Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

Temporomandibular joint degeneration arises spontaneously in STR/ort mice and is prevented by targeted aggrecanase inhibition

OBJECTIVE

Temporomandibular joint osteoarthritis (TMJ-OA) is painful and causes masticatory dysfunction, but current treatment is limited to symptom relief due to an incomplete appreciation of aetiology. Herein, we develop morphological and histological methods for quantitative evaluation of TMJ-OA severity and examine whether STR/Ort mice, which are genetically predisposed to spontaneous knee OA, exhibit protection against TMJ-OA upon genetic gain-of-function modification of an aggrecanase-selective mutant of tissue inhibitor of metalloproteinase (TIMP)-3.

DESIGN

We established morphological changes in mandibular condylar head adapted from human TMJ-OA criteria, and developed and verified the utility of TMJ-OA histological damage scoring adapted from the OARSI system. Mutant TIMP3 containing an extra alanine at the N-Terminus ([-1A] TIMP-3 was overexpressed in STR/Ort and CBA mice. Morphological changes in mandibular condyle and TMJ cartilage degradation were evaluated and quantified using micro-CT and histology in mice aged 10, 20 and 40 weeks.

RESULTS

Whilst no evidence of TMJ-OA was observed in STR/Ort mice aged 10 weeks, bone erosion and osteophyte formation appeared in the mandibular condyle by 20 weeks, with remarkable deformity and bone resorption at 40 weeks in STR/Ort, but not the parental CBA strain. TMJ-OA was less severe in 40 week-old [-1A]TIMP-3 overexpressing STR/Ort and CBA compared to wild-type mice.

CONCLUSIONS

Using our new mouse TMJ-OA scoring system we have found that OA affects joints other than the knee in the STR/Ort strain. Genetic gain-of-function modification of STR/Ort mice with an aggrecanase-selective mutant of tissue inhibitor of metalloproteinase (TIMP)-3 also affords in vivo chondroprotection against this TMJ-OA.

Evaluation of mandibular motions in patients with anterior disc displacement during mouth opening and closing using finite helical axis

Understanding temporomandibular joint (TMJ) kinematics is essential for the clinical diagnosis and treatment of TMJ disorders. Yet, a comprehensive description of mandibular motion information in patients with anterior disc displacement (ADD) is lacking. The finite helical axis (FHA) is a mathematical model describing the motion of a rigid body in space. This model quantifies mandibular motion patterns by differentiating between rotation around the FHA and translation along it. This study aimed to compare the mandibular motion patterns between patients with ADD and asymptomatic subjects during mouth opening and closing utilizing the FHA. Ten asymptomatic subjects (2 females and 8 males, aged 19-22) and ten patients with ADD (8 females and 2 males, aged 19-57) were tracked using an optical motion tracking system for mouth opening and closing. The FHA during mouth opening and closing was determined from motion trajectory. The distance from the condylar center to the FHA (dCP), the angles between the FHA and the head coordinate system (θx, θy, θz), and the global fluctuation of the FHA spatial orientation (θf) were further calculated. In addition, the helical axis of each frame relative to the initial frame was computed to determine the maximum rotation angle (Θmax) and maximum offset (Tmax) of mandibular motion during mouth opening and closing. It was found that Θmax, Tmax, dLCPmean, dLCPmin, θx, and θf for patients with ADD differed significantly from those of asymptomatic subjects. These findings imply that the FHA effectively describes the disparities between patients with ADD and asymptomatic subjects.

Feasibility of simultaneous TMJ arthroscopy in ADDwoR patients undergoing orthognathic surgery for jaw deformity

This study evaluated the feasibility of simultaneous temporomandibular joint (TMJ) arthroscopy and orthognathic surgery as a new treatment strategy for anterior disc displacement without reduction (ADDwoR) patients with severe jaw deformities. Twelve ADDwoR patients with facial deformities who underwent arthroscopy and orthognathic surgery between September 2015 and December 2019 were retrospectively evaluated. Pre- and postoperative maximum incisal opening (MIO) and joint pain were recorded. Computed tomography (CT) and three-dimensional cephalometric analysis were performed at 3 (T1) and ≥6 (T2) months postoperatively. Magnetic resonance imaging (MRI) of the TMJ was performed before, ≤7 days after and ≥6 months after surgery. The lateral profile radiological findings, the symmetry of the maxilla and mandible, and the MRI measurements were compared. Anterior disc displacement did not recur, and the maximum incisal opening (MIO) increased from 27.4 mm to 32.7 mm after surgery (p < 0.05). No significant differences were found in the lateral profile, symmetry indices or condylar height via MRI between T1 and T2. Joint morphology and the position of both the maxilla and mandible remained stable during postoperative follow-up, while joint symptoms were markedly relieved and facial appearance was noticeably improved. Combined arthroscopy and orthognathic surgery is effective and recommended for ADDwoR patients with jaw deformities.

Influence of local factors on the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint anterior disc displacement without reduction: a retrospective longitudinal study

The aim of this retrospective longitudinal study was to investigate the condylar growth after arthroscopic discopexy in adolescents with temporomandibular joint (TMJ) anterior disc displacement without reduction (ADDwoR), and to determine whether local or systemic factors influence this growth. A total of 145 patients aged 10-20 years who were diagnosed with ADDwoR by magnetic resonance imaging were included. Patients who underwent arthroscopic discopexy were assigned to the arthroscopy group (n = 108) and others to the control group (n = 37). Demographic information, clinical assessments, body indicators, and bone density information were collected. Condylar height, disc length, and disc position were measured. The mean condylar height change in the arthroscopy group was 2.12 mm more than that in the control group (P < 0.001). Condylar growth after surgery was negatively correlated with age (P = 0.017) and disc length (P = 0.015), and positively correlated with follow-up duration (P = 0.002) and disc position (P < 0.001). Moreover, arthroscopic discopexy patients had better outcomes regarding improvements in pain (P = 0.024), maximum inter-incisal opening (P < 0.001), and quality of life (P < 0.001) than control patients. In conclusion, arthroscopic discopexy can restore condylar growth and relieve symptoms in ADDwoR patients, and the condylar growth is closely related to the local factors.

The Retrospective Study of Magnetic Resonance Imaging Signal Intensity Ratio in the Quantitative Diagnosis of Temporomandibular Condylar Resorption in Young Female Patients

According to the literature, there is no reliable and quantitative method available for the diagnosis and prognosis of early or potential temporomandibular joint (TMJ) condylar resorption (CR) thus far. The purpose of this study was to raise a new noninvasive method to quantitatively evaluate condylar quality using the signal intensity ratio (SIR) on magnetic resonance imaging (MRI) in order to assist in the diagnosis of TMJ CR. A retrospective exploratory study was performed to compare the condyle-to-cerebral cortex signal intensity ratios (SIR) on MRI among young female patients. We included 60 patients, and they were divided into three groups: the bilateral normal TMJ group (group 1), the bilateral TMJ anterior disc displacement (ADD) but without CR group (group 2), and the bilateral TMJ anterior disc displacement (ADD) with CR group (group 3). The SIR difference between the three groups was analyzed by the Kruskal–Wallis test (K-W test). The sensitivity, specificity, accuracy, and area under curve (AUC) were calculated by the receiver operating characteristic (ROC) curves. There was high consistency between the surgeon and the radiologist in the evaluation of the magnetic signal intensity with intraclass correlation coefficients of 0.939–0.999. The average SIR was 1.07 in the bilateral normal TMJ group (group 1), 1.03 in the ADD without CR group (group 2), and 0.78 in the ADD with CR group (group 3). It could be found by the K-W test that group 3 was significantly different from group 1 and group 2 (p < 0.05), while there was no significant difference between group 1 and group 2. The optimal critical SIR value was 0.96 for the diagnosis of CR according to the ROC curves and Youden index (p < 0.001, AUC = 0.9). The condyle-to-cerebral cortex SIR can be used as a noninvasive diagnostic tool for the quantitative evaluation of condylar quality and diagnosis and prognosis of CR. SIR ≥ 0.96 indicates a healthy condyle, while SIR < 0.96 is considered the optimal critical value for the diagnosis of CR. These findings are important for personalized and accurate treatment and prognosis prediction.

Disc Displacement of the Temporomandibular Joint and Facial Asymmetry in Children and Adolescents: A Systematic Review and Meta-Analysis

Subjects with facial skeletal asymmetries have a higher incidence of anterior temporomandibular joint disc displacement. The objective of the study was to consolidate existing evidence on the connection between temporomandibular joint disc displacement and mandibular asymmetry in youngsters and adolescents. A thorough examination was undertaken in the following databases: PubMed, Scopus, EMBASE, Web of Science, and Cochrane. To judge the publications’ methodological quality Newcastle Ottawa Scale was used. From the 1011 identified records, eight were selected for the qualitative synthesis and five for the quantitative synthesis, amounting to 692 subjects. Fifteen cephalometric variables were meta-analyzed. The distance from menton (Me) to midline (lateral mandibular asymmetry) was significantly shorter [−1.75 (95% CI −2.43–−1.07), p ≤ 0.001] in subjects with disc displacement compared to those without disc displacement. The distance from articulare (Ar) to gonion (Go) was significantly longer [3.74 (95% CI 1.04–6.44), p = 0.007] in subjects with disc displacement compared to those without disc displacement. The relationship between distance from articulare (Ar) to gonion (Go) or sella (S) to gonion (Go) and disc displacement was shown to be close to statistical significance level, but not for other cephalometric data. Disc displacement was associated with several cephalometric measurement variations in children and adolescents.

Short-Term Stability After Segmental Le Fort I Maxillary Impaction Surgery With Mandibular Autorotation in Seven High-Angle Class II Patients: A Case Series

PURPOSE

To retrospectively evaluate skeletal stability after Le Fort I maxillary impaction surgery and mandibular autorotation without bilateral sagittal split osteotomy (BSSO) in high-angle class II patients.

MATERIALS AND METHODS

Seven female high-angle class II patients who underwent maxillary impaction surgery and mandibular autorotation without bilateral sagittal split osteotomy were included in this study. Surgical changes and relapse were measured on lateral cephalograms taken preoperatively and at 1 month, 6 months and 1 year postoperatively.

RESULTS

The horizontal movement of the maxilla at point A was 5.8 ± 3.3 mm backward, and the upward movement at the posterior nasal spine was 3.3 ± 1.4 mm. The mean horizontal change at point A during the 1-year follow-up period was 0.1 ± 0.2 mm, and the vertical change at posterior nasal spine was 0.2 ± 1.3 mm, which were not statistically significant. The horizontal surgical change at point B was 4.0 ± 1.8 mm forward and the vertical surgical change at point B was 4.7 ± 1.8 mm upward. Postoperative relapse was 10.9% and 13.7% in the horizontal and vertical directions, respectively.

CONCLUSIONS

Le Fort I maxillary impaction surgery with mandibular autorotation may be 1 of the suitable procedures for high-angle class II patients.