastic deformation leading to lower maxillary stress. Titanium has a higher mechanical stiffness. It transmits the external load to the maxilla through bone screws with only a small fraction of the work converted into its elastic energy associated with its deformation, hence higher maxillary stress. Among the 3 plating deployment layouts, the “inverted-L and L” layout lead to the lowest maxillary stress, whereas the “backward-L and L” layout offers the highest values. We found the same trend for both Lactosorb and titanium materiAAOMS • 2001
Oral Abstract Session 2: Maxillofacial Reconstruction als. All 3 layouts are stable in transmitting the external load. They lead to different maxillary stress because they undergo different degrees of elastic deformation—with the “inverted-L and L” plating undergoing highest elastic deformation followed by “L and L” and “backward-L and L” layout. Conclusions: Using a computer model, we studied the effects of plating deployment layout on the maxillary stress after a simulated Le Fort I procedure. The modeling reveals that the use of “inverted-L and L” plating
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layout leads to the lowest maxillary stress, followed by “L and L” and “backward-L and L” design. Our studies suggest that differences in the plating system layout can result in different maxillary stresses after a Le Fort I procedure. It is important to identify an optimal plating deployment layout so that a mechanical environment in the maxilla can be obtained after surgery for optimal wound healing. Funding Source: Walter Lorenz Surgical.
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