Intraoperative condylar positioning techniques on mandible in orthognathic surgery

A proximal segment positioning method to enhance condylar stability after bilateral sagittal split ramus osteotomy in skeletal class II patients: A randomized controlled study

This study compared condylar stability using two proximal segment positioning methods during bilateral sagittal split ramus osteotom in patients with skeletal Class II malocclusion. 12 patients in the experimental group underwent positioning guided by preoperative mandibular movement trajectory data, a guiding device, and prebent titanium plates, while 13 patients in the control group had manual positioning. Postoperative imaging was performed at 2 weeks (T1), 3 months (T2), and 6 months (T3) to assess condylar and mandibular positions. At T1, both groups showed increased joint space, but the increase in anterior joint space (AJS) was significantly smaller in the experimental group (0.39 ± 0.70 mm) than in the control group (1.10 ± 0.97 mm, P < 0.05). Between T1 and T2, both groups experienced joint space reduction and upward-inward condylar movement, with a less pronounced reduction in AJS in the experimental group (0.28 ± 1.01 mm) compared to the control group (0.98 ± 0.89 mm, P < 0.05). By T3, condylar positions had stabilized, with mandibular relapse significantly lower in the experimental group (12.71 ± 6.43 %) than in the control group (27.09 ± 8.9 %, P < 0.05). These findings suggest that trajectory-guided proximal segment positioning improves postoperative condylar and mandibular stability.

Application of mixed reality bone registration and positioning technology in orthognathic surgery

In orthognathic surgery, the positioning of the bone segments has a significant impact on the postoperative occlusion, temporomandibular joint, and facial morphology. Within the field of digital surgical planning, the placement of these bone segments represents the transfer of the virtual surgical plan (VSP). Computer-aided design/computer-aided manufacturing-assisted bone segment positioning devices have demonstrated high localization accuracy, but they require complex guide systems. The mixed reality technique described here, based on pre-bent titanium plates, facilitates the transfer of the VSP without the need for complex guide systems and enables dynamic intraoperative navigation under direct vision. This technique could replace 3D-printed tooth-supported guide plates for surgical navigation. The observed registration error was approximately 1 mm and the registration delay was 0.3 s. Application of this technique in the clinical case demonstrated good accuracy, and postoperative stability was achieved.

Case Report: Virtual surgery and 3D printing in a medication-related osteonecrosis of the jaws (MRONJ) pathological mandibular fracture

Introduction

The use of anatomical models, guides, and surgical templates allows for increased precision of interventions and reduced operative times. Thanks to computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies and rapid prototyping through 3D printing, it is possible to obtain accurate models, which are useful to defining surgical planning in the maxillofacial district.

Methods

We present the case of a patient with a pathological fracture of the mandibular body affected by medication-related osteonecrosis of the jaws (MRONJ) in stage III. Through the manipulation of virtual models obtained from thin-layer Computed Tomography (CT), a virtual surgical intervention of sequestrectomy and debridement of necrotic bone tissue, reduction and containment of the fracture was performed. The resulting mandibular model was used as a template for the preoperative modeling of the titanium reconstruction plate used for fracture containment.

Results

The intraoperative result and follow-up demonstrated good accuracy of the model with respect to post-operative mandibular dynamics, condylar-fossa position and a reduced surgical time.

Discussion

Virtual surgery and 3D-printed prototyping represent a feasible technique in MRONJ patients, allowing increased precision of interventions, reduced risks associated with the operation, and improved operative and recovery times for the patient.

Does orthognathic surgery affect mandibular condyle position? A retrospective study

PURPOSE

The aim of this study is to analyze mandibular condyle position changes after bilateral sagittal split osteotomy (BSSO) and bimaxillary orthognathic surgery in patients operated at a single department by two surgeons in 2013-2022. Compared were groups of mandibular advancement vs setback and bimaxillary vs BSSO.

METHODS

Ninety-nine subjects were included. Inclusion criteria were patients who underwent one of the BSSO or bimaxillary surgery and had CT scans performed before and after surgery. Preoperative CT scans were performed 1 day before surgery and postoperative CT scans 6-12 months afterwards. Changes in mandibular condyle position were measured in axial and sagittal planes.

RESULTS

CT condylar position measurements indicated significant postoperative changes in AB angle bilaterally (p =  < 0.001). In mandibular advancement and setback comparison, values were significantly lower in ABL angle values in the setback group (p = 0.011326) and significantly higher in FDR in the advancement group (p = 0.005795). There were no statistically significant changes found in BSSO and bimaxillary group comparison.

CONCLUSION

Within the limitations of this study, it can be concluded that orthognathic surgery does have a moderate effect on position of the condyles, especially condylar rotation in transversal axis.

Comparison of Patient-Specific Condylar Positioning Devices and Manual Methods in Orthognathic Surgery: A Prospective Randomized Trial

BACKGROUND

This study investigated whether patient-specific condylar positioning devices (CPDs) are beneficial compared to the conventional manual positioning of the condyles.

METHODS

In this prospective, randomized trial, patients undergoing orthognathic surgery with a bilateral sagittal split osteotomy of the mandible were included. The ascending ramus was positioned with computer-aided designed and computer-aided manufactured (CAD/CAM) patient-specific devices in the CPD group and manually in the control group. Postoperatively, cone-beam computed tomography (CBCT) was performed to align the virtually planned position with the postoperative result.

RESULTS

Thirty patients were enrolled in the study, with 14 randomized to the CPD group and 16 to the control group. In the CPD group, the ascending ramus differed in the postoperative CBCT scan from the virtually planned position by 0.8 mm in the left/right, 0.8 mm in the front/back, and 1.3 mm in the cranial/caudal direction. The corresponding control-group values were 1.1 mm, 1.3 mm, and 1.6 mm. CPD and controls differed significantly for the left/right movement of the rami (p = 0.04) but not for the other directions or rotations (p > 0.05).

CONCLUSIONS

The results demonstrate that both methods are accurate, and postoperative results matched the virtually planned position precisely. It can be assumed that the described CPDs are beneficial when a condylar position different from the preoperative is desired.

Causes of Reoperation Consultation and Clinical Review of Actual Reoperation After Previous Orthognathic Surgery

OBJECTIVE

To investigate the causes of reoperation consultation, and the actual percentage and procedures of reoperation after previous orthognathic surgery.

METHODS

The samples consisted of 30 patients who visited our clinic for reoperation consultation from October 2015 to September 2021 (6 males and 24 females; mean age at reoperation consultation, 28.4 y). Patient's causes of reoperation consultation were divided into "esthetic dissatisfaction," "airway changes," "temporomandibular disorders," "uncomfortable occlusion," and "other complications". In terms of esthetic dissatisfaction, the more detailed esthetic problem was evaluated by the clinical chart, facial photographs, and radiographs. In patients who actually underwent reoperation, the actual percentage and procedures of reoperation were investigated.

RESULTS

The most prevalent causes for reoperation consultation were "esthetic dissatisfaction" (n = 21, 70.0%), followed by "airway changes" (n = 11, 36.7%), "uncomfortable occlusion" (n = 8, 26.7%), "other complications" (n = 5, 16.7%), and "temporomandibular disorder" (n = 4, 13.3%). Less than half of patients actually underwent reoperation (n = 13, 43.3%). Actual reoperation procedures included minor revision surgery, reconstruction surgery, or complete reoperation according to the patient's need. In case of complete reoperation, more accurate and predictable results were obtained by using virtual surgical planning, customized surgical guides, titanium surgical plates made with computer-aided design and computer-aided manufacturing technique, and a 3-dimensional printing method.

CONCLUSION

It is important to communicate with patients about expectations for facial esthetic improvement by orthognathic surgery for obtaining the patient's postoperative satisfaction.

Evaluation of the Mandibular Condyle Morphologic Relation before and after Orthognathic Surgery in Class II and III Malocclusion Patients Using Cone Beam Computed Tomography

Simple Summary

In individuals with severe malocclusions, orthognathic surgery seeks to rebalance the relationships between the jaws by providing a stable occlusion, a healthy muscle balance, and the functioning of the temporomandibular joint. Cone beam computed tomography may be used to determine the position of the mandibular condyle in the glenoid fossa. This study aimed to assess how the position of the mandibular condyle varies in class II and III malocclusions before and after bimaxillary orthognathic surgery. Before and after orthognathic surgery, 56 TMJs from 28 patients were studied. Following surgery, both class II and class III patients experienced changes in the anterior joint space, posterior joint space, condyle position, and condyle angle. The preliminary findings are promising for determining changes in condyle position and joint spaces that might guide oral and maxillofacial surgeons to address a debilitating clinical affliction.

Abstract

This study aimed at evaluating the mandibular condyle position changes before and after bimaxillary orthognathic surgery in class II and III malocclusion patients. CBCT scans from patients who underwent bimaxillary orthognathic surgery were analyzed: Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO). Both condyles were independently assessed for their largest anterior and posterior joint spaces, smallest medial joint spaces, and condyle angles concerning the transverse line. In the sagittal plane, the minimum size of the anterior and posterior joint spaces was measured. In the coronal plane, the smallest medial joint space was measured. The position of the condyle within the glenoid fossa was determined before and after surgery. A total of 56 TMJs from 28 patients were studied. Following orthognathic surgery, the anterior and posterior space in class II increased. Postoperatively, the anterior joint space in class III decreased. In 42.85% of malocclusion class II patients and 57.14% of malocclusion class III patients, the pre-and post-surgical position of the condyle changed, the condyle was anteriorly positioned (42.85%) in class II patients and centrically positioned (71.4%) in class III patients. Significant changes in the joint space, condylar position, and condyle angle were found in the class II and class III subjects.