potential between rhBMP-2, rhBMP-7 and native bovineBMP groups when the results from both the in vitro andin vivo tests were evaluated. Significant differences (Pless than 0.05) were seen between all groups and theuntreated controls.

Conclusion: These results indicate that we have beenable to successfully isolate the genes transcribing rh-BMP-2 and rhBMP-7. This will now allow us to move tothe next phase in the development of our new lessexpensive synthetic BMP.

References

Hu ZM, Peel SA, Clokie CM: Osteoinductivity assay of the variabilityof repeated extractions of bone morphogenetic proteins from bovinebone at different times. Chin J Traumatol 7:301, 2004

Urist MR: Bone: formation by autoinduction. Science 150:893, 1965Volek-Smith H, Urist MR: Recombinant human bone morphogenetic

protein (rhBMP) induced heterotopic bone development in vivo and invitro. Proc Soc Exp Biol Med 211:265, 1996

Does the Diagnosis of Multiple Warthin’sTumour Influence Outcome? A CaseControlled StudyMadanagopalan Ethunandan, MDS, FDSRCS, FFDRCS,MRCS, Maxillofacial Unit, Queen Alexandra Hospital,Portsmouth PO6 3LY, UK (Morrison A; Higgins B; PrattC; Macpherson D; Wilson A)

Statement of the Problem: Warthin’s tumor stillevokes controversy in relation to its pathogenesis andtreatment. Though the multifocal nature of Warthin’stumor has been well documented, its influence on themanagement of these lesions remains unresolved.

Materials and Methods: A retrospective analysis of allparotidectomies performed in the maxillofacial unit be-tween 1975 and 2004 was undertaken and patients witha diagnosis of Warthin’s tumor were identified. A total of630 patients underwent 641 parotidectomies for neo-plastic conditions in the study period. 150 parotidecto-mies were performed in 141 patients with Warthin’stumor and form the basis of this study.

Method of Data Analysis: The presentation, clinicalfeatures, results of investigations, operative details, his-tological diagnosis, complications, and outcome of pa-tients with solitary and multiple Warthin’s tumors wereevaluated. In addition, the differences in presentationand outcome between these two groups were analyzedusing standard statistical methods.

Results: A painless mass in the tail of the parotid wasthe most frequent clinical presentation. Clinical and im-aging investigations were poor at detecting multiple ip-silateral synchronous tumors, though intra-operative pal-pation identified 53% of multiple tumors. Multiple War-thin’s accounted for 13% of all Warthin’s tumor in ourseries. The demographic features, smoking habits, andsite of tumor were similar in both the groups. Most

interestingly, the outcome following treatment was thesame in the 2 groups. Both groups of patients underwentsuperficial parotidectomy and there were no recur-rences in both the groups and the follow up periodranged from 5 months to 25 years.

Conclusion: Pre-operative clinical and imaging inves-tigations were relatively poor at detecting multiple ipsi-lateral tumors. The demographic details and clinical pre-sentation were similar in patients with single and multi-ple Warthin’s tumors. Superficial parotidectomy, withintra-operative palpation remains the treatment ofchoice for both the groups and there were no recur-rences in our series.

References

Ethunandan M, Pratt CA, Macpherson DW: Changing frequency ofparotid gland neoplasms: Analysis of 560 tumours treated in a districtgeneral hospital. Ann Coll Surg Engl 84:1, 2002

Ethunandan M, Vura G, Umar T, et al: Synchronous and metachro-nous parotid gland neoplasms: The Chischester experience. Br J OralMaxillofac Surg 42:469, 2004

Double Zygomaticus Fixtures in OneStage for the Severely Resorbed MaxillaMarianela Gonzalez, DDS, MS, Centro Integral SantaRosa Office 105, Santa Rosa de Lima, Caracas 1061,Venezuela (Guerrero C; Dominguez E)

Statement of the Problem: Reconstruction of the se-vere atrophic maxilla has been a challenge for the pa-tient, the surgeon, and the prosthodontist due to themultiple surgical procedures needed, number of visits tothe office, and the high failure rate of the conventionalprocedures in the past.

Materials and Methods: In this 4-year retrospectiveclinical study, twenty two patients (12 females, 10males), age range of 48 to 82 were evaluated. Criteria forselection included 1) Healthy maxillary sinuses; 2) Non-smoker or less than 6 cigarettes/day; 3) Severe maxillaryatrophy with minimum of 4 mm alveolar bone height; 4)A minimum of 24 months follow-up. The surgical andprosthetic protocol consisted of placing 2 zygomaticusfixtures (n � 44) (Nobel Biocare) on either side, rangingin length from 40 mm to 52 mm, and 1-4 conventionalBrånemark fixtures on the anterior maxilla. Impressionswere taken at the end of the surgical procedure, theprosthetic bar was tied-in under I.V. sedation 7 dayslater, and the final restoration was installed by day 15.The success criteria were based on fixture success whenthe zygomaticus remained in place since the originalsurgery, stable, without the presence of pathology, andfunctioning adequately with the prosthesis; the prosthe-sis was considered successful when the original restora-tion had been esthetically and biomechanically workingsince surgery. Gold alloy was the material used for theprosthetic bar, and the combination of acrylic resin,

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composite resin, and porcelain for the occlusal surfaces.All prosthetic restorations were implant-supported over-dentures to compensate for the maxillary atrophy andthe soft tissue lack of projection. The prostheses wereremoved every 12 months for evaluation and mainte-nance. Patients were instructed since the beginning touse several methods for oral hygiene.

Method of Data Analysis: Clinical evaluations wereconducted in conjunction with the periodontist, prostho-dontist and surgeon using plaque index (P.I.) for theprosthetic abutments (n � 44), panoramic and periapi-cal radiographs for bony changes. Panoramic radio-graphs were obtained pre surgery (T1), immediatelypost surgery (T2), and at the longest follow-up (T3),using the same magnification and same radiographicequipment. Pathologic and bony changes were evalu-ated at T3-T2. Peri-implant soft tissues, prosthetic adap-tation and all technical failures related with the construc-tion and the follow-up of the prosthesis were also clini-cally recorded in periodic charts, and registered asspecific events for every patient.

Results: Forty four zygomaticus fixtures were evalu-ated with a follow-up of 24 months to 48 months, whereno significant bony radiographic changes, or pathologieswere observed when tracing and evaluating T3-T2. Oneof the dentures required laboratory repair of the acrylicat the junction of the canine to molar area on one side.One patient presented a recurrent facial fistula from theapical end of one zygomaticus. No sinus infection orsinus discomfort was reported. There was no need forremoval of any of the 44 zygomaticus fixtures. No abut-ment screw fractures were encountered along the study,but a total of 4 abutment screws in 2 patients were loose.Six incompletely seated abutments but no frameworkfracture. Gingival hyperplasia was present in 9% of thezygomaticus fixtures around the connections to the pros-thesis; plaque index for the abutments was 0.9 duringthe prosthetic periodontal maintenance at 12-month fol-low-up. No significant hyperplasia or plaque was presentafter 24 months.

Conclusion: All 22 patients received their prostheticreconstruction in a period of 15 days, recuperating backtheir function and esthetics. This clinical study reports a100% success rate of the implants and 91% of the pros-thesis by using double zygomaticus fixtures in the zygo-matic bone, allowing immediate loading in one-stageprostodontic reconstruction. The decrease of multiplevisits to the specialists, number of surgeries, and numberof fixtures reduces the treatment time and cost.

References

Brånemark P-I, Grondahl K, Worthington P: Osseointegration andAutogenous Onlay Bone Grafts: Reconstruction of the Edentulous Atro-phic Maxilla. Illinois, Quintessence, 2001

Brånemark P-I, Grondahl K, Ohrnell L-O, et al: Zygoma fixture in themanagment of advanced atrophy of the maxilla: Technique and long-term results. Scand J Plast Reconstr Surg Hand Surg 38: 70, 2004

Lateral Ridge Augmentation Using thePocket TechniqueOscar Hasson, DDS, Department of OMFS, KaplanMedical Center, Rehovot, Israel POB1

Statement of the Problem: Lateral ridge augmentationhas been performed in order to achieve the desired bonewidth, to properly and safely insert dental implants.Different bone grafts and a number of bone substituteshave been used. The majority of surgical procedures foraugmentation of lateral ridges are open procedures,where after a mucoperiostal flap is raised grafts areinserted and fixated. The pocket technique is a closeprocedure where access to the lateral ridge is gainedthrough a vertical incision only. It is a procedure withlow morbidity since the surgical approach is minimaland there is no need for autologous bone graft. Thepurpose of this study is to describe the pocket tech-nique, as an alternative procedure for lateral ridge aug-mentation. Additional technical improvements to thisalready described technique are also presented.

Materials and Methods: Seven thin alveolar ridges inseven patients were used in this study. Four patientspresented thin alveolar ridge in the posterior region andthree in the anterior region. The technique consisted inperforming a vertical incision mesially located to the thinalveolar ridge. A subperiosteal flap was raised from themesial to the distal portion of the ridge in its lateralportion. The flap was then raised in the crest area of theridge taking care not to dissect the lingual/palatal tissues.Following that, perforations of the lateral bone ridgewere performed using a small round bur mounted in alow speed device, with the objective to produce bleed-ing before the insertion of the graft. A resorbable colla-gen membrane was adapted and inserted in the pocket.Depending on the alveolar ridge deficiency 1.0 to 1.5 gof bovine bone was introduced under the collagen mem-brane. Vertical incision was then sutured with resorb-able sutures. Following 6 months of maturation of thegraft a CT scan was performed to verify the amount ofaugmentation obtained. Dental implants ranging from3.25 to 4.2 diameter were inserted.

Method of Data Analysis: N/AResults: Implants were inserted following standard

alveolar crest incision. Eleven implants were inserted.The clinical appearance of the graft material seemed andfelt to be adequate for implant insertions.

Conclusion: The pocket technique is an alternativesurgical procedure for lateral ridge augmentation. Thesubperiosteal pocket permits the insertion of enoughgraft material to obtain adequate bone volume. Bovinebone seems to be an adequate graft material for ourpurpose. Another important advantage of the techniqueis to permit adequate stabilization of the graft withoutthe need of more complicated and sophisticated graftfixation procedures.

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26 AAOMS • 2005