Intraoral Multistage Mandibular Angle Ostectomy: 10 Years' Experience in Mandibular Contouring in Asians

Evaluating robotic assistance on the learning curve and efficiency of mandibular angle ostectomy: an animal model study

Introduction

This study evaluated the efficacy and learning curve of a maxillofacial surgical robotic system (MSRS) guided by electromagnetic navigation for mandibular angle ostectomy (MAO), compared to traditional surgical methods.

Methods

The study utilized a controlled experiment involving thirty rabbits, paired divided into experimental and control groups. The experimental group underwent MAO using the MSRS, while the control group was treated with conventional surgical techniques. The surgeons performing the procedures were inexperienced in robotic surgery and MAO to assess the learning curve and the impact of robotic assistance. Key parameters measured included the accuracy of ostectomy, setup time, and ostectomy efficiency, with data analyzed through a paired-t test to compare the performance between the two groups.

Results

The study indicated a significant reduction in ostectomy time for the experimental group, with improved accuracy and efficiency in ostectomy. The study found that robotic assistance could decrease the risk of complications and enhance surgical outcomes. It also highlighted the presence of an initial learning curve when adopting new robotic technologies, which could be mitigated through adequate training and simulation practices.

Discussion

Using MSRS for MAO could lead to faster early learning curves and increased ostectomy efficiency compared to traditional surgical methods. It demonstrated the potential benefits of integrating robotic systems into craniofacial surgery, suggesting a promising direction for future surgical practices.

Correcting facial asymmetry through guided plate assisted mandibular angle osteotomy

Background

Asian women prefer a smooth and narrowed mandibular appearance. The purpose of the retrospective cohort study is to evaluate guide plate-assisted mandibular angle ostectomy (MAO) in improving mandibular symmetry for Asian female patients with mandibular angle hypertrophy (MAH) with normal occlusal relationship.

Methods

We retrospectively examined 11 patients with asymmetry MAH with normal occlusal relationship who received MAO at Shanghai Ninth People's Hospital between September, 2020, and January, 2022. Preoperative plans were designed based on CT data and executed using metal guide plate during the operation. Preoperative and one-week postoperative CT scans were used to assess measurements including Height_Go, Divergence_Go, ∠ZyZy-GoGo, and osteotomy volume, to evaluate symmetry. For precision, compare the postoperative CT with the preoperative design, assessing osteotomy distance, angle, and volume error. Patient satisfacation was evaluated with Likert Scale in 6-month follow-up. Secondary lipofilling procedures were given as appropriate. Statistical analysis was performed using paired t-tests in SPSS.

Results

The mean age of the 11 patients was 28.5 years (range 23-34 years). 2 of these underwent lipofilling procedures. No complications were observed during the following-up. Postoperative results were not statistically different from the design, demonstrating a precision of within 2 mm. Height_Go disparity within 5 mm get corrected notably, reducing asymmetry from 15.09% preoperatively to 2.74% postoperatively. Patients satisfaction was rated at 4.5 out of 5 in 6 month follow-up.

Conclusions

Guide plate-assisted mandibular angle osteotomies achieve effective and precise surgery. This approach demonstrates a safe option for correction for mandibular asymmetry, achieving patient satisfaction.

Impact of Mandibular Angle Osteotomy Using a Geometric Mathematical Design on the Aesthetic Osteotomy Line: A Retrospective Observational Study

BACKGROUND

Mandibular angle osteotomy (MAO) is a frequently described technique in Eastern females. The success hinges on the precise positioning of the osteotomy line. The geometric mathematical method is viable. Therefore, we explored the impact of mandibular angle osteotomy using aesthetic standards and printed digital osteotomy templates (DOTs) on the aesthetic osteotomy line.

METHODS

This retrospective observational study included female patients with prominent mandibular angle (PMA) who underwent MAO at our hospital between January 2020 and March 2021. Thirty-three female patients were included, 22 in the DOTs group using new DOTs, and 11 in the traditional group using traditional free-hand techniques.

RESULTS

Regarding the width of the excised bone, the postoperative deviation from the preoperative plan was not significant in the DOTs group (0.5 ± 0.3 mm, P > 0.05), while the deviation was significant for the traditional group (2.5 ± 1.2 mm, P<0.05). The preparation time was longer in the DOTs group than in the traditional group (82 ± 11 vs. 53±4 min, P < 0.001). The osteotomy time and the operation time were shorter in the DOTs group than in the traditional group (osteotomy: 54 ± 5 vs. 73 ± 6 min; preparation: 124 ± 10 vs. 169 ± 13 min; both P < 0.001). The Likert (4.0 ± 0.5 vs. 1.0 ± 0.6, P = 0.006) and FACE-Q scores (17.5 ± 1.7 vs. 15.6 ± 1.3, P = 0.029) were higher in the DOTs group.

CONCLUSIONS

The new method of positioning the new aesthetic osteotomy line based on geometric analysis might provide a possible osteotomy method that strongly suggests effectiveness, safety, individualization, and accuracy, with a shorter operation and higher patient satisfaction.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Computer-assisted mandibular curved osteotomy: An automatic method to design the new aesthetic gonion and osteotomy line

BACKGROUND

Digital technology has been widely used in mandibular curved osteotomy to improve accuracy. However, the planning process still highly dependent on the experience and judgement of the surgeon. This study describes an automatic method to design the new gonion and osteotomy line based on the aesthetic standards in attractive women, and assesses its clinical outcomes.

METHODS

An automatic surgical planning method for mandibular curved osteotomy was developed based on our previous research of mandibular angle aesthetics. A prospective clinical study was conducted from April 2016 to April 2018. Twenty-five female patients with prominent mandibular angle were enrolled. Pre- and postoperative skull computed tomography (CT) was performed. Three-dimensional (3D) CT data were obtained and processed by Mimics 18.0. Surgical templates were designed according to the automatic surgical planning method and 3D printed for the surgery. Preoperative measurements, surgical simulation and postoperative measurements were taken to evaluate the surgical outcomes.

RESULTS

There were significant differences between the preoperative and the postoperative groups' results (p < 0.01). There was no difference between the surgical simulation and the postoperative results. All postoperative measurements were consistent with aesthetic features of mandibles. Patients were satisfied with their outcomes in terms of outline, symmetry and lower facial width.

CONCLUSIONS

Our study developed an automatic method to position the new aesthetic gonion and osteotomy line for prominent mandibular angle patients. We proved that this method is safe, effective and reliable.

Comparison of Bilateral Mandibular Angle Ostectomy Between East Asian Males and Females: A Study Based on Three-Dimensional Computed Tomography Reconstruction

BACKGROUND

Mandibular angle ostectomy is a common plastic surgery for facial contouring in East Asians. However, rarely we could find reports on differences between East Asian males and females undergoing this surgery.

OBJECTIVE

To describe the differences between East Asian males and females before and after mandibular angle ostectomy.

METHODS

A total of 22 Asian males and 52 Asian females who underwent mandibular angle ostectomy from April 2015 to November 2018 were enrolled. Three-dimensional computed tomography was used to evaluate the preoperative and postoperative data of the mandible. Thirteen clinical data were measured on reconstructed mandibular models. The differences in data between males and females were analyzed to identify the causes of the differences before and after surgery. The follow-up was 6-12 months, and patient satisfaction was also evaluated.

RESULTS

The ostectomy volume was positively correlated with the distance from the intersection of the occlusal plane and the anterior margin of the mandibular ramus to gonion (MR-Go; female, p < 0.01; male, p = 0.02). There was a positive correlation between the ostectomy volume and the postoperative drainage fluid (The drainage fluid is mainly blood) volume after surgery in females (p < 0.05), while there is no significant correlation between these two data in males (p = 0.19). Patients with a long distance from the second molar to the lower edge of the mandibular body (SM-MB) tended to have a higher risk of postoperative bleeding (female, r = 0.56, p < 0.01; male, r = 0.73, p = 0.01).

CONCLUSION

Because of the difference in the anatomical size of the mandible and different aesthetic requirements for facial contouring between males and females, surgeons encounter different intraoperative conditions resulting in difficulties during surgery. Understanding differences in mandibular angles predicts differences in ostectomy volume and postoperative bleeding risk, thus aiding surgeons and leading to better operative outcomes.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Mandibular angle resection using cervicofacial lifting surgical approach: Technical note

Facial feminization surgery brings a set of surgical procedures that address the three thirds of the face and aims to give feminine characteristics to a masculine face. The characteristics of the lower third of a male face are a long, broad chin, a prominent mandible with sharp angles (in connection with the insertions of the masseter muscles). Mandibular angle reduction is an important procedure of the male-to-female transformation. It allows to modify the appearance of the lower third of the face, reducing the bi-mandibular distance in the coronal plane and opening the mandibular angle in profile. The classical procedure uses trans-oral surgical approach. However, patients undergoing male-to-female sexual transformation frequently present a mixed indication of cervicofacial lift and angular resection. We present an innovative surgical technique associating cervicofacial lifting and mandibular angle resection using the same cutaneous surgical approach. We describe its advantages and discuss its disadvantages.

Risk factors for seizures after cranioplasty

PURPOSE

Cranioplasty can improve a patient's psychosocial and cognitive functions after decompressive craniectomy, however seizures are a common complication after cranioplasty. The risk factors for early and late seizures after cranioplasty are unclear. This study is to evaluate the risk factors for early and late seizure after cranioplasty.

METHODS

Two hundred and thirty-eight patients who received cranioplasty following craniectomy between January 2012 and December 2014 were included in this study. The risk factors of the patients with early and late post-cranioplasty seizures were compared to those with no post-cranioplasty seizures.

RESULTS

Seizures (73/238, 30.3%) were the most common complication after cranioplasty. Of these 73 patients, 17 (7.1%) had early post-cranioplasty seizures and 56 (23.5%) had late post-cranioplasty seizures. Early post-cranioplasty seizures were related to a longer interval between craniectomy and cranioplasty (P = 0.006), artificial materials (P < 0.001), and patients with late post-craniectomy seizures (P = 0.001). Late post-cranioplasty seizures were related to the presence of neurological deficits (P = 0.042). After stepwise logistic regression analysis, a longer interval between craniectomy and cranioplasty (P = 0.012; OR: 1.004, 95% CI: 1.001-1.007) and late post-craniectomy seizures (P = 0.033; OR: 4.335, 95% CI: 1.127-16.675) were independently associated with early post-cranioplasty seizures.

CONCLUSION

Delayed cranioplasty procedures and seizures before cranioplasty were significantly associated with early post-cranioplasty seizures. Further studies are warranted to investigate whether early surgery after craniectomy can reduce the risk of early post-cranioplasty seizures.

Occlusion-Fit V-Line Guide and Gooseneck Saw for Safe and Accurate Mandibuloplasty in Asians

BACKGROUND

A slender or slim face with narrow facial features is considered esthetically appealing in Asian people. Plastic surgery to obtain an oval face, called a 'V-line,' is popular among young people.

MATERIALS AND METHODS

A total of 20 Korean patients were included in this study. The patients underwent mandibular anguloplasty with three-dimensional computer-aided design and manufacturing surgical guides that were accurately fitted to the upper and lower teeth, allowing for precise replication of a virtual surgery during a real surgical procedure.

RESULTS

There were no significant complications, including severe bleeding, facial nerve injury, or airway obstruction. All patients were satisfied with the esthetic and functional results, except for one who was neutral toward the result. The mean satisfaction score was 4.75, which was between 'satisfied' and 'very satisfied.'

CONCLUSION

The V-line guide and gooseneck saw allowed for safe and fast resection of bone in the mandibular angle area. This technique provides consistent results during surgery as well as minimizing surgical complications.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

"Stamp Perforation" Technique for Correction of Prominent Mandibular Angle: 10 Years of Experience in Mandibular Reshaping in Asians

Resection of a prominent mandibular angle is commonly used in Eastern society to improve the lower one third facial proportion. Historically, this procedure had a high complication rate, such as severe bleeding, asymmetry of the angle reduction, and "second mandibular angle." A safer and more effective way of performing such procedures is needed. The aim of this study is to introduce 3 instruments, a tunable guide handpiece, milling cutter, and flywheel, which were invented by the author, as well as a related ostectomy technique for correcting prominent mandibular angles using a modified full-thickness marginal ostectomy of the mandibular corpus angle, named the "stamp perforation" technique. This technique has 4 highlights: First, it ensures a smooth symmetric contour. Second, it prevents the risks of rupture of the inferior alveolar vessel and facial artery, ensuring the safety of this approach. Third, the "stamp perforation" technique eases the removal of bone fragments, shortening the operation time. Fourth, the recovery time of patients treated with this approach is much shorter than with the traditional approaches. From January 2006 to January 2016, 1106 patients underwent the surgery to contour the prominent mandible angles, and satisfactory results were achieved. Thus, we recommend the instruments as well as the "stamp perforation" technique for correcting prominent mandibular angles, and we hope that our 10 years of experience could provide a reference for other plastic surgeons.

Quantitative Mandibular Angle Ostectomy Facilitated by Oscillating-Blade Saw With Scalable Guide

BACKGROUND

Although various techniques of mandibular angle ostectomy have been devised to correct overly prominent bony contours, none have incorporated methods to delineate the surgical line with precision. Herein, the authors describe one means of marking an ostectomy line more easily, using a specially designed oscillating-blade saw.

METHODS

Between July 2013 and June 2014, a total of 75 patients underwent quantitative mandibular angle ostectomy using a custom oscillating-blade saw equipped with a scalable guide. Corticectomy, also done routinely to improve frontal appearance, called for a reciprocating saw only. Aesthetic outcomes gauged subjectively by the questionnaire about satisfaction and symmetry after postoperative 6 months.

RESULTS

Satisfaction score was 4.9 and symmetric score was 4.7. No major complications, such as persistent nerve injury or fracture, were encountered.

CONCLUSIONS

Use of an oscillating-blade saw equipped with a scalable guide facilitated quantitative mandibular angle ostectomy, enabling precise, and reproducible surgery with satisfactory outcomes with less complications.

The Accuracy of Computer Image-Guided Template for Mandibular Angle Ostectomy

BACKGROUND

Mandibular angle ostectomy (MAO) is commonly used to correct prominent mandibular angles through an intraoral approach. However, limited vision in the operative site may lead to difficulties or complications during surgery. Therefore, it is necessary to develop an effective method for helping surgeons to perform MAO more precisely and safely.

METHODS

In this study, we report a novel method of a computer image-guided surgical template for navigation of MAO, and evaluate its accuracy and clinical outcomes. Nine patients with a prominent mandibular angle were enrolled in this study. A pair of stereolithographic templates was fabricated by computer-aided image design and 3D printing. In all cases, bilateral MAO was performed under the guide of these templates. Post-operative effects were evaluated by 3D curve functions and maximal shell-to-shell deviations.

RESULTS

All patients were satisfied with their cosmetic outcomes. The mean and SD of ICC between R-Sim and R-Post were 0.958 ± 0.011; between L-Sim and L-Post, 0.965 ± 0.014; and between R-Post and L-Post, 0.964 ± 0.013. The maximal shell-to-shell deviations between the simulated mandibular contour and post-operative mandibular contour on the right and left sides were 2.02 ± 0.32 and 1.97 ± 0.41 mm, respectively.

CONCLUSION

The results of this study suggest that this new technique could assist surgeons in making better pre-surgical plans and ensure more accurate and safer manipulation for completion of this procedure.