Reconstruction and Rehabilitation of Severe Mandibular Atrophy Using Distraction Osteogenesis Technique: A Case Report

DENTOALVEOLAR SURGERY

Reconstruction and Rehabilitation of Severe Mandibular Atrophy Using Distraction Osteogenesis Technique: A Case Report Albino Triaca, MD,* Joseph Garibaldi, MD,y Matteo Simonetti, MD,z Paolo Balbi, MD,x Nicola Laffi, MD,k and Alberto Merlini, MD{ Purpose:

The purpose of this article is to describe a rehabilitation technique for patients with severe anterior atrophy using a combination of distraction osteogenesis and implants to support fixed or removable prostheses.

Materials and Methods:

The surgical technique involves the use of an extraosseous distraction device followed by more than 14 mm of distraction of the mandibular symphysis.

Results:

The patient was successfully treated by the application of 4 implants in the region of the mandibular symphysis, stabilized by an Ackerman bar, and a removable prosthesis.

Conclusion:

Osseous distraction techniques, when possible, are preferable to block bone grafting techniques because they present considerable advantages for patients and surgeons. The combination of distraction and implant placement can rehabilitate patients with severe defects. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:2405-2418, 2014

Very often, even when not neoplastic, oral cavity masses can cause severe osseous atrophy and can be an important risk factor for mandibular fractures. Osseous mandibular deficits can be treated with osseous replacement materials, such as hydroxyapatite, or osseous transplants harvested from the calvarial bones or from the iliac crest. However, rehabilitation based on autologous bone transplantation has some limitations: the prognosis is uncertain, a harvest site is necessary, and the sequelae can sometimes be complex.1 Autogenous block bone grafting techniques pertain to maxillofacial surgery and require a general anesthetic and, normally, postsurgical hospitalization. Alternatively, in some cases, it is possible to reestablish the normal anatomy using an osseous distraction technique. This technique, introduced by Abbot2

and Codivilla3 early in the 20th century, consists of generating new bone by distraction (intramembranous histogenesis). Further studies were performed by Ilizarov4-6 who defined the first scientific protocol for human bone lengthening and highlighted the importance of slow distraction and its impact on bone healing. In fact, he observed that when using an almost continuous distraction system, histogenesis progressed more actively and it was difficult to observe the formation of a new fibrous zone between osseous fragments. However, current clinical instruments do not permit continuous distraction. In 1973, Snyder et al7 reported on the experimental use of osseous distraction in the mandible, but credit also must be attributed to McCarty8,9 for the identification of its importance in maxillofacial surgery.10

*Center for Maxillofacial Surgery, Pyramide Clinic, Zurich, Switzerland.

Address correspondence and reprint requests to Dr Simonetti: Via Capo San Rocco, 10/6, 16148 Genoa, Italy; e-mail:

yPrivate Practice, Genoa, Italy.

[email protected]

zDepartment of Oral Surgery, University of Milan, Milan, Italy;

Received March 28 2014

Private Practice, Genoa, Italy.

Accepted June 2 2014

xDepartment of Dentistry, Galliera Hospital, Genoa, Italy; Private Practice, Genoa. kDepartment of Dentistry, Galliera Hospital, Genoa, Italy; Private

Ó 2014 American Association of Oral and Maxillofacial Surgeons 0278-2391/14/01035-0$36.00/0 http://dx.doi.org/10.1016/j.joms.2014.06.418

Practice, Genoa. {Department of Dentistry, Galliera Hospital, Genoa, Italy; Private Practice, Genoa.

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FIGURE 1. Lesion in the region of the mandibular symphysis, which showed an angio-granulomatous inflammatory process with phlogistic and reactive features at histology. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

This method has been used in orthopedics and traumatology to correct congenital deformities, complications derived from incongruous wound healing, and osseous losses from the resection of limb neoplasms. In contrast to transplantation techniques, which lead to a stiff outcome, osseous distraction makes progressive morphologic correction possible, by which the bone can be modeled in different shapes to rectify skeletal asymmetries or deformities.11-13 However, osseous distraction requires a plan that considers the distraction vector characteristics that must be taken into account to activate the distraction system. The effects of distraction have to be considered in 3 dimensions to evaluate the post-treatment osseous morphology.14 The aim of this article is to describe a rehabilitation technique for patients with severe anterior atrophy using a combination of distraction osteogenesis and implants to support fixed or removable prostheses.

Materials and Methods A 52-year-old woman presented to the authors’ clinic with the chief complaint of a lesion in the region of the mandibular symphysis (Fig 1). The patient was a heavy smoker (20 cigarettes per day), had been wearing a removable partial denture for 15 years, and had noticed oral mucosal changes only in the past few months, after the development of pain. Because the clinical appearance and the history were nonspecific, it was necessary to perform a rapid biopsy examination followed by histology, which showed an angio-granulomatous inflammatory process with reactive features. Therefore, the dental foci were rehabilitated with adequate wide-spectrum antibiotics. Even with pharmacologic treatment, the lesion exhibited slow remission; therefore, a swab for culture and sensitivity was used to identify the responsible pathogens and to institute specific treatment. Tissue

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FIGURE 2. Orthopantomogram obtained before bone distraction device placement. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 3. Incision area in the symphyseal mandibular region drawn with a marking pen. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 4. Incision and elevation of flaps to access the mandibular bone. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 5. Osteotomy of the mandibular symphysis using a Lindemann bur and chisels. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 6. Drilling of the mandibular symphysis to place the bone distraction device. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 7. Placement of the 2 bone distraction devices before suturing. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 8. Suture of flaps. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 9. Activation of bone distractor devices on day 7, with 1 complete turn per day, which corresponds to 1 mm. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 10. Orthopantomogram after bone distraction device placement before activation. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 11. Orthopantomogram after bone distraction device placement after activation. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 12. Panorex radiograph after bone distraction device placement after 14 days. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 13. Cone-beam radiograph after bone distraction device placement after 14 days. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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healing with restoration of the integument was obtained within 1 month. The patient re-presented 1 year later with severe difficulties in wearing the total prosthesis. Oral examination showed severe osseous atrophy, with total loss of the vestibular fornix and a shallow mandibular spine. Orthopantomogram and cephalometric radiograph showed marked reabsorption of the mandible in the symphyseal region after the infection. Obviously, with such atrophy, the use of prosthetic implants was not an option (Fig 2). In agreement with the patient, who was not inclined to undergo general anesthesia, a distractor was applied to the intraforaminal region; the patient was informed about the possible risks of fracture (Figs 3-10). The distractor was positioned after osteotomy of the mandibular symphysis using a Lindemann bur and chisels. Seven days after application, the distractor was activated by tightening the screws 1 full turn per day and diverting the osseous segment from the mandibular body at the rate of 1 mm/day for 2 weeks (Figs 11-16). After having obtained the desired distraction of 14 mm, the authors waited 3 months to remove the distractor to achieve complete osseous mineralization (Figs 17-20). This study was approved by the institutional review board of Galliera Hospital (Genoa, Italy) and all participants signed an informed consent agreement. FIGURE 14. Bone distraction device. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 15. Bone distraction device before activation. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 16. Bone distraction device after activation. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

FIGURE 17. Cephalometric radiograph at 3 months after removal of the distractor. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 18. Cone-beam radiograph with surgical guide at 3 months after removal of the distractor. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

Results

Discussion

Cone-beam radiography showed not only the degree of osseous increment (14 mm), but also the adequate 3-dimensional osseous distribution achieved. The patient achieved successful rehabilitation by the application of 4 implants in the mandibular symphysis region, stabilized by an Ackerman Bar, and an overdenture (Figs 21-23).

Treatment of severe maxillary osseous atrophy relies on bone grafts harvested from extraoral sites. These techniques require 2 surgical sites, a general anesthetic, and postsurgical hospitalization. A good outcome of those surgeries is determined by the primary healing of tissues over the graft, because early or late exposure of the graft causes partial or total loss of the graft.

FIGURE 19. Cone-beam radiograph with surgical guide at 3 months after removal of the distractor. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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FIGURE 20. Cone-beam radiograph with surgical guide at 3 months after removal of the distractor. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

Alternatively, in some cases, it is possible to use the osseous distraction technique. This technique does not generally require a general anesthetic or postsurgical hospitalization. Two surgical sites are not necessary, thus lowering the morbidity rate. Moreover, there

are fewer difficulties in handling the soft tissues that are involved in the distraction process. The critical points are correct presurgical planning and the possibility to use distractors, which allow correct 3dimensional planning of the forces.

FIGURE 21. Orthopantomogram after implant placement. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

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To solve this complication, Chin16 proposed the use of an orthodontic appliance to guide the threaded rod. However, this requires that the edentulous space should have teeth at both extremes.

FIGURE 22. Ackerman bar positioned after distraction and implant placement. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

In their article, Garcia et al15 wrote: . an understanding of the potential complications of a given surgical technique, and of appropriate treatments, is fundamental for correct implementation of that technique. Fracture of the transport segment during osteotomy is a complication that can be avoided only by preventative measures. The thickness of the transport segment should be sufficient to withstand the osteotomy maneuvers. Care should be taken in manipulation, and no attempt should be made to move the segment until the osteotomy is complete. Inappropriate direction of distraction may be due to any of several factors. Generally, the distractor will tend to lean to the lingual side. The hole drilled for insertion of the threaded rod may be angled incorrectly.

FIGURE 23. Overdenture. Triaca et al. Rehabilitation of Severe Mandibular Atrophy. J Oral Maxillofac Surg 2014.

When the distractor is assembled and positioned, it is thus important to bear in mind the forces exerted by the lingual mucoperiosteum attached to the segment and to angle the threaded rod slightly outward to compensate for this force during distraction. Perforation of the mucosa by the sharp edges of the transport segment is typically observed as the distraction proceeds. Elimination of the sharp edges allows rapid growth of the mucosa over the bone, in contrast to the situation expected with a free bone graft. In any case this complication does not require interruption of the distraction procedure. Suture dehiscence can be observed in some distraction procedures but does not constitute a problem; indeed, it is not even necessary to interrupt the distraction procedure. The transport segment is vascularized, so epithelium grows normally over it.15 Another complication can be bone formation defects. Klug et al17 proposed that complications of this type can be avoided by fitting a titanium membrane over the defect immediately after osteotomy, to avoid invasion by connective tissue, but this technique may give rise to further complications, such as exposure of the titanium membrane.15 Complications that involve the inferior dental nerve are very infrequent, but especially affect atrophic mandibles.15 Other complications are fracture of the distractor during mandibular alveolar distraction18 or, as presented at the XVth Congress of the European Association for Cranio-Maxillofacial Surgery (Edinburgh, UK; September 5-9, 2000), complications such as dysesthesia of the mental nerve and mandibular fracture.15,17-20 Osseous distraction techniques, when possible, are preferable to bony block grafting techniques because they present considerable advantages for patients and surgeons. Bone grafting techniques require 2 surgical sites and, if the bone is taken from the hip or shin, require general anesthesia and hospitalization. In addition, bone block resorption is not predictable. Distraction osteogenesis is safer, has a low incidence of complications, and has a predictable outcome. Patient compliance during the entire treatment period is essential; thus, careful patient selection is

2418 extremely important. If there is any doubt about presumptive compliance, one should consider alternative options to prevent disappointment for all concerned.21-24 Subsequent implant placement can be used to treat patients with severe maxillary atrophy and fixed or removable prostheses.

References 1. Diemunsch C, Faure F, Trunde F, et al: Three-dimensional modeling system for unilateral mandibular bone distraction: A clinical case. Comput Aided Surg 12:262, 2007 2. Abbot LC: The operative lengthening of the tibia and fibula. J Bone Joint Surg Am 9:128, 1927 3. Codivilla A: On the means of lengthening in the lower limbs, the muscles and tissues which are shortened through deformity. Am J Orthop Surg 2:353, 1905 4. Ilizarov GA, Smelyshev NN: Lengthening of the femur with simultaneous closed arthrodesis of the hip joint. Orthop Travmatol Protez 33:62, 1972 5. Ilizarov GA: The tension-stress effect on the genesis and growth of tissues: I. The influence of stability of fixation and soft-tissue preservation. Clin Orthop 238:249, 1989 6. Ilizarov GA: The tension-stress effect on the genesis and growth of tissues: II. The influence of the rate and frequency of distraction. Clin Orthop 239:263, 1989 7. Snyder CC, Levine GA, Swanson HM, et al: Mandibular lengthening by gradual distraction. Plast Reconstr Surg 51:506, 1973 8. McCarthy JG: Mandibular bone lengthening. Oper Tech Plast Reconstr Surg 1:99, 1994 9. McCarthy JG: The role of distraction osteogenesis in the reconstruction of the mandible in unilateral craniofacial microsomia. Clin Tech Plast Surg 1:105, 1994 10. Kessler P, Neukam FW, Wiltfang J: Effects of distraction forces and frequency of distraction on bony regeneration. Br J Oral Maxillofac Surg 43:392, 2005

REHABILITATION OF SEVERE MANDIBULAR ATROPHY 11. Cope JB, Samchukov ML, Cherkashin AM: Mandibular distraction osteogenesis: A historic perspective and future directions. Am J Orthod Dentofacial Orthop 115:448, 1999 12. Costantino P, Shybut G, Friedman C, et al: Segmental mandibular regeneration by distraction osteogenesis: An experimental study. Arch Otolaryngol Head Neck Surg 116:535, 1990 13. Karp NS, Thorne CM, MacCarthy JG, et al: Bone lengthening in the craniofacial skeleton. Ann Plastic Surg 24:231, 1990 14. Gaggl A, Schultes G, Santler G, et al: Three-dimensional planning of alveolar ridge distraction by means of distraction implants. Comput Aided Surg 5:35, 2000 15. Garcia AG, Martin MS, Vila PG, et al: Minor complications arising in alveolar distraction osteogenesis. J Oral Maxillofac Surg 60: 496, 2002 16. Chin M: Distraction osteogenesis for dental implants. Atlas Oral Maxillofac Clin North Am 7:41, 1999 17. Klug C, Millesi G, Millesi W, et al: Vertical callus distraction for mandibular augmentation: L-shaped osteotomy and GBR by titanium membranes. J Craniomaxillofac Surg 28(suppl 3):55, 2000 18. Gaggl A, Schultes G, K€archer H: Distraction implants in alveolar ridge augmentation: A 2-year follow-up. J Craniomaxillofac Surg 28(suppl 3):101, 2000 19. Nocini PF, Wangerin K, Cortelazzi R, et al: Distraction osteogenesis in preprosthetic surgery. J Craniomaxillofac Surg 28(suppl 3):100, 2000 20. Millesi-Schobel GA, Millesi W, Glaser C, et al: The L-shaped osteotomy for vertical callus distraction in the molar region of the mandible: A technical note. J Craniomaxillofac Surg 28: 176, 2000 21. van Strijen PJ, Breuning KH, Becking AG, et al: Complications in bilateral mandibular distraction osteogenesis using internal devices. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 96: 392, 2003 22. Triaca A, Antonini M, Minoretti R, et al: Segmental distraction osteogenesis of the anterior alveolar process. J Oral Maxillofac Surg 59:26, 2001 23. Triaca A, Minoretti R, Merz B: Treatment of mandibular retrusion by distraction osteogenesis: A new technique. Br J Oral Maxillofac Surg 42:89, 2004 24. Triaca A, Minoretti R, Merz BR: Distraction osteogenesis of the mandibular angle and inferior border to produce facial symmetry: Case report. J Oral Maxillofac Surg 58:1051, 2000