One-piece Lefort osteotomy versus segmental procedure for maxillary skeletal deformities-A retrospective study

Maxillary skeletal deformities can occur in all three planes and are corrected by orthognathic surgery. Osteotomies form the basis for orthognathic surgeries. One of the most commonly used osteotomy techniques for maxillary skeletal deformities is the LeFort osteotomy. The aimof this studywas to compare the application of One Piece LeFort Osteotomy and Segmental Osteotomy procedures in the treatment of maxillary skeletal deformities. The institutional study involved analysis of case sheets of patients who underwent surgical correction of maxillary skeletal deformities in the stipulated time frame and assessment based on the parameters: Demographic data, type of cephalometric analysis, cephalometric values, type of skeletal deformity, and technique of Osteotomy. Statistical analysis was calculated by chi-square test. A p-value<0.05 was considered signi icant. Maxillary skeletal deformities were more prevalent among females (60%) than males (40%). Anterior maxillary segmental osteotomies were more commonly performed (60%), followed by LeFort 1 osteotomy (26.7%). The prevalence of posterior osteotomy technique was 13.3%. A statistically signi icant association was revealed between the type of skeletal malocclusion and technique of Osteotomy used, with a p-value of 0.008<0.05. The type of malocclusion dictates the technique of Osteotomy is used. In a skeletal Class II, segmental malocclusion procedure was more preferred for maxillary deformities.


INTRODUCTION
Oral and Maxillofacial Surgeons are involved in the treatment of a wide range of dentofacial deformities. One such deformity is skeletal malocclusion.
The correction of skeletal malocclusion involves a combination of orthognathic surgery by an oral surgeon and pre-/post-surgical orthodontics by an orthodontist. Orthognathic surgery is an exciting procedure that satis ies both the functional and aesthetic needs of a patient. Osteotomies form the core of orthognathic surgeries. The standard osteotomy procedures are LeFort I Osteotomy, anterior maxillary Osteotomy, posterior maxillary Osteotomy, bilateral sagittal split osteotomy and mandibular subapical Osteotomy.
The osteotomy procedures ind their indications depending on the type of dental or skeletal deformity. These deformities can be -skeletal class I / II / III malocclusion, transverse maxillary discrepancies, vertical maxillary excess, vertical maxillary de iciency, prognathic maxilla or mandible, ret-rognathic maxilla or mandible or segmental deformities. Of the techniques used for the treatment of maxillary skeletal deformities, the common procedures are LeFort I Osteotomy and segmental techniques, i.e. anterior segmental maxillary Osteotomy and posterior segmental maxillary Osteotomy. LeFort I Osteotomy derives its name from the fracture pattern described by Rene LeFort in 1901. It extends from the piriform aperture, along the tooth apices up to the pterygomaxillary junction. This procedure has a wide range of lexibility as it permits movements in all three planes, making it preferable for any skeletal malocclusion, including transverse maxillary discrepancies and vertical maxillary excess (Hyman and Buchanan, 2013). Segmental LeFort I Osteotomy is a preferred technique for transverse maxillary de iciencies and anterior open bite. (Hyman and Buchanan, 2013) Some studies have reported the advantages, disadvantages and complications of these procedures. However, a comparative account of these two techniques of osteotomies is extremely low in the case of literature evidence. Till date, the institutional team has conducted several clinical trials - (Jesudasan et al., 2015;Christabel et al., 2016), in-vitro studies- (Marimuthu et al., 2018), and awareness surveys - (Kumar and Rahman, 2017;Packiri, 2017) in the ield of Oral and Maxillofacial surgery. Hence, this study was designed in a retrospective epidemiological setup to study the population-based difference in the trends.
The current study aims to evaluate the different indications leading to the selection of a One Piece LeFort 1 or a Segmental Osteotomy procedure and to compare the in luence of the type of malocclusion on procedure selection.

Study setting
The study was carried out in an institutional setting with the advantage of being a wide range of data available in digital format and the disadvantage of being an assessment of patients in a single location only.
The study consisted of one reviewer, one assessor and one guide.

Study design
The study was designed to include all dental patients who had undergone treatment for correction of maxillary skeletal deformities. Syndromic patients, cleft lip and palate patients were excluded from the study.

Sampling technique
The study was based on Non-probability convenience sampling. To minimize the sampling bias, all the case sheets of patients who underwent Osteotomy for maxillary skeletal deformities were reviewed and included.

Data collection and Tabulation
Data collection was done using the patient database with the timeframe work of 1st June 2019 to 30th April 2020. Cross veri ication of data was done by a reviewer. The collected data were tabulated based on the following parameters: Patient's demographic details Osteotomy Technique Type of Skeletal deformity Type of cephalometric analysis Cephalometric measurements

Statistical analysis
The variables were coded, and the data was imported to SPSS. Using SPSS Version 20.0, categorical variables were expressed in terms of frequency percentage, and bar graphs were plotted. The statistical signi icance of associations was tested using the Chi-square test.

RESULTS AND DISCUSSION
The correct sample size of the study was n=15. Of these 14 patients had undergone surgery irst orthognathic approach. Only one patient had undergone presurgical orthodontics (6.67%).  Table 1 shows the gender-wise distribution of patients undergoing maxillary osteotomy procedures in the stipulated time period, with 60% (n=9) being females and 40% (n=6) being males.      The association between the type of skeletal malocclusion and technique of Osteotomy was found to be statistically signi icant with a p-value of 0.008<0.05 after a Chi-square test [ Table 3].
Further, a chart was plotted between the technique of Osteotomy and cephalometric analysis [ Figure 3], based on which the following inferences have been made: In Orthognathic surgery consists basically of osteotomy techniques that are performed with an objective of correcting deformities or discrepancies in the endoskeletal system in order to achieve a facial and cranial balance (Sousa and Turrini, 2011;Patil et al., 2017). Lefort, I osteotomy is one of the most common procedures in orthognathic surgery and is used to correct deformities in all three planes. It is used at times in conjunction with mandibular orthognathic procedures such as Bilateral Sagittal Split Osteotomy (Hyman and Buchanan, 2013;Rao and Kumar, 2018). On the other hand, segmental osteotomy procedures also allow correction to be carried out in all three planes and at the same time provide the lexibility to limit correction to a particular segment of the arch and optimal enhancement of the facial skeleton (Hyman and Buchanan, 2013;Rosen, 1989).   An orthognathic surgery proceeds in the following sequence: Preliminary assessment of patient -Cephalometric radiograph -Cephalometric tracing -Analysis and tabulation -inal diagnosis of malocclusion -a selection of osteotomy technique -presurgical orthodontics if required -mock surgery on mounted casts -orthognathic surgery -post-surgical orthodontics (if required) -review and follow up.
A patient undergoing orthognathic surgery is subjected to cephalometric analysis before the surgery to identify and measure certain landmarks that can be altered by surgical procedures (Burstone et al., 1978;Abhinav et al., 2019a) Such a cephalometric analysis enables the operator to assess both hard tissues and soft tissue pro iles. The analysis of soft tissue is particularly important in cases of endoskeletal deformities and helps in achieving proper facial aesthetics (Legan and Burstone, 1980;Abhinav et al., 2019b). The values of dental, skeletal and soft tissue components of these cephalometric analyses are not constant and are subject to variances based on the type of malocclusion, and population. According to Jain and Kalra, the cephalometric norms for a North Indian population showed signi icant variations from the caucasian standards (Jain and Kalra, 2011;Jain et al., 2019).
According to (Janson et al., 2008;Kumar and Sneha, 2016), in a case of skeletal class III malocclusion with temporomandibular pain, a segmental LeFort I Osteotomy procedure gave good results with relief of TMD pain. (Arpornmaeklong et al., 2003;Patturaja and Pradeep, 2016), recommends segmental osteotomy procedures to enhance the occlusal results postoperatively. In another study by (Ho et al., 2010), segmental osteotomies were reported to have comparatively lower complications than other osteotomy procedures. (Hyman and Buchanan, 2013), reported that complications after a One Piece LeFort I Osteotomy occur in about 6.4% of patients, with a higher risk of occurrence in patients with more than 9mm of anterior movement.
(Hernández-Alfaro and Guijarro-Martínez, 2016) in his retrospective study of 50 cases of orthognathic surgery observed that in patients with skeletal class III malocclusion LeFort I Osteotomy is the most preferred technique while segmental LeFort I maxillary osteotomy is preferred for cases of the bimaxillary protrusion. Similarly, Xiong Zing Wu quotes subapical anterior maxillary segmental Osteotomy to be an effective treatment option for cases of the maxillary protrusion (Wu et al., 2010). (Arpornmaeklong et al., 2003) has compared the postoperative stability of single piece and segmental maxillary LeFort advancements wherein the segmental osteotomy techniques had better postoperative stability than One piece LeFort I Osteotomy. However, (Hernández-Alfaro and Guijarro-Martínez, 2016), contradicts these indings through his study with the inference that reaching the vertical versus horizontal target position is more dif icult in a multisegmental LeFort I, but also gives supporting evidence of high stability of multi-segmented osteotomy procedures when compared to one-segment osteotomy technique.
In a systematic review by (Junior et al., 2017) it has been reported that segmental osteotomy technique provides extremely stable results in the sagittal plane but poor stability in the posterior segment. The review also reveals signi icant literature evidence which suggests that the procedure cannot be considered as unsafe or unstable and hence can be con idently used in cases requiring movement in all three planes (Junior et al., 2017). (Moloney et al., 1984), points out the signi icance of posterior maxillary Osteotomy in the closure of posterior edentulous spaces, which was also the exact indications of the patient who underwent posterior maxillary Osteotomy in the current study. (Jayaratne et al., 2010), points out the facial soft tissue response of segmental osteotomy technique being good in reducing the labial prominence as well as increasing the nasolabial angle. (Janson et al., 2008), gives evidence of segmental osteotomy procedure being successful in the treatment of skeletal class III malocclusion with TMD, providing adequate pain relief.
Though the current study possesses few limitations in the sample size being very small and inability to generalize results to a larger population, the results go well-matched with the existing literature evidence, thus making the overall consensus agreeable.

CONCLUSIONS
There are signi icant differences between the two techniques of Osteotomy, i.e. one piece LeFort I osteotomy and segmental Osteotomy, but the type of malocclusion was a major deciding factor, and a segmental procedure has been the most preferred technique for skeletal class II malocclusion in the study population. Future scope of the study allows measurement of postoperative stability and patient satisfaction in a large sample size.

ACKNOWLEDGEMENT
We thank Saveetha Dental College and Hospitals, Saveetha University, Saveetha Institute of Medical and Technical Sciences for supporting the study.

Authors Contributions
The irst author (Kalyani. P) performed the analysis, and interpretation and wrote the manuscript. The second author (Dr Madhulaxmi) contributed to the conception, data design, analysis, interpretation and critically revised the manuscript. The third author (Dr M. P. Santhosh Kumar) participated in the study and revised the manuscript. All three authors have discussed the results and contributed to the inal manuscript.