Three-dimensional analysis of condylar remodeling and skeletal relapse following LeFort-I osteotomy: A one-year follow-up bicenter study

Orthognathic surgery effects on temporomandibular joint compressive stresses

INTRODUCTION

This study tested orthognathic surgery effects on temporomandibular joint (TMJ) compressive stresses.

METHODS

Pre- (T1) and post-surgery (T2) cone-beam computed tomography images were collected from consenting subjects aged ≥15 years. Anatomical data were used to measure surgical changes in anteroposterior mandibular position and occlusal plane angle (FH-OP), estimate condylar loading areas (mm2 ) and calculate T1 and T2 TMJ and jaw muscle forces (N) during canine biting via numerical modelling. Analysis of covariance tested for sex and biting angle differences in T2 - T1 TMJ compressive stresses (TMJ force/loading area, MPa). Principal component analyses identified jaw muscle forces that accounted for changes in T2 - T1 TMJ loads. Regression analyses tested the correlations between surgical changes in mandibular position, FH-OP, TMJ loads and muscle forces.

RESULTS

Of 148 cases screened, 28 females and 16 males provided complete records. Condylar loading areas were significantly smaller (P = .024) for females vs males (124 ± 5 vs 144 ± 7 mm2 ). T2 - T1 differences in TMJ compressive stresses varied by surgical change, biting angle and sex. Overall, the largest increases in TMJ compressive stresses post-surgery were for females with mandibular setbacks where FH-OP angle decreased. T2 - T1 changes in jaw muscle forces had moderate (ipsilateral, λ = 4.59; η2  = 0.071) to large (contralateral, λ = 1.49; η2  = 0.31) effects on TMJ loads.

CONCLUSIONS

T2 - T1 differences in TMJ compressive stresses during canine biting were affected by surgical changes in mandibular position and occlusal plane angle, biting angle and sex. Surgical changes altered jaw muscle forces for the same biting conditions and, thus, affected TMJ loads and compressive stresses.

Condylar positional changes and remodeling following bimaxillary anterior segment osteotomy with and without Le Fort I osteotomy: a three-dimensional comparative analysis

OBJECTIVE

To evaluate 3D condylar displacement and long-term remodeling following the correction of bimaxillary protrusion by anterior segment osteotomy (ASO) with and without Le Fort I surgery.

MATERIALS AND METHOD

This retrospective study included 32 adults with bimaxillary protrusion who underwent ASO alone (group 1) or with concomitant Le Fort I osteotomy (group 2). Subject's computed tomography scans at basic (T0), immediate postoperatively (T1), and at 1 year or more follow-up (T2) were collected. The condyle displacement was measured at superior-inferior, lateromedially, and anteroposterior surfaces, while condyle remodeling was measured at the superior, lateral, anterior, medial, and posterior surfaces. All 3D analyses were performed using 3D Slicer software (4.11.2).

RESULTS

At T1, 52.7%, 86.7%, and 94.4% of condyles in group 1 were displaced inferiorly, laterally, and posteriorly, respectively, as well as 75%, 89.2%, and 53.5% of condyles in group 2, which had not fully returned to the original preoperative positions at T2. Condylar remodeling was observed in both groups at T2, and no significant difference was found in the overall condylar volume between T1 and T2 in both groups. Patients in group 2 exhibited significant bone resorption at both lateral and anterior surfaces compared to group 1 (P = 0.000 and 0.01, respectively).

CONCLUSION

This study's results demonstrated that ASO is associated with a degree of condylar changes even if the posterior mandible is not osteomized. The positional changes vary between bimaxillary ASO alone and those with simultaneous Le Fort I osteotomy. However, both groups' condyle volume remained stable at the long-term follow-up.

Bone Density of the Condyle of Children with Craniofacial Microsomia and its Correlation with Condylar Resorption After Mandible Distraction Osteogenesis

OBJECTIVE

To investigate condylar bone density (BD) in children with craniofacial microsomia (CFM) and identify factors that contribute to early stage condylar resorption (CR) after mandibular distraction osteogenesis (MDO).

DESIGN

Retrospective study.

SETTING

Craniofacial department of a plastic surgery hospital.

PATIENTS

Fifty-one children with CFM classified as Pruzansky IIa based on complete pre-(T0) and post-MDO (T1) computed tomography (CT) data.

INTERVENTION AND MAIN OUTCOME MEASUREMENTS

Mimic 21.0 (Materialise Inc., Belgium) was used to measure bilateral BD and condylar height (CH) and volume (CV) of affected side. Children were split into groups based on either affected side BD or the distraction length (DL,25 mm as cutoff) .Bilateral BD was compared using a paired t-test in each group. The CH and CV of affected side at T0 and T1 were compared. The relative values of the CH and CV (CH ratio) and the volume (CV ratio) of the affected side were compared across the groups.

RESULTS

The BD was lower on affected side than on unaffected side. Regarding BD, CH and CV decreased after MDO in group I, while the CH ratio and CV ratio of group I was lower than that of groups II and III. Regarding DL, the CV ratio was lower in Group L than Group S.

CONCLUSIONS

The condylar bone quality on affected side is compromised in type IIa CFM. A low BD in combination with a larger distraction distance may increase the risk of CR; therefore, MDO in patients with such characteristics should be postponed.

Diagnostic accuracy of fused CBCT images in the evaluation of temporomandibular joint condylar bone resorption

OBJECTIVES

To evaluate the diagnostic accuracy of fused CBCT images for patients with condylar bone resorption of temporomandibular joint (TMJ) osteoarthrosis.

MATERIALS AND METHODS

Forty-two TMJs from twenty-one patients were included. Bone resorption of condyles evaluated by three experts was used as the reference standard. Three oral and maxillofacial radiology residents evaluated the resorption of condyles with a five-point scale for the four sets of images (two consecutive CBCT images without fusion, fused 2D cross-sectional images, fused 3D images, and combining fused 2D cross-sectional images and fused 3D images) randomly and independently. Each set of images was evaluated at least 1 week apart, and a second evaluation was performed 4 weeks later. Intraclass correlation coefficients were calculated to assess the intra- and inter-observer agreement. The areas under the ROC curves (AUCs) were compared among the four image sets using the Z test.

RESULTS

Twenty-four TMJs were determined as condylar bone resorption, and eighteen were determined as no obvious change. The average AUC values from the three observers for the three fused image sets (0.94, 0.93, 0.93) were significantly higher than the image set without fusion (p < 0.01). The intra- and inter-observer agreement on the three fused image sets (0.70-0.89, 0.91-0.92) was higher than the image set without fusion (0.37-0.63, 0.75).

CONCLUSIONS

Fused CBCT images of TMJ osteoarthrosis patients can intuitively display the condylar bone resorption and significantly improve the diagnostic accuracy.

CLINICAL RELEVANCE

Fused CBCT images can help clinicians intuitively observe bone changes of the condyle in TMJ osteoarthrosis patients.

Changes in condylar position after orthognathic surgery and its correlation with temporomandibular symptoms (TMD)- a prospective study

The aim of the study was to assess the changes in the condylar position after orthognathic surgery (OGS) and its effect on temporomandibular disorders (TMD). A total of 37 dentofacial deformity patients included in the study who had undergone OGS were divided into three groups: Group I, Le Fort I maxillary advancement; Group II, bilateral sagittal split osteotomy (BSSO) mandibular advancement ± Le Fort I; and Group III, BSSO mandibular setback ± Le Fort I. Patients were evaluated clinically using Diagnostic Criteria for TMD and by radiography preoperatively and 6 months postoperatively. The positional changes in condyle were correlated with signs and symptoms of TMD. A total of 37 patients in three groups (Group I, 8 patients; Group II, 10 patients; and Group III, 19 patients) were evaluated. Overall, condyles had anterio-medio-inferior movement with 7 of 8 patients in Group I, 6 of 10 patients in Group II and 13 of 19 patients in Group III having ≤2 mm displacement. In angular changes, inward-anterio-medial movement was observed with 6 of 8 patients in Group I; about 5 of 10 patients, and 10 of 19 patients in Group II and III respectively had ≤5° change. Intragroup and intergroup comparisons showed insignificant changes in TMD and linear/angular movement (p ≥ 0.05). Pearson correlation coefficient was found to be nonsignificant on the radiographic and clinical comparison (p ≥ 0.05). Intrarater reliability (Kappa value) was found to be 0.83, confirming the results. Within the limitations of the study it seems that there are minimal linear and angular changes in condyle after orthognathic surgery that were not responsible for the development of temporomandibular disorders in the postoperative course.