Int. J. Oral Maxillofac. Surg. 2016; 45: 472–475 http://dx.doi.org/10.1016/j.ijom.2015.10.008, available online at http://www.sciencedirect.com
Systematic Review Orthognathic Surgery
Mandible-first sequence in bimaxillary orthognathic surgery: a systematic review A. M. Borba, A. H. Borges, P. S. Ce´, B. A. Venturi, M. G. Nacle´rio-Homem, M. Miloro: Mandible-first sequence in bimaxillary orthognathic surgery: a systematic review. Int. J. Oral Maxillofac. Surg. 2016; 45: 472–475. # 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Abstract. The sequencing of bimaxillary orthognathic surgery remains controversial, although the traditional maxilla-first approach is performed routinely. The goal of this study was to present a systematic review of the mandible-first sequence in bimaxillary orthognathic surgery, to provide data that may assist in the decision as to which jaw should undergo osteotomy first in bimaxillary orthognathic surgery cases. A literature search was conducted for articles published in the English language, reporting the use of the altered sequence for bimaxillary orthognathic surgery (mandible-first), using the following descriptors: ‘orthognathic’ and ‘double-jaw’, ‘orthognathic’ and ‘two-jaw’, ‘orthognathic’ and ‘mandible-first’, ‘orthognathic’ and ‘bimaxillary’. Eight hundred eighty-seven abstracts were initially identified and were evaluated for inclusion according to the proposed inclusion criteria. After evaluation of these abstracts and relevant references, six publications met the criteria for consideration. Performing mandible-first surgery in bimaxillary orthognathic cases dates back to the 1970s; however the decision regarding the jaw to be operated on first seems to rely on accurate preoperative planning based upon the surgeon’s experience and preference. While there appear to be significant theoretical advantages to support the use of the altered orthognathic sequence (mandible-first), future prospective studies on its reliability, accuracy, and short- and long-term outcomes are required.
Dentofacial deformities are defined as skeletal abnormalities affecting the maxilla, mandible, or both jaws. The teeth located in the alveolar process of the affected bone(s) will frequently present with malocclusion, crowding, dental compensations, rotations, and misalignments. Orthodontic treatment may be sufficient to 0901-5027/040472 + 04
manage mild dentoskeletal discrepancies, but as the magnitude and severity of the discrepancy increases, treatment with combined orthodontics and orthognathic surgery will be required. Orthognathic surgery may be performed as a single-jaw procedure in which only the maxilla or the mandible is operated on,
A. M. Borba1,2,3, A. H. Borges1, P. S. Ce´1, B. A. Venturi4, M. G. Nacle´rio-Homem2, M. Miloro3 1
Master of Science Program on Integrated Dental Sciences, Faculty of Dentistry of the University of Cuiaba´ – UNIC, Cuiaba´, Brazil; 2 Department of Oral and Maxillofacial Surgery, Traumatology and Prosthesis, Faculty of Dentistry of the University of Sa˜o Paulo – USP, Sa˜o Paulo, Brazil; 3Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago, Chicago, IL, USA; 4Master of Science Program on Orthodontics, Sa˜o Leopoldo Mandic Research Center, Campinas, Brazil
Key words: orthognathic surgery; bimaxillary; double-jaw; two-jaw; altered sequence. Accepted for publication 9 October 2015 Available online 18 November 2015
but when the diagnostic records and presurgical planning indicate that both jaws need to be osteotomized, bimaxillary (or double-jaw) orthognathic surgery must be planned. The sequencing of bimaxillary orthognathic surgery has been the subject of debate for decades.1–4 Recently, several articles have addressed aspects related to
# 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Mandible-first orthognathic surgery
473
the sequence in bimaxillary surgery, comparing the ‘traditional’ maxilla-first to the ‘altered’ mandible-first sequence, and have highlighted the debate regarding whether the sequencing choice in bimaxillary surgery might influence post-surgical outcomes.2,3,5 The aim of the present systematic review was to examine the existing literature regarding the development of and scientific evidence related to the mandible-first sequence in bimaxillary orthognathic surgery, in order to provide data that may assist surgeons in determining the jaw that should be operated on first in bimaxillary orthognathic cases. Materials and methods
A systematic review was conducted, based on the PRISMA guidelines (http://www. prisma-statement.org). The PubMed, Cochrane Library, and Scopus databases were searched for publications in the English language, without any restriction on the type of study (all searched up to 3 June 2015). The search strategy was defined by the following terms: ‘orthognathic’ and ‘double-jaw’, ‘orthognathic’ and ‘twojaw’, ‘orthognathic’ and ‘mandible-first’, ‘orthognathic’ and ‘bimaxillary’. Inclusion criteria encompassed any mention of the mandible-first sequence within the abstract of any article generated by the search, without any restriction on the type of study. The exclusion criterion was the absence of any reference to the mandiblefirst sequence within the abstract. The systematic search was conducted by one author (A.M.B.), and two authors (A.M.B., P.S.C.) independently performed the screening of titles and abstracts. Once an article abstract was selected according to the eligibility criteria (inclusion and exclusion), the full-text article was read, including the references. Any reference that could contribute to the purpose of the systematic review was retrieved. The two authors then presented their list of eligible studies and any difference was discussed until consensus was reached. Results
With the application of the search criteria, the initial search identified a total of 887 abstracts from the different databases (Fig. 1). After reading the full-text versions of the corresponding articles and relevant references, six articles were selected (Table 1). The contents of these six articles addressed the topic of mandiblefirst bimaxillary orthognathic surgery.
Fig. 1. Flow diagram (PRISMA format) of the screening and selection process.
The 884 articles excluded following the review of abstracts were either duplicates or did not mention the mandible-first sequence. The first mention of the altered sequence for bimaxillary orthognathic surgery was provided by Lindorf and Steinha¨user in 1978.6 They stated that bimaxillary orthognathic surgery should start with the mandible, since a stable reference (the maxilla) is needed to accurately reproduce the surgical movements predicted during model surgery to correspond to the actual surgery. The authors performed model surgery starting with the maxilla, then assembling the mandible in the desired final position for the construction of the final inter-occlusal splint; later, the maxilla was returned to its original position, and an intermediate splint fabricated. In the 1980s, Buckley et al. highlighted the disadvantages of starting bimaxillary orthognathic surgery with the maxilla, due to the instability of an already operated maxilla that could be displaced during mandibular manipulation and fixation.7 With two maxillary cast models and one mandibular cast model mounted on a
semi-adjustable articulator, the authors also proposed model surgery to begin with the maxilla, since surgery itself would start with the mandible having the uncut maxilla as a stable reference for the operated mandible. The need for rigid fixation instead of wire osteosynthesis for this technique was emphasized. In the following decade, Cottrell and Wolford published their experience of commencing bimaxillary orthognathic surgery with the mandible first.1 The authors proposed model surgery to start with the mandible based upon the prediction of its position on the final occlusion, thus eliminating errors related to achieving centric relation for model surgery. Moreover, they suggested that even in segmental maxillary surgery, the use of a final splint would be an option; however, their preference was for direct dental interdigitation to achieve the final planned occlusion, in order to eliminate interferences from the splint. It was suggested that these modifications would reduce the time and materials required for this planning step and also result in improved accuracy. Surgery was started with the mandible as long as rigid fixation was used, and
Table 1. Selected publications on the mandible-first orthognathic sequence. Year 1978 1987 1994 2006 2011 2014
Authors, Ref. Lindorf and Steinha¨user Buckley et al.7 Cottrell and Wolford1 Posnick et al.4 Perez and Ellis2 Ritto et al.5
6
Source
Type of study
Manual search Manual search Manual search PubMed, Scopus PubMed, Scopus PubMed, Scopus
Case report Case report Case report Case report Case report Research article
474
Borba et al.
attention was given to properly seating the condyles in their fossa during the stabilization of the proximal mandibular segments. The lack of reliability of the mandible as a stable reference was the subject of another publication related to orthognathic surgery. In 2006, Posnick et al. reported that some patients would present difficulties in registration of centric relation, such as those with congenital incomplete formation or absence of a mandibular condyle (as in hemifacial microsomia) and those with total or partial loss after tumour resection or condylar fracture.4 They stated that in cases without a reliable centric relation, the model surgery sequence should start with the maxilla, and the traditional bimaxillary orthognathic surgery (maxilla-first) should be modified to the mandible-first sequence. The controversy over the choice of the initial jaw osteotomy for bimaxillary orthognathic surgery was recently debated. Turvey stated that it should be a surgeon’s decision whether the maxilla or the mandible will be the first jaw cut in bimaxillary surgery.3 In addition, Perez and Ellis detailed specific instances in which it would be preferable to start the surgery with the mandible, exemplified by modification of the mandibular position used for model surgery after general anesthesia.2 These specific examples warranting consideration of the mandible-first sequence include the following: cases of bimaxillary orthognathic surgery in which down-grafting of the posterior maxilla is planned; when centric relation registration for model surgery is uncertain; when intermaxillary fixation is impaired by a thick intermediate splint if surgery starts with the maxilla; when fixation of the maxilla is not rigid; when concomitant temporomandibular joint surgery is planned with the orthognathic procedure. Model surgery could start with the mandible when only one set of dental models is available, or start with the maxilla when two sets of models are mounted on an articulator. The most recent article selected was the first study to compare whether the choice of jaw operated on first would interfere with the outcomes of orthognathic surgery. In 2014, Ritto et al., using a retrospective sample, demonstrated that the maxilla could be accurately placed in the predicted position, regardless of the choice of the initial jaw operated on for bimaxillary surgery.5 Discussion
During the early years following the introduction of bimaxillary orthognathic
surgery (in the 1960s), Obwegeser confronted the dilemma of which jaw to operate on first in bimaxillary orthognathic surgery. At that time, he performed the osteotomy of both jaws first, having both of them mobilized from the facial skeleton, and used intermaxillary fixation; he then fixated the maxilla and the mandible into their planned positions.8 Since then, orthognathic surgery has evolved, with modifications made to the surgical technique, changes made to the materials used for internal fixation of the osteotomized bony segments, and the use of virtual surgical planning. The advent of rigid internal fixation was essential to allow the mandible to be the first segment operated on in bimaxillary orthognathic surgery, but there are other reasons to consider this altered sequence.1,2,5–7 Model surgery techniques have also been modified over the years. Lindorf and Steinha¨user used only one maxillary cast for model surgery planning, which would vary back and forth from the ‘operated’ to the original position for splint fabrication. In contrast, Buckley advocated the need for two maxillary casts mounted on a semi-adjustable articulator, thus maintaining one of the maxillary models in the original position, while the other maxillary cast was maintained in the ‘operated’ position.6,7 The advantage of having two maxillary models mounted on the articulator is the ability to modify the model surgery protocol at any time, changing the sequence (traditional to altered, and vice versa) or even the surgical movements for each segment, since an original pair of casts (maxilla and mandible) would always be available.2 The difficulty in reproducing centric relation for model surgery as the reason for starting bimaxillary orthognathic surgery with the mandible, was first described by Cottrell and Wolford in 1994, but has more recently been supported by others.1,2,4 The ability to have a stable reference (i.e. the maxilla) to position the unstable freely-movable mandible seems logical in several instances, which could occur due to technical errors when reproducing centric relation on the articulator for model surgery, secondary to functional or morphological alterations at the temporomandibular joint level, or due to the effects of a supine patient position and general anaesthesia on condylar positioning.1,2,4,5,9–11 While the maxillafirst sequence is generally preferred, the modified surgical sequence (mandiblefirst) would be favoured in situations such as counterclockwise rotation of the occlusal plane thus avoiding an intraoperative
anterior open bite, inaccuracy of inter-occlusal records and uncertainty in precise condylar positioning, concomitant TMJ surgery, or an expected difficulty in maxillary fixation as seen in segmental maxillary osteotomies.1,2 The altered bimaxillary orthognathic surgery sequence (mandible-first) might not be preferred with other surgical movements. Clockwise rotations of the occlusal plane and maxillomandibular rotations using posterior maxillary intrusion or anterior maxillary extrusion would require the mandible to be fixed in an ‘open-bite’ intermediate position with a thick intermediate splint in the incisor region, making the application of intermaxillary fixation difficult.2 Also, in cases undergoing the mandible-first sequence in which an unfavourable split of the mandible occurs that is not correctable during surgery, maxillary surgery will have to be postponed until a later date.1 In terms of accuracy of orthognathic surgery, the traditional sequence of bimaxillary orthognathic surgery (maxilla-first) offers variable but well-documented results with acceptable outcomes.12–14 On the other hand, the literature on the altered sequence (mandible-first) provides little outcomes data, and its use is currently supported only by the opinion of authors and a single retrospective case series.1,2,4– 7 Moreover, the role of orthognathic virtual surgical planning, in which bony interferences due to premature segment contacts may be anticipated and the thickness of the intermediate splint can be assessed for beginning the surgery with either the maxilla or the mandible, is yet to be evaluated. The decision to operate on the mandible as the first jaw in a bimaxillary orthognathic procedure dates back to the 1970s. However, up until the present time the decision regarding which segment should be operated on first has relied on accurate preoperative planning based upon individual surgeon experience and preference. While there appear to be significant theoretical advantages to support the use of the altered orthognathic sequence (mandiblefirst), future prospective studies on its reliability, accuracy, and short- and long-term outcomes are required. Funding
There was no financial support for the present research. Competing interests
None declared.
Mandible-first orthognathic surgery Ethical approval
Not required.
6.
Patient consent
Not required.
7.
References 1. Cottrell DA, Wolford LM. Altered orthognathic surgical sequencing and a modified approach to model surgery. J Oral Maxillofac Surg 1994;52:1010–20. discussion 1020-1011. 2. Perez D, Ellis 3rd E. Sequencing bimaxillary surgery: mandible first. J Oral Maxillofac Surg 2011;69:2217–24. http://dx.doi.org/ 10.1016/j.joms.2010.10.053. 3. Turvey T. Sequencing of two-jaw surgery: the case for operating on the maxilla first. J Oral Maxillofac Surg 2011;69:2225. http:// dx.doi.org/10.1016/j.joms.2010.10.050. 4. Posnick JC, Ricalde P, Ng P. A modified approach to ‘‘model planning’’ in orthognathic surgery for patients without a reliable centric relation. J Oral Maxillofac Surg 2006;64:347–56. http://dx.doi.org/10.1016/ j.joms.2005.10.022. 5. Ritto FG, Ritto TG, Ribeiro DP, Medeiros PJ, de Moraes M. Accuracy of maxillary positioning after standard and inverted orthognathic sequencing. Oral Surg Oral Med Oral Pathol
8.
9.
10.
11.
Oral Radiol 2014;117:567–74. http://dx.doi. org/10.1016/j.oooo.2014.01.016. Lindorf HH, Steinha¨user EW. Correction of jaw deformities involving simultaneous osteotomy of the mandible and maxilla. J Maxillofac Surg 1978;6:239–44. Buckley MJ, Tucker MR, Fredette SA. An alternative approach for staging simultaneous maxillary and mandibular osteotomies. Int J Adult Orthodont Orthognath Surg 1987;2:75–8. Obwegeser HL. Orthognathic surgery and a tale of how three procedures came to be: a letter to the next generations of surgeons. Clin Plast Surg 2007;34:331–55. http:// dx.doi.org/10.1016/j.cps.2007.05.014. Bamber MA, Abang Z, Ng WF, Harris M, Linney A. The effect of posture and anesthesia on the occlusal relationship in orthognathic surgery. J Oral Maxillofac Surg 1999;57:1164–72. discussion 11721164. Yaghmaei M, Ejlali M, Nikzad S, Sayyedi A, Shafaeifard S, Pourdanesh F. General anesthesia in orthognathic surgeries: does it affect horizontal jaw relations? J Oral Maxillofac Surg 2013;71:1752–6. http:// dx.doi.org/10.1016/j.joms.2013.05.012. Borba AM, Ribeiro-Junior O, Brozoski MA, Ce PS, Espinosa MM, Deboni MC, et al. Accuracy of perioperative mandibular
475
positions in orthognathic surgery. Int J Oral Maxillofac Surg 2014;43:972–9. http:// dx.doi.org/10.1016/j.ijom.2014.04.017. 12. Gil JN, Claus JD, Manfro R, Lima Jr SM. Predictability of maxillary repositioning during bimaxillary surgery: accuracy of a new technique. Int J Oral Maxillofac Surg 2007;36:296–300. http://dx.doi.org/10.1016/ j.ijom.2006.10.015. 13. Bouchard C, Landry PE. Precision of maxillary repositioning during orthognathic surgery: a prospective study. Int J Oral Maxillofac Surg 2013;42:592–6. http:// dx.doi.org/10.1016/j.ijom.2012.10.034. 14. Park N, Posnick JC. Accuracy of analytic model planning in bimaxillary surgery. Int J Oral Maxillofac Surg 2013;42:807–13. http:// dx.doi.org/10.1016/j.ijom.2013.02.011.
Address: Alexandre Meireles Borba Hospital Geral Universita´rio – Divisa˜o de Odontologia Rua Treze de Junho 2101 Centro Cuiaba´ MT CEP 78025-000 Brazil Tel: +55 65 3315 7150 E-mail: [email protected]
Systematic Review Orthognathic Surgery
Mandible-first sequence in bimaxillary orthognathic surgery: a systematic review A. M. Borba, A. H. Borges, P. S. Ce´, B. A. Venturi, M. G. Nacle´rio-Homem, M. Miloro: Mandible-first sequence in bimaxillary orthognathic surgery: a systematic review. Int. J. Oral Maxillofac. Surg. 2016; 45: 472–475. # 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Abstract. The sequencing of bimaxillary orthognathic surgery remains controversial, although the traditional maxilla-first approach is performed routinely. The goal of this study was to present a systematic review of the mandible-first sequence in bimaxillary orthognathic surgery, to provide data that may assist in the decision as to which jaw should undergo osteotomy first in bimaxillary orthognathic surgery cases. A literature search was conducted for articles published in the English language, reporting the use of the altered sequence for bimaxillary orthognathic surgery (mandible-first), using the following descriptors: ‘orthognathic’ and ‘double-jaw’, ‘orthognathic’ and ‘two-jaw’, ‘orthognathic’ and ‘mandible-first’, ‘orthognathic’ and ‘bimaxillary’. Eight hundred eighty-seven abstracts were initially identified and were evaluated for inclusion according to the proposed inclusion criteria. After evaluation of these abstracts and relevant references, six publications met the criteria for consideration. Performing mandible-first surgery in bimaxillary orthognathic cases dates back to the 1970s; however the decision regarding the jaw to be operated on first seems to rely on accurate preoperative planning based upon the surgeon’s experience and preference. While there appear to be significant theoretical advantages to support the use of the altered orthognathic sequence (mandible-first), future prospective studies on its reliability, accuracy, and short- and long-term outcomes are required.
Dentofacial deformities are defined as skeletal abnormalities affecting the maxilla, mandible, or both jaws. The teeth located in the alveolar process of the affected bone(s) will frequently present with malocclusion, crowding, dental compensations, rotations, and misalignments. Orthodontic treatment may be sufficient to 0901-5027/040472 + 04
manage mild dentoskeletal discrepancies, but as the magnitude and severity of the discrepancy increases, treatment with combined orthodontics and orthognathic surgery will be required. Orthognathic surgery may be performed as a single-jaw procedure in which only the maxilla or the mandible is operated on,
A. M. Borba1,2,3, A. H. Borges1, P. S. Ce´1, B. A. Venturi4, M. G. Nacle´rio-Homem2, M. Miloro3 1
Master of Science Program on Integrated Dental Sciences, Faculty of Dentistry of the University of Cuiaba´ – UNIC, Cuiaba´, Brazil; 2 Department of Oral and Maxillofacial Surgery, Traumatology and Prosthesis, Faculty of Dentistry of the University of Sa˜o Paulo – USP, Sa˜o Paulo, Brazil; 3Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago, Chicago, IL, USA; 4Master of Science Program on Orthodontics, Sa˜o Leopoldo Mandic Research Center, Campinas, Brazil
Key words: orthognathic surgery; bimaxillary; double-jaw; two-jaw; altered sequence. Accepted for publication 9 October 2015 Available online 18 November 2015
but when the diagnostic records and presurgical planning indicate that both jaws need to be osteotomized, bimaxillary (or double-jaw) orthognathic surgery must be planned. The sequencing of bimaxillary orthognathic surgery has been the subject of debate for decades.1–4 Recently, several articles have addressed aspects related to
# 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Mandible-first orthognathic surgery
473
the sequence in bimaxillary surgery, comparing the ‘traditional’ maxilla-first to the ‘altered’ mandible-first sequence, and have highlighted the debate regarding whether the sequencing choice in bimaxillary surgery might influence post-surgical outcomes.2,3,5 The aim of the present systematic review was to examine the existing literature regarding the development of and scientific evidence related to the mandible-first sequence in bimaxillary orthognathic surgery, in order to provide data that may assist surgeons in determining the jaw that should be operated on first in bimaxillary orthognathic cases. Materials and methods
A systematic review was conducted, based on the PRISMA guidelines (http://www. prisma-statement.org). The PubMed, Cochrane Library, and Scopus databases were searched for publications in the English language, without any restriction on the type of study (all searched up to 3 June 2015). The search strategy was defined by the following terms: ‘orthognathic’ and ‘double-jaw’, ‘orthognathic’ and ‘twojaw’, ‘orthognathic’ and ‘mandible-first’, ‘orthognathic’ and ‘bimaxillary’. Inclusion criteria encompassed any mention of the mandible-first sequence within the abstract of any article generated by the search, without any restriction on the type of study. The exclusion criterion was the absence of any reference to the mandiblefirst sequence within the abstract. The systematic search was conducted by one author (A.M.B.), and two authors (A.M.B., P.S.C.) independently performed the screening of titles and abstracts. Once an article abstract was selected according to the eligibility criteria (inclusion and exclusion), the full-text article was read, including the references. Any reference that could contribute to the purpose of the systematic review was retrieved. The two authors then presented their list of eligible studies and any difference was discussed until consensus was reached. Results
With the application of the search criteria, the initial search identified a total of 887 abstracts from the different databases (Fig. 1). After reading the full-text versions of the corresponding articles and relevant references, six articles were selected (Table 1). The contents of these six articles addressed the topic of mandiblefirst bimaxillary orthognathic surgery.
Fig. 1. Flow diagram (PRISMA format) of the screening and selection process.
The 884 articles excluded following the review of abstracts were either duplicates or did not mention the mandible-first sequence. The first mention of the altered sequence for bimaxillary orthognathic surgery was provided by Lindorf and Steinha¨user in 1978.6 They stated that bimaxillary orthognathic surgery should start with the mandible, since a stable reference (the maxilla) is needed to accurately reproduce the surgical movements predicted during model surgery to correspond to the actual surgery. The authors performed model surgery starting with the maxilla, then assembling the mandible in the desired final position for the construction of the final inter-occlusal splint; later, the maxilla was returned to its original position, and an intermediate splint fabricated. In the 1980s, Buckley et al. highlighted the disadvantages of starting bimaxillary orthognathic surgery with the maxilla, due to the instability of an already operated maxilla that could be displaced during mandibular manipulation and fixation.7 With two maxillary cast models and one mandibular cast model mounted on a
semi-adjustable articulator, the authors also proposed model surgery to begin with the maxilla, since surgery itself would start with the mandible having the uncut maxilla as a stable reference for the operated mandible. The need for rigid fixation instead of wire osteosynthesis for this technique was emphasized. In the following decade, Cottrell and Wolford published their experience of commencing bimaxillary orthognathic surgery with the mandible first.1 The authors proposed model surgery to start with the mandible based upon the prediction of its position on the final occlusion, thus eliminating errors related to achieving centric relation for model surgery. Moreover, they suggested that even in segmental maxillary surgery, the use of a final splint would be an option; however, their preference was for direct dental interdigitation to achieve the final planned occlusion, in order to eliminate interferences from the splint. It was suggested that these modifications would reduce the time and materials required for this planning step and also result in improved accuracy. Surgery was started with the mandible as long as rigid fixation was used, and
Table 1. Selected publications on the mandible-first orthognathic sequence. Year 1978 1987 1994 2006 2011 2014
Authors, Ref. Lindorf and Steinha¨user Buckley et al.7 Cottrell and Wolford1 Posnick et al.4 Perez and Ellis2 Ritto et al.5
6
Source
Type of study
Manual search Manual search Manual search PubMed, Scopus PubMed, Scopus PubMed, Scopus
Case report Case report Case report Case report Case report Research article
474
Borba et al.
attention was given to properly seating the condyles in their fossa during the stabilization of the proximal mandibular segments. The lack of reliability of the mandible as a stable reference was the subject of another publication related to orthognathic surgery. In 2006, Posnick et al. reported that some patients would present difficulties in registration of centric relation, such as those with congenital incomplete formation or absence of a mandibular condyle (as in hemifacial microsomia) and those with total or partial loss after tumour resection or condylar fracture.4 They stated that in cases without a reliable centric relation, the model surgery sequence should start with the maxilla, and the traditional bimaxillary orthognathic surgery (maxilla-first) should be modified to the mandible-first sequence. The controversy over the choice of the initial jaw osteotomy for bimaxillary orthognathic surgery was recently debated. Turvey stated that it should be a surgeon’s decision whether the maxilla or the mandible will be the first jaw cut in bimaxillary surgery.3 In addition, Perez and Ellis detailed specific instances in which it would be preferable to start the surgery with the mandible, exemplified by modification of the mandibular position used for model surgery after general anesthesia.2 These specific examples warranting consideration of the mandible-first sequence include the following: cases of bimaxillary orthognathic surgery in which down-grafting of the posterior maxilla is planned; when centric relation registration for model surgery is uncertain; when intermaxillary fixation is impaired by a thick intermediate splint if surgery starts with the maxilla; when fixation of the maxilla is not rigid; when concomitant temporomandibular joint surgery is planned with the orthognathic procedure. Model surgery could start with the mandible when only one set of dental models is available, or start with the maxilla when two sets of models are mounted on an articulator. The most recent article selected was the first study to compare whether the choice of jaw operated on first would interfere with the outcomes of orthognathic surgery. In 2014, Ritto et al., using a retrospective sample, demonstrated that the maxilla could be accurately placed in the predicted position, regardless of the choice of the initial jaw operated on for bimaxillary surgery.5 Discussion
During the early years following the introduction of bimaxillary orthognathic
surgery (in the 1960s), Obwegeser confronted the dilemma of which jaw to operate on first in bimaxillary orthognathic surgery. At that time, he performed the osteotomy of both jaws first, having both of them mobilized from the facial skeleton, and used intermaxillary fixation; he then fixated the maxilla and the mandible into their planned positions.8 Since then, orthognathic surgery has evolved, with modifications made to the surgical technique, changes made to the materials used for internal fixation of the osteotomized bony segments, and the use of virtual surgical planning. The advent of rigid internal fixation was essential to allow the mandible to be the first segment operated on in bimaxillary orthognathic surgery, but there are other reasons to consider this altered sequence.1,2,5–7 Model surgery techniques have also been modified over the years. Lindorf and Steinha¨user used only one maxillary cast for model surgery planning, which would vary back and forth from the ‘operated’ to the original position for splint fabrication. In contrast, Buckley advocated the need for two maxillary casts mounted on a semi-adjustable articulator, thus maintaining one of the maxillary models in the original position, while the other maxillary cast was maintained in the ‘operated’ position.6,7 The advantage of having two maxillary models mounted on the articulator is the ability to modify the model surgery protocol at any time, changing the sequence (traditional to altered, and vice versa) or even the surgical movements for each segment, since an original pair of casts (maxilla and mandible) would always be available.2 The difficulty in reproducing centric relation for model surgery as the reason for starting bimaxillary orthognathic surgery with the mandible, was first described by Cottrell and Wolford in 1994, but has more recently been supported by others.1,2,4 The ability to have a stable reference (i.e. the maxilla) to position the unstable freely-movable mandible seems logical in several instances, which could occur due to technical errors when reproducing centric relation on the articulator for model surgery, secondary to functional or morphological alterations at the temporomandibular joint level, or due to the effects of a supine patient position and general anaesthesia on condylar positioning.1,2,4,5,9–11 While the maxillafirst sequence is generally preferred, the modified surgical sequence (mandiblefirst) would be favoured in situations such as counterclockwise rotation of the occlusal plane thus avoiding an intraoperative
anterior open bite, inaccuracy of inter-occlusal records and uncertainty in precise condylar positioning, concomitant TMJ surgery, or an expected difficulty in maxillary fixation as seen in segmental maxillary osteotomies.1,2 The altered bimaxillary orthognathic surgery sequence (mandible-first) might not be preferred with other surgical movements. Clockwise rotations of the occlusal plane and maxillomandibular rotations using posterior maxillary intrusion or anterior maxillary extrusion would require the mandible to be fixed in an ‘open-bite’ intermediate position with a thick intermediate splint in the incisor region, making the application of intermaxillary fixation difficult.2 Also, in cases undergoing the mandible-first sequence in which an unfavourable split of the mandible occurs that is not correctable during surgery, maxillary surgery will have to be postponed until a later date.1 In terms of accuracy of orthognathic surgery, the traditional sequence of bimaxillary orthognathic surgery (maxilla-first) offers variable but well-documented results with acceptable outcomes.12–14 On the other hand, the literature on the altered sequence (mandible-first) provides little outcomes data, and its use is currently supported only by the opinion of authors and a single retrospective case series.1,2,4– 7 Moreover, the role of orthognathic virtual surgical planning, in which bony interferences due to premature segment contacts may be anticipated and the thickness of the intermediate splint can be assessed for beginning the surgery with either the maxilla or the mandible, is yet to be evaluated. The decision to operate on the mandible as the first jaw in a bimaxillary orthognathic procedure dates back to the 1970s. However, up until the present time the decision regarding which segment should be operated on first has relied on accurate preoperative planning based upon individual surgeon experience and preference. While there appear to be significant theoretical advantages to support the use of the altered orthognathic sequence (mandiblefirst), future prospective studies on its reliability, accuracy, and short- and long-term outcomes are required. Funding
There was no financial support for the present research. Competing interests
None declared.
Mandible-first orthognathic surgery Ethical approval
Not required.
6.
Patient consent
Not required.
7.
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Address: Alexandre Meireles Borba Hospital Geral Universita´rio – Divisa˜o de Odontologia Rua Treze de Junho 2101 Centro Cuiaba´ MT CEP 78025-000 Brazil Tel: +55 65 3315 7150 E-mail: [email protected]
