모바일 메뉴
Search
Search

KJO Korean Journal of Orthodontics

Open Access

pISSN 2234-7518
eISSN 2005-372X

퀵메뉴 버튼

Article

home All Articles View
Split Viewer

Original Article

Korean J Orthod 2024; 54(2): 128-135   https://doi.org/10.4041/kjod23.166

First Published Date March 8, 2024, Publication Date March 25, 2024

Copyright © The Korean Association of Orthodontists.

Is three-piece maxillary segmentation surgery a stable procedure?

Renata Mayumi Katoa , João Roberto Gonçalvesa, Jaqueline Ignácioa, Larry Wolfordb , Patricia Bicalho de Melloc , Julianna Parizottoa , Jonas Bianchia,d

aDepartment of Morphology and Pediatric Clinic, School of Dentistry of Araraquara, São Paulo State University, Araraquara, Brazil
bDepartments of Oral and Maxillofacial Surgery and Orthodontics, Texas A&M University Health Science Center, Baylor College of Dentistry, Dallas, TX, USA
cPrivate Practice, Nova Lima, Brazil
dDepartment of Orthodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, CA, USA

Correspondence to:João Roberto Gonçalves.
Professor. Department of Morphology and Pediatric Clinic, School of Dentistry of Araraquara, Sao Paulo State University, Humaita St. 1680, Araraquara 14801-385, Brazil.
Tel +55-16-98124-1424 e-mail joao.goncalves@unesp.br

How to cite this article: Kato RM, Gonçalves JR, Ignácio J, Wolford L, de Mello PB, Parizotto J, Bianchi J. Is three-piece maxillary segmentation surgery a stable procedure? Korean J Orthod 2024;54(2):128-135. https://doi.org/10.4041/kjod23.166

Received: August 8, 2023; Revised: February 26, 2024; Accepted: March 3, 2024

Abstract

Objective: The number of three-piece maxillary osteotomies has increased over the years; however, the literature remains controversial. The objective of this study was to evaluate the skeletal stability of this surgical modality compared with that of one-piece maxillary osteotomy. Methods: This retrospective cohort study included 39 individuals who underwent Le Fort I maxillary osteotomies and were divided into two groups: group 1 (three pieces, n = 22) and group 2 (one piece, n = 17). Three cone-beam computed tomography scans from each patient (T1, pre-surgical; T2, post-surgical; and T3, follow-up) were used to evaluate the three-dimensional skeletal changes. Results: The differences within groups were statistically significant only for group 1 in terms of surgical changes (T2-T1) with a mean difference in the canine region of 3.09 mm and the posterior region of 3.08 mm. No significant differences in surgical stability were identified between or within the groups. The mean values of the differences between groups were 0.05 mm (posterior region) and –0.39 mm (canine region). Conclusions: Our findings suggest that one- and three-piece maxillary osteotomies result in similar post-surgical skeletal stability.

Keywords: Maxillary osteotomy, Tomography, Surgical procedures

INTRODUCTION

Adult skeletal malocclusion may require orthodontic surgery. Le Fort I maxillary osteotomy is one of the most commonly performed surgical procedures. This procedure is highly versatile and recommended for the correction of sagittal and vertical discrepancies.1 Osteotomies can be performed in single or multiple segments. When performed in multiple segments, the procedure is commonly executed on three distinct dentoskeletal pieces.2-5 This surgical approach facilitates the correction of transverse maxillary deficiency in patients with skeletal maturity. However, the benefits of maxillary segmentation extend beyond transverse correction, allowing for the correction of several other discrepancies.6

Segmental Le Fort I (three-piece surgery) allows correction of vertical, sagittal, and transverse discrepancies in a single surgical procedure, which is advantageous for patients.7 Other benefits include the possibility of improving the maxillary anterior segment, correction of inadequate inclination of the upper incisors,8 tooth size discrepancy,9 and pronounced curves of Spee and Curve of Wilson.9 Some clinical complications have been reported in the literature;10-13 however, these complications might be attributed to the lack of specific training in the technique. A previous study demonstrated low morbidity related to multi-segment maxillary osteotomies.14 This procedure has frequently been performed by surgeons in the United States.15 In addition, another study with a large sample (5,413 patients) and 10-year follow-up reported that the osteotomy type, including segmental Le Fort I osteotomies, did not impact the rates of morbidity, readmission, or reoperation for complications.16 Furthermore, several studies have confirmed that maxillary segmentation does not promote major skeletal or dental instability when appropriate bone grafting is performed. Therefore, the procedure should be considered when indicated.3,17-20

Despite the versatile design of the three-piece Le Fort I maxillary osteotomy,21 the stability of three-piece maxillary segmentation surgery remains controversial in the literature.2,6,22 Previous studies have reported relapse of incisor position changes achieved through segmentation surgical procedures in approximately 90% of the samples.6 Additionally, maxillary widening achieved with segmentation has been identified as an unpredictable procedure among various orthognathic surgical modalities.2,22 Proffit et al.23 demonstrated that the stability of Le Fort I multimaxillary segmentation for correcting transverse discrepancies ranks among the least reliable procedures commonly employed in various orthognathic surgical movements. Nevertheless, they could not assess skeletal changes independently from dental shifts. Additionally, their surgical protocol included segmentation between the canines and premolars, lack of palatal splints, and limited skeletal fixation systems. As a frequently employed surgical procedure in clinical practice, segmentation execution should be meticulously planned, and long-term stability must be considered. The lack of information and standardization regarding pre-surgical facial patterns, surgical techniques, location of the segmentations, post-surgical retainer protocols, and differentiation from skeletal and dental stability limit most studies published so far.4,22-24

Another limitation of previous studies is the utilization of two-dimensional methods3-6,20,23 to assess three-dimensional (3D) structures. The number of landmarks depends on the nature of the forms under study. In large structures, many landmarks can be used as homologous points.25 As the neurocranial structure is composed of relatively large, smooth bones with few sutural intersections, foramina, and bony prominences, the Euclidean distance matrix25 should be the selected analysis type. Collecting data from images of biological forms introduces challenges in landmark identification as the characteristics of the images can exert influence, potentially leading to a reduction in the number of landmarks or alterations in their types. Euclidean distances allow us to quantitatively compare the shapes of biological objects, offering advantages over other measurable components, including the maintenance of the relative position of all biological loci of interest or the geometric integrity of the form, as represented by landmarks.25 Considering the deficiencies in the literature, this study aimed to evaluate the skeletal stability of three-piece osteotomy surgery compared to one-piece maxillary osteotomy using Euclidean distances in a 3D cone-beam computed tomography (CBCT) methodology.

MATERIALS AND METHODS

This retrospective cohort study was approved by the Institutional Research Ethics Committee of School of Dentistry of Araraquara, São Paulo State University (IRB number: 01032912.2.0000.5416). Written informed consent was obtained from all participants. The sample consisted of CBCT scans of patients following the inclusion criteria: underwent Le Fort I with one-piece or three-piece maxillary segments and bilateral sagittal ramus osteotomies with counter-clockwise rotation of the maxillo-mandibular complex, performed by the same surgeon (LW), following the surgical protocol described by Wolford et al.,26 and Bennett and Wolford.27 Minimum age of 16 for women and 18 for men, along with adequate CBCT examinations were also considered a prerequisite. The exclusion criteria included the presence of syndromes, cleft lip and palate, history of facial trauma, and previous maxillo-mandibular surgeries. The sample size was calculated based on changes of at least 2 mm2, a minimum intergroup difference of 2.0 mm, an alpha value of 5%, and a statistical power of 80%. The sample size of each group comprised of 17 participants.

From a database of 163 patients, 39 skeletal Class II patients met the inclusion criteria (26 women and 13 men) and were divided into two groups. Group 1 (n = 22) underwent three-piece Le Fort I maxillary segmentation and group 2 (n = 17) underwent one-piece Le Fort I maxillary osteotomy. The patients underwent counter-clockwise rotation of the maxilla-mandibular complex and mandibular advancement. The sample was selected considering the growth pattern (SN-GoMe ≥ 36º) and surgery was performed (maxillo-mandibular advancement with counter-clockwise rotation) for adequate comparisons between groups. Moreover, CBCT acquisition was performed with a resolution of 0.3 mm voxel during a 17.8-second scan and a field of view of 17 × 23 cm (I-Cat Platinum unit; Imaging Sciences, Hatfield, PA, USA). For each patient, CBCT examinations were performed at three different time points: T1, initial (1–5 days before surgery); T2, post-surgical (1–10 days after surgery); and T3, follow-up (minimum of 10 months after surgery). The mean time between T1 and T2 was 5.56 days and that between T2 and T3 was 476.14 days. The image size was computationally reduced to a 0.5 mm voxel size and the 3D voxel-based registration was conducted in the cranial base using the 3D Slicer and ITK-SNAP software (https://www.slicer.org and www.itksnap.org).28,29

Cephalometric values were obtained from the lateral radiographs to characterize the samples (Supplementary Table 1). Consequently, 3D skull surface models were constructed at T1, T2, and T3 using 3D Slicer 4.4.0.30,31 Landmarks were placed on the surface of the maxillary model using the “Q3DC” tool to assess the distances between the CBCT intervals and groups. Landmarks were placed at specific points on the 3D maxillary surface and in the cortical bone of the maxilla at the vertical level of the tooth apices (Table 1 and Figure 1). The 3D Euclidean distances25 were obtained using landmarks through two different methods: 1) between 3D models (Figure 2) to evaluate surgical changes (T2-T1 distance) and skeletal stability (T3-T2 distance), and 2) within the surface model (Figure 3) to evaluate surgical changes (T2-T1) and skeletal stability (T3-T2).

Figure 1. Landmark points marked on the three-dimensional maxillary surface.
PR, posterior right; CR, canine right; AR, anterior right; AL, anterior left; CL, canine left; PL, posterior left.

Figure 2. Example of the Euclidean three-dimensional (3D) distance using two landmarks on a 3D surface. PR measurements within groups. Example: PR T2-PR T1.
T1, pre-surgical; T2, post-surgical; PR, posterior right.

Figure 3. Euclidean three-dimensional distance obtained using two landmarks within the model. Example: posterior right to posterior left.

Table 1 . Landmarks, variable definitions, and localizations

AbbreviationDescriptionLocalization
PRPosterior rightLandmark at bone relative to the root apex of upper right second molar
PLPosterior leftLandmark at bone relative to the root apex of upper left second molar
ARAnterior rightLandmark at bone relative to the root apex of upper right central incisor
ALAnterior leftLandmark at bone relative to the root apex of upper left central incisor
CRCanine rightLandmark at bone relative to the root apex of upper right canine
CLCanine leftLandmark at bone relative to the root apex of upper left canine
PR-PLPosterior right to posterior leftDistance of the posterior right to posterior left landmarks
CR-CLCanine right to canine leftDistance of the canine right to canine left landmarks

RESULTS

Reproducibility was assessed using the intraclass correlation coefficient (ICC) and normality was confirmed using the Kolmogorov–Smirnov test. The ICC values were above 0.90 for all measurements, except for the variables posterior left (PL) (T3-T2) and canine right to canine left (CR-CL) (T3) which were 0.80. Student’s t test evaluated the equality of means and tested the hypothesis that the skeletal change averages between times and groups were equal to zero. Supplementary Table 1 lists the cephalometric measurements of the samples. The two groups were initially similar at T1, and surgical changes (T2-T1) demonstrated no statistically significant differences. In addition, group 1 exhibited a significant difference for variables in T2–T1 (surgical changes), except for anterior inferior facial height (AIFH). Furthermore, group 2 also presented a significant difference for variables in T2-T1 except for SNA angle and AIFH. Descriptive statistics of the surgical changes and stability measures within the groups using 3D models are presented in Supplementary Tables 2 and 3. A comparison of T3-T2 also displayed no statistical difference between the groups (Table 2), indicating the same stability behavior. The descriptive statistics for each group (T1, T2, and T3) and the differences within groups (T2-T1 and T3-T2) for the CR-CL and posterior right-PL variables (within the surface model) are presented in Supplementary Table 3. All the aforementioned findings are consistent with the results displayed in Table 3. Statistically significant surgical changes (T2-T1) and similar stability (T3-T2) were also observed in the surface model.

Table 2 . Student’s t test for surgical changes (T2-T1) and stability (T3-T2) between group 1 and group 2 (between three-dimensional models)

Measurement (Group 1- Group 2)Surgical change (T2-T1 distance)Stability (T3-T2 distance)
Mean (mm) SEP valueMean (mm)SEP value
CR0.730.640.2580.210.240.398
CL0.920.700.1960.410.210.063
PR1.390.990.1690.100.310.746
PL–0.121.070.9080.420.270.128
AR0.510.720.4850.070.290.813
AL0.660.750.3890.230.280.426

Student’s t test with α = 5%.

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR, canine right; CL, canine left; PR, posterior right; PL, posterior left; AR, anterior right; AL, anterior left.



Table 3 . Differences between groups for T2-T1 and T3-T2 (within the surface model)

Measurement
(Group 1-Group 2)
T2-T1T3-T2
Mean (mm)SEP valueMean (mm)SEP value
CR-CL3.060.57< 0.001***–0.390.650.555
PR-PL3.440.54< 0.001***0.050.370.888

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR-CL, canine right to canine left; PR-PL, posterior right to posterior left.

***P < 0.001 is statistically significant.


DISCUSSION

The objective of this study was to compare the 3D stability of one-piece and three-piece Le Fort I maxillary osteotomies in a sample of hyperdivergent patients who were subjected to counter-clockwise rotation of the maxillo-mandibular complex and mandibular advancement. Considering a lack of literature, we aimed to homogenize the sample, which comprised patients with vertical pre-surgical facial pattern (SN-GoMe ≥ 36º: group 1, 41.00º ± 9.05º; group 2, 39.82º ± 7.58º), submitted to a surgical protocol preconized in the literature.26,27 All patients in group 1 underwent interdental segmentation between the lateral incisors and canines. Other studies have also segmented canines and first premolars, which can influence stability. This is because the right and left canines belong to the anterior segment and are susceptible to vertical and transversal relapse. A palatal splint was used as a stability tool.21 Considering that dental instability can be influenced by skeletal instability alone or by skeletal in addition to dentoalveolar instability, our objective was to assess skeletal component instability in overall relapse.

Maxillary multi-segmentation in the treatment of dental skeletal deformities represents an important surgical alternative and is considered a useful tool for the 3D surgical correction of maxillary malposition.11 A previous study10 evaluated the clinical outcomes and satisfaction of orthodontists who treated patients undergoing maxillary multi-segmentation. According to the orthodontists, 96% demonstrated improved occlusion after the surgical procedure. The present study did not incorporate orthodontist’s assessments of treatment outcomes. However, all patients from both groups in our study sample exhibited good occlusion at the longest follow-up, meeting the requirements of the American.32

Our results displayed similar stability when comparing one- and three-piece maxillary Le Fort I osteotomies (Tables 2 and 3). As landmarks are not influenced by tooth movement, this study focused on evaluating skeletal rather than dental stability. The average values for stability between 3D models (T3-T2 distance), within both groups, remained very close to each other, ranging from 1.26 to 1.69 mm for group 1 and 0.96 to 1.47 mm for group 2, with no significant difference observed between groups in any variable. The stability observed in both surgical techniques suggests that the clinical practice of maxillary segmentation does not increase the inherent instability of the Le Fort I osteotomy with counter-clockwise rotation and maxillo-mandibular advancement. Another factor that may have contributed to the positive stability results was that all patients in the sample were operated on by an experienced surgeon (LW). The skill of the surgeon is related to the etiology of relapse.

In patients who underwent maxillary multi-segmentation, a parasagittal incision was placed on the soft palate to prevent elastic movement contrary to the surgical change, causing an opposite effect.33 During the postoperative period, this group used a splint without occlusal coverage to eliminate the instability factor.21 This clinical practice can be considered a factor in stability improvement and perhaps could be one of the factors contributing to stability, aligning with findings from other studies.11,34,35 T2 scans were performed within a maximum of 19 days postoperatively to reduce the possibility of adaptive responses during this period. For the analysis within the surface model between groups, this statistical hypothesis was also accepted, indicating average values of –0.39 between canine regions (CR-CL) and 0.05 between posterior regions. These results demonstrate that neither surgical technique interfered with postoperative instability. Mandibular instability was not addressed in this study, however, we included only similar maxillo-mandibular movements to avoid the possible influence of mandibular post-surgical behavior (Supplementary Table 1).

In contrast, previous studies reported that instability rates for multi-segmental Le Fort I osteotomies vary from 23% to approximately 95%.2,4,6,36 However, these studies focused on the measurement of dentoalveolar surgical changes, either through radiographs or plaster models. After removal of the splint and completion of orthodontic treatment, these regions are subject to alterations and adaptations, generating dental and non-skeletal recurrences. In addition, no specific description was available of the surgical techniques employed or postoperative retention. Furthermore, in contrast to our study, simultaneous premolar extraction was performed during orthognathic surgery in one of the previous studies,6 which can result in additional surgical complications.

The main limitations of our study included the limited sample size, due to standardization requirements and the challenge of locating individuals with T2 CBCT scans, which are not commonly requested in clinical practice. However, the sample size was within an acceptable range considering the statistical power estimation for the variables studied. Nevertheless, the groups were selected considering the same growth patterns and surgical management for adequate comparisons. This is one of the few studies comparing the stability of one- and three-piece maxillary osteotomies using 3D Euclidean distances in a standardized sample. However, future studies with long longitudinal follow-ups and large samples should be conducted, especially because negative stability results have been reported in classic studies.2,4,6,36

CONCLUSIONS

One- and three-piece maxillary osteotomies demonstrated similar post-surgical skeletal stability.

FUNDING

FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for financial support (Processes 2013/05831-8 and 2014/09152-0).

AUTHOR CONTRIBUTIONS

Conceptualization: JRG, JI. Data curation: JI, PBM, JP. Formal analysis: RMK. Investigation: RMK, JRG, JI, PBM, JP. Methodology: JI. Project administration: JRG, JB. Resources: LW. Supervision: JRG, LW, JB. Validation: RMK. Visualization: RMK, JB. Writing–original draft: RMK, JI, PBM, JP. Writing–review & editing: RMK, JRG, LW, JB.

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

SUPPLEMENTARY MATERIAL

Supplementary data is available at https://doi.org/10.4041/kjod23.166.

References

  1. Bell WH, Fonseca RJ, Kenneky JW, Levy BM. Bone healing and revascularization after total maxillary osteotomy. J Oral Surg 1975;33:253-60. https://pubmed.ncbi.nlm.nih.gov/1054396/
  2. Proffit WR, Turvey TA, Phillips C. The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension. Head Face Med 2007;3:21. https://doi.org/10.1186/1746-160X-3-21
    Pubmed KoreaMed CrossRef
  3. Kretschmer WB, Baciut G, Baciut M, Zoder W, Wangerin K. Stability of Le Fort I osteotomy in bimaxillary osteotomies: single-piece versus 3-piece maxilla. J Oral Maxillofac Surg 2010;68:372-80. https://doi.org/10.1016/j.joms.2009.09.053
    Pubmed CrossRef
  4. Kretschmer WB, Baciut G, Baciut M, Zoder W, Wangerin K. Transverse stability of 3-piece Le Fort I osteotomies. J Oral Maxillofac Surg 2011;69:861-9. https://doi.org/10.1016/j.joms.2010.05.024
    Pubmed CrossRef
  5. Blæhr TL, Jensen T, Due KM, Neumann-Jensen B. Stability of the anterior maxillary segment and teeth after segmental Le Fort I osteotomy and postoperative skeletal elastic fixation with or without occlusal splint. J Oral Maxillofac Res 2014;5:e4. https://doi.org/10.5037/jomr.2014.5304
    Pubmed KoreaMed CrossRef
  6. Tai W, Leung YY, Li DTS. Le Fort I osteotomy with segmentation for the treatment of maxillary dentoalveolar protrusion: a single-centre, 10-year outcome study. Int J Oral Maxillofac Surg 2022;51:1197-204. https://doi.org/10.1016/j.ijom.2022.01.012
    Pubmed CrossRef
  7. Kahnberg KE, Hagberg C. The approach to dentofacial skeletal deformities using a multisegmentation technique. Clin Plast Surg 2007;34:477-84. https://doi.org/10.1016/j.cps.2007.05.003
    Pubmed CrossRef
  8. Morgan TA, Fridrich KL. Effects of the multiple-piece maxillary osteotomy on the periodontium. Int J Adult Orthodon Orthognath Surg 2001;16:255-65. https://pubmed.ncbi.nlm.nih.gov/12390003/
  9. Reyneke JP, Conley RS. Surgical/orthodontic correction of transverse maxillary discrepancies. Oral Maxillofac Surg Clin North Am 2020;32:53-69. https://doi.org/10.1016/j.coms.2019.08.007
    Pubmed CrossRef
  10. Posnick JC, Adachie A, Choi E. Segmental maxillary osteotomies in conjunction with bimaxillary orthognathic surgery: indications - safety - outcome. J Oral Maxillofac Surg 2016;74:1422-40. https://doi.org/10.1016/j.joms.2016.01.051
    Pubmed CrossRef
  11. Haas Junior OL, Guijarro-Martínez R, de Sousa Gil AP, da Silva Meirelles L, de Oliveira RB, Hernández-Alfaro F. Stability and surgical complications in segmental Le Fort I osteotomy: a systematic review. Int J Oral Maxillofac Surg 2017;46:1071-87. https://doi.org/10.1016/j.ijom.2017.05.011
    Pubmed CrossRef
  12. Kramer FJ, Baethge C, Swennen G, Teltzrow T, Schulze A, Berten J, et al. Intra- and perioperative complications of the LeFort I osteotomy: a prospective evaluation of 1000 patients. J Craniofac Surg 2004;15:971-7; discussion 978-9. https://doi.org/10.1097/00001665-200411000-00016
    Pubmed CrossRef
  13. Kahnberg KE, Vannas-Löfqvist 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. https://doi.org/10.1016/j.ijom.2005.04.016
    Pubmed CrossRef
  14. Rodrigues DB, Campos PSF, Wolford LM, Ignácio J, Gonçalves JR. Maxillary interdental osteotomies have low morbidity for alveolar crestal bone and adjacent teeth: a cone beam computed tomography-based study. J Oral Maxillofac Surg 2018;76:1763-71. https://doi.org/10.1016/j.joms.2018.01.031
    Pubmed CrossRef
  15. Venugoplan SR, Nanda V, Turkistani K, Desai S, Allareddy V. Discharge patterns of orthognathic surgeries in the United States. J Oral Maxillofac Surg 2012;70:e77-86. https://doi.org/10.1016/j.joms.2011.09.030
    Pubmed CrossRef
  16. Jodeh DS, Nguyen ATH, Rottgers SA. Le Fort 1 and bimaxillary osteotomies increase the length of stay but not postoperative morbidity compared to mandibular osteotomies and single jaw procedures. J Craniofac Surg 2020;31:1734-8. https://doi.org/10.1097/SCS.0000000000006514
    Pubmed CrossRef
  17. Perez MM, Sameshima GT, Sinclair PM. The long-term stability of LeFort I maxillary downgrafts with rigid fixation to correct vertical maxillary deficiency. Am J Orthod Dentofacial Orthop 1997;112:104-8. https://doi.org/10.1016/s0889-5406(97)70280-4
    Pubmed CrossRef
  18. Hoppenreijs TJ, Freihofer HP, Stoelinga PJ, Tuinzing DB, van't Hof MA, van der Linden FP, et al. Skeletal and dento-alveolar stability of Le Fort I intrusion osteotomies and bimaxillary osteotomies in anterior open bite deformities. A retrospective three-centre study. Int J Oral Maxillofac Surg 1997;26:161-75. https://doi.org/10.1016/s0901-5027(97)80813-2
    Pubmed CrossRef
  19. Bailey LJ, Phillips C, Proffit WR, Turvey TA. Stability following superior repositioning of the maxilla by Le Fort I osteotomy: five-year follow-up. Int J Adult Orthodon Orthognath Surg 1994;9:163-73. https://pubmed.ncbi.nlm.nih.gov/7814921/
  20. Arpornmaeklong P, Heggie AA, Shand JM. A comparison of the stability of single-piece and segmental Le Fort I maxillary advancements. J Craniofac Surg 2003;14:3-9. https://doi.org/10.1097/00001665-200301000-00002
    Pubmed CrossRef
  21. Parizotto JOL, Borsato KT, Peixoto AP, Bianchi J, Cassano DS, Gonçalves JR. Can palatal splint improve stability of segmental Le Fort I osteotomies?. Orthod Craniofac Res 2020;23:486-92. https://doi.org/10.1111/ocr.12399
    Pubmed CrossRef
  22. Bailey L', Cevidanes LH, Proffit WR. Stability and predictability of orthognathic surgery. Am J Orthod Dentofacial Orthop 2004;126:273-7. https://pubmed.ncbi.nlm.nih.gov/15356484/
    Pubmed KoreaMed CrossRef
  23. Proffit WR, Turvey TA, Phillips C. Orthognathic surgery: a hierarchy of stability. Int J Adult Orthodon Orthognath Surg 1996;11:191-204. https://pubmed.ncbi.nlm.nih.gov/9456622/
  24. Bailey LJ, White RP Jr, Proffit WR, Turvey TA. Segmental LeFort I osteotomy for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:728-31. https://doi.org/10.1016/s0278-2391(97)90588-7
    Pubmed CrossRef
  25. Lele S, Richtsmeier JT. Euclidean distance matrix analysis: a coordinate-free approach for comparing biological shapes using landmark data. Am J Phys Anthropol 1991;86:415-27. https://doi.org/10.1002/ajpa.1330860307
    Pubmed CrossRef
  26. Wolford LM, Bennett MA, Rafferty CG. Modification of the mandibular ramus sagittal split osteotomy. Oral Surg Oral Med Oral Pathol 1987;64:146-55. https://doi.org/10.1016/0030-4220(87)90080-6
    Pubmed CrossRef
  27. Bennett MA, Wolford LM. The maxillary step osteotomy and Steinmann pin stabilization. J Oral Maxillofac Surg 1985;43:307-11. https://doi.org/10.1016/0278-2391(85)90297-6
    Pubmed CrossRef
  28. Yushkevich PA, Piven J, Hazlett HC, Smith RG, Ho S, Gee JC, et al. User-guided 3D active contour segmentation of anatomical structures: significantly improved efficiency and reliability. Neuroimage 2006;31:1116-28. https://doi.org/10.1016/j.neuroimage.2006.01.015
    Pubmed CrossRef
  29. Cevidanes LH, Bailey LJ, Tucker GR Jr, Styner MA, Mol A, Phillips CL, et al. Superimposition of 3D cone-beam CT models of orthognathic surgery patients. Dentomaxillofac Radiol 2005;34:369-75. https://doi.org/10.1259/dmfr/17102411
    Pubmed KoreaMed CrossRef
  30. Ruellas AC, Tonello C, Gomes LR, Yatabe MS, Macron L, Lopinto J, et al. Common 3-dimensional coordinate system for assessment of directional changes. Am J Orthod Dentofacial Orthop 2016;149:645-56. https://doi.org/10.1016/j.ajodo.2015.10.021
    Pubmed KoreaMed CrossRef
  31. Ruellas AC, Yatabe MS, Souki BQ, Benavides E, Nguyen T, Luiz RR, et al. 3D mandibular superimposition: comparison of regions of reference for voxel-based registration. PLoS One 2016;11:e0157625. https://doi.org/10.1371/journal.pone.0157625
    Pubmed KoreaMed CrossRef
  32. Casko JS, Vaden JL, Kokich VG, Damone J, James RD, Cangialosi TJ, et al. Objective grading system for dental casts and panoramic radiographs. American Board of Orthodontics. Am J Orthod Dentofacial Orthop 1998;114:589-99. https://doi.org/10.1016/s0889-5406(98)70179-9
    Pubmed CrossRef
  33. Wolford LM, Rieche-Fischel O, Mehra P. Soft tissue healing after parasagittal palatal incisions in segmental maxillary surgery: a review of 311 patients. J Oral Maxillofac Surg 2002;60:20-5; discussion 26. https://doi.org/10.1053/joms.2002.29068
    Pubmed CrossRef
  34. Haas Junior OL, Guijarro-Martínez R, de Sousa Gil AP, da Silva Meirelles L, Scolari N, Muñoz-Pereira ME, et al. Hierarchy of surgical stability in orthognathic surgery: overview of systematic reviews. Int J Oral Maxillofac Surg 2019;48:1415-33. https://doi.org/10.1016/j.ijom.2019.03.003
    Pubmed CrossRef
  35. Starch-Jensen T, Blæhr TL. Transverse expansion and stability after segmental Le Fort I osteotomy versus surgically assisted rapid maxillary expansion: a systematic review. J Oral Maxillofac Res 2016;7:e1. https://doi.org/10.5037/jomr.2016.7401
    Pubmed KoreaMed CrossRef
  36. Marchetti C, Pironi M, Bianchi A, Musci A. Surgically assisted rapid palatal expansion vs. segmental Le Fort I osteotomy: transverse stability over a 2-year period. J Craniomaxillofac Surg 2009;37:74-8. https://doi.org/10.1016/j.jcms.2008.08.006
    Pubmed CrossRef

Article

Original Article

Korean J Orthod 2024; 54(2): 128-135   https://doi.org/10.4041/kjod23.166

First Published Date March 8, 2024, Publication Date March 25, 2024

Copyright © The Korean Association of Orthodontists.

Is three-piece maxillary segmentation surgery a stable procedure?

Renata Mayumi Katoa , João Roberto Gonçalvesa, Jaqueline Ignácioa, Larry Wolfordb , Patricia Bicalho de Melloc , Julianna Parizottoa , Jonas Bianchia,d

aDepartment of Morphology and Pediatric Clinic, School of Dentistry of Araraquara, São Paulo State University, Araraquara, Brazil
bDepartments of Oral and Maxillofacial Surgery and Orthodontics, Texas A&M University Health Science Center, Baylor College of Dentistry, Dallas, TX, USA
cPrivate Practice, Nova Lima, Brazil
dDepartment of Orthodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, CA, USA

Correspondence to:João Roberto Gonçalves.
Professor. Department of Morphology and Pediatric Clinic, School of Dentistry of Araraquara, Sao Paulo State University, Humaita St. 1680, Araraquara 14801-385, Brazil.
Tel +55-16-98124-1424 e-mail joao.goncalves@unesp.br

How to cite this article: Kato RM, Gonçalves JR, Ignácio J, Wolford L, de Mello PB, Parizotto J, Bianchi J. Is three-piece maxillary segmentation surgery a stable procedure? Korean J Orthod 2024;54(2):128-135. https://doi.org/10.4041/kjod23.166

Received: August 8, 2023; Revised: February 26, 2024; Accepted: March 3, 2024

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective: The number of three-piece maxillary osteotomies has increased over the years; however, the literature remains controversial. The objective of this study was to evaluate the skeletal stability of this surgical modality compared with that of one-piece maxillary osteotomy. Methods: This retrospective cohort study included 39 individuals who underwent Le Fort I maxillary osteotomies and were divided into two groups: group 1 (three pieces, n = 22) and group 2 (one piece, n = 17). Three cone-beam computed tomography scans from each patient (T1, pre-surgical; T2, post-surgical; and T3, follow-up) were used to evaluate the three-dimensional skeletal changes. Results: The differences within groups were statistically significant only for group 1 in terms of surgical changes (T2-T1) with a mean difference in the canine region of 3.09 mm and the posterior region of 3.08 mm. No significant differences in surgical stability were identified between or within the groups. The mean values of the differences between groups were 0.05 mm (posterior region) and –0.39 mm (canine region). Conclusions: Our findings suggest that one- and three-piece maxillary osteotomies result in similar post-surgical skeletal stability.

Keywords: Maxillary osteotomy, Tomography, Surgical procedures

INTRODUCTION

Adult skeletal malocclusion may require orthodontic surgery. Le Fort I maxillary osteotomy is one of the most commonly performed surgical procedures. This procedure is highly versatile and recommended for the correction of sagittal and vertical discrepancies.1 Osteotomies can be performed in single or multiple segments. When performed in multiple segments, the procedure is commonly executed on three distinct dentoskeletal pieces.2-5 This surgical approach facilitates the correction of transverse maxillary deficiency in patients with skeletal maturity. However, the benefits of maxillary segmentation extend beyond transverse correction, allowing for the correction of several other discrepancies.6

Segmental Le Fort I (three-piece surgery) allows correction of vertical, sagittal, and transverse discrepancies in a single surgical procedure, which is advantageous for patients.7 Other benefits include the possibility of improving the maxillary anterior segment, correction of inadequate inclination of the upper incisors,8 tooth size discrepancy,9 and pronounced curves of Spee and Curve of Wilson.9 Some clinical complications have been reported in the literature;10-13 however, these complications might be attributed to the lack of specific training in the technique. A previous study demonstrated low morbidity related to multi-segment maxillary osteotomies.14 This procedure has frequently been performed by surgeons in the United States.15 In addition, another study with a large sample (5,413 patients) and 10-year follow-up reported that the osteotomy type, including segmental Le Fort I osteotomies, did not impact the rates of morbidity, readmission, or reoperation for complications.16 Furthermore, several studies have confirmed that maxillary segmentation does not promote major skeletal or dental instability when appropriate bone grafting is performed. Therefore, the procedure should be considered when indicated.3,17-20

Despite the versatile design of the three-piece Le Fort I maxillary osteotomy,21 the stability of three-piece maxillary segmentation surgery remains controversial in the literature.2,6,22 Previous studies have reported relapse of incisor position changes achieved through segmentation surgical procedures in approximately 90% of the samples.6 Additionally, maxillary widening achieved with segmentation has been identified as an unpredictable procedure among various orthognathic surgical modalities.2,22 Proffit et al.23 demonstrated that the stability of Le Fort I multimaxillary segmentation for correcting transverse discrepancies ranks among the least reliable procedures commonly employed in various orthognathic surgical movements. Nevertheless, they could not assess skeletal changes independently from dental shifts. Additionally, their surgical protocol included segmentation between the canines and premolars, lack of palatal splints, and limited skeletal fixation systems. As a frequently employed surgical procedure in clinical practice, segmentation execution should be meticulously planned, and long-term stability must be considered. The lack of information and standardization regarding pre-surgical facial patterns, surgical techniques, location of the segmentations, post-surgical retainer protocols, and differentiation from skeletal and dental stability limit most studies published so far.4,22-24

Another limitation of previous studies is the utilization of two-dimensional methods3-6,20,23 to assess three-dimensional (3D) structures. The number of landmarks depends on the nature of the forms under study. In large structures, many landmarks can be used as homologous points.25 As the neurocranial structure is composed of relatively large, smooth bones with few sutural intersections, foramina, and bony prominences, the Euclidean distance matrix25 should be the selected analysis type. Collecting data from images of biological forms introduces challenges in landmark identification as the characteristics of the images can exert influence, potentially leading to a reduction in the number of landmarks or alterations in their types. Euclidean distances allow us to quantitatively compare the shapes of biological objects, offering advantages over other measurable components, including the maintenance of the relative position of all biological loci of interest or the geometric integrity of the form, as represented by landmarks.25 Considering the deficiencies in the literature, this study aimed to evaluate the skeletal stability of three-piece osteotomy surgery compared to one-piece maxillary osteotomy using Euclidean distances in a 3D cone-beam computed tomography (CBCT) methodology.

MATERIALS AND METHODS

This retrospective cohort study was approved by the Institutional Research Ethics Committee of School of Dentistry of Araraquara, São Paulo State University (IRB number: 01032912.2.0000.5416). Written informed consent was obtained from all participants. The sample consisted of CBCT scans of patients following the inclusion criteria: underwent Le Fort I with one-piece or three-piece maxillary segments and bilateral sagittal ramus osteotomies with counter-clockwise rotation of the maxillo-mandibular complex, performed by the same surgeon (LW), following the surgical protocol described by Wolford et al.,26 and Bennett and Wolford.27 Minimum age of 16 for women and 18 for men, along with adequate CBCT examinations were also considered a prerequisite. The exclusion criteria included the presence of syndromes, cleft lip and palate, history of facial trauma, and previous maxillo-mandibular surgeries. The sample size was calculated based on changes of at least 2 mm2, a minimum intergroup difference of 2.0 mm, an alpha value of 5%, and a statistical power of 80%. The sample size of each group comprised of 17 participants.

From a database of 163 patients, 39 skeletal Class II patients met the inclusion criteria (26 women and 13 men) and were divided into two groups. Group 1 (n = 22) underwent three-piece Le Fort I maxillary segmentation and group 2 (n = 17) underwent one-piece Le Fort I maxillary osteotomy. The patients underwent counter-clockwise rotation of the maxilla-mandibular complex and mandibular advancement. The sample was selected considering the growth pattern (SN-GoMe ≥ 36º) and surgery was performed (maxillo-mandibular advancement with counter-clockwise rotation) for adequate comparisons between groups. Moreover, CBCT acquisition was performed with a resolution of 0.3 mm voxel during a 17.8-second scan and a field of view of 17 × 23 cm (I-Cat Platinum unit; Imaging Sciences, Hatfield, PA, USA). For each patient, CBCT examinations were performed at three different time points: T1, initial (1–5 days before surgery); T2, post-surgical (1–10 days after surgery); and T3, follow-up (minimum of 10 months after surgery). The mean time between T1 and T2 was 5.56 days and that between T2 and T3 was 476.14 days. The image size was computationally reduced to a 0.5 mm voxel size and the 3D voxel-based registration was conducted in the cranial base using the 3D Slicer and ITK-SNAP software (https://www.slicer.org and www.itksnap.org).28,29

Cephalometric values were obtained from the lateral radiographs to characterize the samples (Supplementary Table 1). Consequently, 3D skull surface models were constructed at T1, T2, and T3 using 3D Slicer 4.4.0.30,31 Landmarks were placed on the surface of the maxillary model using the “Q3DC” tool to assess the distances between the CBCT intervals and groups. Landmarks were placed at specific points on the 3D maxillary surface and in the cortical bone of the maxilla at the vertical level of the tooth apices (Table 1 and Figure 1). The 3D Euclidean distances25 were obtained using landmarks through two different methods: 1) between 3D models (Figure 2) to evaluate surgical changes (T2-T1 distance) and skeletal stability (T3-T2 distance), and 2) within the surface model (Figure 3) to evaluate surgical changes (T2-T1) and skeletal stability (T3-T2).

Figure 1. Landmark points marked on the three-dimensional maxillary surface.
PR, posterior right; CR, canine right; AR, anterior right; AL, anterior left; CL, canine left; PL, posterior left.

Figure 2. Example of the Euclidean three-dimensional (3D) distance using two landmarks on a 3D surface. PR measurements within groups. Example: PR T2-PR T1.
T1, pre-surgical; T2, post-surgical; PR, posterior right.

Figure 3. Euclidean three-dimensional distance obtained using two landmarks within the model. Example: posterior right to posterior left.

Table 1 . Landmarks, variable definitions, and localizations.

AbbreviationDescriptionLocalization
PRPosterior rightLandmark at bone relative to the root apex of upper right second molar
PLPosterior leftLandmark at bone relative to the root apex of upper left second molar
ARAnterior rightLandmark at bone relative to the root apex of upper right central incisor
ALAnterior leftLandmark at bone relative to the root apex of upper left central incisor
CRCanine rightLandmark at bone relative to the root apex of upper right canine
CLCanine leftLandmark at bone relative to the root apex of upper left canine
PR-PLPosterior right to posterior leftDistance of the posterior right to posterior left landmarks
CR-CLCanine right to canine leftDistance of the canine right to canine left landmarks

RESULTS

Reproducibility was assessed using the intraclass correlation coefficient (ICC) and normality was confirmed using the Kolmogorov–Smirnov test. The ICC values were above 0.90 for all measurements, except for the variables posterior left (PL) (T3-T2) and canine right to canine left (CR-CL) (T3) which were 0.80. Student’s t test evaluated the equality of means and tested the hypothesis that the skeletal change averages between times and groups were equal to zero. Supplementary Table 1 lists the cephalometric measurements of the samples. The two groups were initially similar at T1, and surgical changes (T2-T1) demonstrated no statistically significant differences. In addition, group 1 exhibited a significant difference for variables in T2–T1 (surgical changes), except for anterior inferior facial height (AIFH). Furthermore, group 2 also presented a significant difference for variables in T2-T1 except for SNA angle and AIFH. Descriptive statistics of the surgical changes and stability measures within the groups using 3D models are presented in Supplementary Tables 2 and 3. A comparison of T3-T2 also displayed no statistical difference between the groups (Table 2), indicating the same stability behavior. The descriptive statistics for each group (T1, T2, and T3) and the differences within groups (T2-T1 and T3-T2) for the CR-CL and posterior right-PL variables (within the surface model) are presented in Supplementary Table 3. All the aforementioned findings are consistent with the results displayed in Table 3. Statistically significant surgical changes (T2-T1) and similar stability (T3-T2) were also observed in the surface model.

Table 2 . Student’s t test for surgical changes (T2-T1) and stability (T3-T2) between group 1 and group 2 (between three-dimensional models).

Measurement (Group 1- Group 2)Surgical change (T2-T1 distance)Stability (T3-T2 distance)
Mean (mm) SEP valueMean (mm)SEP value
CR0.730.640.2580.210.240.398
CL0.920.700.1960.410.210.063
PR1.390.990.1690.100.310.746
PL–0.121.070.9080.420.270.128
AR0.510.720.4850.070.290.813
AL0.660.750.3890.230.280.426

Student’s t test with α = 5%..

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR, canine right; CL, canine left; PR, posterior right; PL, posterior left; AR, anterior right; AL, anterior left..



Table 3 . Differences between groups for T2-T1 and T3-T2 (within the surface model).

Measurement
(Group 1-Group 2)
T2-T1T3-T2
Mean (mm)SEP valueMean (mm)SEP value
CR-CL3.060.57< 0.001***–0.390.650.555
PR-PL3.440.54< 0.001***0.050.370.888

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR-CL, canine right to canine left; PR-PL, posterior right to posterior left..

***P < 0.001 is statistically significant..


DISCUSSION

The objective of this study was to compare the 3D stability of one-piece and three-piece Le Fort I maxillary osteotomies in a sample of hyperdivergent patients who were subjected to counter-clockwise rotation of the maxillo-mandibular complex and mandibular advancement. Considering a lack of literature, we aimed to homogenize the sample, which comprised patients with vertical pre-surgical facial pattern (SN-GoMe ≥ 36º: group 1, 41.00º ± 9.05º; group 2, 39.82º ± 7.58º), submitted to a surgical protocol preconized in the literature.26,27 All patients in group 1 underwent interdental segmentation between the lateral incisors and canines. Other studies have also segmented canines and first premolars, which can influence stability. This is because the right and left canines belong to the anterior segment and are susceptible to vertical and transversal relapse. A palatal splint was used as a stability tool.21 Considering that dental instability can be influenced by skeletal instability alone or by skeletal in addition to dentoalveolar instability, our objective was to assess skeletal component instability in overall relapse.

Maxillary multi-segmentation in the treatment of dental skeletal deformities represents an important surgical alternative and is considered a useful tool for the 3D surgical correction of maxillary malposition.11 A previous study10 evaluated the clinical outcomes and satisfaction of orthodontists who treated patients undergoing maxillary multi-segmentation. According to the orthodontists, 96% demonstrated improved occlusion after the surgical procedure. The present study did not incorporate orthodontist’s assessments of treatment outcomes. However, all patients from both groups in our study sample exhibited good occlusion at the longest follow-up, meeting the requirements of the American.32

Our results displayed similar stability when comparing one- and three-piece maxillary Le Fort I osteotomies (Tables 2 and 3). As landmarks are not influenced by tooth movement, this study focused on evaluating skeletal rather than dental stability. The average values for stability between 3D models (T3-T2 distance), within both groups, remained very close to each other, ranging from 1.26 to 1.69 mm for group 1 and 0.96 to 1.47 mm for group 2, with no significant difference observed between groups in any variable. The stability observed in both surgical techniques suggests that the clinical practice of maxillary segmentation does not increase the inherent instability of the Le Fort I osteotomy with counter-clockwise rotation and maxillo-mandibular advancement. Another factor that may have contributed to the positive stability results was that all patients in the sample were operated on by an experienced surgeon (LW). The skill of the surgeon is related to the etiology of relapse.

In patients who underwent maxillary multi-segmentation, a parasagittal incision was placed on the soft palate to prevent elastic movement contrary to the surgical change, causing an opposite effect.33 During the postoperative period, this group used a splint without occlusal coverage to eliminate the instability factor.21 This clinical practice can be considered a factor in stability improvement and perhaps could be one of the factors contributing to stability, aligning with findings from other studies.11,34,35 T2 scans were performed within a maximum of 19 days postoperatively to reduce the possibility of adaptive responses during this period. For the analysis within the surface model between groups, this statistical hypothesis was also accepted, indicating average values of –0.39 between canine regions (CR-CL) and 0.05 between posterior regions. These results demonstrate that neither surgical technique interfered with postoperative instability. Mandibular instability was not addressed in this study, however, we included only similar maxillo-mandibular movements to avoid the possible influence of mandibular post-surgical behavior (Supplementary Table 1).

In contrast, previous studies reported that instability rates for multi-segmental Le Fort I osteotomies vary from 23% to approximately 95%.2,4,6,36 However, these studies focused on the measurement of dentoalveolar surgical changes, either through radiographs or plaster models. After removal of the splint and completion of orthodontic treatment, these regions are subject to alterations and adaptations, generating dental and non-skeletal recurrences. In addition, no specific description was available of the surgical techniques employed or postoperative retention. Furthermore, in contrast to our study, simultaneous premolar extraction was performed during orthognathic surgery in one of the previous studies,6 which can result in additional surgical complications.

The main limitations of our study included the limited sample size, due to standardization requirements and the challenge of locating individuals with T2 CBCT scans, which are not commonly requested in clinical practice. However, the sample size was within an acceptable range considering the statistical power estimation for the variables studied. Nevertheless, the groups were selected considering the same growth patterns and surgical management for adequate comparisons. This is one of the few studies comparing the stability of one- and three-piece maxillary osteotomies using 3D Euclidean distances in a standardized sample. However, future studies with long longitudinal follow-ups and large samples should be conducted, especially because negative stability results have been reported in classic studies.2,4,6,36

CONCLUSIONS

One- and three-piece maxillary osteotomies demonstrated similar post-surgical skeletal stability.

FUNDING

FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for financial support (Processes 2013/05831-8 and 2014/09152-0).

AUTHOR CONTRIBUTIONS

Conceptualization: JRG, JI. Data curation: JI, PBM, JP. Formal analysis: RMK. Investigation: RMK, JRG, JI, PBM, JP. Methodology: JI. Project administration: JRG, JB. Resources: LW. Supervision: JRG, LW, JB. Validation: RMK. Visualization: RMK, JB. Writing–original draft: RMK, JI, PBM, JP. Writing–review & editing: RMK, JRG, LW, JB.

CONFLICTS OF INTEREST

No potential conflict of interest relevant to this article was reported.

SUPPLEMENTARY MATERIAL

Supplementary data is available at https://doi.org/10.4041/kjod23.166.

Fig 1.

Figure 1.Landmark points marked on the three-dimensional maxillary surface.
PR, posterior right; CR, canine right; AR, anterior right; AL, anterior left; CL, canine left; PL, posterior left.
Korean Journal of Orthodontics 2024; 54: 128-135https://doi.org/10.4041/kjod23.166

Fig 2.

Figure 2.Example of the Euclidean three-dimensional (3D) distance using two landmarks on a 3D surface. PR measurements within groups. Example: PR T2-PR T1.
T1, pre-surgical; T2, post-surgical; PR, posterior right.
Korean Journal of Orthodontics 2024; 54: 128-135https://doi.org/10.4041/kjod23.166

Fig 3.

Figure 3.Euclidean three-dimensional distance obtained using two landmarks within the model. Example: posterior right to posterior left.
Korean Journal of Orthodontics 2024; 54: 128-135https://doi.org/10.4041/kjod23.166

Table 1 . Landmarks, variable definitions, and localizations.

AbbreviationDescriptionLocalization
PRPosterior rightLandmark at bone relative to the root apex of upper right second molar
PLPosterior leftLandmark at bone relative to the root apex of upper left second molar
ARAnterior rightLandmark at bone relative to the root apex of upper right central incisor
ALAnterior leftLandmark at bone relative to the root apex of upper left central incisor
CRCanine rightLandmark at bone relative to the root apex of upper right canine
CLCanine leftLandmark at bone relative to the root apex of upper left canine
PR-PLPosterior right to posterior leftDistance of the posterior right to posterior left landmarks
CR-CLCanine right to canine leftDistance of the canine right to canine left landmarks

Table 2 . Student’s t test for surgical changes (T2-T1) and stability (T3-T2) between group 1 and group 2 (between three-dimensional models).

Measurement (Group 1- Group 2)Surgical change (T2-T1 distance)Stability (T3-T2 distance)
Mean (mm) SEP valueMean (mm)SEP value
CR0.730.640.2580.210.240.398
CL0.920.700.1960.410.210.063
PR1.390.990.1690.100.310.746
PL–0.121.070.9080.420.270.128
AR0.510.720.4850.070.290.813
AL0.660.750.3890.230.280.426

Student’s t test with α = 5%..

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR, canine right; CL, canine left; PR, posterior right; PL, posterior left; AR, anterior right; AL, anterior left..


Table 3 . Differences between groups for T2-T1 and T3-T2 (within the surface model).

Measurement
(Group 1-Group 2)
T2-T1T3-T2
Mean (mm)SEP valueMean (mm)SEP value
CR-CL3.060.57< 0.001***–0.390.650.555
PR-PL3.440.54< 0.001***0.050.370.888

T1, pre-surgical; T2, post-surgical; T3, follow-up; SE, standard error; CR-CL, canine right to canine left; PR-PL, posterior right to posterior left..

***P < 0.001 is statistically significant..


References

  1. Bell WH, Fonseca RJ, Kenneky JW, Levy BM. Bone healing and revascularization after total maxillary osteotomy. J Oral Surg 1975;33:253-60. https://pubmed.ncbi.nlm.nih.gov/1054396/
  2. Proffit WR, Turvey TA, Phillips C. The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension. Head Face Med 2007;3:21. https://doi.org/10.1186/1746-160X-3-21
    Pubmed KoreaMed CrossRef
  3. Kretschmer WB, Baciut G, Baciut M, Zoder W, Wangerin K. Stability of Le Fort I osteotomy in bimaxillary osteotomies: single-piece versus 3-piece maxilla. J Oral Maxillofac Surg 2010;68:372-80. https://doi.org/10.1016/j.joms.2009.09.053
    Pubmed CrossRef
  4. Kretschmer WB, Baciut G, Baciut M, Zoder W, Wangerin K. Transverse stability of 3-piece Le Fort I osteotomies. J Oral Maxillofac Surg 2011;69:861-9. https://doi.org/10.1016/j.joms.2010.05.024
    Pubmed CrossRef
  5. Blæhr TL, Jensen T, Due KM, Neumann-Jensen B. Stability of the anterior maxillary segment and teeth after segmental Le Fort I osteotomy and postoperative skeletal elastic fixation with or without occlusal splint. J Oral Maxillofac Res 2014;5:e4. https://doi.org/10.5037/jomr.2014.5304
    Pubmed KoreaMed CrossRef
  6. Tai W, Leung YY, Li DTS. Le Fort I osteotomy with segmentation for the treatment of maxillary dentoalveolar protrusion: a single-centre, 10-year outcome study. Int J Oral Maxillofac Surg 2022;51:1197-204. https://doi.org/10.1016/j.ijom.2022.01.012
    Pubmed CrossRef
  7. Kahnberg KE, Hagberg C. The approach to dentofacial skeletal deformities using a multisegmentation technique. Clin Plast Surg 2007;34:477-84. https://doi.org/10.1016/j.cps.2007.05.003
    Pubmed CrossRef
  8. Morgan TA, Fridrich KL. Effects of the multiple-piece maxillary osteotomy on the periodontium. Int J Adult Orthodon Orthognath Surg 2001;16:255-65. https://pubmed.ncbi.nlm.nih.gov/12390003/
  9. Reyneke JP, Conley RS. Surgical/orthodontic correction of transverse maxillary discrepancies. Oral Maxillofac Surg Clin North Am 2020;32:53-69. https://doi.org/10.1016/j.coms.2019.08.007
    Pubmed CrossRef
  10. Posnick JC, Adachie A, Choi E. Segmental maxillary osteotomies in conjunction with bimaxillary orthognathic surgery: indications - safety - outcome. J Oral Maxillofac Surg 2016;74:1422-40. https://doi.org/10.1016/j.joms.2016.01.051
    Pubmed CrossRef
  11. Haas Junior OL, Guijarro-Martínez R, de Sousa Gil AP, da Silva Meirelles L, de Oliveira RB, Hernández-Alfaro F. Stability and surgical complications in segmental Le Fort I osteotomy: a systematic review. Int J Oral Maxillofac Surg 2017;46:1071-87. https://doi.org/10.1016/j.ijom.2017.05.011
    Pubmed CrossRef
  12. Kramer FJ, Baethge C, Swennen G, Teltzrow T, Schulze A, Berten J, et al. Intra- and perioperative complications of the LeFort I osteotomy: a prospective evaluation of 1000 patients. J Craniofac Surg 2004;15:971-7; discussion 978-9. https://doi.org/10.1097/00001665-200411000-00016
    Pubmed CrossRef
  13. Kahnberg KE, Vannas-Löfqvist 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. https://doi.org/10.1016/j.ijom.2005.04.016
    Pubmed CrossRef
  14. Rodrigues DB, Campos PSF, Wolford LM, Ignácio J, Gonçalves JR. Maxillary interdental osteotomies have low morbidity for alveolar crestal bone and adjacent teeth: a cone beam computed tomography-based study. J Oral Maxillofac Surg 2018;76:1763-71. https://doi.org/10.1016/j.joms.2018.01.031
    Pubmed CrossRef
  15. Venugoplan SR, Nanda V, Turkistani K, Desai S, Allareddy V. Discharge patterns of orthognathic surgeries in the United States. J Oral Maxillofac Surg 2012;70:e77-86. https://doi.org/10.1016/j.joms.2011.09.030
    Pubmed CrossRef
  16. Jodeh DS, Nguyen ATH, Rottgers SA. Le Fort 1 and bimaxillary osteotomies increase the length of stay but not postoperative morbidity compared to mandibular osteotomies and single jaw procedures. J Craniofac Surg 2020;31:1734-8. https://doi.org/10.1097/SCS.0000000000006514
    Pubmed CrossRef
  17. Perez MM, Sameshima GT, Sinclair PM. The long-term stability of LeFort I maxillary downgrafts with rigid fixation to correct vertical maxillary deficiency. Am J Orthod Dentofacial Orthop 1997;112:104-8. https://doi.org/10.1016/s0889-5406(97)70280-4
    Pubmed CrossRef
  18. Hoppenreijs TJ, Freihofer HP, Stoelinga PJ, Tuinzing DB, van't Hof MA, van der Linden FP, et al. Skeletal and dento-alveolar stability of Le Fort I intrusion osteotomies and bimaxillary osteotomies in anterior open bite deformities. A retrospective three-centre study. Int J Oral Maxillofac Surg 1997;26:161-75. https://doi.org/10.1016/s0901-5027(97)80813-2
    Pubmed CrossRef
  19. Bailey LJ, Phillips C, Proffit WR, Turvey TA. Stability following superior repositioning of the maxilla by Le Fort I osteotomy: five-year follow-up. Int J Adult Orthodon Orthognath Surg 1994;9:163-73. https://pubmed.ncbi.nlm.nih.gov/7814921/
  20. Arpornmaeklong P, Heggie AA, Shand JM. A comparison of the stability of single-piece and segmental Le Fort I maxillary advancements. J Craniofac Surg 2003;14:3-9. https://doi.org/10.1097/00001665-200301000-00002
    Pubmed CrossRef
  21. Parizotto JOL, Borsato KT, Peixoto AP, Bianchi J, Cassano DS, Gonçalves JR. Can palatal splint improve stability of segmental Le Fort I osteotomies?. Orthod Craniofac Res 2020;23:486-92. https://doi.org/10.1111/ocr.12399
    Pubmed CrossRef
  22. Bailey L', Cevidanes LH, Proffit WR. Stability and predictability of orthognathic surgery. Am J Orthod Dentofacial Orthop 2004;126:273-7. https://pubmed.ncbi.nlm.nih.gov/15356484/
    Pubmed KoreaMed CrossRef
  23. Proffit WR, Turvey TA, Phillips C. Orthognathic surgery: a hierarchy of stability. Int J Adult Orthodon Orthognath Surg 1996;11:191-204. https://pubmed.ncbi.nlm.nih.gov/9456622/
  24. Bailey LJ, White RP Jr, Proffit WR, Turvey TA. Segmental LeFort I osteotomy for management of transverse maxillary deficiency. J Oral Maxillofac Surg 1997;55:728-31. https://doi.org/10.1016/s0278-2391(97)90588-7
    Pubmed CrossRef
  25. Lele S, Richtsmeier JT. Euclidean distance matrix analysis: a coordinate-free approach for comparing biological shapes using landmark data. Am J Phys Anthropol 1991;86:415-27. https://doi.org/10.1002/ajpa.1330860307
    Pubmed CrossRef
  26. Wolford LM, Bennett MA, Rafferty CG. Modification of the mandibular ramus sagittal split osteotomy. Oral Surg Oral Med Oral Pathol 1987;64:146-55. https://doi.org/10.1016/0030-4220(87)90080-6
    Pubmed CrossRef
  27. Bennett MA, Wolford LM. The maxillary step osteotomy and Steinmann pin stabilization. J Oral Maxillofac Surg 1985;43:307-11. https://doi.org/10.1016/0278-2391(85)90297-6
    Pubmed CrossRef
  28. Yushkevich PA, Piven J, Hazlett HC, Smith RG, Ho S, Gee JC, et al. User-guided 3D active contour segmentation of anatomical structures: significantly improved efficiency and reliability. Neuroimage 2006;31:1116-28. https://doi.org/10.1016/j.neuroimage.2006.01.015
    Pubmed CrossRef
  29. Cevidanes LH, Bailey LJ, Tucker GR Jr, Styner MA, Mol A, Phillips CL, et al. Superimposition of 3D cone-beam CT models of orthognathic surgery patients. Dentomaxillofac Radiol 2005;34:369-75. https://doi.org/10.1259/dmfr/17102411
    Pubmed KoreaMed CrossRef
  30. Ruellas AC, Tonello C, Gomes LR, Yatabe MS, Macron L, Lopinto J, et al. Common 3-dimensional coordinate system for assessment of directional changes. Am J Orthod Dentofacial Orthop 2016;149:645-56. https://doi.org/10.1016/j.ajodo.2015.10.021
    Pubmed KoreaMed CrossRef
  31. Ruellas AC, Yatabe MS, Souki BQ, Benavides E, Nguyen T, Luiz RR, et al. 3D mandibular superimposition: comparison of regions of reference for voxel-based registration. PLoS One 2016;11:e0157625. https://doi.org/10.1371/journal.pone.0157625
    Pubmed KoreaMed CrossRef
  32. Casko JS, Vaden JL, Kokich VG, Damone J, James RD, Cangialosi TJ, et al. Objective grading system for dental casts and panoramic radiographs. American Board of Orthodontics. Am J Orthod Dentofacial Orthop 1998;114:589-99. https://doi.org/10.1016/s0889-5406(98)70179-9
    Pubmed CrossRef
  33. Wolford LM, Rieche-Fischel O, Mehra P. Soft tissue healing after parasagittal palatal incisions in segmental maxillary surgery: a review of 311 patients. J Oral Maxillofac Surg 2002;60:20-5; discussion 26. https://doi.org/10.1053/joms.2002.29068
    Pubmed CrossRef
  34. Haas Junior OL, Guijarro-Martínez R, de Sousa Gil AP, da Silva Meirelles L, Scolari N, Muñoz-Pereira ME, et al. Hierarchy of surgical stability in orthognathic surgery: overview of systematic reviews. Int J Oral Maxillofac Surg 2019;48:1415-33. https://doi.org/10.1016/j.ijom.2019.03.003
    Pubmed CrossRef
  35. Starch-Jensen T, Blæhr TL. Transverse expansion and stability after segmental Le Fort I osteotomy versus surgically assisted rapid maxillary expansion: a systematic review. J Oral Maxillofac Res 2016;7:e1. https://doi.org/10.5037/jomr.2016.7401
    Pubmed KoreaMed CrossRef
  36. Marchetti C, Pironi M, Bianchi A, Musci A. Surgically assisted rapid palatal expansion vs. segmental Le Fort I osteotomy: transverse stability over a 2-year period. J Craniomaxillofac Surg 2009;37:74-8. https://doi.org/10.1016/j.jcms.2008.08.006
    Pubmed CrossRef