Agenesis of the temporomandibular condyle is a congenital/developmental disorder that can present with the absence of the condyle and an incomplete development of the articular fossa and eminence, resulting in facial asymmetry as well as masticatory dysfunction. The purpose of this report is to present the case of a three-year-old girl with absence of the left temporomandibular condyle. The patient presented with pain and dysfunction in the left masseter muscle, pre-auricular area and ear as well as mild chin deviation to the left. The most common treatment modality is to wait and treat this condition with surgical intervention once the patient is grown. However, oral orthopedic appliances can be considered to promote bone formation prior to surgery. Prompt recognition and early treatment is advisable to take advantage of the child\'s growth and avoid further facial asymmetry, pain and dysfunction.

OBJECTIVE: This systematic review aims to summarize and synthesize the evidence that investigates the secondary effects of the application of botulinum toxin (BT) into the masticatory muscles and its effects on bone density.
METHODS: Database searches were conducted until March 19th, 2024. The quality of the studies was assessed by the Cochrane tool risk of bias for the randomized controlled trials and the ROBINS-I tool for non-randomized studies. The Cochrane Grading of Recommendations Assessment Development and Evaluation (GRADE) was used to evaluate the confidence in the overall evidence.
RESULTS: Five studies looking at the effects of botulinum toxin on bone density and resorption when applied to masticatory muscles were found. No significant changes were observed in most of the studies when looking at the effects of botulinum toxin on mandibular condyle volume, density, mandibular angle thickness, and coronoid process volume. The only finding that was statistically and clinically relevant was the difference between patients who received a double application of BT when compared with patients who received a single application (SMD: -0.99 [95%CI: -1.94,-0.05]) on the volume of the mandibular angle.
CONCLUSIONS: There is no clear pattern on whether the application of botulinum toxin is associated with bone resorption or not. Although some studies show statistical significance of the findings, the magnitude of the changes in bone density and their clinical significance are not completely clear.
CONCLUSIONS: To understand the effectiveness of the use of botulinum toxin into the masticatory muscles and its possible secondary adverse effects on the density of the mandible.

The objectives of this study were to compare the chondrogenic potential of cells derived from different layers of Mandibular condyle cartilage and to gain further understanding of the impact of chondrogenic cues when embedded into a novel hydrogel scaffold (PGH, a polymer blend of poly (ethylene glycol), gelatin, and heparin) compared to a gelatin hydrogel scaffold (GEL). Cartilage layer cells (CLCs) and fibroblastic superficial layer cells (SLCs) were harvested from the mandibular condyle of boer goats obtained from a local abattoir. After expansion, cells were seeded into PGH and GEL hydrogels and cultured in chondrogenic media for 3 weeks. Scaffolds were harvested at 0, 1, and 3 week(s) and processed for gross appearance, histochemical, biochemical, and mechanical assays. In terms of chondrogenesis, major differences were observed between scaffold materials, but not cell types. Glycosaminoglycan (GAG) staining showed GEL scaffolds deposited GAG during the 3 week period, which was also confirmed with the biochemical testing. Moreover, GEL scaffolds had significantly higher compressive modulus and peak stress than PGH scaffolds at all time points with the largest difference seen in week 3. It can be concluded that GEL outperformed PGH in chondrogenesis. It can also be concluded that materials play a more important role in the process of chondrogenesis than the tested cell populations. Fibroblastic SLCs were shown to have similar chondrogenic potential as CLCs cells, suggesting a rich pool of progenitor cells in the superficial fibroblastic layer capable of undergoing chondrogenesis given appropriate physical and chemical cues.

UNASSIGNED: To explore the effect of amyloid-β peptide (Aβ) on mandibular condyle to develop a new treatment for postmenopausal women with Temporomandibular joint osteoarthritis.
UNASSIGNED: A murine bone loss model was established by ovariectomy. Microstructure parameters of the condyle were measured by microcomputed tomography before and after intraperitoneal injection with Aβ. Flow cytometry, Alizarin red staining, RT-qPCR assays, FITC/PI staining, Oil Red O staining and western blotting were used to evaluate the effect of Aβ on the osteogenic differentiation of mouse bone marrow stromal stem cells (mBMSCs).
UNASSIGNED: In vivo, condylar microstructure parameters increased. Serum osteoprotegerin and procollagen type 1 N propeptide increased in a dose-dependent manner after the injection of Aβ, which were opposite the changes observed in c-terminal telopeptides of type I collagen, tumor necrosis factor-α and the high serum level of leptin. In vitro, Aβ promoted calcium nodule formation in the cells. The expression of ALP, Runx2, osteorix and osteocalcin increased significantly. The expression of mRNAs related to the Wnt signaling pathway was significantly upregulated, which could be blocked by DKK1.
UNASSIGNED: Aβ can reverse bone loss in the mandibular condyle in ovariectomized mice through promoting the osteogenic differentiation of mBMSCs via the Wnt pathway.

OBJECTIVE: To investigate the clinical and pathological features of osteochondroma in maxillofacial region, and to summarize the clinicopathological features of rare osteochondroma malignant transformation in order to provide clinical guidance.
METHODS: From January 2018 to September 2023, a total of 171 patients with osteochondroma were retrospectively collected in Shanghai Ninth People\'s Hospital, Shanghai Jiao Tong University School of Medicine. Their preoperative CT and clinicopathological features were analyzed.
RESULTS: Of the 171 patients with osteochondroma in maxillofacial bone, 66%（113/171） were females and 34% were male. Their age ranged from 11-76 with an average age was 44 years old. Of the 171 cases, 95.3%（163/171）in mandible condyle, 4%(7/171) in mandible processus coronoideus, and 0.5%（1/171） in zygomatic arch. The imaging findings showed that the thickness of cartilaginous cap was less than 1 cm in 98%（159/161） cases with condyle lesions. Only 2 cases(2/171, 1.1%) had malignant transformation. One was diagnosed with secondary chondrosarcoma, another developed low-grade osteosarcoma.
CONCLUSIONS: Osteochondroma in maxillofacial region mostly occurs in females, and most commonly located in condylar process, with a malignant change rate of 1.1%, which is similar to that of other parts of the body. Imaging findings have important guiding significance for the diagnosis of osteochondroma malignant change.

OBJECTIVE: To investigate the correlation between the occlusal canting and the bilateral temporomandibular joint (TMJ) space in adult and juvenile mandibular deviation patients and study the mutual influence between the occlusal canting and mandibular position, in order to provide references for clinical treatment.
METHODS: CBCT data of mandibular deviation patients（20 adults，20 juveniles）were selected. Inivo5 Dental Anatomage software was used to reconstruct the structures. The occlusal cant and vertical height of the bilateral maxillary from canines to first molars were measured, and the vertical heights difference between the same teeth on both sides was calculated. The anterior, superior and posterior space of temporomandibular joint were measured respectively in both groups. Pearson correlation analysis between the occlusal canting and bilateral condylar space was carried out by using SPSS 17.0 software package.
RESULTS: In the juvenile group, negative correlations were found between the occlusal cant and the superior TMJ space on the deviated side (P＜0.05). Negative correlation was found between the vertical height difference of bilateral canines and the anterior TMJ space on the deviated side in the juvenile group(P＜0.05). In the adult group, no significant correlation was observed among those correlated examination (P＞0.05).
CONCLUSIONS: The occlusal canting is moderately correlated with mandibular position in the early stage of mandibular deviation patients. Early treatment of mandibular deviation is of great importance in preventing its progression into severe skeletal malocclusion, and more attention should be paid on the correction of the canted frontal occlusion plane.

BACKGROUND: The aim of this study was to evaluate whether degenerative bone changes in the mandibular condyle on cone beam computed tomography images are associated with the Eichner index.
METHODS: 336 cone beam computed tomography images condyle images of 168 patients were analyzed for degenerative bone changes. These changes were named as condyle flattening, osteophytes, erosions, subchondral sclerosis, generalized sclerosis and subchondral cysts. The edentulous status of the patients was classified as group A-B-C and subtypes according to the Eichner index. Categorical variables were evaluated with chi-square test and p < 0.05 was considered statistically significant.
RESULTS: According to the results of the study, the most common degenerative condyle change was flattening of the condyle. Among the Eichner index groups, the most common group was A and the least common group was C. Condyle changes on the right and left sides were most commonly observed in group A patients. The statistically significant majority of patients with right-sided condyle flattening and erosion were in group C. No significant difference was found between all other condyle changes and Eichner index groups. There was no significant relationship between Eichner index and gender.
CONCLUSIONS: Degenerative bone changes (flattening and erosion of the condyle) in the condyle region were more common in group C patients with more tooth loss. There is a significant relationship between condyle changes and posterior toothlessness.

BACKGROUND: This study aims primarily to assess the mandibular condyles and patient response to MAD therapy using cone-beam computed tomography (CBCT). Also, the study proposes to analyze whether variations in condylar position, OSA severity and mandibular protrusion influence patient response.
METHODS: 23 patients diagnosed with mild/moderate OSA and treated with MAD comprised the sample. Clinical, CBCT, and PSG assessments were conducted at baseline and with MAD in therapeutic protrusion (4-6 months of MAD use). The condyle position was vertically and horizontally evaluated at baseline and at the therapeutic protrusion.
RESULTS: The condyle position significantly changed with MAD, showing anterior (7.3 ± 2.8 mm; p < 0.001) and inferior (3.5 ± 1 mm; p < 0.001) displacement. Patients with mild OSA required more protrusion (p = 0.02) for improvement. Responders exhibited a significantly prominent (p = 0.04) anterior baseline condyle position. A negative modest correlation was found between treatment response and baseline condyle anterior position (p = 0.03; r=-0.4), as well as between OSA severity and the percentage of maximum protrusion needed for therapeutic protrusion (p = 0.02; r=-0.4). The patient protrusion amount did not predict condylar positional changes. Neither condyle position, OSA severity, nor therapeutic protrusion were predictors of MAD treatment response.
CONCLUSIONS: MAD resulted in anterior and inferior condylar displacement, and the amount of protrusion did not predict condylar positional changes. Responders showed a more anterior baseline condyle position. OSA severity and mandibular protrusion did not predict treatment response.

OBJECTIVE: This study aimed to investigate possible differences of functional occlusal variables between a group of migraine patients (MG) and a control group (CG).
METHODS: Each group included 50 individuals. Instrumental functional analysis and digital occlusal analysis were performed. Variables examined were condylar displacement from a reference position to maximum intercuspation; angular difference between the steepness of the articular eminence and the contra-lateral canine guidance; and angular difference between the steepness of the articular eminence and the ipsilateral central incisor guidance and occlusal plane inclination. Self-reported grinding and occlusal index were also investigated.
RESULTS: There were statistically significant differences in the extent of retral condylar displacement assessed both clinically [MG: 0.49 mm (SD 0.67 mm), CG: 0.29 mm (SD 0.27 mm), p = 0.012] and digital-mechanically [MG: 1.53 mm (SD 0.95 mm), CG: 0.9 mm (SD 0.66 mm), p = 0.001], the angular difference between the steepness of the articular eminence and the contra-lateral canine guidance [MG: 13.11° (SD 8.33°), CG: 9.47° (SD 7.08°), p = 0.021 and MG: 12.94° (SD 8.71°), CG: 9.44° (SD 8.70°), p = 0.017], and the occlusal plane inclination [MG: 11.16° (SD 4.66°), CG: 9.09° (SD 4.37°), p = 0.024]. Self-reported grinding (MG: 39/50, CG: 12/50, p < 0.001) and occlusal index [MG: 1.92 (SD 0.46), CG: 0.21 (SD 0.66), p < 0.001] were also significantly higher in migraineurs.
CONCLUSIONS: Articular and occlusal structures could play a role in migraine and thus should be considered in an interdisciplinary approach.

OBJECTIVE: The potential influence of psychological factors on temporomandibular joint disorders has been clinically documented. To date, all research examining the impact of psychological stress on the temporomandibular joint has been conducted on animals. This study aims to explore the relationship between psychological stress and the structure of the human mandibular condyle.
METHODS: This cross-sectional study was performed on individuals, who were referred to the radiology division of 5th Azar Hospital for head and neck Computed Tomography (CT) scans. All participants completed a perceived stress questionnaire to determine their level of stress. Bone density and cortical bone thickness were measured as indicators of mandibular condyle structure. Based on multi-slice CT scan data, bone density was calculated in the anterior, middle, and posterior mandibular condyle. The cortical bone thickness was also measured at the anterior and posterior mandibular condyle. Statistical analysis was performed in R 4.0.2 software.
RESULTS: Seventy individuals, aged 18-59 years, participated in this study. The CT scans revealed a decrease in Hounsfield units (HU) and bone mineral density (BMD) in both the anterior and posterior regions. However, in the high-stress group, there was no significant difference in cortical bone thickness in the anterior and posterior regions of the condyle, nor in HU and BMD in the middle region of the condyle. An inverse correlation was observed between BMD and perceived stress in the anterior, middle, and posterior regions of both condyles.
CONCLUSIONS: The current findings indicate that recent psychological stress is associated with changes in the structure of the condyle.