Towards clinically applicable automated mandibular canal segmentation on CBCT.

OBJECTIVES: To develop a deep learning-based system for precise, robust, and fully automated segmentation of the mandibular canal on cone beam computed tomography (CBCT) images. METHODS: The system was developed on 536 CBCT scans (training set: 376, validation set: 80, testing set: 80) from one center and validated on an external dataset of 89 CBCT scans from 3 centers. Each scan was annotated using a multi-stage annotation method and refined by oral and maxillofacial radiologists. We proposed a three-step strategy for the mandibular canal segmentation: extraction of the region of interest based on 2D U-Net, global segmentation of the mandibular canal, and segmentation refinement based on 3D U-Net. RESULTS: The system consistently achieved accurate mandibular canal segmentation in the internal set (Dice similarity coefficient [DSC], 0.952; intersection over union [IoU], 0.912; average symmetric surface distance [ASSD], 0.046 mm; 95% Hausdorff distance [HD95], 0.325 mm) and the external set (DSC, 0.960; IoU, 0.924; ASSD, 0.040 mm; HD95, 0.288 mm). CONCLUSIONS: These results demonstrated the potential clinical application of this AI system in facilitating clinical workflows related to mandibular canal localization. CLINICAL SIGNIFICANCE: Accurate delineation of the mandibular canal on CBCT images is critical for implant placement, mandibular third molar extraction, and orthognathic surgery. This AI system enables accurate segmentation across different models, which could contribute to more efficient and precise dental automation systems.

Increased joint loading induces subchondral bone loss of the temporomandibular joint via the RANTES-CCRs-Akt2 axis.

Early-stage temporomandibular joint osteoarthritis (TMJOA) is characterized by excessive subchondral bone loss. Emerging evidence suggests that TMJ disc displacement is involved, but the pathogenic mechanism remains unclear. Here, we established a rat model of TMJOA that simulated disc displacement with a capacitance-based force-sensing system to directly measure articular surface pressure in vivo. Micro-CT, histological staining, immunofluorescence staining, IHC staining, and Western blot were used to assess pathological changes and underlying mechanisms of TMJOA in the rat model in vivo as well as in RAW264.7 cells in vitro. We found that disc displacement led to significantly higher pressure on the articular surface, which caused rapid subchondral bone loss via activation of the RANTES-chemokine receptors-Akt2 (RANTES-CCRs-Akt2) axis. Inhibition of RANTES or Akt2 attenuated subchondral bone loss and resulted in improved subchondral bone microstructure. Cytological studies substantiated that RANTES regulated osteoclast formation by binding to its receptor CCRs and activating the Akt2 pathway. The clinical evidence further supported that RANTES was a potential biomarker for predicting subchondral bone loss in early-stage TMJOA. Taken together, this study demonstrates important functions of the RANTES-CCRs-Akt2 axis in the regulation of subchondral bone remodeling and provides further knowledge of how disc displacement causes TMJOA.

Viability of the quintessential 5 temporomandibular disorder symptoms as a TMD screener.

OBJECTIVE: This study explored the viability of using the 5 temporomandibular disorder (TMD) symptoms (5Ts) of the Diagnostic Criteria for TMDs (DC/TMD) as a TMD screener. STUDY DESIGN: A total of 1039 adults (≥18 years old) with a mean age of 32.65 ± 12.95 years (77.4% women) from a tertiary dental hospital were enrolled. The 5Ts questionnaire (involving items on TMD/facial pain, headaches, temporomandibular joint noises, and closed- and open-locking) was administered, and TMD diagnoses were derived through clinical interviews and examinations, radiographic investigations, and the DC/TMD diagnostic algorithms and diagnostic tree. Diagnostic accuracy of the 5Ts was assessed using the area under the receiver operating characteristics curve and various measures, including sensitivity, specificity, predictive values, and likelihood ratios. RESULTS: Among the participants, 80.2% (n = 833) were 5Ts-positive, and 19.8% (n = 206) were 5Ts-negative, whereas 51.3% and 85.7% received at least 1 pain-related and intra-articular DC/TMD diagnosis, respectively. The 5Ts showed high accuracy for detecting all TMDs, pain-related and intra-articular, with area under the receiver operating characteristics curves of 0.98, 1.00, and 0.98, respectively. Sensitivity ranged from 96.1% to 99.2%, whereas specificity was 100.0%. CONCLUSIONS: The 5Ts demonstrated high diagnostic accuracy for identifying pain-related and/or intra-articular disorders.

Number and type of temporomandibular disorder symptoms: their associations with psychological distress and oral health-related quality of life.

OBJECTIVE: In this case-control study, we investigated the presence of differing numbers and types of temporomandibular disorder (TMD) symptoms, their association with psychological distress, and their impact on oral health-related quality of life (OHRQoL). STUDY DESIGN: We recruited a total of 814 participants with TMD and 147 control subjects. The participants were instructed to complete the Diagnostic Criteria for Temporomandibular Disorders Symptom Questionnaire; the Depression, Anxiety and Stress Scale-21; and the Oral Health Impact Profile-Temporomandibular Disorders. The participants were subsequently categorized by their number and type of TMD symptoms. Data were analyzed with the Kruskal-Wallis/Mann-Whitney U test (α = .05). RESULTS: The mean age of the participants (N = 961) was 32.99 ± 13.14 years, and 79.2% were women. Participants with more and all types of TMD symptoms generally exhibited significantly higher levels of psychological distress and worse OHRQoL (P < .001). Those with TMD pain plus temporomandibular joint (TMJ) sounds/dysfunction had significantly greater psychological distress, whereas those with painful symptoms and TMJ dysfunction experienced significantly more impairment in OHRQoL than individuals with only TMJ sounds. CONCLUSIONS: Psychological states and OHRQoL are influenced by the number and type of TMD symptoms. Individuals with more and all types of pain-related TMD symptoms with/without intra-articular features had greater psychological distress and OHRQoL impairment.

Increased chemokine RANTES in synovial fluid and its role in early-stage degenerative temporomandibular joint disease.

BACKGROUND: Degenerative joint disease (DJD) of the temporomandibular joints (TMJs) in adolescents and young adults is closely associated with disc displacement without reduction (DDw/oR). OBJECTIVE: This study aimed to determine the pathogenesis of early-stage TMJ DJD induced by DDw/oR. METHODS: 31 female subjects aged 12-30 years were enrolled, comprising 12 patients with DDw/oR without DJD, 13 with DDw/oR and early-stage DJD, and 6 healthy volunteers. The synovial fluid samples of the subjects were screened for 27 inflammatory-related cytokines using multiple cytokine array. Significantly increased cytokines and a key regulator of osteoclastogenesis "receptor activator of nuclear factor-κB ligand" (RANKL) were further determined by sandwich immunoassay. These factors were also assessed for the possible pathophysiologic actions on RAW264.7 cell proliferation, migration, osteoclastogenesis and bone-resorbing activity using Cell Counting Kit-8, Transwell system, tartrate-resistant acid phosphatase staining and osteo assay plates. RESULTS: Macrophage-derived inflammatory protein-1 beta (MIP-1ß) and regulated upon activation normal T cell expressed and secreted (RANTES) were found to vary significantly in relation to the controls. In contrast to an unchanged concentration of RANKL, a strong increase in the level of RANTES was detected in subjects with DDw/oR and early-stage DJD. MIP-1ß concentrations were only elevated in subjects with DDw/oR without DJD. Functionally, both MIP-1ß and RANTES could enhance macrophage migration in a concentration-dependent manner, while only RANTES exhibited a promoting effect on osteoclast formation and bone-resorbing activity. CONCLUSIONS: Chemokine RANTES was significantly upregulated and might be a key regulator of osteoclastogenesis contributing to DDw/oR-induced early-stage TMJ DJD.

Expert Consensus on Procedures and Operations of Navigation-guided Needle Biopsy Techniques for Skull Base Tumours.

Skull base surgery is an interdisciplinary subject. The anatomical structures in the skull base related to oral and maxillofacial surgery include the parapharyngeal space, the pterygopalatine fossa and the infratemporal space. This operative area is one of the most challenging surgical areas in oral and maxillofacial surgery due to its deep site, complex anatomy and high risk. Obtaining pathological information of the tumour preoperatively may help surgeons optimise their treatment plan. Needle biopsy is one of the major minimally invasive techniques that allows preoperative pathological results to be obtained. The navigation technology, which is developing rapidly nowadays, provides a reliable assistance for deep tissue biopsy surgery. Experts from the Society of Oral and Maxillofacial Surgery, Chinese Stomatological Association formulated an expert consensus on the procedures and operations of navigation-guided needle biopsy techniques for skull base tumours, so as to standardise and promote the application and operation of navigation-guided needle biopsy for skull base tumours.

Contribution of microglial reaction to increased nociceptive responses in high-fat-diet (HFD)-induced obesity in male mice.

The progressive increase in the prevalence of obesity in the population can result in increased healthcare costs and demands. Recent studies have revealed a positive correlation between pain and obesity, although the underlying mechanisms still remain unknown. Here, we aimed to clarify the role of microglia in altered pain behaviors induced by high-fat diet (HFD) in male mice. We found that C57BL/6CR mice on HFD exhibited enhanced spinal microglial reaction (increased cell number and up-regulated expression of p-p38 and CD16/32), increased tumor necrosis factor-α (TNF-α) mRNA and brain-derived neurotrophic factor (BDNF) protein expression as well as a polarization of spinal microglial toward a pro-inflammatory phenotype. Moreover, we found that using PLX3397 (a selective colony-stimulating factor-1 receptor (CSF1R) kinase inhibitor) to eliminate microglia in HFD-induced obesity mice, inflammation in the spinal cord was rescued, as was abnormal pain hypersensitivity. Intrathecal injection of Mac-1-saporin (a saporin-conjugated anti-mac1 antibody) resulted in a decreased number of microglia and attenuated both mechanical allodynia and thermal hyperalgesia in HFD-fed mice. These results indicate that the pro-inflammatory functions of spinal microglia have a special relevance to abnormal pain hypersensitivity in HFD-induced obesity mice. In conclusion, our data suggest that HFD induces a classical reaction of microglia, characterized by an enhanced phosphorylation of p-38 and increased CD16/32 expression, which may in part contribute to increased nociceptive responses in HFD-induced obesity mice.

[Radiological characteristics of the cyst-like lesion of condyle in temporomandibular joint by cone beam computed tomography].

OBJECTIVE: To analyze the radiological characteristics and classifications of the cyst-like lesion of condyle in temporomandibular joint (TMJ) by cone beam computed tomography (CBCT). METHODS: The study was conducted retrospectively on TMJ images from 194 patients who underwent CBCT examinations. Location, size, amount, surrounding bone trabecula, cortical bone white line of cyst-like lesion, and the overall condition of the condylar bone were evaluated. According to the overall condition of the condylar bone, the cyst-like lesion of condyle were divided into typesⅠand Ⅱ. The location, size, amount, surrounding bone trabecula, and cortical bone white line of the two types of cyst-like lesions were compared. RESULTS: In 198 condylars of 194 patients, cyst-like lesions were detected in the left side of 94 patients, in the right of 96 patients, and in both sides of 4 patients. The size of lesions ranged from 1.2 mm to 13.5 mm, with an average size of (3.4±1.5) mm. Half of the cyst-like lesions were located underneath the anterior lateral cortical bony layer (99 condylars, 50.0%). Most cyst-like lesions were solitary (149 condylars, 75.3%), while 62.6% (124 condylars) were surrounded by continuous bony white lines. Bone sclerosis could be observed in 160 condylars (80.8%). A total of 132 condyles (66.7%) were accompanied by changes in late-stage osteoarthrosis, while the others were only accompanied by early-stage osteoarthrosis (10 osteoarthrosis, 5.1%) or showed no evidence of osteoarthrosis (56 osteoarthrosis, 28.3%). Statistical difference were observed in the location, amount, and surrounding bone trabecula of the two types of cyst-like lesions. TypeⅠcyst-like lesions had more frequent and bone sclerosis than type Ⅱ, whereas type Ⅱ cyst-like lesions occurred more on condylar internal or condyle neck than typeⅠ. CONCLUSIONS: The pathogenesis and mechanism of the two types of cyst-like lesions may be different from each other.

[CT imaging features of diffuse tenosynovial giant cell tumor of temporomandibular joint].

OBJECTIVE: This study aimed to investigate the characteristic features of CT images of diffuse tenosynovial giant cell tumor (D-TSGCT) from the temporomandibular joint (TMJ) to understand CT imaging diagnosis of the disease. METHODS: CT images and clinical information from 10 patients with D-TSGCT of TMJ were recruited for retrospective analysis from March 2013 to March 2017 in Peking University Hospital of Stomatology. All cases were treated by surgery and confirmed by pathology. RESULTS: CT scan demonstrated hyperdense soft-tissue masses and various kinds of calcification in all of the 10 subjects. Contrast-enhanced scan exhibited obvious enhancement in six patients. Bone destruction of the mandibular condyles and skull base was found in seven and six subjects, respectively. CONCLUSIONS: CT appearance of D-TSGCT of the TMJ is characterized by hyperdense soft tissue with calcification, further enhancement in contrast-enhanced scan, and bone destruction in the mandibular condyles and skull base in some cases.

Metrical analysis of disc-condyle relation with different splint treatment positions in patients with TMJ disc displacement

Abstract Objective: To evaluate the effect of bite positions characterizing different splint treatments (anterior repositioning and stabilization splints) on the disc-condyle relation in patients with TMJ disc displacement with reduction (DDwR), using magnetic resonance imaging (MRI). Material and Methods: 37 patients, with a mean age of 18.8±4.3 years (7 male and 30 females) and diagnosed with DDwR based on the RDC/TMD, were recruited. MRI metrical analysis of the spatial changes of the disc/condyle, as well as their relationships, was done in three positions: maximum intercuspation (Position 1), anterior repositioning splint position (Position 2), and stabilization splint position (Position 3). Disc/condyle coordinate measurements and disc condyle angles were determined and compared. Results: In Position 1, the average disc-condyle angle was 53.4° in the 60 joints with DDwR, while it was −13.3° with Position 2 and 30.1° with Position 3. The frequency of successful "disc recapture" with Position 2 was significantly higher (58/60, 96.7%) than Position 3 (20/60, 33.3%). In Positions 2 and 3, the condyle moved forward and downward while the disc moved backward. The movements were, however, more remarkable with Position 2. Conclusions: Anterior repositioning of the mandible improves the spatial relationship between the disc and condyle in patients with DDwR. In addition to anterior and inferior movement of the condyle, transitory posterior movement of the disc also occurred.

Degenerative temporomandibular joint changes associated with recent-onset disc displacement without reduction in adolescents and young adults.

This study evaluated the occurrence of degenerative temporomandibular joint (TMJ) changes in adolescents and young adults with recent on-set disc displacement without reduction (DDw/oR) using high-resolution cone beam computed tomography (CBCT). The associations between types of osteoarthrosis (OA) changes and clinical factors including disease duration were also examined. CBCT and clinical data of 300 patients (84.70% females, mean age 20.93 ± 4.77 years) diagnosed with unilateral DDw/oR (≤12 months) based on RDC/TMD were acquired. CBCT images of both symptomatic and contralateral asymptomatic TMJs were independently evaluated and scored by two radiologists. Associations between OA changes and gender, age, mouth opening and duration of DDw/oR were analyzed statistically. Condylar OA changes were present in 59.30% of the joints with DDw/oR. Early-stage OA changes (loss of continuity of articular cortex and/or surface destruction) constituted most (45.67%) of the alterations. Prevalence of early-stage OA increased from 24% to about 60% one month after TMJ closed-lock occurred. Logistic regression analysis showed the risk of developing early-stage OA changes was 5.33 times higher one month after onset of DDw/oR. A high prevalence of degenerative TMJ changes was observed with recent on-set DDw/oR in adolescents and young adults. Early diagnosis and intervention of DDw/oR is therefore prudent.

Alendronate Attenuates Spinal Microglial Activation and Neuropathic Pain.

UNLABELLED: Many derivatives of bisphosphonates, which are inhibitors of bone resorption, have been developed as promising agents for painful pathologies in patients with bone resorption-related diseases. The mechanism for pain relief by bisphosphonates remains uncertain. Studies have reported that bisphosphonates could reduce central neurochemical changes involved in the generation and maintenance of bone cancer pain. In this study, we hypothesized that bisphosphonates would inhibit spinal microglial activation and prevent the development of hyperalgesia caused by peripheral tissue injury. We investigated the effects of alendronate (a nitrogen-containing bisphosphonate) on the development of neuropathic pain and its role in modulating microglial activation in vivo and in vitro. Intrathecal and intraperitoneal administration of alendronate relieved neuropathic pain behaviors induced by chronic constriction sciatic nerve injury. Alendronate also significantly attenuated spinal microglial activation and p38 mitogen-activated protein kinase (MAPK) phosphorylation without affecting astrocytes. In vitro, alendronate downregulated phosphorylated p38 and phosphorylated extracellular signal regulated kinase expression in lipopolysaccharide-stimulated primary microglia within 1 hour, and pretreatment with alendronate for 12 and 24 hours decreased the expression of inflammatory cytokines (tumor necrosis factor α, and interleukins 1ß and 6). These findings indicate that alendronate could effectively relieve chronic constriction sciatic nerve injury-induced neuropathic pain by at least partially inhibiting the activation of spinal microglia and the p38 MAPK signaling pathway. PERSPECTIVE: Alendronate could relieve neuropathic pain behaviors in animals by inhibiting the activation of spinal cord microglia and the p38 MAPK cell signaling pathway. Therapeutic applications of alendronate may be extended beyond bone metabolism-related disease.

Dynamics of spinal microglia repopulation following an acute depletion.

Our understanding on the function of microglia has been revolutionized in the recent 20 years. However, the process of maintaining microglia homeostasis has not been fully understood. In this study, we dissected the features of spinal microglia repopulation following an acute partial depletion. By injecting intrathecally Mac-1-saporin, a microglia selective immunotoxin, we ablated 50% microglia in the spinal cord of naive mice. Spinal microglia repopulated rapidly and local homeostasis was re-established within 14 days post-depletion. Mac-1-saporin treatment resulted in microglia cell proliferation and circulating monocyte infiltration. The latter is indeed part of an acute, transient inflammatory reaction that follows cell depletion, and was characterized by an increase in the expression of inflammatory molecules and by the breakdown of the blood spinal cord barrier. During this period, microglia formed cell clusters and exhibited a M1-like phenotype. MCP-1/CCR2 signaling was essential in promoting this depletion associated spinal inflammatory reaction. Interestingly, ruling out MCP-1-mediated secondary inflammation, including blocking recruitment of monocyte-derived microglia, did not affect depletion-triggered microglia repopulation. Our results also demonstrated that newly generated microglia kept their responsiveness to peripheral nerve injury and their contribution to injury-associated neuropathic pain was not significantly altered.

[Effect of segmental Le Fort I osteotomy and bilateral sagittal split ramus osteotomy on the condyle position in skeletal class III malocclusion patients].

OBJECTIVE: To investigate the effect of segmental Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) on the condyle position in skeletal class III malocclusion patients. METHODS: In this retrospective study, 19 patients with skeletal class III malocclusion who met the inclusion criteria were enrolled. All the patients underwent the segmental Le Fort I osteotomy and BSSRO. Cone beam computed tomography (CBCT) scans were performed in the following phases: T1: within one week before the surgeries; T2: within one week post-surgery;T3:three months post-surgery; T4: 6 to 14 months post-surgery. The posterior spaces, anterior spaces and the superior spaces of the bilateral temporomandibular joints were measured according to the Kamelchuk method respectively. The fossa ratios of the condyle and the distribution of the condyle positions related to the glenoid fossa (anterior, concentric and posterior position)were calculated. The results were analyzed statistically. RESULTS: The posterior space, the anterior space and the superior space of bilateral temporomandibular joints in T2 phase[right: (2.78±1.23) mm, (2.47±0.89) mm, (3.07±0.85) mm; left: (2.93±0.83) mm, (2.69±1.14) mm, (3.44±1.16) mm] showed significantly larger spaces than those in T1 phase [right: (1.81±0.95) mm, (1.65±0.55) mm, (2.13±0.52) mm; left: (2.12± 1.05) mm, (1.79±0.59) mm, (2.15±0.93) mm],in T3 phase [right: (2.08±1.25) mm, (1.79±0.68) mm, (1.80±0.76) mm; left: (2.05±0.75) mm, (1.99±0.94) mm, (2.14±0.71) mm] and in T4 phase [right: (1.94±0.77) mm, (1.81±0.69) mm, (2.05±0.69) mm; left: (1.89±0.69) mm, (1.80±0.61) mm, (2.19±0.75) mm], P<0.05. No significant differences were observed among T1,T3 and T4 phases in the terms of the joint spaces of both sides(P>0.05).The fossa ratio and the condyle position related to the glenoid fossa had no significant difference in all the four phases (P>0.05).The results suggested that the condyle moved downward in T2 phase and changed to the original pre-surgery position in T3 phase, then keot stable in T4 phase. CONCLUSION: Segmental Le Fort I osteotomy and BSSRO caused significant and transient changes of the condyle position in skeletal class III malocclusion patients. However, the condyle tended to move back to the original pre-surgery position and might keep stable.

[Three-dimensional evaluation of condylar morphology remodeling after orthognathic surgery in mandibular retrognathism by cone-beam computed tomography].

OBJECTIVE: To evaluate the effect of orthognathic surgery on condylar morphology changes by comparing three-dimension surface reconstructions of condyles using cone-beam computed tomography (CBCT) data. METHODS: In the study, 18 patients with mandible retrognathism deformities were included and CBCT data of 36 temporomandibular joints were collected before surgery and 12 months after surgery. Condyles were reconstructed and superimposed pre- and post-operatively to compare the changes of condylar surfaces. One-sample t test and χ2 test were performed for the analysis of three-dimension metric measurement and condylar head remodeling signs. P<0.05 was considered significant. RESULTS: The root-mean-square (RMS) of condylar surface changes before and after the surgery was (0.37±0.11) mm, which was significant statistically (P<0.05). The distribution of condylar remodeling signs showed significant difference (P<0.05). Bone resorption occurred predominantly in the posterior area of condylar head and bone formation occurred mainly in the anterior area. CONCLUSION: Three-dimension superimposition method based on CBCT data showed that condylar morphology had undergone remodeling after mandibular advancement.

Short- and long-term changes of condylar position after bilateral sagittal split ramus osteotomy for mandibular advancement in combination with Le Fort I osteotomy evaluated by cone-beam computed tomography.

PURPOSE: Bilateral sagittal split ramus osteotomy (BSSO) may change condylar position, which can be one of the factors contributing to skeletal relapse. This study evaluated short- and long-term changes in condylar position using cone-beam computed tomography (CBCT) and investigated changes in temporomandibular joint (TMJ) signs after BSSO for mandibular advancement in combination with Le Fort I osteotomy. MATERIALS AND METHODS: Thirty-one patients were included, and CBCT data of 62 TMJs were collected before surgery (T0), immediately after surgery (T1), 3 months after surgery (T2), and at the last follow-up at 12.1 ± 3.0 months after surgery (T3). The relation of the condyle to the fossa was evaluated by the method of Pullinger and Hollender (Oral Surg Oral Med Oral Pathol 62:719, 1986). Clinical examination, with a special focus on signs of temporomandibular disorder (TMD), was documented at T0, T2, and T3. Repeated-measures analysis of variance (P = .05) and χ2 test (P = .05) were performed. RESULTS: Data of 27 patients were used for statistical analysis. Values from the formula of Pullinger and Hollender changed significantly with time, but there was no significant difference between the right and left condyles. Condyles moved inferoposteriorly immediately after surgery (T0 to T1) followed by anterosuperior movement 3 months after surgery (T1 to T2). The superimposed effect showed posterosuperior movement compared with the initial position before surgery (T0 to T2) and this position remained stable at 1-year follow-up (T2 to T3). A decrease of TMD signs over time, from 22.6% (T0) to 12.9% (T2) and 9.7% (T3), was observed, which showed no statistical significance. CONCLUSIONS: There were obvious changes in condylar position after BSSO in combination with Le Fort I osteotomy. Condyles tended to be located in a concentric position in relation to the glenoid fossa 3 months after surgery and remained stable during the 1-year follow-up. These changes did not cause an increase of TMD signs.

Subarticular, cystlike lesion associated with avascular necrosis of the mandibular condyle: a case report.

Little is known about avascular necrosis of the mandibular condyle, which is necrosis of the epiphyseal or subarticular bone secondary to a diminished or disrupted blood supply in the absence of infection. We present a case of a large subarticular cystlike lesion that was found using cone-beam computed tomography (CBCT). There was an absence of osteoarthrosis, and the condylar articular surface was relatively intact. The patient's history, physical examination, and magnetic resonance images supported the diagnosis of avascular necrosis of the mandibular condyle. After 4 months of conservative therapy, new bone was observed in the cystlike marrow lesion, and a smooth articular surface was reestablished. Subarticular cystlike lesions without the collapse of the articular surface of mandibular condyles may be an early indicator of avascular necrosis.

Condylar subchondral formation of cortical bone in adolescents and young adults.

We investigated subchondral formation of cortical bone in the condyles of adolescents and young adults, and looked for age-related and sex-related differences in bony formation with the aid of cone-beam computed tomography data in 1438 subjects aged between 10 and 30 years. The scans were part of the hospital's clinical protocol for patients seeking orthodontic or orthognathic treatment. No patient had signs or symptoms of temporomandibular disorders. Central images of the coronal and sagittal planes of the condyle were acquired and scored. Subchondral formation of cortical bone was seen as a high-density compact linear image, and subjects were classified into complete, partial, and no formation. Subchondral formation of cortical bone was first seen at the ages of 13-14 in boys and 12-13 in girls. Complete cortical bony formation was seen after the age of 22 years for men and 21 for women. We conclude that cortical bone begins to form around the periphery of the condyles during adolescence (12-14 years). A continuous, homogeneous, and compact cortical bony layer is established in young adults by the age of 21-22, indicating full development of the mandibular condyle. The condylar bone developed gradually and was generally fully developed a year earlier in women than men.

Condylar remodeling accompanying splint therapy: a cone-beam computerized tomography study of patients with temporomandibular joint disk displacement.

OBJECTIVE: The aim of this study was to evaluate osseous changes accompanying anterior repositioning splint (ARS) therapy in patients with temporomandibular joint disk displacement. STUDY DESIGN: Cone-beam computerized tomography (CBCT) data of 36 patients with intermittent or permanent closed-lock were used; 23 patients with permanent closed-lock had their displaced disks physically reduced by mandibular manipulation before ARS therapy. CBCT was performed before and ≈ 6 months after ARS therapy. The presence and location of "double contour" images suggesting condylar bone remodeling were statistically analyzed. RESULTS: The "double contour" images after ARS therapy were observed in ≈ 80% of patients, more frequently in joints with signs of displaced disks. The "double contour" appeared more often on the posterior bevel as well as the medial and middle part of condyles (P < .01). CONCLUSIONS: ARS therapy can facilitate regenerative remodeling of condyles. CBCT is a useful tool for monitoring osseous changes in condyles.

Clinical characteristics of lateral pterygoid myospasm: a retrospective study of 18 patients.

The available scientific literature on masticatory myospasm-induced oromandibular dystonia is limited. The objective of this study was to determine the clinical characteristics of lateral pterygoid myosapsm in a series of 18 patients. Clinical and electromyographic (EMG) data of 36 patients diagnosed with masticatory muscle myospasm were reviewed, and data from 18 patients with needle EMG-confirmed lateral pterygoid myospasm were extracted for retrospective study. The study population included 6 men and 12 women with a mean age of 53.2 ± 15.3 years. Patients' chief complaints, severity and frequency of myospasm, clinical observations, video recordings, and surface/needle EMG recordings were analyzed. Despite the variety of manifestations, 3 characteristic signs and symptoms of lateral pterygoid myospasm were observed. These were: 1) jaw function disabilities; 2) difficulty in jaw closing after wide opening; and 3) involuntary jaw movements. A differential diagnosis of lateral pterygoid myospasm should be included when oromandibular dystonia is accompanied by the fore mentioned.