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The Approach to Dentofacial Skeletal Deformities Using a Multisegmentation Technique
477
CLINICS IN PLASTIC SURGERY Clin Plastic Surg 34 (2007) 477–484
The Approach to Dentofacial Skeletal Deformities Using a Multisegmentation Technique Karl-Erik Kahnberg, DDS, PhD, Dr Odonta,*, Catharina Hagberg, DDS, PhD, Dr Odontb
-
Orthodontic planning Surgical technique Postoperative orthodontic management
Today repositioning the maxilla to correct various midfacial dentofacial skeletal deformities has become a routine procedure. A single-piece maxilla can be repositioned in the sagittal plane, impacted or lengthened in the vertical plane, and rotated, depending on the clinical situation. When patients present with an anterior open bite, cross-bite, asymmetry, or more complex deformities of the jaws, however, the ability to multisegment the maxilla can be an invaluable technique for the maxillofacial surgeon. Although surgically assisted rapid palatal expansion can correct transpalatal constriction, it is limited in correcting the dental arch deformity in a single transverse plane and requires a second surgical procedure to correct the deformity when it coexists in other planes. Today the authors’ preference is a multisegmentation approach that corrects the dentofacial deformity in multiple planes: transverse maxillary expansion and lowering of the segmented palate while simultaneously correcting the sagittal and vertical maxillary–mandibular relationship (Figs. 1 and 2) [1]. At the Institute of Odontology at the Sahlgrenska Academy, University of Goteborg, multisegmen-
-
Complications Summary References
tation of the maxilla is well established and is accepted by the authors’ orthodontic colleagues when presurgical orthodontic expansion is replaced by surgical expansion at the time of the formal orthognathic procedure in most of patients. This approach, however, requires precise handling of oral, gingival, and palatal mucosa to maintain an adequate blood supply to the multiple segments following manipulation and to ensure that each of the dental arch segments remains adherent to the underlying periosteum. The most critical part of the procedure is executing the interdental osteotomies. The authors have found that it is technically easier to make interdental osteotomies when the space between the teeth is narrow but large enough to allow a thin osteotome to fit between the adjacent teeth.
Orthodontic planning As with all orthognathic surgical procedures, the patients are managed by an experienced orthodonticsurgical team. A successful outcome requires an understanding of the limitations in what can be achieved during the orthodontic presurgical
a Department of Oral and Maxillofacial Surgery, Institute of Odontology, The Sahlgrenska Academy, University of Goteborg, Sweden b Department of Orthodontics and Jaw Orthopedics, Institute of Odontology, The Sahlgrenska Academy, University of Goteborg, Sweden * Corresponding author. E-mail address: [email protected] (K-E. Kahnberg).
0094-1298/07/$ – see front matter ª 2007 Elsevier Inc. All rights reserved.
plasticsurgery.theclinics.com
doi:10.1016/j.cps.2007.05.003
478
Kahnberg & Hagberg
Fig. 1. (A–C) The patient presented with a severely constricted maxilla with a high arched palatal vault. Presurgical orthodontics involved extraction of 1st premolars to relieve crowding, alignment, and leveling. (D) No attempt was made to correct the constricted transverse width orthodontically. (E) The occlusion and (F) postoperative appearance after multisegmental maxillary surgery.
treatment as well as the limitations for surgical procedures by each of the member of the team. Risks for postsurgical relapse caused by factors such as occlusal instability, changes in muscular function, and tongue thrust should be considered in advance and managed appropriately. Although the treatment plan for each patient is unique, general guidelines concerning presurgical orthodontics and maxillary osteotomy with multisegmentation have evolved based on the authors’ long-term experience. When there is a transverse discrepancy between the maxillary and mandibular dental arches, orthodontic expansion of the maxilla should be avoided when surgery is planned. Otherwise, the authors have found, the transverse width frequently is insufficient for orthodontic management alone. In many instances segmentation is needed at the time of
the surgery to coordinate the dental arches ideally. Although other centers may prefer to diverge the dental roots to facilitate interdental osteotomies, the orthodontists at the authors’ center do not routinely diverge the roots, because the authors usually feel comfortable performing the interdental osteotomies without that procedure. When space at the dental level must be closed surgically, however, it is important to have sufficient space between the roots to execute this closure at the time of the surgical procedure. In cases with an anterior open bite, the presurgical orthodontics should be planned to close the open bite with the surgical procedure, and no attempt should be made to close the bite with orthodontic mechanics. Thus it is important to assess overbite and overjet continuously during
The Approach to Dentofacial Skeletal Deformities
Fig. 2. The patient presented with (A) a long-face syndrome, (B) an anterior open bite deformity, and (C) a constricted maxilla. (D–F) The postoperative result after a multisegmented maxilla with simultaneous mandibular surgery.
the presurgical treatment phase with serial photographs, radiographs, and dental models. To perform necessary tooth movement (eg, to align the teeth or close spaces after extraction), many orthodontists prefer to use segmented arch wires. When a nonsegmented wire technique is used, vertical steps or sweep is necessary to maintain the open bite vertically. When the open bite has been reduced orthodontically, it is essential that a sectional wire be used in the maxilla in the last 2 to 3 months before surgery to avoid relapse. Sectioning the arch wire allows the open bite to become evident before surgery. This precaution is essential to avoid postsurgical relapse. The arch wire must be passive and not cause any undesired tooth movement at the time of the final surgical planning [2]. When the patient comes to surgery, the final arch
wire should be a rectangular stainless steel arch wire, typically 0.019 0.025, sectioned according to the treatment plan with surgical hooks placed in as many interdental spaces as possible within each of the sections. Another source of error is bonding brackets in the region of the lower incisors too close to the incisal edge. These brackets need to be repositioned to achieve an appropriate overbite at the time of surgery to avoid interference with the bracket placement. Additionally, the second molars must be banded in both the upper and lower jaw. In the upper jaw care must to be taken not to extrude or tip the molars buccally; otherwise, the palatal cusp will result in interference when the surgical occlusion is achieved. Serial dental casts should be used to follow the progress of the
479
480
Kahnberg & Hagberg
orthodontic treatment and for the timing of surgery. Model surgery with segmentation should be performed to simulate the surgery and to ensure coordination of the dental arches (Fig. 3).
Surgical technique Maxillary osteotomy according to the LeFort I method is made in a routine fashion after Obwegeser. An oral mucosal vestibular incision is made above the attached gingiva. The maxilla and nasal piriform are exposed in the subperiosteal plane. An osteotomy of the maxilla is made sectioning the medial, anterior, and posterior lateral walls. The septum is separated from the vomer. The
vertical interdental osteotomies then are made. Depending on the surgical orthodontic plan, these osteotomies can be between the canine and the first premolar, between the lateral incisor and the canine, or between the central incisors. The osteotomy is not completed fully but covers about two thirds of the distance. The vertical interdental osteotomy is initially done with a fine Lindemann burr and then is completed with a very thin osteotome. The pterygoid process then is separated from the palatine bone. The maxilla is downfractured and then fully mobilized maximally to gain access to the hard palate. In a four-piece maxilla, osteotomies are made on both sides of the midline, one on each side parallel to the residual septum resulting (Fig. 4); and in six-piece maxilla, two osteotomies are made on each side of septum (Fig. 5) [1]. When needed, it also is possible to make an osteotomy between the central upper incisors to widen the arch between the cuspids. This procedure results in a seven-piece maxilla (Fig. 6). An occlusal wafer is placed, as determined in the model surgery, and the patient is placed in maxillary-mandibular fixation. The bone segments then are fixed with titanium plates and screws. Iliac bone graft is placed in the vertical gaps when the osteotomy gap exceeds 2 to 3 mm. Bone graft from the iliac crest normally is used when the maxilla is sagitally and/or vertically repositioned with a discrepancy between maxilla and midface of more than 3 to 4 mm. Otherwise, the authors fill small postoperative interdental spaces with bone fragments from the posterior sinus wall. With due care to avoid injury to the periosteum and maintenance of the vascular supply throughout the procedure, these osteotomies allow the surgeon to correct the maxillary deformity in multiple planes simultaneously with the transverse expansion of the maxilla and vertical corrections between the anterior and posterior segments of the maxilla. With this approach it is possible to correct various open-bite deformities and transverse discrepancies at the time of the surgical procedure, avoiding multiple staged surgical procedures and increased orthodontic treatment time. This approach, however, requires intraoperative precision and attention to the vascular supply of the multiple segments.
Postoperative orthodontic management Fig. 3. Model surgery: The maxillary dental cast is segmented to improve the arch form and coordinated with the mandibular dental arch. An occlusal splint is fabricated and used in the operative procedure to replicate the model surgery.
As soon as the intermaxillary fixation and the occlusal wafer have been removed by the surgeon, typically at 8 weeks, the orthodontist sees the patient. The sectioned wire in the upper jaw then is changed to a continuous (nonsectioned)
The Approach to Dentofacial Skeletal Deformities
Fig. 4. Osteotomies are made on both sides of the palate resulting in a four-piece maxilla.
passive rectangular steel wire to maintain stability when the patient returns to normal oral-motor functioning. The occlusion can be guided by using light elastics or rectangular boxes in a class II or III direction depending on the original sagittal relationship between the jaws. When the authors believe there is an increased risk for relapse in open-bite deformities, they prefer using light dental elastics at the anterior segment during the night. After an initial phase of changeable elastics for guidance of the occlusion, the final orthodontic adjustments can be performed to maximize coordination of the dental arches. As with single-segment maxillary cases, the orthodontic treatment is completed approximately 6 months after surgery. The patients are followed with serial radiographs including periapical films to assess the dentition adjacent to the interdental osteotomy sites. The orthodontic retention principles are the same as those in nonsurgical orthodontic cases. Normally retention is maintained by the use of bonded lingual retainers in both the upper and lower anterior dental segments between the canines. Retention plates are used to preserve the transverse expansion of the maxilla. Because of the significant change in the muscular function in their chewing, swallowing, and breathing patterns, these patients should be followed more frequently and for a longer period of time once they are in the retention period. Close follow-up can result in earlier detection of relapse that may be related to
function, and functional orthodontic appliances can be used to minimize relapse.
Complications The authors have had nearly 30 years’ experience in multisegmenting the maxilla. Their studies focusing on the complication rate and tendency for relapse have confirmed the stability of the surgical approach and the paucity of complications [3]. Today 321 maxillas have been segmented; complications have occurred in less than 3% of these cases. The stability of transverse widening has been examined in a follow-up study using both clinical assessment and study cast models. Although a small degree of relapse does occur in the transverse direction, it is thought to be within the acceptable limits of orthodontic stability [4]. In a recent publication the first author and colleagues [3] analyzed the frequency of complications associated with segmentalization of the maxilla. Eighty-two consecutive patients who underwent dentofacial correction by segmented maxillary osteotomy alone or in combination with simultaneous mandibular surgery between 1992 and 1998 were followed for up to 30 months postoperatively. A total of 158 interdental osteotomies were performed, involving a total of 316 teeth. In this series the investigators found only a small number of complications, which included osteolytic processes, marginal bone destruction, root resorption, or
481
482
Kahnberg & Hagberg
Fig. 5. (A) Additional parallel palatal osteotomies can be made resulting in a six-segment maxilla. (B) The additional parallel palatal osteotomies in the six-piece maxilla allow greater expansion and flexibility of the dental segments and simultaneously lower a high-vaulted palate. Care is taken to not strip off the palatal mucosa.
Fig. 6. An additional osteotomy between the central incisors allows expansion of the anterior segment to correct the canine width.
The Approach to Dentofacial Skeletal Deformities
Fig. 7. (A, B) No adverse affects are seen in the periapical radiographs at 30 months after interdental osteotomies distal to the canines on both sides. In contrast, in another case, there is a small loss of approximately 3 mm of marginal bone distal to the canine between the (C) preoperative and the (D) postoperative periapical at 30 months. (E) A periapical radiograph of iatrogenic damage 30 months postoperatively; however, there is no evidence of osteolysis or resorption around either the remaining root or the root fragment.
mechanical injuries to the teeth (Fig. 7). They found root resorption after surgery in eight teeth, four of which were in a single patient. This finding should be considered in the context of the 31 teeth that were observed to have root resorption before the surgery. Three teeth were injured directly by surgical trauma, but all three were healthy at 30 months despite the root transection. The reader can find further details in the investigators’ report [3].
Summary This article describes the authors’ approach to correcting dentofacial skeletal deformities requiring multisegmentation of the maxilla. Achieving optimal results requires a close collaboration within the orthodontic-surgical team. The importance of attention to detail in the course of the surgical procedure cannot be overemphasized, because complications of avascular necrosis cannot be corrected
483
484
Kahnberg & Hagberg
easily. The multisegmental maxilla is a valuable technique and adds to the versatility of the LeFort I in the treatment of open bite and transverse discrepancies in dentoalveolar deformities.
References [1] Krekmanov L, Kahnberg KE. Transverse surgical correction of the maxilla. J Craniomaxillofac Surg 1990;18:332–4.
[2] Proffit WR, White RP Jr. Combined surgical-orthodontic treatment: who does what, when? In: Surgical orthodontic treatment. Mosby-Year book, Inc; 1990. p. 192–224. [3] Kahnberg KE, Vannas-Lo¨fqvist L, Zellin G. Complications associated with segmentation of the maxilla: a retrospective radiographic follow-up of 82 patients. Int J Oral Maxillofac Surg 2005; 34:840–5. [4] Kahnberg KE. Transverse expansion of the maxilla using a multisegmentation technique. Scand J Plast Reconstr Surg Hand Surg, in press.
CLINICS IN PLASTIC SURGERY Clin Plastic Surg 34 (2007) 477–484
The Approach to Dentofacial Skeletal Deformities Using a Multisegmentation Technique Karl-Erik Kahnberg, DDS, PhD, Dr Odonta,*, Catharina Hagberg, DDS, PhD, Dr Odontb
-
Orthodontic planning Surgical technique Postoperative orthodontic management
Today repositioning the maxilla to correct various midfacial dentofacial skeletal deformities has become a routine procedure. A single-piece maxilla can be repositioned in the sagittal plane, impacted or lengthened in the vertical plane, and rotated, depending on the clinical situation. When patients present with an anterior open bite, cross-bite, asymmetry, or more complex deformities of the jaws, however, the ability to multisegment the maxilla can be an invaluable technique for the maxillofacial surgeon. Although surgically assisted rapid palatal expansion can correct transpalatal constriction, it is limited in correcting the dental arch deformity in a single transverse plane and requires a second surgical procedure to correct the deformity when it coexists in other planes. Today the authors’ preference is a multisegmentation approach that corrects the dentofacial deformity in multiple planes: transverse maxillary expansion and lowering of the segmented palate while simultaneously correcting the sagittal and vertical maxillary–mandibular relationship (Figs. 1 and 2) [1]. At the Institute of Odontology at the Sahlgrenska Academy, University of Goteborg, multisegmen-
-
Complications Summary References
tation of the maxilla is well established and is accepted by the authors’ orthodontic colleagues when presurgical orthodontic expansion is replaced by surgical expansion at the time of the formal orthognathic procedure in most of patients. This approach, however, requires precise handling of oral, gingival, and palatal mucosa to maintain an adequate blood supply to the multiple segments following manipulation and to ensure that each of the dental arch segments remains adherent to the underlying periosteum. The most critical part of the procedure is executing the interdental osteotomies. The authors have found that it is technically easier to make interdental osteotomies when the space between the teeth is narrow but large enough to allow a thin osteotome to fit between the adjacent teeth.
Orthodontic planning As with all orthognathic surgical procedures, the patients are managed by an experienced orthodonticsurgical team. A successful outcome requires an understanding of the limitations in what can be achieved during the orthodontic presurgical
a Department of Oral and Maxillofacial Surgery, Institute of Odontology, The Sahlgrenska Academy, University of Goteborg, Sweden b Department of Orthodontics and Jaw Orthopedics, Institute of Odontology, The Sahlgrenska Academy, University of Goteborg, Sweden * Corresponding author. E-mail address: [email protected] (K-E. Kahnberg).
0094-1298/07/$ – see front matter ª 2007 Elsevier Inc. All rights reserved.
plasticsurgery.theclinics.com
doi:10.1016/j.cps.2007.05.003
478
Kahnberg & Hagberg
Fig. 1. (A–C) The patient presented with a severely constricted maxilla with a high arched palatal vault. Presurgical orthodontics involved extraction of 1st premolars to relieve crowding, alignment, and leveling. (D) No attempt was made to correct the constricted transverse width orthodontically. (E) The occlusion and (F) postoperative appearance after multisegmental maxillary surgery.
treatment as well as the limitations for surgical procedures by each of the member of the team. Risks for postsurgical relapse caused by factors such as occlusal instability, changes in muscular function, and tongue thrust should be considered in advance and managed appropriately. Although the treatment plan for each patient is unique, general guidelines concerning presurgical orthodontics and maxillary osteotomy with multisegmentation have evolved based on the authors’ long-term experience. When there is a transverse discrepancy between the maxillary and mandibular dental arches, orthodontic expansion of the maxilla should be avoided when surgery is planned. Otherwise, the authors have found, the transverse width frequently is insufficient for orthodontic management alone. In many instances segmentation is needed at the time of
the surgery to coordinate the dental arches ideally. Although other centers may prefer to diverge the dental roots to facilitate interdental osteotomies, the orthodontists at the authors’ center do not routinely diverge the roots, because the authors usually feel comfortable performing the interdental osteotomies without that procedure. When space at the dental level must be closed surgically, however, it is important to have sufficient space between the roots to execute this closure at the time of the surgical procedure. In cases with an anterior open bite, the presurgical orthodontics should be planned to close the open bite with the surgical procedure, and no attempt should be made to close the bite with orthodontic mechanics. Thus it is important to assess overbite and overjet continuously during
The Approach to Dentofacial Skeletal Deformities
Fig. 2. The patient presented with (A) a long-face syndrome, (B) an anterior open bite deformity, and (C) a constricted maxilla. (D–F) The postoperative result after a multisegmented maxilla with simultaneous mandibular surgery.
the presurgical treatment phase with serial photographs, radiographs, and dental models. To perform necessary tooth movement (eg, to align the teeth or close spaces after extraction), many orthodontists prefer to use segmented arch wires. When a nonsegmented wire technique is used, vertical steps or sweep is necessary to maintain the open bite vertically. When the open bite has been reduced orthodontically, it is essential that a sectional wire be used in the maxilla in the last 2 to 3 months before surgery to avoid relapse. Sectioning the arch wire allows the open bite to become evident before surgery. This precaution is essential to avoid postsurgical relapse. The arch wire must be passive and not cause any undesired tooth movement at the time of the final surgical planning [2]. When the patient comes to surgery, the final arch
wire should be a rectangular stainless steel arch wire, typically 0.019 0.025, sectioned according to the treatment plan with surgical hooks placed in as many interdental spaces as possible within each of the sections. Another source of error is bonding brackets in the region of the lower incisors too close to the incisal edge. These brackets need to be repositioned to achieve an appropriate overbite at the time of surgery to avoid interference with the bracket placement. Additionally, the second molars must be banded in both the upper and lower jaw. In the upper jaw care must to be taken not to extrude or tip the molars buccally; otherwise, the palatal cusp will result in interference when the surgical occlusion is achieved. Serial dental casts should be used to follow the progress of the
479
480
Kahnberg & Hagberg
orthodontic treatment and for the timing of surgery. Model surgery with segmentation should be performed to simulate the surgery and to ensure coordination of the dental arches (Fig. 3).
Surgical technique Maxillary osteotomy according to the LeFort I method is made in a routine fashion after Obwegeser. An oral mucosal vestibular incision is made above the attached gingiva. The maxilla and nasal piriform are exposed in the subperiosteal plane. An osteotomy of the maxilla is made sectioning the medial, anterior, and posterior lateral walls. The septum is separated from the vomer. The
vertical interdental osteotomies then are made. Depending on the surgical orthodontic plan, these osteotomies can be between the canine and the first premolar, between the lateral incisor and the canine, or between the central incisors. The osteotomy is not completed fully but covers about two thirds of the distance. The vertical interdental osteotomy is initially done with a fine Lindemann burr and then is completed with a very thin osteotome. The pterygoid process then is separated from the palatine bone. The maxilla is downfractured and then fully mobilized maximally to gain access to the hard palate. In a four-piece maxilla, osteotomies are made on both sides of the midline, one on each side parallel to the residual septum resulting (Fig. 4); and in six-piece maxilla, two osteotomies are made on each side of septum (Fig. 5) [1]. When needed, it also is possible to make an osteotomy between the central upper incisors to widen the arch between the cuspids. This procedure results in a seven-piece maxilla (Fig. 6). An occlusal wafer is placed, as determined in the model surgery, and the patient is placed in maxillary-mandibular fixation. The bone segments then are fixed with titanium plates and screws. Iliac bone graft is placed in the vertical gaps when the osteotomy gap exceeds 2 to 3 mm. Bone graft from the iliac crest normally is used when the maxilla is sagitally and/or vertically repositioned with a discrepancy between maxilla and midface of more than 3 to 4 mm. Otherwise, the authors fill small postoperative interdental spaces with bone fragments from the posterior sinus wall. With due care to avoid injury to the periosteum and maintenance of the vascular supply throughout the procedure, these osteotomies allow the surgeon to correct the maxillary deformity in multiple planes simultaneously with the transverse expansion of the maxilla and vertical corrections between the anterior and posterior segments of the maxilla. With this approach it is possible to correct various open-bite deformities and transverse discrepancies at the time of the surgical procedure, avoiding multiple staged surgical procedures and increased orthodontic treatment time. This approach, however, requires intraoperative precision and attention to the vascular supply of the multiple segments.
Postoperative orthodontic management Fig. 3. Model surgery: The maxillary dental cast is segmented to improve the arch form and coordinated with the mandibular dental arch. An occlusal splint is fabricated and used in the operative procedure to replicate the model surgery.
As soon as the intermaxillary fixation and the occlusal wafer have been removed by the surgeon, typically at 8 weeks, the orthodontist sees the patient. The sectioned wire in the upper jaw then is changed to a continuous (nonsectioned)
The Approach to Dentofacial Skeletal Deformities
Fig. 4. Osteotomies are made on both sides of the palate resulting in a four-piece maxilla.
passive rectangular steel wire to maintain stability when the patient returns to normal oral-motor functioning. The occlusion can be guided by using light elastics or rectangular boxes in a class II or III direction depending on the original sagittal relationship between the jaws. When the authors believe there is an increased risk for relapse in open-bite deformities, they prefer using light dental elastics at the anterior segment during the night. After an initial phase of changeable elastics for guidance of the occlusion, the final orthodontic adjustments can be performed to maximize coordination of the dental arches. As with single-segment maxillary cases, the orthodontic treatment is completed approximately 6 months after surgery. The patients are followed with serial radiographs including periapical films to assess the dentition adjacent to the interdental osteotomy sites. The orthodontic retention principles are the same as those in nonsurgical orthodontic cases. Normally retention is maintained by the use of bonded lingual retainers in both the upper and lower anterior dental segments between the canines. Retention plates are used to preserve the transverse expansion of the maxilla. Because of the significant change in the muscular function in their chewing, swallowing, and breathing patterns, these patients should be followed more frequently and for a longer period of time once they are in the retention period. Close follow-up can result in earlier detection of relapse that may be related to
function, and functional orthodontic appliances can be used to minimize relapse.
Complications The authors have had nearly 30 years’ experience in multisegmenting the maxilla. Their studies focusing on the complication rate and tendency for relapse have confirmed the stability of the surgical approach and the paucity of complications [3]. Today 321 maxillas have been segmented; complications have occurred in less than 3% of these cases. The stability of transverse widening has been examined in a follow-up study using both clinical assessment and study cast models. Although a small degree of relapse does occur in the transverse direction, it is thought to be within the acceptable limits of orthodontic stability [4]. In a recent publication the first author and colleagues [3] analyzed the frequency of complications associated with segmentalization of the maxilla. Eighty-two consecutive patients who underwent dentofacial correction by segmented maxillary osteotomy alone or in combination with simultaneous mandibular surgery between 1992 and 1998 were followed for up to 30 months postoperatively. A total of 158 interdental osteotomies were performed, involving a total of 316 teeth. In this series the investigators found only a small number of complications, which included osteolytic processes, marginal bone destruction, root resorption, or
481
482
Kahnberg & Hagberg
Fig. 5. (A) Additional parallel palatal osteotomies can be made resulting in a six-segment maxilla. (B) The additional parallel palatal osteotomies in the six-piece maxilla allow greater expansion and flexibility of the dental segments and simultaneously lower a high-vaulted palate. Care is taken to not strip off the palatal mucosa.
Fig. 6. An additional osteotomy between the central incisors allows expansion of the anterior segment to correct the canine width.
The Approach to Dentofacial Skeletal Deformities
Fig. 7. (A, B) No adverse affects are seen in the periapical radiographs at 30 months after interdental osteotomies distal to the canines on both sides. In contrast, in another case, there is a small loss of approximately 3 mm of marginal bone distal to the canine between the (C) preoperative and the (D) postoperative periapical at 30 months. (E) A periapical radiograph of iatrogenic damage 30 months postoperatively; however, there is no evidence of osteolysis or resorption around either the remaining root or the root fragment.
mechanical injuries to the teeth (Fig. 7). They found root resorption after surgery in eight teeth, four of which were in a single patient. This finding should be considered in the context of the 31 teeth that were observed to have root resorption before the surgery. Three teeth were injured directly by surgical trauma, but all three were healthy at 30 months despite the root transection. The reader can find further details in the investigators’ report [3].
Summary This article describes the authors’ approach to correcting dentofacial skeletal deformities requiring multisegmentation of the maxilla. Achieving optimal results requires a close collaboration within the orthodontic-surgical team. The importance of attention to detail in the course of the surgical procedure cannot be overemphasized, because complications of avascular necrosis cannot be corrected
483
484
Kahnberg & Hagberg
easily. The multisegmental maxilla is a valuable technique and adds to the versatility of the LeFort I in the treatment of open bite and transverse discrepancies in dentoalveolar deformities.
References [1] Krekmanov L, Kahnberg KE. Transverse surgical correction of the maxilla. J Craniomaxillofac Surg 1990;18:332–4.
[2] Proffit WR, White RP Jr. Combined surgical-orthodontic treatment: who does what, when? In: Surgical orthodontic treatment. Mosby-Year book, Inc; 1990. p. 192–224. [3] Kahnberg KE, Vannas-Lo¨fqvist L, Zellin G. Complications associated with segmentation of the maxilla: a retrospective radiographic follow-up of 82 patients. Int J Oral Maxillofac Surg 2005; 34:840–5. [4] Kahnberg KE. Transverse expansion of the maxilla using a multisegmentation technique. Scand J Plast Reconstr Surg Hand Surg, in press.