A systematic review of soft-to-hard tissue ratios in orthognathic surgery. Part IV: 3D analysis - Is there evidence?

Artificial Intelligence Used for Diagnosis in Facial Deformities: A Systematic Review

AI is included in a lot of different systems. In facial surgery, there are some AI-based software programs oriented to diagnosis in facial surgery. This study aims to evaluate the capacity and training of models for diagnosis of dentofacial deformities in class II and class III patients using artificial intelligence and the potential use for indicating orthognathic surgery. The search strategy is from 1943 to April 2024 in PubMed, Embase, Scopus, Lilacs, and Web of Science. Studies that used imaging to assess anatomical structures, airway volume, and craniofacial positions using the AI algorithm in the human population were included. The methodological quality of the studies was assessed using the Effective Public Health Practice Project instrument. The systematic search identified 697 articles. Eight studies were obtained for descriptive analysis after exclusion according to our inclusion and exclusion criteria. All studies were retrospective in design. A total of 5552 subjects with an age range between 14.7 and 56 years were obtained; 2474 (44.56%) subjects were male, and 3078 (55.43%) were female. Six studies were analyzed using 2D imaging and obtained highly accurate results in diagnosing skeletal features and determining the need for orthognathic surgery, and two studies used 3D imaging for measurement and diagnosis. Limitations of the studies such as age, diagnosis in facial deformity, and the included variables were observed. Concerning the overall analysis bias, six studies were at moderate risk due to weak study designs, while two were at high risk of bias. We can conclude that, with the few articles included, using AI-based software allows for some craniometric recognition and measurements to determine the diagnosis of facial deformities using mainly 2D analysis. However, it is necessary to perform studies based on three-dimensional images, increase the sample size, and train models in different populations to ensure accuracy of AI applications in this field. After that, the models can be trained for dentofacial diagnosis.

Photographic Parameters in Three-Dimensional Facial Image Acquisition. A Scoping Review

OBJECTIVE

Orthognathic surgery is a viable and reproducible treatment for facial deformities. Despite the precision of the skeletal planning of surgical procedures, there is little information about the relations between hard and soft tissues in three-dimensional (3D) analysis, resulting in unpredictable soft tissue outcomes. Three-dimensional photography is a viable tool for soft tissue analysis because it is easy to use, has wide availability, low cost, and is harmless. This review aims to establish parameters for acquiring consistent and reproducible 3D facial images.

METHODS

A scoping review was conducted across PubMed, SCOPUS, Scientific Electronic Library Online (SciELO), and Web of Science databases, adhering to "Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews" guidelines. Articles presenting 3D facial photographs in the diagnostic phase were considered.

RESULTS

A total of 79 articles were identified, of which 29 were selected for analysis.

CONCLUSION

The predominant use of automated systems like 3dMD and VECTRA M3 was noted. User positioning has highest agreement among authors. Noteworthy aspects include the importance of proper lighting, facial expression, and dental positioning, with observed discrepancies and inconsistencies among authors. Finally, the authors proposed a 3D image acquisition protocol based on this research findings.

Exploring the relationship between the number of systematic reviews and quality of evidence: an orthognathic surgery-based study

OBJECTIVE

We analyzed the quality and quantity of systematic reviews (SRs) of orthognathic surgery, the most frequently published topic in maxillofacial surgery.

STUDY DESIGN

We searched the PubMed database for SRs of orthognathic surgery with no restriction on the language of publication date. We assessed the certainty of evidence presented according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol and the Leiden Manifesto using the Grading of Recommendations Assessment, Development, and Evaluation approach. We analyzed the data using descriptive statistics, Pearson´s correlation test, and linear regression.

RESULTS

Of the 171 SRs evaluated, approximately one fifth presented evidence with a high level of certainty. The number of orthognathic surgery SRs has been increasing, and many SRs were published after very similar topics had already been published. There is no relationship between the impact factor and the certainty of evidence.

CONCLUSIONS

An excessive number of SRs of orthognathic surgery are published, and many SRs are superfluous, simply reporting previous findings. Clinicians should not base treatment decisions solely on the evidence presented in SRs, and journal editors and reviewers should evaluate these SRs more critically, particularly when they address topics that have already been covered in the literature.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Improve Facial Appearance?

BACKGROUND

Facial aesthetics may be optimized based on a deeper understanding of soft tissue changes after orthognathic surgery.

PURPOSE

The purpose of the study was to delineate facial soft tissue changes after clockwise rotation (CWR) of the maxillomandibular complex (MMC) to correct mandibular prognathism using the surgery-first approach.

STUDY DESIGN, SETTING, SAMPLE

This prospective cohort study enrolled patients over 18 years of age with skeletal Class III malocclusion in the craniofacial center. The patients were excluded with previous history of craniofacial syndrome, orthognathic surgery trauma, infection at surgical sites, chin deviation (menton deviation ≥4 mm), 2 or more missing data points after surgery, or without informed consent. This study compared significant facial changes before (T0) and after orthodontic debonding (T1) in the CWR and control groups.

PREDICTOR VARIABLE

The patients were divided in accordance with maxillary occlusal plane change (OPC) after surgery into CWR (OPC >4°) and control (OPC ≤4°) groups.

MAIN OUTCOME VARIABLE

The primary outcome variable was frontal lip curvature (FLC: Right Cheilion-Stomion-Left Cheilion, degree) with or without upper lip curving upward at T1, where upper lip curving upward was considered more favorable.

COVARIATES

The covariates included age, sex, and various cephalometric measurements.

ANALYSES

The Mann-Whitney U test, paired, and independent t-test were implemented to compare the intragroup and intergroup differences. Statistical significance was indicated by P value <.05.

RESULTS

The study comprised 34 patients (21 women) in the control group and 37 (29 women) in the CWR group; their mean ages were 23.64 ± 4.38 and 24.21 ± 3.84 years, respectively (P value = .562). At T1, the CWR group had significant increased FLC (P value = .001), alar width (P value = .034), and lower vermilion height (P value = .018), and decreased lower lip length (P value = .004). The high FLC group had significant decreased upper lip projection (P value = .002) and increased nasolabial angle (P value = .013). The significant relationship between CWR and high FLC was supported by the χ2 test (P value = .018) and multiple logistic regression (P value = .017).

CONCLUSION

Greater CWR of the MMC increased FLC and lower vermilion height and reduced lower lip length. High FLC resulting from the CWR of the MMC improved facial appearance by moving the upper lip curve upward.

Latest Evidence on Orthognathic Surgery Techniques and Potential Changes in Oral Microbiota related to Intermaxillary Fixation in Orthodontic Patients: A Systematic Review

Background:

Orthognathic surgery is often applied for the correction of facial dysmorphia, and different findings were highlighted regarding the techniques applied. After surgical treatment, intermaxillary fixation is placed, which compromises oral hygiene and, consequently, can lead to increased plaque accumulation and microbiological changes, promoting the proliferation of periodontopathogenic bacteria. Therefore, the aims of the present review are to describe the main evidence from the last 20 years of clinical studies concerning surgical techniques applied to orthognathic surgery and, finally, to analyze potential changes in the oral microbiota.

Materials and Methods:

An electronic search was conducted in the PubMed (MEDLINE) and Scopus databases; the MeSH (Medical Subject Heading) terms are bacteria, dental plaque, evidence-based practice, maxillomandibular fixation, microbiota, operative procedures, and orthognathic surgery.

Results:

At the end of the search process, 31 relevant articles were finally included and analyzed in this systematic review, which has a low risk of bias. Clinical studies on humans have been considered in this review. Based on the studies included it would be preferable to use piezoelectric technology in osteotomies because of its many advantages, “surgery-first” technique allows for results comparable to the standard technique in Class III malocclusions while improving quality of life more rapidly, the “mandible-first” technique seems to have more advantages than the “maxilla-first” technique, Computer-Aided Design and Manufacturing (CAD/CAM) could provide more accurate and precise results, and finally, Laser can be applied with different advantages. Regarding intermaxillary fixation, no long-term increase in the concentration of periodontal bacteria was recorded.

Conclusion:

Several findings still need to be confirmed with reference to the best suturing technique to reconstitute the nasal wing base, the real effectiveness of “surgery-first,” “maxilla-first,” and “mandible-first” approaches in patients with Class III malocclusion, the use of CAD/CAM and Laser, more studies should be conducted to evaluate quantitative and qualitative changes in other microorganisms following intermaxillary fixation.

Facial changes in patients with skeletal class III deformity after bimaxillary surgery: an evaluation based on three-dimensional photographs registered with computed tomography

The objective of this study was to evaluate facial soft and hard tissue changes, individually and relative to each other, in patients with skeletal class III deformity after bimaxillary surgery using three-dimensional (3D) photos obtained by white light scanning. Thirty patients with skeletal class III deformity who underwent bimaxillary surgery were selected. Each patient underwent white light scanning and spiral computed tomography (CT) within two weeks before (T0) and six months after surgery (T1). The 3D photos were registered with CT soft tissue models for T0 and T1, and the skeletal area unaffected by treatment (cranial base) was used to register T0 and T1. Then, the 3D colour-coded map was analysed to assess both skeletal and soft tissue changes between T0 and T1. Changes in the 3D coordinates of each anatomical landmark were analysed using the Student's t-test. Maxillary advancement by 2-3 mm and mandibular recession by 5-6 mm were observed; the mandible was shortened in the vertical direction. Compared with the preoperative values, the nasal columella was 0.51 mm shorter, the upper lip was 0.71 mm longer, the base of the alar cartilage was 1.38 mm wider, and the nasolabial angle became larger. The ratio of change in the position of soft tissue point Sn to hard tissue point A was 0.73:1, and that of soft tissue point Pg to hard tissue point Pog was 0.86:1. Images obtained by structured white light scanning registered with CT can be used as an alternative to study facial changes after orthognathic surgery.

A Quantitative and Qualitative Clinical Validation of Soft Tissue Simulation for Orthognathic Surgery Planning

The purpose of this study was to perform a quantitative and qualitative validation of a soft tissue simulation pipeline for orthognathic surgery planning, necessary for clinical use. Simulation results were retrospectively obtained in 10 patients who underwent orthognathic surgery. Quantitatively, error was measured at 9 anatomical landmarks for each patient and different types of comparative analysis were performed considering two mesh resolutions, clinically accepted error, simulation time and error measured by means of percentage of the whole surface. Qualitatively, evaluation and binary questions were asked to two surgeons, both before and after seeing the actual surgical outcome, and their answers were compared. Finally, the quantitative and qualitative results were compared to check if these two types of validation are correlated. The quantitative results were accurate, with greater errors corresponding to gonions and lower lip. Qualitatively, surgeons answered similarly mostly and their evaluations improved when seeing the actual outcome of the surgery. The quantitative validation was not correlated to the qualitative validation. In this study, quantitative and qualitative validations were performed and compared, and the need to carry out both types of analysis in validation studies of soft tissue simulation software for orthognathic surgery planning was proved.

Comparison of two alar cinch base suture in orthognathic surgery: a randomized clinical trial

Le Fort I osteotomy is widely used in orthognathic surgery to correct maxillary deformities. However, this osteotomy may be related with the increase of alar base width. The aims of the present study were to compare two alar cinch suture after Le Fort I osteotomy and observe which type presents a better result in controlling the enlargement of the alar base after maxillary repositioning in orthognathic surgery. A randomized clinical trial was carried out with 40 patients randomly assigned in two intervention groups: group 1 - patients submitted to internal suture and group 2 - patients submitted to external suture. Of the 40 patients, 65% were female and 35% were male. The mean age of the patients was 30,25 in group I and 28,6 in group II. There was an increase in the alar base width in both groups, with significant difference between the means (P < 0,001). It was possible to compare the evolution of the means of the alar base width between group I and group II. Thus, it was observed that the external technique (group II) better controlled alar base width after Le Fort I osteotomy. It was not possible to relate the enlargement of the alar cinch with maxillary movement performed (P > 0,05). Overall, alar base cinch suture is an essential component of Le Fort osteotomies to control the alar base width. In this study, the external technique was more effective when compared to the internal technique in controlling the enlargement of the alar base width.

Local Soft Tissue and Bone Displacements Following Midfacial Bipartition Distraction in Apert Syndrome - Quantification Using a Semi-Automated Method

ABSTRACT

Patients with Apert syndrome experience midfacial hypoplasia, hypertelorism, and downslanting palpebral fissures which can be corrected by midfacial bipartition distraction with rigid external distraction device. Quantitative studies typically focus on quantifying rigid advancement and rotation postdistraction, but intrinsic shape changes of bone and soft tissue remain unknown. This study presents a method to quantify these changes. Pre- and post-operative computed tomography scans from patients with Apert syndrome undergoing midfacial bipartition distraction with rigid external distraction device were collected. Digital Imaging and Communications in Medicine files were converted to three-dimensional bone and soft tissue reconstructions. Postoperative reconstructions were aligned on the preoperative maxilla, followed by nonrigid iterative closest point transformation to determine local shape changes. Anatomical point-to-point displacements were calculated and visualized using a heatmap and arrow map. Nine patients were included.Zygomatic arches and frontal bone demonstrated the largest changes. Mid-lateral to supra-orbital rim showed an upward, inward motion. Mean bone displacements ranged from 3.3 to 12.8 mm. Soft tissue displacements were relatively smaller, with greatest changes at the lateral canthi. Midfacial bipartition distraction with rigid external distraction device results in upward, inward rotation of the orbits, upward rotation of the zygomatic arch, and relative posterior motion of the frontal bone. Local movements were successfully quantified using a novel method, which can be applied to other surgical techniques/syndromes.

Three-dimensional nasolabial changes after maxillary advancement osteotomy in class III individuals: a systematic review and meta-analysis

Background Class III malocclusions with maxillary retrognathia are commonly treated with single jaw Le Fort I maxillary advancement. The three-dimensional (3D) effects of surgery on the nasolabial region varies among the clinical studies. Quantifying these changes is of great importance for surgical planning and obtaining valid consent. Objectives To investigate the 3D relationship between soft tissue and skeletal changes secondary to Le Fort I maxillary advancement surgery in skeletal class III patients.Search methods Comprehensive search of multiple electronic databases supplemented by a manual and grey literature search were undertaken from inception to 9 June 2020.Selection criteria Studies that evaluated the 3D soft tissue changes of patients before and after maxillary advancement surgery alone.Data collection and analysis Study selection, data extraction and risk of bias assessment were performed independently by two reviewers, with disputes resolved by a third reviewer. A quantitative synthesis of the data was pre-planned for pooling similar outcome measures.Results Four studies were included in the final review and meta-analysis, with a total of 105 patients (mean age 16.7 + 33.9 years). The mean maxillary advancement of the included studies was 5.58 mm (95% CI 5.20-5.96). The sagittal effects of surgery on nose tip projection and prominence were insignificant (P >0.05, two studies); however, subnasal projection (MD 1.7 mm, two studies) and upper lip projection (MD 2.90 mm, four studies) increased significantly in a forward direction after surgery (P <0.05). Le Fort I osteotomy widens the upper philtrum width (MD 0.84 mm, two studies) (P <0.05). Inconsistencies among the included studies were identified; therefore, the results should be interpreted with caution.Conclusions There is weak evidence based on quantitative assessments that Le Fort I maxillary advancement significantly affects the nasolabial soft tissue envelope mainly in a sagittal dimension. These changes are concentrated around the central zone of the nasolabial region. Future prospective studies on maxillary advancement osteotomy with a standardised method of assessment, taking into consideration the confounding factors, are required.

Soft Tissue Changes After Clockwise Rotation of Maxillo-Mandibular Complex in Class III Patients: Three-Dimensional Stereophotogrammetric Evaluation

OBJECTIVES

To evaluate the linear, angular, and volumetric changes of soft tissue after clockwise repositioning of the maxillo-mandibular complex in skeletal class III patients using three-dimensional (3D) stereophotogrammetry and to determine the correlation between changes in the skeletal and soft tissue variables.

METHODS

This study included 18 skeletal class III patients who underwent two-jaw surgery; superior impaction and clockwise rotational movement of the maxilla with the rotation center at upper incisors, and setback of the mandible. Lateral cephalograms and 3D photographs taken before and 6 months after surgery were compared.

RESULTS

After maxillary impaction of anteriorly 1.7 mm and posteriorly 3.1 mm, and mandibular setback of 8.7 mm, the volume of lower lip and chin region decreased significantly by 33.6 cm3 (13% net change, P < 0.001), while paranasal and upper lip region volume increased by 3.2 cm3 (2%) and 7.2 cm3 (4%), respectively.

CONCLUSION

The clockwise rotation of maxillo-mandibular complex in class III patients significantly reduced lower lip and chin volume with minimal increase in paranasal and upper lip volumes. 3D stereophotogrammetry can provide quantitative evaluation of facial soft tissue volumetric changes.

A New Approach to Set the Absolute Midsagittal Plane of the Mandible Using a Similarity Index in Skeletal Class III Patients with Facial Asymmetry

This study sought to test the feasibility of a newly developed plane called computed modified absolute mandibular midsagittal plane (cmAMP) based on the similarity index (SI) for evaluating the stereoscopical symmetry of the mandible by comparison with other proposed midsagittal planes. This study involved 29 adult patients (15 men, 14 women; average age, 23.1 ± 6.9 years) with skeletal Class III facial asymmetry who underwent bimaxillary orthognathic surgery. Using cone-beam computed tomography images taken before and 1 year after surgery, cmAMP with the highest SI value between the two anterior segments of the hemi-mandible was set by a computer algorithm. Results show that the SI using cmAMP had the highest value (0.83 ± 0.04) before surgery compared to the other midsagittal planes, and was not significantly different from the SI (0.80 ± 0.05) using a facial midsagittal plane (MSP) after surgery. The distance (1.15 ± 0.74 mm) and angle (2.02 ± 0.82°) between MSP and cmAMP after surgery were significantly smaller than those between MSP and other midsagittal planes. In conclusion, the cmAMP plane best matches the two anterior segments of hemi-mandible symmetrically and is the closest to MSP after orthognathic surgery in skeletal Class III patients with facial asymmetry.

Differences in soft-tissue thickness changes after bimaxillary surgery between patients with vertically high angle and normal angle

INTRODUCTION

We evaluated soft-tissue thickness changes after bimaxillary surgery according to vertical facial patterns in patients with skeletal Class III malocclusion with mandibular prognathism.

METHODS

Forty-three Korean patients (16 men and 27 women; mean age, 22.6 ± 4.1 years) with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into 2 groups: normal-angle group (N group) and high-angle group (H group), on the basis of the presurgical angle of the mandibular plane relative to the sella-nasion plane (SN-MP). Changes in hard-tissue landmarks and soft-tissue thickness before and after surgery were analyzed from reconstructed 3-dimensional cone-beam computed tomography images. Postoperative soft-tissue thickness in both groups was compared with that in 40 patients with normal skeletal Class I malocclusion in the reference group.

RESULTS

Group N (27°-37°) and group H (>37°) did not differ significantly in terms of sex and age before surgery. Preoperative pogonion (Pog) thickness was significantly less in group H (9.7 ± 1.6 mm) than in group N (10.8 ± 1.9 mm) (P = 0.042). Adjusted multiple linear regression analysis showed a weak positive linear relationship between the SN-MP before surgery and soft-tissue Pog thickness change (R² of 0.361; P = 0.001) after surgery, but the area below the lower lips was not completely normalized despite surgery.

CONCLUSIONS

The thickness of the soft-tissue Pog may increase slightly after surgery in patients with skeletal Class III malocclusion with a higher preoperative mandibular plane angle, but normalization in the area cannot be completely achieved despite surgery.

Mandibular Angle Contouring Using Porous Polyethylene Stock or PEEK-based Patient Specific Implants. A Critical Analysis

ABSTRACT

Contour augmentation and mandibular angle modification surgery is becoming increasingly. The aim of this research is to compare technique and outcomes in augmentations done with standard implants or PEEK-based patient specific implants (PSI) in mandibular angle. Data from surgical planning, operative and post-operative of 6 months follow-up were revised for 21 patients who were submitted to facial surgery using a stock implant obtained from companies currently on the market or 3D implants created with CAD/CAM technology using PEEK 3D printing. Surgical time, intra-operative and post-operative complications were compared, analyzing the advantages and disadvantage of each technique. Statistical analyses using t-test and chi-squared were performed considering P value< 0.05 for statistical differences. Twelve patients were operated on with stock implants and nine patients with PSI. The surgical time was 15 minutes less for the 3D implant surgeries (P = 0.021) and intraoperatively only the stock implants needed modifications with wear and adaptation methods; post-operative infections were observed in both groups with no significant differences (P > 0.05). The 3D implants had greater levels of facial symmetry than the stock implants, although they did not present significant differences.Considering the limitations of this study, mandibular angle implants with a PEEK-based 3D CAD/CAM are efficient, stable and have a low complication rate; the CAD/CAM strategy is useful in facial surgery and can be integrated as a standard for surgical planning in facial makeover surgery.

A prospective study of soft- and hard-tissue changes after mandibular advancement surgery: Midline changes in the chin area

INTRODUCTION

The purpose of this research was to prospectively determine the ratio of 2 soft-tissue landmarks, pogonion (sPg) and menton (sMe), to their hard-tissue counterparts (Pg and Me) in the sagittal and vertical directions for mandibular lengthening surgeries.

METHODS

We drew a sample from the prospective Orthognathic and Orthofacial Surgery Research study, consisting of patients who underwent surgical mandibular lengthening (alone or in combination with maxillary osteotomy) without genioplasty. We digitized landmarks using Facewizz software and determined the relationships between the hard- and soft-tissue changes by correlation analysis.

RESULTS

Pearson correlation test showed a significant correlation between the type of surgery and the sPg:Pg and sMe:Me ratios. The sPg:Pg ratio was 87% for mandibular lengthening only and 102% for mandibular lengthening in combination with maxillary surgery. The sMe:Me ratio was 85% and 96% for upward and downward movements, respectively.

CONCLUSIONS

The average ratios presented in this study for the pogonion and menton can aid in preoperative planning by providing estimates for soft-tissue behavior. Further stratifications will be possible after the Orthognathic and Orthofacial Surgery Research database is enriched with more inclusions.

Three-Dimensional Computer-Assisted Single-Splint 2-Jaw Cleft Orthognathic Surgery: Toward Patient-Centered Surgical Rationale

Skeletally mature patients with cleft lip and palate commonly present with skeletofacial deformities characterized by varying degrees of intrinsic and acquired dentoskeletal and soft tissue abnormalities. These abnormalities are associated with scarring from previous surgeries and the asymmetric midline and facial contour that impose challenges for adequate reconstruction. These patients frequently require 2-jaw orthognathic surgery to improve occlusal function and for correction of facial deformities. In this article, we have detailed a 3-dimensional computer-assisted single-splint 2-jaw orthognathic surgery technique as a surgical approach for cleft skeletofacial reconstruction, allowing for the surgery to be tailored according to the specific needs and requests of the patients. Further, we have addressed the multidimensionality and specificities of cleft treatment, the wide versatility, adaptability, and applicability of this technique, and the patient-centered rationale for the adoption of this method.

The Prediction Capacity 3-D Software, on a 2-D Analysis, in Planning the Positioning of the Upper Lip After Maxillary Advancement

Purpose

The maxillary advancement using Le Fort I osteotomy directly affects in the positioning of the upper lip (UL) and the nasolabial angle (NLA), which plays an important role in facial expression and aesthetics, because of this, the aim of this study was to evaluate the ability of Dolphin Imaging 11.8 software in predicting changes to the UL position and NLA in patients undergoing maxillary advancement.

Materials and Methods

It was a retrospective cohort study. Predictive and final tracings using pre- and postoperative Cone beam computed tomography (CBCT) of 24 patients undergoing maxillary advancement, regardless of mandibular movement, were compared. Whether the amount of advancement changes this predictability was also analyzed. The predictive and the 12-month postoperative data were evaluated using Dolphin Imaging 11.8 software and compared. Student t test was used to get the results.

Results

The vertical analysis of the incisal tip and cementoenamel junction of the upper central incisor (UCI) and of the UL were statistically significant (P = .001 for all). The horizontal measurements of the same variables (P = .238, P = .516, P = .930, respectively) and the NLA (P = .060) showed no statistical significance. The amount of advancement did not interfere with the variables analyzed, except for the exposure (P = .009) and inclination of the UCI (P = .010).

Conclusion

It was concluded that the amount of maxillary advancement does not interfere with the UL prediction; the prediction capacity of the software was good for the horizontal measurements, but had a significant error index for vertical measurements.

[Three-dimensional study of facial soft tissue changes in patients with skeletal Class malocclusion before and after orthognathic surgery]

Objective

To investigate the changes of facial soft tissue before and after orthognathic surgery in patients with skeletal Class Ⅲ malocclusion.

Methods

Between August 2016 and April 2017, 30 patients with skeletal Class Ⅲ malocclusion who underwent maxillary LeFort Ⅰ osteotomy and sagittal split mandible osteotomy were selected as study subjects. Among them, 11 were male and 19 were female with an average age of 22.6 years (range, 18-35 years). Full head CT scan and facial soft tissue three-dimensional image scan were performed within 2 weeks before surgery and at 6 months after surgery. A three-dimensional facial image model was established using Artec Studio 11.0 and CMF Proplan 3.0 software to analyze the facial soft tissue changes before and after surgery. The soft tissue anatomical landmarks in each area of the face were measured and compared before and after surgery.

Results

The area of facial soft tissue change after surgery was the maxillary nose and the lower jaw area, and the two sides did not exceed the vertical boundary of the outer canthus. After surgery, the horizontal points of bilateral alar bases and bilateral cheeks changed significantly ( P<0.05). The sagittal points of subnasale, pronasale, bilateral alar bases, upper lip margin significantly forwarded ( P<0.05); the sagittal points of the bilateral cheilions, lower lip margin, midpoint of chin-lip groove, pogonion, and menton significantly backwarded ( P<0.05). The vertical points of the upper lip margin, bilateral cheilions, lower lip margin, bilateral cheeks, and bilateral inner canthus points significantly descended ( P<0.05), and the vertical point of the menton significantly elevated ( P<0.05). After surgery, the nasal column was significantly shortened, the upper lip got longer and the alar base widened when compared with those before surgery ( P<0.05).

Conclusion

The overall change of face after double jaw surgery is shorter and fuller, and the mandible of facial soft tissue change is larger than that of maxillary, which suggests that the postoperative facial changes should be taken into account in the surgical design.