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Dental implant–assisted prosthetic rehabilitation of a patient with a bilateral maxillectomy defect secondary to mucormycosis
Dental implant–assisted prosthetic rehabilitation of a patient with a bilateral maxillectomy defect secondary to mucormycosis Won-suck Oh, DDS, MS,a and Eleni Roumanas, DDSb University of Michigan School of Dentistry, Ann Arbor, Mich; University of California Los Angeles School of Dentistry, Los Angeles, Calif Prosthodontic rehabilitation of patients with bimaxillary resection involving the maxillae, hard and soft palates, and paranasal sinuses presents a significant challenge in restoring speech, deglutition, mastication, and respiration. This clinical report describes the prosthodontic management of a young girl treated for leukemia who required a bilateral maxillectomy secondary to mucormycosis. Distraction osteogenesis, bone grafts, osseointegrated implants, and magnet attachments were used to provide retention, support, and stability of a large definitive obturator. (J Prosthet Dent 2006;96:88-95.)
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eukemia is characterized by neoplastic change of the blood-forming elements of the body.1,2 The chief clinical signs and symptoms are similar to those of lowgrade viral infections and include malaise, fatigue, and fever. Unlike viral syndromes, however, the symptoms do not abate but may progress. Differential blood counts may demonstrate elevated white blood cell count, presence of atypical cells, neutropenia, or thrombocytopenia. Chemotherapeutic control is the primary component of medical management for leukemia.3 Treatment is usually divided into 2 phases of a multimodal therapy: induction and maintenance. Its aim is to initially eliminate or reduce the leukemic cell population and sequentially deliver the chemotherapy at regular intervals over a 2-year period to prevent reappearance of the disease. Institution of systemic anti-tumor chemotherapy leaves leukemic patients myelosuppressed and adversely affects the patient’s immune defense mechanism. Opportunistic fungal infections may develop as secondary invaders in the mouth, nasal area, and paranasal sinuses in patients receiving chemotherapy.4-6 Mucormycosis is caused by the organism Mucorales that can be cultured from normal, nonpathogenic individuals.5 These organisms have an affinity for blood vessel walls. Once they gain access to the mucous membranes, they proliferate rapidly and invade the nearby blood vessels causing vascular thrombosis and subsequent necrosis. The resultant oral manifestations are tissue destruction, including nonhealing progressive necrotic ulcers with underlying bony destruction. The maxillary antrum is the usual site of origin of the infection. As the antrum is progressively eroded, perforation ensues, with osseous destruction and oroantral fistula formation.7,8 Aggressive surgical debridement is commonly instituted to control the nonhealing ulcers a
Clinical Associate Professor, Department of Biologic and Materials Sciences, University of Michigan School of Dentistry. b Professor and Director, Graduate Prosthodontics, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, University of California Los Angeles School of Dentistry.
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and necrotic tissues. This often results in the loss of the palate, maxillae, and contiguous structures, followed by difficulties with speech, deglutition, mastication, and respiration. An obturator prosthesis is most frequently the choice of treatment due to the complexity of maxillary surgical reconstruction and the uncertainty of the functional outcome.9-14 The prosthesis recreates a partition between the oral and nasal cavities, restores facial contour, improves mastication, articulation, and speech intelligibility, provides lip support, and reduces drooling.9,15 Patients with a bilateral maxillary resection present a challenging situation for the maxillofacial prosthodontist.16,17 Support and retention of the prosthesis is often difficult to achieve due to the absence of teeth, lack of favorable tissue undercuts, and presence of nonkeratinized nasal mucosa. Retention of such large obturator prostheses is generally a problem, and patients often must balance the obturator on the dorsum of their tongue.17 Bilateral undercuts in the lateral aspects of the resulting defect are favored and may assist with retention of the obturator. However, severe bimaxillary undercuts often make proper lateral extension of a rigid obturator prosthesis impossible. This may result in the loss of border seal, retention, and stability of the obturator prosthesis and the presence of space in which debris may collect. Osseointegrated implants have been successful in providing retention, support, and stability of dental and craniofacial prostheses.18-29 Distraction osteogenesis is a useful reconstructive surgical technique that involves osteotomy and gradual displacement of a bony segment, either vertically or horizontally, to expand soft tissue and bone volume.22,26,29-33 The biologic basis and concept of the surgical process described by Ilizarov,30 a Russian orthopedic surgeon, have been adapted and modified for use in facial skeletal reconstruction, deformities of the jaws, and dentoalveolar process. The regenerated tissue formed by the controlled transport of skeletal fragments provides a stable, functional bone volume for an endosseous implant-supported dental VOLUME 96 NUMBER 2
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restoration.26,29,31-33 This clinical report describes the prosthodontic management of a patient with a bilateral maxillectomy secondary to mucormycosis, in which distraction osteogenesis, bone graft, osseointegrated implants, and magnet attachments were used to assist with retention, support, and stability of the definitive obturator.
CLINICAL REPORT A 12-year-old white girl presented to the Maxillofacial Prosthetics Clinic at the University of California in Los Angeles for replacement of her existing obturator. The patient’s medical history revealed that she was diagnosed with acute lymphoblastic leukemia (ALL) when she was 4 years old. When the diagnosis was made, chemotherapy was started for control of the disease at Primary Children’s Hospital in Salt Lake City, Utah. Two weeks into the chemotherapy, a fungal infection (mucormycosis) developed in her palate and progressed rapidly, involving the entire area of the hard and soft palates. Multiple debridements over several months, including palatal reconstruction with a rib graft, were attempted. Failure of the graft with gradual exposure of the graft material required complete removal of the rib graft and hardware. Chemotherapy was completed over 2.5 years without any further negative events. Over the ensuing years, oral function was maintained with an obturator prosthesis. A single remaining tooth, the right maxillary central incisor, served as an abutment for the prosthesis. The obturator function, however, was significantly compromised when the tooth was removed secondary to progressive tooth decay. Clinical examination revealed that the patient’s maxillae, nasal septum, and all components of the hard and soft palates and pyriform aperture were absent. There was no evidence of a skin graft on the lateral walls of the defect, and the superior surface was entirely lined with nonkeratinized mucosa. Mandibular movement was within the normal range, with no evidence of super-eruption of mandibular teeth. Tongue function was normal, and speech was fair without the obturator and considered good with the prosthesis in place. The patient indicated that the prosthesis was not retentive and stable even after multiple follow-up visits for adjustments and relining with a resilient tissue-conditioning material. Placement of osseointegrated implants was planned to provide retention, stability, and support of a new obturator. A diagnostic maxillary impression was made with an irreversible hydrocolloid (Jeltrate; Dentsply Caulk, Milford, Del), using a stock metal tray (Coe Impression Tray; GC America, Alsip, Ill). The impression was poured in American Dental Association (ADA) type V dental stone (Die Keen; Heraeus Kulzer Inc, Armonk, NY) for designing of the definitive obturator and planning for placement of dental implants. AUGUST 2006
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Radiographic evaluation revealed inadequate volume of remaining bone in the midfacial skeleton for implant placement. Bilateral extraosseous distractors (KLS Martin, Track 1.5 mm system; Lorenz Surgical Inc, Jacksonville, Fla) were placed on the remaining maxillary segments to lengthen the midfacial bony remnants, adjust central skeletal positioning, and provide temporary retention of the existing obturator prosthesis (Fig. 1, A). After a 1-week latency healing period, distraction was initiated at a rate of approximately 1 mm/ day (0.3 mm for 1 turn), for a total of 10 mm vertical distraction of the zygomatico-maxillary residual bone. The 10-day period of distraction was followed by a 6-month period of consolidation. A second-stage reconstruction included augmentation of the anterior maxillary ridge with posterior iliac cortical cancellous onlay grafts, performed at Shriner’s Hospital for Children in Los Angeles, California. The distractors were removed, and 4 immediate provisional implants (IPI; Nobel Biocare, Goteborg, Sweden) were placed for obturator retention. Five 2-stage osseointegrated dental implants (Branemark System; Nobel Biocare) were placed in the residual maxillae: diameter of 3.75 mm and length of 13 mm in right maxillary second molar site, diameter of 3.3 mm and length of 13 mm in right maxillary canine site, diameter of 3.3 mm and length of 10 mm in right maxillary lateral incisor site, diameter of 3.25 mm and length of 13 mm micro-mini implant in left maxillary lateral incisor site, and diameter of 3.75 mm and length of 10 mm in left maxillary canine site. The patient subsequently lost 2 IPI and 3 osseointegrated implants (right maxillary canine and right and left maxillary lateral incisors). The remaining 2 implants were successfully uncovered. Two additional osseointegrated implants (Nobel Biocare), with a diameter of 4 mm and length of 15 mm in the right maxillary third molar site and a diameter of 4 mm and length of 18 mm in the left maxillary third molar site, were placed and will remain unexposed for a protracted period of time as need arises, anticipating future implant failures (Fig. 1, B and C). Magnets were used to assist with retention of the obturator. Due to excessive soft tissue thickness overlying the implants, the magnet abutments were custom made. The castable nonsegmented direct abutment (GoldAdapt Non-Engaging; Nobel Biocare) was cut to the proper length and contoured with wax to customize the connection with the attachment. The abutment screw was secured into position by adding wax in the internal aspect of the abutment plastic sleeve. The superior aspect of the abutment was indented to receive the extension of the magnetic keeper (Magfit; Aichi Steel Corp, Tokai, Japan). The modified abutment was cast using ADA type IV high noble alloy (550 SL; Leach & Dillon Dental Alloys, San Diego, Calif). After polishing, the magnetic keepers were cemented to the superior surface of the abutment with resin cement (Panavia F2.0F; 89
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Fig. 2. A, Customized nonsegmented abutment along with magnetic keeper cemented to abutment with resin cement. B, Positional relation of magnets to magnetic keepers transferred to custom impression tray using acrylic resin.
Fig. 1. A, Panoramic radiographic image showing bilateral extraosseous distractors placed on remaining maxillae. B, Panoramic radiographic image showing 2 immediate provisional implants and 4 osseointegrated dental implants placed in residual maxillae. C, Intraoral view of defect demonstrating absence of hard and soft palates and associated anatomic structures.
Kuraray Medical Inc, Okayama, Japan) (Fig. 2, A). The completed abutments were inserted and tightened onto the implants of the right maxillary second molar and left maxillary canine sites. 90
A custom impression tray (Ostron 100; GC America Inc) was evaluated and adjusted for proper extension. A transfer procedure was performed using acrylic resin (Pattern Resin LS; GC America) to lute the magnets to the custom tray (Fig. 2, B). Each magnet was centered on the coupling magnetic keeper with a thin (0.001 inch) separating sheet (Yates & Bird, Chicago, Ill) interposed to prevent acrylic resin from locking onto the abutment. A small amount of acrylic resin was added on the intaglio surface of the tray where magnets were secured. The tray was inserted intraorally and seated in the center portion of the defect to attach the magnets. The tray was further stabilized by using acrylic resin to adapt it to the axial wall of the IPI. Once the tray was stabilized and retained by the magnets, it was border molded to the defect with modeling plastic impression compound (ISO Functional; GC Corp, Tokyo, Japan) (Fig. 3, A). The impression compound was cut back, and a physiologic definitive impression was made of the defect using a resilient lining material (Visco-gel; Dentsply DeTrey GmbH, Konstanz, Germany) (Fig. 3, B). The loaded tray was carefully inserted intraorally, taking care to assure accurate VOLUME 96 NUMBER 2
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Fig. 3. A, Border-molded custom impression tray. Note magnets attached on intaglio surface of tray. B, Physiologic definitive impression made using resilient lining material.
positioning and complete seating of the tray over the magnets. The patient was instructed to function normally for 1 hour to simulate the movements of the jaw, facial musculature, and pharyngeal wall on swallowing, mastication, speaking, and other functional jaw movements. Conventional prosthodontic protocols of boxing17 and pouring the impression with ADA type III dental stone (Denstone; Heraeus Kulzer Inc) were used to create a definitive cast (Fig. 4, A). After adapting a layer of baseplate wax (Modern No. 3 Pink Wax; Jelenko Co, Armonk, NY) to the defect (Fig. 4, B), the definitive cast was flasked and processed in the customary manner34 to fabricate a thin record base, using heat-activated methyl methacrylate (Lucitone 199; Dentsply Intl) at 165°F for 9 hours (Fig. 4, C and D).
Fig. 4. A, Definitive cast with magnets. B, Single layer of baseplate wax adapted to defect. C, Flasking and packing of definitive cast. D, Fabricated thin, heat-processed acrylic resin record base.
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The processed record base was evaluated intraorally and adjusted to allow complete seating and engagement of the magnets. Baseplate wax (Jelenko Co) was then used to contour the palate and occlusal rim. The wax rim was adjusted to provide adequate vertical dimension and lip support. A maxillomandibular jaw relation record using modeling plastic impression compound (ISO Functional) was made, and the processed record base indexed into silicone putty (Coltene/Whaledent Inc, Cuyahoga Falls, Ohio) was mounted in an articulator (Hanau Wide-Vue 183; Teledyne Technologies, Los Angeles, Calif) that had been specially modified to accept large prostheses. Denture teeth (Ivoclar Vivadent, Amherst, NY) were arranged and evaluated intraorally. Dentolabial relation, lip support, and horizontal and vertical jaw relations were evaluated and verified. Pressure indicating paste (Mizzy Inc, Cherry Hill, NJ) was placed on the arbitrarily contoured wax palate, and the vault was adjusted based on phonetics and swallowing. Care was taken to allow adequate space in the posterior aspect of the palate for the tongue to articulate clear guttural sounds. Upon the patient’s approval, waxing and festooning of the gingival and palatal portions of the obturator were completed, the processed base was reinvested, and the palate and gingival wax were processed into heat-activated methyl methacrylate (Lucitone 199) at 135°F for 12 hours (Fig. 5, A-C). The completed prosthesis was fitted intraorally and remounted to equilibrate occlusion before final insertion (Fig. 5, D). Further stability and retention of the obturator was achieved by using a silicone resilient lining material (SoftLine; Kerr Corp, Romulus, Mich) around the remaining IPIs at the postinsertion appointment. Oral hygiene instructions, especially around the dental implants, were reinforced, and routine recall appointments were scheduled on a regular basis to periodically replace the resilient liner. The last follow-up of the patient was 9 months following the insertion of the new prosthesis. The patient was functioning well with the new obturator prosthesis, and no signs of failure associated with implants were detected. The tissue appeared healthy, and the prosthesis restored functions of speech, deglutition, esthetics, and psychological well-being.
DISCUSSION Osseointegrated implants may assist retention, stability, and support of obturator prostheses.20-22,25 The use of endosseous implants in maxillofacial defects, however, can be complex, particularly in bilateral maxillectomy defects, where there is frequently inadequate residual bone for implant placement. Further alterations in normal anatomy by surgical resection, radiation, and/or chemotherapy reduce the opportunities for the 92
Fig. 5. Definitive obturator prosthesis; A, Frontal view. B, Occlusal view. C, Posterior view. D, Patient with prosthesis in place.
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clinician to place and restore endosseous implants in this group of patients.20,23 The principles of distraction osteogenesis have been well established in endochondral bones and, more recently, applied to the craniofacial skeleton to generate viable osseous tissue by gradual separation of osteotomized bone edges.26,29-33 Interruption of marrow vasculature by osteotomy surgery starts to revascularize within 24 hours and is well vascularized within 1 week. Endochondral revascularization potential is secured for the mobilized segment during the latency period, which plays an important role in supporting matrix proliferation as distraction osteogenesis progresses (1 mm per day).30-32 For the patient in this study, bilateral distraction was conducted for vertical growth for 10 days and stabilized for 6 months, although 3 months is usually sufficient.32 The extended period of fixation time was primarily for the patient’s convenience, to accommodate her school and travel schedule. Meanwhile, the distractor served to assist retention of the existing obturator. The patient experienced some difficulties with the procedure due to the paucity of bone within which to stabilize the distractors and soft tissue dehiscence due to the compromised blood supply; however, the dehiscence was completely epithelialized at the time of distractor removal. An additional challenge with maxillectomy patients is the need for continuous adjustment of the obturator during the distraction process to ensure patient comfort and function. An autologous bone graft was taken from the iliac crest in a more posterior location to preserve the option of a free tissue transfer for future palatal restoration.26,29 Both cancellous and cortical grafts were harvested and placed in soft tissue envelops with the intention to augment the existing facial skeleton to support the implants and provide stability of the obturator prosthesis. Bone grafting was phased into 2 procedures: first, bilateral augmentation of antral maxillary ridge with screw fixation of posterior iliac crest bone onlay bloc grafts with packing of cancellous bone; and secondly, bilateral cortical cancellous veneer blocs to the anterior maxilla, bilateral inlay nasal floor grafts (primarily cancellous), right posterior maxillary onlay corticocancellous bone graft, and placement of 4 IPIs into the bilateral neomaxillary ridges. These temporary IPIs (1-piece 14-mm implants with 2.8-mm cortical engaging threads) were placed posteriorly to help support and stabilize the existing obturator and to protect the graft from premature loading during the multistage bone grafting procedures.20,23,29 The autologous grafts were allowed to mature for 9 months before the placement of implants. The interim IPIs were engaged to retain the existing obturator; however, the regular dental implants were covered and free from direct loading during the healing period. Healing of the submerged implants was not AUGUST 2006
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disturbed until the transmucosal exposure, which was performed 1 year after the initial placement. Two out of 4 IPIs and 3 out of 7 implants were lost during the healing phase. The relatively high failure rate may be associated with the quantity and quality of the residual bone and grafted bone.20,23 Implant sites were newly formed from distraction osteogenesis and augmented with bone graft that was soft and deficient in volume, although a lengthy healing period was allowed. The role of chemotherapy on implant loss may be negligible, although it has not been well documented. Fugazzotto23 placed 626 titanium plasma-sprayed cylindrical implants in regenerated bone and reported 94% cumulative success rate over a period of 51 months. In this report, 1 patient underwent protracted chemotherapy 14 months after implant function began and accounted for 33% (3 of 9) of the total implant loss in the study. If this patient were excluded from the study, the cumulative success rate was 96%. The report did not clearly specify whether the implants were placed concomitantly with guided bone regeneration or in bony ridges that had been previously augmented. Chemotherapy delivered during early stages of loading may have adversely affected the implant-tissue interface. Highly proliferating tissues (bone forming cells) are more susceptible to the damaging effects of chemotherapy than quiescent tissues.6 The dental implant-tissue interface is a dynamic zone consisting of remodeling activities of the osseous cells and extracellular matrices.24 In the present report, a series of chemotherapeutic agents (Methotrexate, Vincristine, 6MP) were delivered to the patient over 2.5 years; however, chemotherapy was completed 8 years before the placement of implants. Thus, it is presumed that the cytotoxic effect of this chemotherapy would be negligible in suppressing the viability of the bone to integrate with the dental implants. Suboptimal implant angulation and compromised access for hygiene maintenance and prosthodontic procedures may not allow strict regimen protocol for abutment connection. Individual magnets directly connected onto the implants have been reported to be useful and successful when the angulation and position of implants are less than ideal.25 Magnetic attachments resist tensile separating forces, but do not prevent lateral sliding force, thus avoiding lateral stress on the implants. Strain at dislodgement is much lower than bar/clip design, which may be desirable in these types of situations for long-term implant success.21,25,28 Implants placed in the current patient extended through nonkeratinized mucosa of moderate thickness. Peri-implant mucosa is known to establish a cuff-like barrier, with collagen fibers parallel to the titanium abutment surface.18 Peri-implant mucosa may develop inflammatory reactions depending on mucosal characteristics, location of the implant platform, plaque 93
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accumulation, and design of the prosthesis.19 Excessive submucosal placement of the implant shoulder in conjunction with loosely attached, poorly keratinized, mobile tissue may be problematic19; however, soft tissue health and stability can be managed with appropriate oral hygiene maintanance.27 Alternatively, surgical reconstruction of the palate may involve free-tissue transfer using a variety of available osteocutaneous flaps, including fibula, scapula, rib, and iliac crest. Soft tissue reconstruction may provide a stable permanent partition between oral and nasal cavities; however, it gives way to gravity, distorting palatal contours and preventing access into the defect for support and retention of the prosthesis. Osteocutaneous free flaps address the maxillary bony skeleton, and dental implants can be placed secondarily for prosthetic rehabilitation. However, it is difficult to orient the bone to restore palate and maxillary form and provide an adequate amount of cheek support.10 A slit-like retentive feature can also be designed using a fibula osteocutaneous free flap allowing the obturator prosthesis to engage tissue undercut.11 Surgically reconstructed defects may or may not improve the treatment outcome when compared with conventional prosthetic rehabilitation of a nonsurgically reconstructed defect.12-14 Zygomatic implants have also been proposed in the rehabilitation of maxillary defects, but this option was eliminated because of the lack of available bone.22
SUMMARY Patients with bilateral maxillary resections present a challenging situation for the maxillofacial prosthodontist. Prosthetic rehabilitation is often difficult to achieve due to the absence of teeth, lack of favorable tissue undercuts, and presence of nonkeratinized nasal mucosa. Obturator prostheses should recreate a partition between the oral and nasal cavities to restore oral function and esthetics. This clinical report presented the prosthodontic management of a patient with a bilateral maxillectomy secondary to mucormycosis using distraction osteogenesis, bone graft, osseointegrated implants, and magnet attachments to assist with retention, support, and stability of a definitive obturator prosthesis.
REFERENCES 1. Shafer WG, Hine MK, Levy BM. Textbook of oral pathology. Philadelphia: W.B. Saunders; 1974. p. 358-9. 2. Bueso-Ramos CE, Ferrajoli A, Medeiros LJ, Keating MJ, Estrov Z. Aberrant morphology, proliferation, and apoptosis of B-cell chronic lymphocytic leukemia cells. Hematology 2004;9:279-86. 3. Schellong G, Creutzig U, Ritter J. Treatment of acute myelogenous leukemia in children. Med Oncol Tumor Pharmacother 1985;2: 17-25. 4. Milroy CM, Blanshard JD, Lucas S, Michaels L. Aspergillosis of the nose and paranasal sinuses. J Clin Pathol 1989;42:123-7.
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5. Karpovich-Tate N, Dewey FM, Smith EJ, Lund VJ, Gurr PA, Gurr SJ. Detection of fungi in sinus fluid of patients with allergic fungal rhinosinusitis. Acta Otolaryngol 2000;120:296-302. 6. Sonis ST, Sonis AL, Lieberman A. Oral complications in patients receiving treatment for malignancies other than of the head and neck. J Am Dent Assoc 1978;97:468-72. 7. Leitner C, Hoffmann J, Zerfowski M, Reinert S. Mucormycosis: necrotizing soft tissue lesion of the face. J Oral Maxillofac Surg 2003;61: 1354-8. 8. Shand JM, Albrecht RM, Burnett HF 3rd, Miyake A. Invasive fungal infection of the midfacial and orbital complex due to Scedosporium apiospermum and mucormycosis. J Oral Maxillofac Surg 2004;62:231-4. 9. Rieger J, Wolfaardt J, Seikaly H, Jha N. Speech outcomes in patients rehabilitated with maxillary obturator prostheses after maxillectomy: a prospective study. Int J Prosthodont 2002;15:139-44. 10. Futran ND, Wadsworth JT, Villaret D, Farwell DG. Midface reconstruction with the fibula free flap. Arch Otolaryngol Head Neck Surg 2002;128: 161-6. 11. Mukohyama H, Haraguchi M, Sumita YI, Iida H, Hata Y, Kishimoto S, et al. Rehabilitation of a bilateral maxillectomy patient with a free fibula osteocutaneous flap. J Oral Rehabil 2005;32:541-4. 12. Pigno MA. Conventional prosthetic rehabilitation after free flap reconstruction of a maxillectomy defect: a clinical report. J Prosthet Dent 2001;86:578-81. 13. Genden EM, Wallace DI, Okay D, Urken ML. Reconstruction of the hard palate using the radial forearm free flap: indications and outcomes. Head Neck 2004;26:808-14. 14. Genden EM, Okay D, Stepp MT, Rezaee RP, Mojica JS, Buchbinder D, et al. Comparison of functional and quality-of-life outcomes in patients with and without palatomaxillary reconstruction: a preliminary report. Arch Otolaryngol Head Neck Surg 2003;129:775-80. 15. Kornblith AB, Zlotolow IM, Gooen J, Huryn JM, Lerner T, Strong EW, et al. Quality of life of maxillectomy patients using an obturator prosthesis. Head Neck 1996;18:323-34. 16. Desjardins RP, Laney WR. Prosthetic rehabilitation after cancer resection in the head and neck. Surg Clin North Am 1977;57:809-22. 17. Beumer J, Curtis TA, Marunick MT. Maxillofacial rehabilitation prosthodontic and surgical consideration. St. Louis: Ishiyaku Euroamerica; 1996. p. 225-47. 18. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991; 2:81-90. 19. Berglundh T, Lindhe J, Marinello C, Ericsson I, Liljenberg B. Soft tissue reaction to de novo plaque formation on implants and teeth. An experimental study in the dog. Clin Oral Implants Res 1992;3:1-8. 20. Roumanas ED, Nishimura RD, Davis BK, Beumer J. Clinical evaluation of implants retaining edentulous maxillary obturator prostheses. J Prosthet Dent 1997;77:184-90. 21. Markt JC. An endosseous, implant-retained obturator for the rehabilitation of a recurrent central giant cell granuloma: a clinical report. J Prosthet Dent 2001;85:116-20. 22. Schmidt BL, Pogrel MA, Young CW, Sharma A. Reconstruction of extensive maxillary defects using zygomaticus implants. J Oral Maxillofac Surg 2004;62:82-9. 23. Fugazzotto PA. Success and failure rates of osseointegrated implants in function in regenerated bone for 6 to 51 months: a preliminary report. Int J Oral Maxillofac Implants 1997;12:17-24. 24. Steflik DE, Parr GR, Sisk AL, Lake FT, Hanes PJ, Berkery DJ, et al. Osteoblast activity at the dental implant-bone interface: transmission electron microscopic and high voltage electron microscopic observations. J Periodontol 1994;65:404-13. 25. Matsumura H, Kawasaki K. Magnetically connected removable sectional denture for a maxillary defect with severe undercut: a clinical report. J Prosthet Dent 2000;84:22-6. 26. Buis J, Rousseau P, Soupre V, Martinez H, Diner PA, Vazquez MP. ‘‘Distraction’’ of grafted alveolar bone in cleft case using endosseous implant. Cleft Palate Craniofac J 2001;38:405-9. 27. Giannopoulou C, Bernard JP, Buser D, Carrel A, Belser UC. Effect of intracrevicular restoration margins on peri-implant health: clinical, biochemical, and microbiologic findings around esthetic implants up to 9 years. Int J Oral Maxillofac Implants 2003;18:173-81. 28. Chung KH, Chung CY, Cagna DR, Cronin RJ Jr. Retention characteristics of attachment systems for implant overdentures. J Prosthodont 2004;13: 221-6.
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29. Block MS, Baughman DG. Reconstruction of severe anterior maxillary defects using distraction osteogenesis, bone grafts, and implants. J Oral Maxillofac Surg 2005;63:291-7. 30. Ilizarov GA. The principles of the Ilizarov method. Bull Hosp Jt Dis Orthop Inst 1988;48:1-11. 31. Karp NS, McCarthy JG, Schreiber JS, Sissons HA, Thorne CH. Membranous bone lengthening: a serial histological study. Ann Plast Surg 1992; 29:2-7. 32. McCarthy JG. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 1994; 21:625-31. 33. Block MS, Almerico B, Crawford C, Gardiner D, Chang A. Bone response to functioning implants in dog mandibular alveolar ridges augmented with distraction osteogenesis. Int J Oral Maxillofac Implants 1998;13: 342-51. 34. Javid NS, Boucher CO. Flasking for easy deflasking. J Prosthet Dent 1973; 29:581-5.
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Reprint request to: DR WON-SUCK OH DEPARTMENT OF BIOLOGIC AND MATERIALS SCIENCES UNIVERSITY OF MICHIGAN SCHOOL OF DENTISTRY 1011 NORTH UNIVERSITY ANN ARBOR, MI 48109-1078 FAX: 734-763-3453 E-MAIL: [email protected] 0022-3913/$32.00 Copyright Ó 2006 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2006.05.004
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eukemia is characterized by neoplastic change of the blood-forming elements of the body.1,2 The chief clinical signs and symptoms are similar to those of lowgrade viral infections and include malaise, fatigue, and fever. Unlike viral syndromes, however, the symptoms do not abate but may progress. Differential blood counts may demonstrate elevated white blood cell count, presence of atypical cells, neutropenia, or thrombocytopenia. Chemotherapeutic control is the primary component of medical management for leukemia.3 Treatment is usually divided into 2 phases of a multimodal therapy: induction and maintenance. Its aim is to initially eliminate or reduce the leukemic cell population and sequentially deliver the chemotherapy at regular intervals over a 2-year period to prevent reappearance of the disease. Institution of systemic anti-tumor chemotherapy leaves leukemic patients myelosuppressed and adversely affects the patient’s immune defense mechanism. Opportunistic fungal infections may develop as secondary invaders in the mouth, nasal area, and paranasal sinuses in patients receiving chemotherapy.4-6 Mucormycosis is caused by the organism Mucorales that can be cultured from normal, nonpathogenic individuals.5 These organisms have an affinity for blood vessel walls. Once they gain access to the mucous membranes, they proliferate rapidly and invade the nearby blood vessels causing vascular thrombosis and subsequent necrosis. The resultant oral manifestations are tissue destruction, including nonhealing progressive necrotic ulcers with underlying bony destruction. The maxillary antrum is the usual site of origin of the infection. As the antrum is progressively eroded, perforation ensues, with osseous destruction and oroantral fistula formation.7,8 Aggressive surgical debridement is commonly instituted to control the nonhealing ulcers a
Clinical Associate Professor, Department of Biologic and Materials Sciences, University of Michigan School of Dentistry. b Professor and Director, Graduate Prosthodontics, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, University of California Los Angeles School of Dentistry.
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and necrotic tissues. This often results in the loss of the palate, maxillae, and contiguous structures, followed by difficulties with speech, deglutition, mastication, and respiration. An obturator prosthesis is most frequently the choice of treatment due to the complexity of maxillary surgical reconstruction and the uncertainty of the functional outcome.9-14 The prosthesis recreates a partition between the oral and nasal cavities, restores facial contour, improves mastication, articulation, and speech intelligibility, provides lip support, and reduces drooling.9,15 Patients with a bilateral maxillary resection present a challenging situation for the maxillofacial prosthodontist.16,17 Support and retention of the prosthesis is often difficult to achieve due to the absence of teeth, lack of favorable tissue undercuts, and presence of nonkeratinized nasal mucosa. Retention of such large obturator prostheses is generally a problem, and patients often must balance the obturator on the dorsum of their tongue.17 Bilateral undercuts in the lateral aspects of the resulting defect are favored and may assist with retention of the obturator. However, severe bimaxillary undercuts often make proper lateral extension of a rigid obturator prosthesis impossible. This may result in the loss of border seal, retention, and stability of the obturator prosthesis and the presence of space in which debris may collect. Osseointegrated implants have been successful in providing retention, support, and stability of dental and craniofacial prostheses.18-29 Distraction osteogenesis is a useful reconstructive surgical technique that involves osteotomy and gradual displacement of a bony segment, either vertically or horizontally, to expand soft tissue and bone volume.22,26,29-33 The biologic basis and concept of the surgical process described by Ilizarov,30 a Russian orthopedic surgeon, have been adapted and modified for use in facial skeletal reconstruction, deformities of the jaws, and dentoalveolar process. The regenerated tissue formed by the controlled transport of skeletal fragments provides a stable, functional bone volume for an endosseous implant-supported dental VOLUME 96 NUMBER 2
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restoration.26,29,31-33 This clinical report describes the prosthodontic management of a patient with a bilateral maxillectomy secondary to mucormycosis, in which distraction osteogenesis, bone graft, osseointegrated implants, and magnet attachments were used to assist with retention, support, and stability of the definitive obturator.
CLINICAL REPORT A 12-year-old white girl presented to the Maxillofacial Prosthetics Clinic at the University of California in Los Angeles for replacement of her existing obturator. The patient’s medical history revealed that she was diagnosed with acute lymphoblastic leukemia (ALL) when she was 4 years old. When the diagnosis was made, chemotherapy was started for control of the disease at Primary Children’s Hospital in Salt Lake City, Utah. Two weeks into the chemotherapy, a fungal infection (mucormycosis) developed in her palate and progressed rapidly, involving the entire area of the hard and soft palates. Multiple debridements over several months, including palatal reconstruction with a rib graft, were attempted. Failure of the graft with gradual exposure of the graft material required complete removal of the rib graft and hardware. Chemotherapy was completed over 2.5 years without any further negative events. Over the ensuing years, oral function was maintained with an obturator prosthesis. A single remaining tooth, the right maxillary central incisor, served as an abutment for the prosthesis. The obturator function, however, was significantly compromised when the tooth was removed secondary to progressive tooth decay. Clinical examination revealed that the patient’s maxillae, nasal septum, and all components of the hard and soft palates and pyriform aperture were absent. There was no evidence of a skin graft on the lateral walls of the defect, and the superior surface was entirely lined with nonkeratinized mucosa. Mandibular movement was within the normal range, with no evidence of super-eruption of mandibular teeth. Tongue function was normal, and speech was fair without the obturator and considered good with the prosthesis in place. The patient indicated that the prosthesis was not retentive and stable even after multiple follow-up visits for adjustments and relining with a resilient tissue-conditioning material. Placement of osseointegrated implants was planned to provide retention, stability, and support of a new obturator. A diagnostic maxillary impression was made with an irreversible hydrocolloid (Jeltrate; Dentsply Caulk, Milford, Del), using a stock metal tray (Coe Impression Tray; GC America, Alsip, Ill). The impression was poured in American Dental Association (ADA) type V dental stone (Die Keen; Heraeus Kulzer Inc, Armonk, NY) for designing of the definitive obturator and planning for placement of dental implants. AUGUST 2006
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Radiographic evaluation revealed inadequate volume of remaining bone in the midfacial skeleton for implant placement. Bilateral extraosseous distractors (KLS Martin, Track 1.5 mm system; Lorenz Surgical Inc, Jacksonville, Fla) were placed on the remaining maxillary segments to lengthen the midfacial bony remnants, adjust central skeletal positioning, and provide temporary retention of the existing obturator prosthesis (Fig. 1, A). After a 1-week latency healing period, distraction was initiated at a rate of approximately 1 mm/ day (0.3 mm for 1 turn), for a total of 10 mm vertical distraction of the zygomatico-maxillary residual bone. The 10-day period of distraction was followed by a 6-month period of consolidation. A second-stage reconstruction included augmentation of the anterior maxillary ridge with posterior iliac cortical cancellous onlay grafts, performed at Shriner’s Hospital for Children in Los Angeles, California. The distractors were removed, and 4 immediate provisional implants (IPI; Nobel Biocare, Goteborg, Sweden) were placed for obturator retention. Five 2-stage osseointegrated dental implants (Branemark System; Nobel Biocare) were placed in the residual maxillae: diameter of 3.75 mm and length of 13 mm in right maxillary second molar site, diameter of 3.3 mm and length of 13 mm in right maxillary canine site, diameter of 3.3 mm and length of 10 mm in right maxillary lateral incisor site, diameter of 3.25 mm and length of 13 mm micro-mini implant in left maxillary lateral incisor site, and diameter of 3.75 mm and length of 10 mm in left maxillary canine site. The patient subsequently lost 2 IPI and 3 osseointegrated implants (right maxillary canine and right and left maxillary lateral incisors). The remaining 2 implants were successfully uncovered. Two additional osseointegrated implants (Nobel Biocare), with a diameter of 4 mm and length of 15 mm in the right maxillary third molar site and a diameter of 4 mm and length of 18 mm in the left maxillary third molar site, were placed and will remain unexposed for a protracted period of time as need arises, anticipating future implant failures (Fig. 1, B and C). Magnets were used to assist with retention of the obturator. Due to excessive soft tissue thickness overlying the implants, the magnet abutments were custom made. The castable nonsegmented direct abutment (GoldAdapt Non-Engaging; Nobel Biocare) was cut to the proper length and contoured with wax to customize the connection with the attachment. The abutment screw was secured into position by adding wax in the internal aspect of the abutment plastic sleeve. The superior aspect of the abutment was indented to receive the extension of the magnetic keeper (Magfit; Aichi Steel Corp, Tokai, Japan). The modified abutment was cast using ADA type IV high noble alloy (550 SL; Leach & Dillon Dental Alloys, San Diego, Calif). After polishing, the magnetic keepers were cemented to the superior surface of the abutment with resin cement (Panavia F2.0F; 89
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Fig. 2. A, Customized nonsegmented abutment along with magnetic keeper cemented to abutment with resin cement. B, Positional relation of magnets to magnetic keepers transferred to custom impression tray using acrylic resin.
Fig. 1. A, Panoramic radiographic image showing bilateral extraosseous distractors placed on remaining maxillae. B, Panoramic radiographic image showing 2 immediate provisional implants and 4 osseointegrated dental implants placed in residual maxillae. C, Intraoral view of defect demonstrating absence of hard and soft palates and associated anatomic structures.
Kuraray Medical Inc, Okayama, Japan) (Fig. 2, A). The completed abutments were inserted and tightened onto the implants of the right maxillary second molar and left maxillary canine sites. 90
A custom impression tray (Ostron 100; GC America Inc) was evaluated and adjusted for proper extension. A transfer procedure was performed using acrylic resin (Pattern Resin LS; GC America) to lute the magnets to the custom tray (Fig. 2, B). Each magnet was centered on the coupling magnetic keeper with a thin (0.001 inch) separating sheet (Yates & Bird, Chicago, Ill) interposed to prevent acrylic resin from locking onto the abutment. A small amount of acrylic resin was added on the intaglio surface of the tray where magnets were secured. The tray was inserted intraorally and seated in the center portion of the defect to attach the magnets. The tray was further stabilized by using acrylic resin to adapt it to the axial wall of the IPI. Once the tray was stabilized and retained by the magnets, it was border molded to the defect with modeling plastic impression compound (ISO Functional; GC Corp, Tokyo, Japan) (Fig. 3, A). The impression compound was cut back, and a physiologic definitive impression was made of the defect using a resilient lining material (Visco-gel; Dentsply DeTrey GmbH, Konstanz, Germany) (Fig. 3, B). The loaded tray was carefully inserted intraorally, taking care to assure accurate VOLUME 96 NUMBER 2
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Fig. 3. A, Border-molded custom impression tray. Note magnets attached on intaglio surface of tray. B, Physiologic definitive impression made using resilient lining material.
positioning and complete seating of the tray over the magnets. The patient was instructed to function normally for 1 hour to simulate the movements of the jaw, facial musculature, and pharyngeal wall on swallowing, mastication, speaking, and other functional jaw movements. Conventional prosthodontic protocols of boxing17 and pouring the impression with ADA type III dental stone (Denstone; Heraeus Kulzer Inc) were used to create a definitive cast (Fig. 4, A). After adapting a layer of baseplate wax (Modern No. 3 Pink Wax; Jelenko Co, Armonk, NY) to the defect (Fig. 4, B), the definitive cast was flasked and processed in the customary manner34 to fabricate a thin record base, using heat-activated methyl methacrylate (Lucitone 199; Dentsply Intl) at 165°F for 9 hours (Fig. 4, C and D).
Fig. 4. A, Definitive cast with magnets. B, Single layer of baseplate wax adapted to defect. C, Flasking and packing of definitive cast. D, Fabricated thin, heat-processed acrylic resin record base.
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The processed record base was evaluated intraorally and adjusted to allow complete seating and engagement of the magnets. Baseplate wax (Jelenko Co) was then used to contour the palate and occlusal rim. The wax rim was adjusted to provide adequate vertical dimension and lip support. A maxillomandibular jaw relation record using modeling plastic impression compound (ISO Functional) was made, and the processed record base indexed into silicone putty (Coltene/Whaledent Inc, Cuyahoga Falls, Ohio) was mounted in an articulator (Hanau Wide-Vue 183; Teledyne Technologies, Los Angeles, Calif) that had been specially modified to accept large prostheses. Denture teeth (Ivoclar Vivadent, Amherst, NY) were arranged and evaluated intraorally. Dentolabial relation, lip support, and horizontal and vertical jaw relations were evaluated and verified. Pressure indicating paste (Mizzy Inc, Cherry Hill, NJ) was placed on the arbitrarily contoured wax palate, and the vault was adjusted based on phonetics and swallowing. Care was taken to allow adequate space in the posterior aspect of the palate for the tongue to articulate clear guttural sounds. Upon the patient’s approval, waxing and festooning of the gingival and palatal portions of the obturator were completed, the processed base was reinvested, and the palate and gingival wax were processed into heat-activated methyl methacrylate (Lucitone 199) at 135°F for 12 hours (Fig. 5, A-C). The completed prosthesis was fitted intraorally and remounted to equilibrate occlusion before final insertion (Fig. 5, D). Further stability and retention of the obturator was achieved by using a silicone resilient lining material (SoftLine; Kerr Corp, Romulus, Mich) around the remaining IPIs at the postinsertion appointment. Oral hygiene instructions, especially around the dental implants, were reinforced, and routine recall appointments were scheduled on a regular basis to periodically replace the resilient liner. The last follow-up of the patient was 9 months following the insertion of the new prosthesis. The patient was functioning well with the new obturator prosthesis, and no signs of failure associated with implants were detected. The tissue appeared healthy, and the prosthesis restored functions of speech, deglutition, esthetics, and psychological well-being.
DISCUSSION Osseointegrated implants may assist retention, stability, and support of obturator prostheses.20-22,25 The use of endosseous implants in maxillofacial defects, however, can be complex, particularly in bilateral maxillectomy defects, where there is frequently inadequate residual bone for implant placement. Further alterations in normal anatomy by surgical resection, radiation, and/or chemotherapy reduce the opportunities for the 92
Fig. 5. Definitive obturator prosthesis; A, Frontal view. B, Occlusal view. C, Posterior view. D, Patient with prosthesis in place.
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clinician to place and restore endosseous implants in this group of patients.20,23 The principles of distraction osteogenesis have been well established in endochondral bones and, more recently, applied to the craniofacial skeleton to generate viable osseous tissue by gradual separation of osteotomized bone edges.26,29-33 Interruption of marrow vasculature by osteotomy surgery starts to revascularize within 24 hours and is well vascularized within 1 week. Endochondral revascularization potential is secured for the mobilized segment during the latency period, which plays an important role in supporting matrix proliferation as distraction osteogenesis progresses (1 mm per day).30-32 For the patient in this study, bilateral distraction was conducted for vertical growth for 10 days and stabilized for 6 months, although 3 months is usually sufficient.32 The extended period of fixation time was primarily for the patient’s convenience, to accommodate her school and travel schedule. Meanwhile, the distractor served to assist retention of the existing obturator. The patient experienced some difficulties with the procedure due to the paucity of bone within which to stabilize the distractors and soft tissue dehiscence due to the compromised blood supply; however, the dehiscence was completely epithelialized at the time of distractor removal. An additional challenge with maxillectomy patients is the need for continuous adjustment of the obturator during the distraction process to ensure patient comfort and function. An autologous bone graft was taken from the iliac crest in a more posterior location to preserve the option of a free tissue transfer for future palatal restoration.26,29 Both cancellous and cortical grafts were harvested and placed in soft tissue envelops with the intention to augment the existing facial skeleton to support the implants and provide stability of the obturator prosthesis. Bone grafting was phased into 2 procedures: first, bilateral augmentation of antral maxillary ridge with screw fixation of posterior iliac crest bone onlay bloc grafts with packing of cancellous bone; and secondly, bilateral cortical cancellous veneer blocs to the anterior maxilla, bilateral inlay nasal floor grafts (primarily cancellous), right posterior maxillary onlay corticocancellous bone graft, and placement of 4 IPIs into the bilateral neomaxillary ridges. These temporary IPIs (1-piece 14-mm implants with 2.8-mm cortical engaging threads) were placed posteriorly to help support and stabilize the existing obturator and to protect the graft from premature loading during the multistage bone grafting procedures.20,23,29 The autologous grafts were allowed to mature for 9 months before the placement of implants. The interim IPIs were engaged to retain the existing obturator; however, the regular dental implants were covered and free from direct loading during the healing period. Healing of the submerged implants was not AUGUST 2006
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disturbed until the transmucosal exposure, which was performed 1 year after the initial placement. Two out of 4 IPIs and 3 out of 7 implants were lost during the healing phase. The relatively high failure rate may be associated with the quantity and quality of the residual bone and grafted bone.20,23 Implant sites were newly formed from distraction osteogenesis and augmented with bone graft that was soft and deficient in volume, although a lengthy healing period was allowed. The role of chemotherapy on implant loss may be negligible, although it has not been well documented. Fugazzotto23 placed 626 titanium plasma-sprayed cylindrical implants in regenerated bone and reported 94% cumulative success rate over a period of 51 months. In this report, 1 patient underwent protracted chemotherapy 14 months after implant function began and accounted for 33% (3 of 9) of the total implant loss in the study. If this patient were excluded from the study, the cumulative success rate was 96%. The report did not clearly specify whether the implants were placed concomitantly with guided bone regeneration or in bony ridges that had been previously augmented. Chemotherapy delivered during early stages of loading may have adversely affected the implant-tissue interface. Highly proliferating tissues (bone forming cells) are more susceptible to the damaging effects of chemotherapy than quiescent tissues.6 The dental implant-tissue interface is a dynamic zone consisting of remodeling activities of the osseous cells and extracellular matrices.24 In the present report, a series of chemotherapeutic agents (Methotrexate, Vincristine, 6MP) were delivered to the patient over 2.5 years; however, chemotherapy was completed 8 years before the placement of implants. Thus, it is presumed that the cytotoxic effect of this chemotherapy would be negligible in suppressing the viability of the bone to integrate with the dental implants. Suboptimal implant angulation and compromised access for hygiene maintenance and prosthodontic procedures may not allow strict regimen protocol for abutment connection. Individual magnets directly connected onto the implants have been reported to be useful and successful when the angulation and position of implants are less than ideal.25 Magnetic attachments resist tensile separating forces, but do not prevent lateral sliding force, thus avoiding lateral stress on the implants. Strain at dislodgement is much lower than bar/clip design, which may be desirable in these types of situations for long-term implant success.21,25,28 Implants placed in the current patient extended through nonkeratinized mucosa of moderate thickness. Peri-implant mucosa is known to establish a cuff-like barrier, with collagen fibers parallel to the titanium abutment surface.18 Peri-implant mucosa may develop inflammatory reactions depending on mucosal characteristics, location of the implant platform, plaque 93
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accumulation, and design of the prosthesis.19 Excessive submucosal placement of the implant shoulder in conjunction with loosely attached, poorly keratinized, mobile tissue may be problematic19; however, soft tissue health and stability can be managed with appropriate oral hygiene maintanance.27 Alternatively, surgical reconstruction of the palate may involve free-tissue transfer using a variety of available osteocutaneous flaps, including fibula, scapula, rib, and iliac crest. Soft tissue reconstruction may provide a stable permanent partition between oral and nasal cavities; however, it gives way to gravity, distorting palatal contours and preventing access into the defect for support and retention of the prosthesis. Osteocutaneous free flaps address the maxillary bony skeleton, and dental implants can be placed secondarily for prosthetic rehabilitation. However, it is difficult to orient the bone to restore palate and maxillary form and provide an adequate amount of cheek support.10 A slit-like retentive feature can also be designed using a fibula osteocutaneous free flap allowing the obturator prosthesis to engage tissue undercut.11 Surgically reconstructed defects may or may not improve the treatment outcome when compared with conventional prosthetic rehabilitation of a nonsurgically reconstructed defect.12-14 Zygomatic implants have also been proposed in the rehabilitation of maxillary defects, but this option was eliminated because of the lack of available bone.22
SUMMARY Patients with bilateral maxillary resections present a challenging situation for the maxillofacial prosthodontist. Prosthetic rehabilitation is often difficult to achieve due to the absence of teeth, lack of favorable tissue undercuts, and presence of nonkeratinized nasal mucosa. Obturator prostheses should recreate a partition between the oral and nasal cavities to restore oral function and esthetics. This clinical report presented the prosthodontic management of a patient with a bilateral maxillectomy secondary to mucormycosis using distraction osteogenesis, bone graft, osseointegrated implants, and magnet attachments to assist with retention, support, and stability of a definitive obturator prosthesis.
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5. Karpovich-Tate N, Dewey FM, Smith EJ, Lund VJ, Gurr PA, Gurr SJ. Detection of fungi in sinus fluid of patients with allergic fungal rhinosinusitis. Acta Otolaryngol 2000;120:296-302. 6. Sonis ST, Sonis AL, Lieberman A. Oral complications in patients receiving treatment for malignancies other than of the head and neck. J Am Dent Assoc 1978;97:468-72. 7. Leitner C, Hoffmann J, Zerfowski M, Reinert S. Mucormycosis: necrotizing soft tissue lesion of the face. J Oral Maxillofac Surg 2003;61: 1354-8. 8. Shand JM, Albrecht RM, Burnett HF 3rd, Miyake A. Invasive fungal infection of the midfacial and orbital complex due to Scedosporium apiospermum and mucormycosis. J Oral Maxillofac Surg 2004;62:231-4. 9. Rieger J, Wolfaardt J, Seikaly H, Jha N. Speech outcomes in patients rehabilitated with maxillary obturator prostheses after maxillectomy: a prospective study. Int J Prosthodont 2002;15:139-44. 10. Futran ND, Wadsworth JT, Villaret D, Farwell DG. Midface reconstruction with the fibula free flap. Arch Otolaryngol Head Neck Surg 2002;128: 161-6. 11. Mukohyama H, Haraguchi M, Sumita YI, Iida H, Hata Y, Kishimoto S, et al. Rehabilitation of a bilateral maxillectomy patient with a free fibula osteocutaneous flap. J Oral Rehabil 2005;32:541-4. 12. Pigno MA. Conventional prosthetic rehabilitation after free flap reconstruction of a maxillectomy defect: a clinical report. J Prosthet Dent 2001;86:578-81. 13. Genden EM, Wallace DI, Okay D, Urken ML. Reconstruction of the hard palate using the radial forearm free flap: indications and outcomes. Head Neck 2004;26:808-14. 14. Genden EM, Okay D, Stepp MT, Rezaee RP, Mojica JS, Buchbinder D, et al. Comparison of functional and quality-of-life outcomes in patients with and without palatomaxillary reconstruction: a preliminary report. Arch Otolaryngol Head Neck Surg 2003;129:775-80. 15. Kornblith AB, Zlotolow IM, Gooen J, Huryn JM, Lerner T, Strong EW, et al. Quality of life of maxillectomy patients using an obturator prosthesis. Head Neck 1996;18:323-34. 16. Desjardins RP, Laney WR. Prosthetic rehabilitation after cancer resection in the head and neck. Surg Clin North Am 1977;57:809-22. 17. Beumer J, Curtis TA, Marunick MT. Maxillofacial rehabilitation prosthodontic and surgical consideration. St. Louis: Ishiyaku Euroamerica; 1996. p. 225-47. 18. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991; 2:81-90. 19. Berglundh T, Lindhe J, Marinello C, Ericsson I, Liljenberg B. Soft tissue reaction to de novo plaque formation on implants and teeth. An experimental study in the dog. Clin Oral Implants Res 1992;3:1-8. 20. Roumanas ED, Nishimura RD, Davis BK, Beumer J. Clinical evaluation of implants retaining edentulous maxillary obturator prostheses. J Prosthet Dent 1997;77:184-90. 21. Markt JC. An endosseous, implant-retained obturator for the rehabilitation of a recurrent central giant cell granuloma: a clinical report. J Prosthet Dent 2001;85:116-20. 22. Schmidt BL, Pogrel MA, Young CW, Sharma A. Reconstruction of extensive maxillary defects using zygomaticus implants. J Oral Maxillofac Surg 2004;62:82-9. 23. Fugazzotto PA. Success and failure rates of osseointegrated implants in function in regenerated bone for 6 to 51 months: a preliminary report. Int J Oral Maxillofac Implants 1997;12:17-24. 24. Steflik DE, Parr GR, Sisk AL, Lake FT, Hanes PJ, Berkery DJ, et al. Osteoblast activity at the dental implant-bone interface: transmission electron microscopic and high voltage electron microscopic observations. J Periodontol 1994;65:404-13. 25. Matsumura H, Kawasaki K. Magnetically connected removable sectional denture for a maxillary defect with severe undercut: a clinical report. J Prosthet Dent 2000;84:22-6. 26. Buis J, Rousseau P, Soupre V, Martinez H, Diner PA, Vazquez MP. ‘‘Distraction’’ of grafted alveolar bone in cleft case using endosseous implant. Cleft Palate Craniofac J 2001;38:405-9. 27. Giannopoulou C, Bernard JP, Buser D, Carrel A, Belser UC. Effect of intracrevicular restoration margins on peri-implant health: clinical, biochemical, and microbiologic findings around esthetic implants up to 9 years. Int J Oral Maxillofac Implants 2003;18:173-81. 28. Chung KH, Chung CY, Cagna DR, Cronin RJ Jr. Retention characteristics of attachment systems for implant overdentures. J Prosthodont 2004;13: 221-6.
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29. Block MS, Baughman DG. Reconstruction of severe anterior maxillary defects using distraction osteogenesis, bone grafts, and implants. J Oral Maxillofac Surg 2005;63:291-7. 30. Ilizarov GA. The principles of the Ilizarov method. Bull Hosp Jt Dis Orthop Inst 1988;48:1-11. 31. Karp NS, McCarthy JG, Schreiber JS, Sissons HA, Thorne CH. Membranous bone lengthening: a serial histological study. Ann Plast Surg 1992; 29:2-7. 32. McCarthy JG. The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Plast Surg 1994; 21:625-31. 33. Block MS, Almerico B, Crawford C, Gardiner D, Chang A. Bone response to functioning implants in dog mandibular alveolar ridges augmented with distraction osteogenesis. Int J Oral Maxillofac Implants 1998;13: 342-51. 34. Javid NS, Boucher CO. Flasking for easy deflasking. J Prosthet Dent 1973; 29:581-5.
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Reprint request to: DR WON-SUCK OH DEPARTMENT OF BIOLOGIC AND MATERIALS SCIENCES UNIVERSITY OF MICHIGAN SCHOOL OF DENTISTRY 1011 NORTH UNIVERSITY ANN ARBOR, MI 48109-1078 FAX: 734-763-3453 E-MAIL: [email protected] 0022-3913/$32.00 Copyright Ó 2006 by The Editorial Council of The Journal of Prosthetic Dentistry.
doi:10.1016/j.prosdent.2006.05.004
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