- Email: [email protected]
Intraoral bone transport in clefting
Oral Maxillofacial Surg Clin N Am 14 (2002) 509 – 523
Intraoral bone transport in clefting Cesar A. Guerrero, DDS Santa Rosa Oral and Maxillofacial Surgery Center, Centro Integral Santa Rosa #105, Caracas 1061, Venezuela
Distraction osteogenesis is a surgical technique based on the principle of ‘‘tension-stress’’ that allows bone and soft tissue lengthening through a progressively controlled fracture separation [1,2]. Since its introduction in the field of oral and maxillofacial surgery [3 – 12], the research has been oriented to decreasing the surgical insult by better instrumentation, miniaturizing the distraction devices, developing multidirectional distractors, and using the intraoral route to avoid facial scars and social inconvenience [13 – 19]. All new technology requires a time of introduction during which surgeons cautiously await refinements, improved instrumentation, variation on surgical techniques, and, most importantly, well-analyzed postoperative data. The latest research on biology and biomechanics has been oriented to speeding up the healing process by means of finding ideal surgical management and the use of products (eg, bone morphogenetic proteins, platelet-rich plasma, and particulate bone grafts) that might help the healing process. In terms of biomechanics, smaller but stronger intraoral distractors have been developed, unidirectional, bidirectional, and multidirectional vector appliances are on the market, and some of the devices could be changed easily from one direction to a corrected one as the occlusion requires. All the recent efforts in distractor development and design have been designed to return patients to regular activities 2 to 3 weeks after surgery on a soft to regular diet and without being cosmetically impaired (Figs. 1 – 19). In cleft patients, distraction osteogenesis can play a role in certain deficiency situations with high failure rate, as in bone grafting in adult alveolar clefts. Alveolar clefts in untreated patients after the age of 8 to 11 years are difficult to treat. The teeth next to
E-mail address: [email protected]
the cleft are partially erupted and are often poorly aligned in the alveolus, which limits the possibility to place a bone graft successfully and adequately create a watertight buccal, palatine, and nasal surfaces closure. The saliva and bacteria could contaminate the graft through the periodontal ligament or through the wound, which produces partial or total graft failure. The indications for alveolar reconstruction are maxillary discontinuity, lack of adequate alveolar bone, oronasal fistulas, lack of nasal base support, unstable orthodontic treatment, and unpleasant gingival contour when smiling. The possibility of using distraction osteogenesis to treat alveolar clefts after the age of 13 years seems attractive to avoid all the complications related to bone grafts or the use of fixed prostheses. Two publications open the door to this new field of distraction osteogenesis [20,21]. Currently, surgeons, orthodontists, periodontists, and prosthodontists are working to define the precise indications of distraction osteogenesis over traditional surgery. When and how to obtain the maximum benefit from existing distraction techniques, the long-term stability, and predictability and quantifying the need for overcorrection is being investigated. Several scientific articles already have been written on the healing variables that may alter the final clinical outcome, most common complications, and their management [22 – 28].
Intraoral bone transport The pioneering work of Costantino et al [29] demonstrated the possibility of reconstructing the mandible in dogs and in humans based on the surgical principles of Ilizarov. An osteotomy is performed in a nontreated area, and a bony segment is transported through soft tissue guided by a distraction device
1042-3699/02/$ – see front matter D 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 9 9 ( 0 2 ) 0 0 0 5 2 - 3
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C.A. Guerrero / Oral Maxillofacial Surg Clin N Am 14 (2002) 509–523
Fig. 1. (A) Preoperative frontal view of a 12-year-old boy with left alveolar cleft. (B) Intraoral frontal view.
until there is an abutment between the transported bone or disc to the docking site (bone host), which creates bone continuity by the distraction healing process. Other researchers [30,31] used different extraoral devices to repeat the mandibular reconstruction obtained by Costantino. A major step forward
was to obtain similar clinical results with the use of internal distractors [32,33]. Some clinical situations proved difficult to manage, however. Because of the shape of the mandible, it was difficult to achieve the width and height that were needed in the reconstruction for dental implant placement in long segment
Fig. 2. (A,B) Diagrams show the alveolar defect and the treatment planning by intraoral bone transport.
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Fig. 3. (A,B) The alveolar defect and the segmental osteotomy design to perform the alveolar bone transport for reconstruction.
reconstruction. It was also understood that the distraction osteogenesis process happens from the point of origin to the point of destination. When the disc was transported along a curve, the collagen fibers within the distraction site that eventually would mineralize always followed a straight line pattern.
Another important issue was the reconstruction of long defects. Ilizarov confronted this situation in the treatment of the limbs. Because the bone segments travel a long way, the patients and animal research subjects showed a contraction of the periosteum that eventually would form thinner bone, which creates a
Fig. 4. (A) A small vertical incision is made deep in the sulcus to osteotomize the transport disk. The bone cut starts with a 701 bur in the cortical bone above and high between the dental roots under abundant irrigation. (B) A spatula osteotome is used through the small incision to complete the osteotomy. (C) Left maxillary segment repositioning with orthognathic surgery and rigid fixation to close the open bite. (D) Intraoral distractor placement after the osteotomies are completed and wounds are closed. Note the superior arms fixed with bicortical screws to gain bone anchorage and the inferior arms interdentally attached with the use of wires and acrylic.
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required, and as an alternative for high surgical costs and long hospitalizations.
Surgical technique in the cleft patient
Fig. 5. After a 7-day latency period the appliance is activated 1 mm per day until the desired movement is achieved. Acrylic is placed on top of the device to resume regular diet.
problem called hourglass deformity. This would be the weakest point in the healed bone. A possible remedy for larger segments or a way to go around a curve is to create two discs that come into the midline using the same surgical principles of distraction. This procedure is called bifocal or trifocal bone transport according to the clinical situation, and it was possible to use two different distraction vectors to obtain a particular bone shape as needed. The intraoral bone transport technique has been used to treat patients after gunshot wounds, benign and malignant tumor removal, osteomyelitis, and malunion. It is indicated as the first surgical alternative in patients with a poor prognosis or reinterventions, for medically compromised individuals when minimal surgery and no bone grafts are
Patients should undergo orthodontic treatment when teeth are aligned and leveled in segments and rectangular arch wires are placed. The mechanics are not oriented to move the anterior teeth into the alveolar cleft if the root is exposed to the cleft because saliva and bacteria infiltrate, which causes chronic periodontal disease and a poor environment for grafting. A surgeon’s biggest challenge is to adequately create a three-dimensional soft tissue envelope to locate the grafting material properly. Even if this goal is achieved with delicate and meticulous surgery, saliva and bacteria contaminate the graft through the periodontal ligament. Using bone transport, the surgeon can decrease the size of the recipient site and enlarge the soft tissues around the site. The metabolic activity of the distraction process also augments the local blood supply, stem cells, and nutrients. A small incision at the depth of the vestibule is made through the mucosa, muscles, and periosteum. The soft tissues are carefully elevated and small retractors are used to expose the bone adequately. An interdental osteotomy is performed under abundant irrigation. Bone overheating should be avoided at all times. The bony segment is completely separated with the use of a spatula osteotome. The surgical wound is closed carefully. The periosteal layer, which is responsible for most of the bone
Fig. 6. (A,B) Docking site surgery. Once the distraction disk has reached the objective area, the epithelium between the bone surfaces is removed. A 701 bur is used to drill holes and make the bone bleed, cancellous autologous bone grafts are obtained either from the chin or the tuberosity, and the grafts are placed over the docking area. Finally, a posterior sliding flap is elevated and advanced and a water-tight closure is performed.
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Fig. 7. (A – C) An occlusal view shows a severe bone discontinuity on the left side and its alveolar reconstruction after bone transport. A palatal splint was used to maintain the orthognathic surgery on the left segment. A plastic pontic is placed over the distraction area awaiting the mineralization for implant positioning. The palatal fistula was closed using a lateral palatal flap during the docking site surgery.
healing process, must be reunited meticulously. A miniaturized distraction device is used to separate the osteodental segment from its original position progressively, which decreases the size of the alveolar cleft because the distractor is activated. The device must be attached firmly to the bone disc and to the
Fig. 8. Dental photograph shows the alveolar reconstruction using bone transport.
maxilla. Too much motion between the fragments results in the development of fibrous and cartilaginous tissue. Minimal micromotion is obtained by cutting the distractor arms to the smallest size possible. The device is fixed to the basal bone with long screws, and at the tooth level interdental wires covered with dental resin or acrylic for rigidity are used. The wiring avoids any damage to the dental structures by screws. A latency period of 7 days is enacted before activation begins at 0.5 mm twice a day. Activation is continued until the mucosa of the two fragments meets. When the disc or bullet arrives at the target area, the patient is scheduled for the second stage surgery. Once the two segments are together a second surgery, called ‘‘the docking site surgery,’’ is needed. In the orthopedic literature there are reports about activating the appliance after the disc or bullet has approached the docking site to create a fusion between the two segments. The fragments in the maxilla are so small, however, that they cannot fuse. Because of this inability, the following steps are taken: removing the epithelium between the two bone
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Fig. 9. (A – C) Panoramic radiographs show the defect, the appliance positioning, and appearance 12 days after activation.
fragments, preparing the two borders by removing the cartilage-like tissue that develops as the disc travels through the softer tissues, perforating the bony edges with a 701 bur to produce internal bleeding, and obtaining bone graft either from the chin or tuberosity areas, which is placed over the joining bones. After the cartilage-like tissue is removed, a space is created, usually between 4 and 6 mm. The distractor should be activated to consolidate bone fragments together by an immediate movement and not the usual 1 mm a day. An alternative possibility could be the use of one or two lighter plates. Different soft tissue designs can be used to cover the docking site area properly, especially after the placement of intraoral bone grafts. Advancing, sliding, or three-dimensional flaps could be used. Improper management of this surgical stage ends in malunion, fibrous union, or bone segment dislocation, which happens if the docking site is wide or if the bone graft is contaminated with saliva and bone resorption occurs. Clinical judgment is needed to determine the best approach for the particular reconstruction and choose from the different ways to consolidate the two bony fragments. The distraction process ends once the mineralization process is completed, usually 10 to 12 months after surgery.
Important variables that may modify the surgical outcome include age of the patient, amount of movement, quality and quantity of bone, surgical technique (clean cuts under abundant irrigation), and adequate wound closure without gaps that allows postoperative contamination of saliva and food. The presence of an infection in the distraction site partially or completely stops the healing process and creates a situation that ranges from a nonunion to partial mineralization. These clinical situations are accompanied by correspondent radiologic findings, which were reported by Samchukov. Although the oral cavity is well vascularized and infections are rarely seen after distraction osteogenesis, the surgical principles must be kept in mind to avoid surgical complications.
Summary The advantages of this technique over the traditional alveolar reconstruction are as follows: no need for bone grafts, which involve a donor site, minimal surgical time, no hospitalization, progressive improvement with excellent psychological adaptation, bone height and width that are similar to the neighboring alveolus with excellent possibilities for
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Fig. 10. (A) Frontal view of a 25-year-old woman with bilateral alveolar cleft after premaxillectomy. (B) Intraoral frontal view shows the discontinuity defect in the anterior maxilla. (C,D) Preoperative dental lateral views. (E) Preoperative occlusal view shows the alveolar defect and the oronasal communication.
dental implants, and a natural reconstruction that aids the orthodontist with final tooth movement. Finally, the morbidity is minimal. The disadvantages are few; long treatment requires patient cooperation and close follow-up. Implant placement ideally should happen 6 to 8 months after the initial surgery. A crestal incision is made to expose the newly developed alveolar bone, and a fixture of adequate size and length is inserted. If
further bone augmentation is needed on the buccal side of the alveolus, the bone collected from the suction tramp may be mixed with alloplastic materials and layered over. A collagen membrane also may be used. The alternatives of taking grafts from the chin or tuberosity also may be considered. There is still the chance to augment the soft tissues at the uncovering stage by various surgical techniques to obtain an ideal alveolar ridge.
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Fig. 11. Diagram shows the treatment planning to reconstruct the anterior maxilla by intraoral bone transport.
Fig. 12. (A) A reconstruction plate is countered and fixed to teeth using interdental wires and acrylic to serve as a guide in the bone transport movement reconstructing the maxillar normal shape. (B) A small incision is made and a osteotomy of the transport disk is performed in both sides of the alveolar discontinuity defect. (C) After water-tight closure, the intraoral devices are placed over the reconstruction plate using transmucosal 2-mm screws and interdental wires.
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Fig. 13. (A – C) After the distraction surgery is accomplished, a 7-day latency period follows and the activation period starts at a 1-mm per day rate until the reconstruction of the continuity defect is achieved. (D) Occlusal view in the activation period. Observe that the nasal communication no longer exists.
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Fig. 14. (A – E) Clinical follow-up of the reconstruction process in the right side of the alveolar defect. Preoperative, after distractor removal, implant placement, abutment preparation, and temporary prosthesis views demonstrate the real maxillary reconstruction obtained with this technique.
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Fig. 15. (A – E) Clinical sequence on the left side. Observe the new tissues created for implant placement and further reconstruction with provisional prosthesis over implants.
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Fig. 16. (A,B) Note the important changes in the dental frontal view. The anteroposterior deficiency was corrected with the forward projection of the bone segments.
Fig. 17. (A – D) Occlusal view of the reconstruction stages when using bone transport by distraction osteogenesis.
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Fig. 18. (A – E) To correct the alveolar defect, a transport disk was design bilaterally taking two teeth in either side. A trifocal bone transport was performed to create new bone that would serve as the implant’s host. Observe how the distraction site has ossified.
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Fig. 19. (A,B) Profile views before and after distraction osteogenesis was accomplished.
References [1] Ilizarov GA. The tension-stress effect on the genesis and growth of tissues. In: Ilizarov GA, editor. Transosseous osteosynthesis. Berlin: Springer-Verlag; 1992. p. 137 – 255. [2] Wagner H. Operative lengthening of the femur. Clin Orthop Rel Res 1978;136:125 – 42. [3] Bell WH, Epker BN. Surgical orthodontic expansion of the maxilla. Am J Orthod 1976;70:517 – 8. [4] Guerrero C. Expansio´n mandibular quiru´rgica. Rev Venez Ortod 1990;48:48 – 50. [5] McCarthy JG, Schreiber J, Karp N, Thorne CH, Grayson BH. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 1992;89:1 – 10. [6] Molina F, Ortiz Monasterio F. Mandibular elongation and remodeling by distraction: a farewell to major osteotomies. Plast Reconstr Surg 1995;96:825 – 40. [7] Wangerin K, Gropp H. Intraoral distraction osteogenesis for lengthening of the horizontal mandibular ramus. International Congress on Cranial and Facial Bone Distraction Processes 1997; paper #36. [8] Diner PA, Kollar EM, Viguier E, Maurin N, Vazquez MP. Intraoral submerged bidirectional device for man-
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dibular distraction. In: Diner PA, Vazquez MP, editors. International Congress on Cranial and Facial Bone Distraction Processes. Paris: Monduzzi; 1997. p. 67 – 74. Walker D, Nish I. Multi-directional buried mandibular distraction osteogenesis appliances and techniques. J Craniofac Surg 1998;26:205. Karaharju-Suvanto T, Peltonen J, Kahri A, et al. Distraction osteogenesis of the mandible: an experimental study on sheep. J Oral Maxillofac Surg 1992;21: 118 – 21. Guerrero CA, Flores A, Bell WH. Intraoral mandibular distraction osteogenesis. J Oral Maxillofac Surg 1994; 52(Suppl):115 – 6. Block MS, Brister GK. Use of distraction osteogenesis for maxillary advancement: preliminary results. J Oral Maxillofac Surg 1992;52:282 – 91. Hoffmeister B, Wangerin K. Callus distraction technique by an intraoral approach: the floating bone concept. Int J Oral Maxillofac Surg 1997;26(Suppl 1):76. Cohen SR, Rutrick RE, Burstein FD. Distraction osteogenesis of the human craniofacial skeleton: initial experience with a new distraction system. J Craniofac Surg 1995;6:368 – 74. Chin M, Toth BA. Distraction osteogenesis in maxil-
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lofacial surgery using internal devices: report of five cases. J Oral Maxillofac Surg 1996;54:45 – 53. Samchucov ML, Cherkashin AM, Cope JB. Distraction osteogenesis: history and biologic basis of new bone formation. In: Lynch SE, Genco RJ, Marx RE, editors. Tissue engineering: applications in maxillofacial surgery and periodontics. Quintessence: Carol Springs, IL; 1999;131 – 46. Cope J, Samchukov ML, Cherkashin AM, Wolford LM, Franco PF. Biomechanics of mandibular distractor orientation: an animal model analysis. J Oral Maxillofac Surg 1999;57:952 – 62. Bell WH, Gonzalez M, Samchukov ML, Guerrero CA. Intraoral widening and lengthening of the mandible in baboons by distraction osteogenesis. J Oral Maxillofac Surg 1999;57:548 – 62. Oda T, Sawaki Y, Ueda M. Experimental alveolar ridge augmentation by distraction osteogenesis using a simple device that permits secondary implant placement. Int J Oral Maxillofac Surg 2000;15:95 – 102. Guerrero CA, Bell WH, Meza LS. Intraoral distraction osteogenesis: maxillary and mandibular lengthening. Atlas Oral Maxillofac Surg Clin North Am 1999;7: 111 – 51. Liou EJW, Chen PKT, Huang C, Chen YR. Interdental distraction osteogenesis and rapid orthodontic tooth movement: a novel approach to approximate a wide alveolar cleft or bony defect. Plast Reconstr Surg 2000;4:1262 – 72. Guerrero CA, Contasti GI. Transverse mandibular deficiency. In: Bell WH, editor. Modern practice in orthognathic and reconstructive surgery. Philadelphia: WB Saunders; 1992. p. 2383 – 97. Epker BN. Distraction osteogenesis for mandibular widening. Atlas Oral Maxillofac Surg Clin N Am 1999;7:29 – 39. Perrott DH, Berger R, Vargervik K, Kaban LB. Use of a skeletal distraction device to widen the mandible: a case report. J Oral Maxillofac Surg 1993;51:435 – 8. Guerrero CA, Bell WH. Intraoral distraction. In: McCarthy JG, editor. Distraction of the craniofacial skeleton. New York: Springer-Verlag; 1999. p. 219 – 48.
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[26] Contasti GI, Rodriguez AM, Guerrero CA. Orthodontics in intraoral mandibular distraction osteogenesis. In: Samchucov ML, Cope JB, Cherkashin AM, editors. Craniofacial distraction osteogenesis. St. Louis: CV Mosby; 2001. p. 149 – 55. [27] Ueda M. Maxillofacial bone distraction processes using osseointegrated implants and an intraoral device. In: Diner PA, Vasquez MP, editors. International Congress on Cranial and Facial Bone Distraction Processes. Paris: Monduzzi; 1997. p. 75 – 84. [28] Guerrero CA, Gonzalez M, Laplana R, Rojas A. Reconstrucß a˜o do rebordo alveolar mediante distracß a˜o ostogeˆnica para implantes osseointegrados. In: Dinato JC, Polido W, editors. Implantes osseeointegrados: cirugia e pro´ tese. Sao Paolo, Brazil: Artes Me` dicas; 2001. p. 423 – 39. [29] Costantino PD, Shybut G, Friedman CD, et al. Segmental mandibular regeneration by distraction osteogenesis: an experimental study. Arch Otolaryngol Head Neck Surg 1990;116:535 – 45. [30] Fedotov SN. Dosed distraction of the mandible fragments by extra-mouth apparatus in patients with bone defect and mandible fractures. In: Diner PA, Vasquez MP, editors. International Congress on Cranial and Facial Bone Distraction Processes. Paris: Monduzzi; 1997. p. 155 – 60. [31] Klein C. Craniofacial distraction osteogenesis using the ‘‘Frankfurt Craniofacial Distraction Systems.’’ In: Diner PA, Vasquez MP, editors. International Congress on Cranial and Facial Bone Distraction Processes. Paris: Monduzzi; 1997. p. 345 – 51. [32] Guerrero CA, Bell WH, Gonzalez M, Figueroa F. Maxillo-mandibular reconstruction by intraoral bone transport. In: Arnaud E, Diner PA, editors. International Congress on Cranial and Facial Bone Distraction Processes. Paris: Monduzzi; 2001. p. 569 – 74. [33] Guerrero C, Bell W, Gonzalez M, Meza L. Intraoral distraction osteogenesis (bone transport). In: Fonseca R, editor. Oral and maxillofacial surgery. Philadelphia: WB Saunders; 2000. p. 343 – 402.
Intraoral bone transport in clefting Cesar A. Guerrero, DDS Santa Rosa Oral and Maxillofacial Surgery Center, Centro Integral Santa Rosa #105, Caracas 1061, Venezuela
Distraction osteogenesis is a surgical technique based on the principle of ‘‘tension-stress’’ that allows bone and soft tissue lengthening through a progressively controlled fracture separation [1,2]. Since its introduction in the field of oral and maxillofacial surgery [3 – 12], the research has been oriented to decreasing the surgical insult by better instrumentation, miniaturizing the distraction devices, developing multidirectional distractors, and using the intraoral route to avoid facial scars and social inconvenience [13 – 19]. All new technology requires a time of introduction during which surgeons cautiously await refinements, improved instrumentation, variation on surgical techniques, and, most importantly, well-analyzed postoperative data. The latest research on biology and biomechanics has been oriented to speeding up the healing process by means of finding ideal surgical management and the use of products (eg, bone morphogenetic proteins, platelet-rich plasma, and particulate bone grafts) that might help the healing process. In terms of biomechanics, smaller but stronger intraoral distractors have been developed, unidirectional, bidirectional, and multidirectional vector appliances are on the market, and some of the devices could be changed easily from one direction to a corrected one as the occlusion requires. All the recent efforts in distractor development and design have been designed to return patients to regular activities 2 to 3 weeks after surgery on a soft to regular diet and without being cosmetically impaired (Figs. 1 – 19). In cleft patients, distraction osteogenesis can play a role in certain deficiency situations with high failure rate, as in bone grafting in adult alveolar clefts. Alveolar clefts in untreated patients after the age of 8 to 11 years are difficult to treat. The teeth next to
E-mail address: [email protected]
the cleft are partially erupted and are often poorly aligned in the alveolus, which limits the possibility to place a bone graft successfully and adequately create a watertight buccal, palatine, and nasal surfaces closure. The saliva and bacteria could contaminate the graft through the periodontal ligament or through the wound, which produces partial or total graft failure. The indications for alveolar reconstruction are maxillary discontinuity, lack of adequate alveolar bone, oronasal fistulas, lack of nasal base support, unstable orthodontic treatment, and unpleasant gingival contour when smiling. The possibility of using distraction osteogenesis to treat alveolar clefts after the age of 13 years seems attractive to avoid all the complications related to bone grafts or the use of fixed prostheses. Two publications open the door to this new field of distraction osteogenesis [20,21]. Currently, surgeons, orthodontists, periodontists, and prosthodontists are working to define the precise indications of distraction osteogenesis over traditional surgery. When and how to obtain the maximum benefit from existing distraction techniques, the long-term stability, and predictability and quantifying the need for overcorrection is being investigated. Several scientific articles already have been written on the healing variables that may alter the final clinical outcome, most common complications, and their management [22 – 28].
Intraoral bone transport The pioneering work of Costantino et al [29] demonstrated the possibility of reconstructing the mandible in dogs and in humans based on the surgical principles of Ilizarov. An osteotomy is performed in a nontreated area, and a bony segment is transported through soft tissue guided by a distraction device
1042-3699/02/$ – see front matter D 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 9 9 ( 0 2 ) 0 0 0 5 2 - 3
510
C.A. Guerrero / Oral Maxillofacial Surg Clin N Am 14 (2002) 509–523
Fig. 1. (A) Preoperative frontal view of a 12-year-old boy with left alveolar cleft. (B) Intraoral frontal view.
until there is an abutment between the transported bone or disc to the docking site (bone host), which creates bone continuity by the distraction healing process. Other researchers [30,31] used different extraoral devices to repeat the mandibular reconstruction obtained by Costantino. A major step forward
was to obtain similar clinical results with the use of internal distractors [32,33]. Some clinical situations proved difficult to manage, however. Because of the shape of the mandible, it was difficult to achieve the width and height that were needed in the reconstruction for dental implant placement in long segment
Fig. 2. (A,B) Diagrams show the alveolar defect and the treatment planning by intraoral bone transport.
C.A. Guerrero / Oral Maxillofacial Surg Clin N Am 14 (2002) 509–523
511
Fig. 3. (A,B) The alveolar defect and the segmental osteotomy design to perform the alveolar bone transport for reconstruction.
reconstruction. It was also understood that the distraction osteogenesis process happens from the point of origin to the point of destination. When the disc was transported along a curve, the collagen fibers within the distraction site that eventually would mineralize always followed a straight line pattern.
Another important issue was the reconstruction of long defects. Ilizarov confronted this situation in the treatment of the limbs. Because the bone segments travel a long way, the patients and animal research subjects showed a contraction of the periosteum that eventually would form thinner bone, which creates a
Fig. 4. (A) A small vertical incision is made deep in the sulcus to osteotomize the transport disk. The bone cut starts with a 701 bur in the cortical bone above and high between the dental roots under abundant irrigation. (B) A spatula osteotome is used through the small incision to complete the osteotomy. (C) Left maxillary segment repositioning with orthognathic surgery and rigid fixation to close the open bite. (D) Intraoral distractor placement after the osteotomies are completed and wounds are closed. Note the superior arms fixed with bicortical screws to gain bone anchorage and the inferior arms interdentally attached with the use of wires and acrylic.
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required, and as an alternative for high surgical costs and long hospitalizations.
Surgical technique in the cleft patient
Fig. 5. After a 7-day latency period the appliance is activated 1 mm per day until the desired movement is achieved. Acrylic is placed on top of the device to resume regular diet.
problem called hourglass deformity. This would be the weakest point in the healed bone. A possible remedy for larger segments or a way to go around a curve is to create two discs that come into the midline using the same surgical principles of distraction. This procedure is called bifocal or trifocal bone transport according to the clinical situation, and it was possible to use two different distraction vectors to obtain a particular bone shape as needed. The intraoral bone transport technique has been used to treat patients after gunshot wounds, benign and malignant tumor removal, osteomyelitis, and malunion. It is indicated as the first surgical alternative in patients with a poor prognosis or reinterventions, for medically compromised individuals when minimal surgery and no bone grafts are
Patients should undergo orthodontic treatment when teeth are aligned and leveled in segments and rectangular arch wires are placed. The mechanics are not oriented to move the anterior teeth into the alveolar cleft if the root is exposed to the cleft because saliva and bacteria infiltrate, which causes chronic periodontal disease and a poor environment for grafting. A surgeon’s biggest challenge is to adequately create a three-dimensional soft tissue envelope to locate the grafting material properly. Even if this goal is achieved with delicate and meticulous surgery, saliva and bacteria contaminate the graft through the periodontal ligament. Using bone transport, the surgeon can decrease the size of the recipient site and enlarge the soft tissues around the site. The metabolic activity of the distraction process also augments the local blood supply, stem cells, and nutrients. A small incision at the depth of the vestibule is made through the mucosa, muscles, and periosteum. The soft tissues are carefully elevated and small retractors are used to expose the bone adequately. An interdental osteotomy is performed under abundant irrigation. Bone overheating should be avoided at all times. The bony segment is completely separated with the use of a spatula osteotome. The surgical wound is closed carefully. The periosteal layer, which is responsible for most of the bone
Fig. 6. (A,B) Docking site surgery. Once the distraction disk has reached the objective area, the epithelium between the bone surfaces is removed. A 701 bur is used to drill holes and make the bone bleed, cancellous autologous bone grafts are obtained either from the chin or the tuberosity, and the grafts are placed over the docking area. Finally, a posterior sliding flap is elevated and advanced and a water-tight closure is performed.
C.A. Guerrero / Oral Maxillofacial Surg Clin N Am 14 (2002) 509–523
513
Fig. 7. (A – C) An occlusal view shows a severe bone discontinuity on the left side and its alveolar reconstruction after bone transport. A palatal splint was used to maintain the orthognathic surgery on the left segment. A plastic pontic is placed over the distraction area awaiting the mineralization for implant positioning. The palatal fistula was closed using a lateral palatal flap during the docking site surgery.
healing process, must be reunited meticulously. A miniaturized distraction device is used to separate the osteodental segment from its original position progressively, which decreases the size of the alveolar cleft because the distractor is activated. The device must be attached firmly to the bone disc and to the
Fig. 8. Dental photograph shows the alveolar reconstruction using bone transport.
maxilla. Too much motion between the fragments results in the development of fibrous and cartilaginous tissue. Minimal micromotion is obtained by cutting the distractor arms to the smallest size possible. The device is fixed to the basal bone with long screws, and at the tooth level interdental wires covered with dental resin or acrylic for rigidity are used. The wiring avoids any damage to the dental structures by screws. A latency period of 7 days is enacted before activation begins at 0.5 mm twice a day. Activation is continued until the mucosa of the two fragments meets. When the disc or bullet arrives at the target area, the patient is scheduled for the second stage surgery. Once the two segments are together a second surgery, called ‘‘the docking site surgery,’’ is needed. In the orthopedic literature there are reports about activating the appliance after the disc or bullet has approached the docking site to create a fusion between the two segments. The fragments in the maxilla are so small, however, that they cannot fuse. Because of this inability, the following steps are taken: removing the epithelium between the two bone
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Fig. 9. (A – C) Panoramic radiographs show the defect, the appliance positioning, and appearance 12 days after activation.
fragments, preparing the two borders by removing the cartilage-like tissue that develops as the disc travels through the softer tissues, perforating the bony edges with a 701 bur to produce internal bleeding, and obtaining bone graft either from the chin or tuberosity areas, which is placed over the joining bones. After the cartilage-like tissue is removed, a space is created, usually between 4 and 6 mm. The distractor should be activated to consolidate bone fragments together by an immediate movement and not the usual 1 mm a day. An alternative possibility could be the use of one or two lighter plates. Different soft tissue designs can be used to cover the docking site area properly, especially after the placement of intraoral bone grafts. Advancing, sliding, or three-dimensional flaps could be used. Improper management of this surgical stage ends in malunion, fibrous union, or bone segment dislocation, which happens if the docking site is wide or if the bone graft is contaminated with saliva and bone resorption occurs. Clinical judgment is needed to determine the best approach for the particular reconstruction and choose from the different ways to consolidate the two bony fragments. The distraction process ends once the mineralization process is completed, usually 10 to 12 months after surgery.
Important variables that may modify the surgical outcome include age of the patient, amount of movement, quality and quantity of bone, surgical technique (clean cuts under abundant irrigation), and adequate wound closure without gaps that allows postoperative contamination of saliva and food. The presence of an infection in the distraction site partially or completely stops the healing process and creates a situation that ranges from a nonunion to partial mineralization. These clinical situations are accompanied by correspondent radiologic findings, which were reported by Samchukov. Although the oral cavity is well vascularized and infections are rarely seen after distraction osteogenesis, the surgical principles must be kept in mind to avoid surgical complications.
Summary The advantages of this technique over the traditional alveolar reconstruction are as follows: no need for bone grafts, which involve a donor site, minimal surgical time, no hospitalization, progressive improvement with excellent psychological adaptation, bone height and width that are similar to the neighboring alveolus with excellent possibilities for
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Fig. 10. (A) Frontal view of a 25-year-old woman with bilateral alveolar cleft after premaxillectomy. (B) Intraoral frontal view shows the discontinuity defect in the anterior maxilla. (C,D) Preoperative dental lateral views. (E) Preoperative occlusal view shows the alveolar defect and the oronasal communication.
dental implants, and a natural reconstruction that aids the orthodontist with final tooth movement. Finally, the morbidity is minimal. The disadvantages are few; long treatment requires patient cooperation and close follow-up. Implant placement ideally should happen 6 to 8 months after the initial surgery. A crestal incision is made to expose the newly developed alveolar bone, and a fixture of adequate size and length is inserted. If
further bone augmentation is needed on the buccal side of the alveolus, the bone collected from the suction tramp may be mixed with alloplastic materials and layered over. A collagen membrane also may be used. The alternatives of taking grafts from the chin or tuberosity also may be considered. There is still the chance to augment the soft tissues at the uncovering stage by various surgical techniques to obtain an ideal alveolar ridge.
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Fig. 11. Diagram shows the treatment planning to reconstruct the anterior maxilla by intraoral bone transport.
Fig. 12. (A) A reconstruction plate is countered and fixed to teeth using interdental wires and acrylic to serve as a guide in the bone transport movement reconstructing the maxillar normal shape. (B) A small incision is made and a osteotomy of the transport disk is performed in both sides of the alveolar discontinuity defect. (C) After water-tight closure, the intraoral devices are placed over the reconstruction plate using transmucosal 2-mm screws and interdental wires.
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Fig. 13. (A – C) After the distraction surgery is accomplished, a 7-day latency period follows and the activation period starts at a 1-mm per day rate until the reconstruction of the continuity defect is achieved. (D) Occlusal view in the activation period. Observe that the nasal communication no longer exists.
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Fig. 14. (A – E) Clinical follow-up of the reconstruction process in the right side of the alveolar defect. Preoperative, after distractor removal, implant placement, abutment preparation, and temporary prosthesis views demonstrate the real maxillary reconstruction obtained with this technique.
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Fig. 15. (A – E) Clinical sequence on the left side. Observe the new tissues created for implant placement and further reconstruction with provisional prosthesis over implants.
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Fig. 16. (A,B) Note the important changes in the dental frontal view. The anteroposterior deficiency was corrected with the forward projection of the bone segments.
Fig. 17. (A – D) Occlusal view of the reconstruction stages when using bone transport by distraction osteogenesis.
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Fig. 18. (A – E) To correct the alveolar defect, a transport disk was design bilaterally taking two teeth in either side. A trifocal bone transport was performed to create new bone that would serve as the implant’s host. Observe how the distraction site has ossified.
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Fig. 19. (A,B) Profile views before and after distraction osteogenesis was accomplished.
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