Quantitative assessment of condyle positional changes before and after orthognathic surgery based on fused 3D images from cone beam computed tomography.

OBJECTIVES: To establish one method that can be used to quantitatively evaluate the condyle positional changes with 3D images in postoperative mandibular prognathism patients. MATERIALS AND METHODS: This is a retrospective observational study. Twenty-one patients who underwent bilateral sagittal split ramus osteotomy (BSSRO) were scanned with cone beam computed tomography (CBCT) for temporomandibular joints (TMJs) at 1 week preoperatively (T0), 1 to 2 weeks (T1), 3 months (T2), 6 months (T3), and 12 months (T4) postoperatively. The data were then grouped into T0T1, T1T2, T2T3, T3T4 and T0T1, T0T2, T0T3, and T0T4. Semi-automatic registration was conducted, and the condyle positional changes were measured in segmented 3D models. Inter- and intra-observer variability and the repeatability of registration were analyzed with paired t test; the repeated measurement analysis of variance was used for analyzing the repeatability of the marked points; the consistency of segmentation was analyzed with nonparametric test of multiple paired samples (Friedman test) and the independent-sample t test was applied to comparing changes between different periods of time. Differences were considered to be statistically significant when P < 0.05. RESULTS: In T0T1 and T1T2, the condylar position was changed greatly. In T2T3, the mean condylar translations were less than 0.2 mm in all directions, the mean rotational changes of condyle were less than 0.2 mm; in the period of T3T4, the mean condylar translations in all directions were less than 0.02 mm. For series 2, the condyle translational changes in axial, coronal, and sagittal views were within 0.10 mm, and the rotation direction of condyle in all three views was the same within 1 year after operation. CONCLUSIONS: Fused three-dimensional images can be used to qualitatively and quantitatively evaluate condyle positional changes. The condylar position might be stable at 3 months postoperatively. The condyles of most of patients did not fully return to their preoperative position within 1 year after the operation. CLINICAL RELEVANCE: One method for fusing images has been established to detect the condylar positional changes. This method may be applied to estimate the bony changes of condyle, even bony changes in other part of dentomaxillofacial region. Meanwhile, the data of condyle positional changes from asymptomatic patients after the surgery within 1 year can be used as a reference for further exploration of the relationship between orthognathic surgery and the occurrence of osteoarthritis postoperatively in the future. KEY POINTS: • By fused 3D images, the change of condylar position after bilateral sagittal split ramus osteotomy can be observed intuitively. • For the patients with mandibular prognathism, the condylar position would be stable at 3 months postoperatively. • The condyles of most mandibular prognathism patients did not fully return to their preoperative position within 1 year after operation.

Diagnosis of Bilateral Calcifications of Temporomandibular Joint Disc by Image Fusion.

The calcification of the articular disc is an uncommon lesion, usually discovered in hips, elbows, and shoulders, but rarely in temporomandibular joints (TMJ). The TMJ disc calcification may be related to pain and limitation of the mandibular mobility, however, most of the patients were asymptomatic. A 61-year-old female was referred to our hospital after a maxillofacial fist injury, bilateral TMJ disc calcifications were found accidentally by radiological examination. Here the significance of image fusion of cone-beam computed tomography and magnetic resonance imaging (MRI) in the diagnosis of this lesion was emphasized.

Age estimation based on pulp cavity/chamber volume of 13 types of tooth from cone beam computed tomography images.

AIM: The aims of this study are to identify which type of tooth has the strong relationship between age and pulp cavity/chamber volume among 13 types of tooth from the same dentition and to determine whether the inclusion of multiple types of tooth may improve the accuracy of age estimation. MATERIALS AND METHODS: Cone beam computed tomography (CBCT) images from 115 females and 125 males aged between 16 and 63 years were analyzed. The DICOM data of all the images were imported into ITK-SNAP 2.4 for the calculation of pulp cavity/chamber volumes. Logarithmic regression analysis and multiple linear regression analysis were applied to establish the relationship between age and pulp cavity/chamber volumes. RESULTS: Among the 13 types of tooth, maxillary second molars have the largest R (2) (0.491, 0.642, and 0.498) and the smallest SEE (8.119, 6.754, and 8.022) in male, female, and pooled gender samples, respectively. The multiple linear regression analysis for the combination of multi-types of tooth indicated that a larger R (2) (0.627, 0.701, and 0.631) and smaller SEE (7.100, 6.258, and 6.970) than the counterpart calculated from the logarithmic regression analysis of a single type of tooth in male, female, and pooled gender samples, respectively. CONCLUSION: The pulp chamber volume of the maxillary second molars has the largest correlation coefficient with age. Using multiple types of tooth may improve the accuracy of age estimation compared with only one type of tooth used.

[Diagnosis and treatment of the ganglion cysts and synovial cysts arising from the temporomandibular joints].

OBJECTIVE: To give a reference for the early diagnosis and treatment of the cysts arising from the temporomandibular joint. METHODS: Nine patients finally diagnosed as temporomandibular joint cysts at the Peking University Hospital of Stomatology from May 1998 to August 2013 were selected and reviewed. Their clinical manifestations, imaging features, diagnoses and differential diagnoses, treatments and follow-ups were summarized and discussed. RESULTS: In the 9 patients, 3 were males and 6 females. Their ages ranged from 33 to 62 years with a median age of 39 years; the course of the disease ranged from 2 weeks to 3 years with a median of 4 months. The image examinations were performed with conventional X-ray examinations in 7 cases, CT scans in 8 cases, MRI in 6 cases and ultrasound in one case. Of the 9 cases, 7 were finally diagnosed as ganglion cyst and 2 as synovial cyst. Ganglion cysts mainly presented as the mass of preauricular area or joint area, with no obvious symptoms or only local discomfort, occasionally with pain. The synovial cysts manifested as the painful swelling of preauricular area and limited mouth-opening, accompanying with occlusal disorders. The treatments included surgical resection in 8 cases, repeated arthrocenteses and lavages in one case. The follow-ups were from 3 months to 9 years, one case with recurrence, and the remaining eight cases without recurrence. CONCLUSION: MRI examinations are very helpful in the early diagnosis and treatment planning of temporomandibular joint cysts. Surgical resection can have good results. Repeated arthrocenteses and lavages also have a good result, which may be an alternative choice for synovial cyst, but more accumulation of clinical experience is further needed.

[Investigation on radiographic signs of osteoarthrosis in temporomandibular joint with cone beam computed tomography in adolescents].

OBJECTIVE: To investigate the occurrence and radiographic signs of osteoarthrosis of the temporomandibular joints (TMJOA) with cone beam computed tomography (CBCT) in adolescents. METHODS: Individuals with temporomandibular disorders (aged 10-19 years) in the patients group (n=386) and pre-orthodontic patients with malocclusion (aged 10-19 years) in the control group (n=339) were included in the present study. All the patients in both groups had been examined by CBCT. The abnormalities of the condyle were evaluated. The results of radiological findings were compared between the patients group and the controls by using chi-square tests. Inter- and intra-examiner agreements were assessed using Cohen's Kappa coefficient and all statistical analysis was performed using SPSS 13.0. RESULTS: 157 patients in the patients group and 41 subjects in the control group had radiographic signs of TMJOA. The occurrence of OA was significantly higher in the patients group (40.7%, 157/386) than in the controls (12.1%, 41/339), the difference was statistically significant (P<0.05). The occurrence of TMJOA was significantly higher in females (44.6%, 123/276) than in males (30.9%, 34/110) in the patients group (P<0.05) but showed no significant difference in the controls (females: 13.7%, 32/234, and male: 8.6%, 9/105, P>0.05). In addition, the patients group showed significantly higher occurrence of ill-defined cortical bone (31.7%, 65/205) small bony defect and extensive erosion (25.4%, 52/205) than the controls (1.7%, 1/58 and 5.2%, 3/58, respectively, P<0.05), while the subjects in the control group had significantly higher occurrence of flattening and shortening of the condyle (39.7%, 23/58) and sclerosis (39.7%, 23/58) than patients with temporomandibular disorders (6.3%,13/205 and 14.6%, 30/205, respectively, P<0.05). CONCLUSION: TMJOA is not uncommon in adolescent patients with TMD and with malocclusion. Patients in the two study groups had different radiographic signs of OA. The patients with temporomandibular disorders often demonstrate erosive changes, while the pre-orthodontic patients with malocclusion often demonstrate relatively stable radiographic signs.

Detection accuracy of proximal caries by phosphor plate and cone-beam computerized tomography images scanned with different resolutions.

This study was carried out to assess whether the spatial resolution has an impact on the detection accuracy of proximal caries in flat panel CBCT (cone beam computerized tomography) images and if the detection accuracy can be improved by flat panel CBCT images scanned with high spatial resolution when compared to digital intraoral images. The CBCT test images of 45 non-restored human permanent teeth were respectively scanned with the ProMax 3D and the DCT Pro scanners at different resolutions. Digital images were obtained with a phosphor plate imaging system Digora Optime. Eight observers evaluated all the test images for carious lesion within the 90 proximal surfaces. With the histological examination serving as the reference standard, observer performances were evaluated by receiver operating characteristic (ROC) curves. The areas under the ROC curves were analyzed with two-way analysis of variance. No significant differences were found among the CBCT images and between CBCT and digital images when only proximal enamel caries was detected (p = 0.989). With respect to the detection of proximal dentinal caries, significant difference was found between CBCT and digital images (p < 0.001) but not among CBCT images. The spatial resolution did not have an impact on the detection accuracy of proximal caries in flat panel CBCT images. The flat panel CBCT images scanned with high spatial resolution did not improve the detection accuracy of proximal enamel caries compared to digital intraoral images. CBCT images scanned with high spatial resolutions could not be used for proximal caries detection.

[Detection accuracy of occlusal caries by cone-beam computed tomography images scanned with different parameters].

OBJECTIVE: To compare the detection accuracy of occlusal caries in cone-beam computed tomography (CBCT) images scanned with different scanning parameters. METHODS: Thirty-seven extracted human premolars and molars without restorations or obvious cavities were selected for this study. The teeth 3 or 4 as a group were mounted in 12 plaster blocks and scanned with DCT Pro (VATECH, Co., Ltd., Yongin-Si, S.Korea) at normal and high resolution settings and with ProMax 3D (Planmeca Oy, Helsinki, Finland) at low, normal and high resolution settings. In addition, the tooth blocks were imaged with the ProMax 3D at three different tube currents. Ten doctoral candidates of Peking University School and Hospital of Stomatology evaluated all the images of the tooth blocks using a five-level confident scale. Actual presence and the extent of caries were established by histological examinations. The areas under the ROC curves (Az value) were analyzed. RESULTS: Eleven (29.7%, 11/37) teeth were sound, 13 (35.1%, 13/37) had enamel caries and 13 (35.1%, 13/37) had dentine caries. There were no significant differences between normal resolution and high resolution for DCT Pro on the detection accuracy of occlusal (enamel+dentine) caries (0.698 ± 0.064 vs. 0.735 ± 0.044, P>0.05).No significant differences were found for ProMax 3D among low, normal and high resolution (0.700 ± 0.031 vs. 0.700±0.054 vs. 0.701 ± 0.041, P>0.05). For dentinal caries, there were no significant differences between CBCT images scanned with different resolutions for DCT Pro(0.776 ± 0.078 vs. 0.811 ± 0.047, P>0.05) or ProMax 3D (0.713 ± 0.039 vs. 0.685 ± 0.063 vs. 0.713 ± 0.040, P>0.05). No significant differences were found for enamel caries detection for DCT Pro (0.620 ± 0.068 vs. 0.659 ± 0.048, P>0.05)or ProMax 3D (0.686 ± 0.050 vs. 0.685 ± 0.063 vs. 0.689 ± 0.063, P>0.05). For ProMax 3D, there were no significant differences among different tube currents on the detection accuracy of occlusal caries (0.653 ± 0.065 vs. 0.700 ± 0.054 vs. 0.67 ± 0.062, P>0.05). CONCLUSION: Different resolutions did not have an impact on the detection accuracy of occlusal caries. The tube currents for ProMax 3D did not show any effect on occlusal caries detection.

Intraosseous embolotherapy of central arteriovenous malformations in the jaw: long-term experience with 8 cases.

PURPOSE: To investigate the long-term effects of direct intraosseous histoacryl embolotherapy on central arteriovenous malformations (AVMs) of the jaw. MATERIALS AND METHODS: Eight patients with central AVMs of the jaw (3 in the maxilla and 5 in the mandible) were treated with direct intraosseous histoacryl injection. These AVMs exhibited cystic radiolucency, with (n = 5) or without (n = 3) honeycombed component. On angiography, all the AVMs exhibited a large intraosseous nidus with multiple suppliers and drainages. The intraosseous lesions were percutaneously punctured with an 18- to 20-gauge needle, and NBCA diluted 30% to 40% with iodized oil was injected during venous compression. RESULTS: Postembolic arteriograms showed that all the AVMs were completely or nearly completely devascularized after single or multiple injections at the initial treatment. The follow-up period ranged from 3 to 8 years. Two AVMs experienced postembolic curettage and were anatomically cured. Three AVMs were anatomically cured after 1 to 3 sessions of embolotherapy. The other 3 AVMs were clinically cured after 1 (n = 2) to 4 (n = 1) sessions of embolotherapy. There were no procedure-related severe complications. CONCLUSIONS: Direct intraosseous glue embolotherapy can be a simple and safe technique for endovascular management of central AVMs in the jaw and is particularly effective in an emergency. Complete reossification of the intraosseous nidus can be anticipated if a complete occlusion is obtained.

Congenital infiltrating lipomatosis of the face: A subtype of hemifacial hyperplasia.

OBJECTIVE: To investigate the clinical, imaging and pathological features of congenital infiltrating lipomatosis of the face (CILF) and to discuss whether it is a subtype of hemifacial hyperplasia (HH). METHODS: Sixteen patients diagnosed with CILF were included in this study. All patients had undergone panoramic radiography and spiral CT examinations. Thirteen patients received biopsy, surgery treatment and pathological examination. The clinical documentation and imaging data were retrospectively reviewed. RESULTS: The cheeks (14/16), parotid glands (12/16), tongues (9/16), masticatory muscles (8/16) and the lips (7/16) were the most frequently affected soft tissue organs. The maxilla (14/16), zygoma (13/16), mandible (13/16) were involved among the maxillofacial bones. Dental malformations included macrodontia (8/16), poor formation of the roots (7/16), accelerated tooth germ development or premature eruption of permanent teeth (7/16) and missing of the permanent teeth (4/16). All malformations were restricted to one side of the face and did not trespass the middle line. Pathologically, CILF was featured by the diffuse infiltration of redundant mature adipose tissue into the tissue of the affected organ. CONCLUSION: CILF is a congenital developmental facial malformation characterized by infiltration of nonencapsulated, mature adipose tissue, resulting in facial soft and hard tissue hypertrophy and dental malformations in hemifacial structures. CILF could be considered as a subtype of HH.

A three-dimensional study of hemimandibular hyperplasia, hemimandibular elongation, solitary condylar hyperplasia, simple mandibular asymmetry and condylar osteoma or osteochondroma.

PURPOSE: To investigate the morphological features of hemimandibular hyperplasia (HH) in comparison to other condylar hyperplasia-associated asymmetries, including hemimandibular elongation (HE), solitary condylar hyperplasia (SCH), simple mandibular asymmetry (SMA) and condylar osteoma or osteochondroma (COS). MATERIALS AND METHODS: A total of 31 HH, 9 HE, 6 SCH, 10 SMA and 10 COS patients were included in this study. Clinical documentation, panoramic radiography and computed tomography data were retrospectively reviewed. The three-dimensional measurements were performed on multi-planar reformation images and volume rendering images. The accuracy of the subjective radiological signs was evaluated using sensitivity, specificity and receiver operating curve analysis. Discriminant analysis was performed to generate predictive formulas using quantitative data. RESULTS: The condyles in HH were regularly or irregularly enlarged, with significantly enlarged anterior-posterior length [16.2/5.29 (mean/SD, mm) P < 0.001] and volume [5.3/2.9(mean/SD, cm3) P < 0.001] compared to the normal values. The condyles in HE and SMA were normally shaped, and the quantitative measurements were within the normal range. The ramus heights in the HH patients [55.7/5.4(mean/SD, mm)] were enlarged in comparison to the contralateral side (P < 0.001) and normal values (P < 0.001). The ramus heights in the HE [52.4/7.1 (mean/SD, mm), P < 0.001] and SMA [50.3/5.0(mean/SD, mm), P = 0.002] patients were enlarged in the contralateral side comparison but were within the normal range. The mandibular body heights in HH were enlarged in the premolar [16.6/1.3 (mean/SD, mm), P < 0.001] and molar [24.8/1.4 (mean/SD, mm), P < 0.001] regions. The inferior convexity of the lower mandibular border and inferiorly displaced mandibular canal produced high specificity, sensitivity and area under the curve for the diagnosis of HH. Discriminant analysis could predict the diagnoses with a cross-validation accuracy rate of 85.7%. CONCLUSIONS: HH is a distinct clinical entity characterized by enlargement of the condyle, ramus and mandibular body. The inferior convexity of the lower mandibular border and inferiorly displaced mandibular canal is accurate and specific for the diagnosis of HH. The condyles in HE are not hyperplastic. The term "condylar hyperplasia" alone cannot be used to refer to HH or HE.

Spontaneous brain activity and connectivity in female patients with temporomandibular joint synovitis pain: a pilot functional magnetic resonance imaging study.

OBJECTIVE: It has been proposed that mechanisms in the central nervous system contribute to the development and maintenance of pain in temporomandibular disorders. In this study, we tested whether spontaneous brain activity and functional connectivity (FC) were altered in patients with temporomandibular joint synovitis pain. STUDY DESIGN: A prospective, cross-sectional design was adopted. Each of 8 patients and 10 healthy controls (HCs) underwent 2 sessions of functional magnetic resonance imaging: mouth closed and mouth open (painful for patients). Regional homogeneity (ReHo) was used to measure spontaneous brain activity in each participant. Brain areas with altered ReHo in patients compared with HCs were identified, and their FCs with the rest of the brain was examined and compared. RESULTS: Compared with HCs, patients showed decreased pain-related ReHo in the right anterior insula (rAI). The rAI showed a weaker positive FC with the left middle cingulate cortex (MCC) and a weaker negative FC with the right precuneus in patients compared with HCs. Furthermore, the rAI-MCC FC showed a negative correlation with pain intensity in patients. CONCLUSIONS: These results provide evidence supporting altered pain-related spontaneous brain activity and functional connectivity in the central nervous system in patients with temporomandibular joint synovitis pain.

Buccal mucosa cell damage in individuals following dental X-ray examinations.

The aim of the present study was to monitor genotoxic and cytotoxic effect of X-ray on exfoliated buccal mucosa cells and investigate the association between the effects and the accumulated absorbed doses of oral mucosa. 98 participants' buccal mucosa cells were collected before and 10 days after different series of dental radiographs performed. Cytological preparations were successively dyed with the methods of Feulgen and fast-green, and analyzed under a light microscope. Micronuclei (MN)and other cells were scored. Accumulated absorbed dose of buccal mucosa was estimated with the method of anthropomorphic phantom and dosimeter chips. The dose rang was 0.18-3.54 mGy. A significant difference in the rate of MN cell was found before and after X-ray examinations (P = 0.008) as well as in the rates of Pyknotic (p < 0.001) and Karyolytic cell (p = 0.0021). When only the patients whose mucosa absorbed dose is lower than 1 mGy was analyzed, significant differences were not found except for Karyolytic cells (p = 0.0313). There was a correlation between the accumulated does and the change rate (ρ = 0.25, p = 0.0118). The frequency of micronuclei cells in buccal mucosa may be increased when a series of dental radiographs including a CBCT examination was performed.

Bifid variations of the mandibular canal: cone beam computed tomography evaluation of 1000 Northern Chinese patients.

OBJECTIVES: The aim of this study was to evaluate and quantify variations of bifid mandibular canals (BMCs) in a population of Northern China by using cone beam computed tomography (CBCT). STUDY DESIGN: CBCT images of 1000 consecutive patients were analyzed by using the NewTom proprietary software. BMCs were identified and classified on the basis of the Naitoh classification. Linear and angular measurements of BMCs were performed. Statistical analyses were conducted by using χ2 and Wilcoxon tests. RESULTS: BMCs were observed in 13.2% of 1000 patients and 8.4% of 2000 sides. The prevalence of BMCs was significantly lower in patients in the first 2 decades and in cases with a class II molar relationship. The retromolar canal (68.4%) was the most common type of BMC observed. No buccolingual canals were identified; however, 2 special canals were detected. A classification system of 3 subtypes of retromolar canals was suggested. On average, the beginning site of the branches from the opening of the main canal was at a distance of 8.1 mm. The mean diameter and length of BMCs were 2.1 mm and 12.6 mm, respectively. CONCLUSIONS: This study underlined the prevalence and characteristics of BMCs in a population of Northern China. Preoperative identification of BMCs with CBCT may help prevent postoperative complications.

Aquaporin-1 and aquaporin-3 expressions in the temporo-mandibular joint condylar cartilage after an experimentally induced osteoarthritis.

BACKGROUND: Over 70% of the total tissue weight in the cartilage matrix consists of water, and the early-stage osteoarthritic cartilage is characterized by swelling. Water transport in the cartilage matrix and across the membranes of chondrocytes may be important in normal and pathological conditions of cartilage. The purpose of this study was to identify aquaporin-1 (AQP1) and aquaporin-3 (AQP3) expressions in the mandibular condylar cartilage after experimentally induced osteoarthritis (OA) in rats. METHODS: An experimental temporomandibular joint OA was induced by partial discectomy in rats. The pathological characteristics of the normal, early-stage, and late-stage osteoarthritic TMJ cartilages were verified by histological techniques. The AQP1 and AQP3 gene expressions in the normal and osteoarthritic cartilages were measured using quantitative real-time reverse-transcription PCR analysis. The cartilage sections were incubated in primary polyclonal antibodies to AQP3; immunofluorescent microscopy was used to examine the AQP3 expression shown by its protein level. RESULTS: The mRNA expression levels of AQP1 and AQP3, analyzed using quantitative PCR, revealed that AQP3 mRNA was highly up-regulated in the OA cartilage, which was considered significant. There was no notable difference in the expression of AQP1 mRNA between OA and normal controls. With the progressing of the OA, the localization of the AQP3 protein was quite different from that of the normal cartilage. Compared to the normal cartilage, the expressions of AQP3 protein were observed mainly in the proliferative zone and the upper mid-zone chondrocytes at the early-stage of OA, and were observed to appear frequently throughout the mid- and deep zone during the late-stage of OA. CONCLUSIONS: The high expression of AQP3 mRNA in the OA cartilage and the different localization of the AQP3 protein suggest that it may play a particular role in OA pathogenesis. Further study of AQP3 function may provide new insight into the understanding of the molecular mechanisms underlying OA.

[Diagnostic evaluation of the temporomandibular joint osteoarthritis using cone beam computed tomography compared with conventional radiographic technology].

OBJECTIVE: Osteoarthritic lesions of Temporomandibular joint(TMJ) were assessed by dental cone beam computed tomography(CBCT), and compared with conventional radiographic technology. METHODS: The study was conducted retrospectively on 511 joints of 350 patients, who had undergone dental CBCT, panoramic radiography, transcranial projection and transpharygeal projection of TMJ. The results were compared and the accuracy with CBCT was assessed. The types of osseous condylar abnormalities were observed. RESULTS: (1) The occurrence of osteoarthritis in male and female were 59.04% and 69.66%, respectively, with no significant difference. (2) Compared with CBCT, panoramic radiography, transpharygeal projection examination showed no significant difference, with the accuracy being 90.64% and 94.10%, respectively; However, transcranial projection indicated a significant difference in comparison with CBCT and the accuracy was 86.97%. (3) A higher occurrence of osteoarthritic lesions of the condyle was sclerosis (39.86%). Bony proliferation or osteophyte (28.18%) and ill-defined cortical bone (18.90%) were followed. CONCLUSION: Cone beam CT, which reproduces multiple images including axial, coronal and sagittal planes of the joint, provides a complete radiographic investigation of the bony components of the TMJ. It is one of the best choices of imaging diagnosis of TMJ osteoarthritis. Panoramic radiography and transpharygeal projection examination are also good choices for showing osseous condylar abnormalities in the clinic, but transcranial projection examination is inferior.

The secreted protein WNT5A regulates condylar chondrocyte proliferation, hypertrophy and migration.

OBJECTIVE: Our previous study showed that WNT5A, a member of the noncanonical WNT pathway, is involved in interleukin-1beta induced matrix metalloproteinase expression in temporomandibular joint (TMJ) condylar chondrocytes. The purpose of this study is to further explore the roles of WNT5A in cartilage biology of the TMJ. METHODS: An early TMJ osteoarthritis-like rat model was constructed by a mechanical method (steady mouth-opening). The gene and protein levels of WNT5A during the condylar cartilage changes were measured. Effects of WNT5A on chondrocyte proliferation, hypertrophy and migration were analyzed after WNT5A gain or loss of function in vitro. A c-Jun N-terminal kinase (JNK) inhibitor SP600125 was used to evaluate the involvement of JNK pathway in these effects of WNT5A. The expression and transcription activity of cell cycle regulators c-MYC and Cyclin D1 were examined to determine the mechanism behind WNT5A regulation of chondrocyte proliferation. RESULTS: WNT5A was significantly upregulated in the condylar cartilage of rats in the early TMJ osteoarthritis-like model. Activating WNT5A facilitated condylar chondrocyte proliferation, hypertrophy and migration. Conversely, inhibiting WNT5A activity in chondrocytes decreased their proliferation, hypertrophy and migration. Blockage of the JNK pathway by its inhibitor, SP600125, impaired these effects of WNT5A on chondrocytes. WNT5A regulated both the expression and transcriptional activity of c-MYC and Cyclin D1 in chondrocytes, both of which were upregulated in condylar cartilage of the rat early TMJ osteoarthritis. CONCLUSION: WNT5A regulates condylar chondrocyte proliferation, hypertrophy and migration. These findings provide new insights into the role of WNT5A signaling in TMJ cartilage biology and its potential in future therapy for TMJ degenerative diseases.

Evaluation of trabecular structure changes in osteoarthritis of the temporomandibular joint with cone beam computed tomography imaging.

OBJECTIVES: To explore the possibility of using 2-dimensional image assessments in combination with cone beam computed tomography (CBCT) in patients with temporomandibular joint osteoarthritis (TMJOA) to enhance the clinical significance and applicability of the CBCT findings on TMJOA changes. STUDY DESIGN: Fifty-two patients with unilateral TMJOA and 40 healthy adults who had undergone CBCT in preparation for orthodontic treatment were selected for this study. Temporomandibular joint images were acquired with CBCT. All images were classified into 4 phases (slight erosion, widespread erosion, appearance of bone maintenance, and partial loss of condylar head with a remodeled cortical surface) and 4 levels of severity (absent, slight, moderate, and extensive). Quantitative microstructural analysis, including bone value fraction (BV/TV), trabecular number (Tb.N), trabecular thickness, and trabecular separation (Tb.Sp) of each image, was performed by using a customized software. RESULTS: In patients with unilateral TMJOA, the affected side had significantly higher BV/TV and Tb.N and significantly lower Tb.Sp compared with the unaffected side. Compared with healthy individuals, the affected joints in patients with TMJOA had significantly higher BV/TV and trabecular thickness and significantly lower Tb.N and Tb.Sp. No significant difference was found among different phase groups or different severity levels. CONCLUSIONS: CBCT combined with a software investigation protocol for microstructure measurement can be used to provide reliable trabecular parameters in assessing TMJOA.

Comparison of micro-CT and cone beam CT on the feasibility of assessing trabecular structures in mandibular condyle.

OBJECTIVES: To evaluate the accuracy of CBCT in assessing trabecular structures. METHODS: Two human mandibles were scanned by micro-CT (Skyscan 1173 high-energy spiral scan micro-CT; Skyscan NV, Kontich, Belgium) and CBCT (3D Accuitomo 170; Morita, Japan). The CBCT images were reconstructed with 0.5 and 1 mm thicknesses. The condylar images were selected for registration. A parallel algorithm for histogram computation was introduced to perform the registration. A mutual information (MI) value was used to evaluate the match between the images obtained from micro-CT and CBCT. RESULTS: In comparison with the micro-CT image for the two samples, the CBCT image with 0.5 mm thickness has a MI value of 0.873 and 0.903 while that with 1.0 mm thickness has a MI value of 0.741 and 0.752. The CBCT images with 0.5 mm thickness were better matched with micro-CT images. CONCLUSIONS: CBCT shows comparable accuracy with high-resolution micro-CT in assessing trabecular structures. CBCT can be a feasible tool to evaluate osseous changes of jaw bones.

DNA methylation profiling in different phases of temporomandibular joint osteoarthritis in rats.

OBJECTIVE: Temporomandibular joint osteoarthritis (TMJOA) is a complex disease with strong genetic and epigenetic components in its pathogenesis. The aim of this study was to evaluate DNA methylation in mandibular head cartilage in different phases of experimentally-induced TMJOA in rats. DESIGN: DNA methylation was evaluated using microarrays in the mandibular head cartilage of early, intermediate and late stage experimentally-induced TMJOA, and of the normal age-matched control groups. Genes with differentially methylated CpG sites were analyzed to reveal the over-represented gene ontologies and pathways at different stages, and were compared with published expression profiles to assess their overlappings. The DNA methylation patterns of the target genes were validated by methylated DNA immunoprecipitation qPCR in additional independent cartilage samples and mRNA levels were analyzed by real-time PCR. RESULTS: We observed 9489 differentially methylated regions between the TMJOA and controls. A total of 440 consistently altered genes were revealed in all three stages; most (80%) were hypomethylated and many were associated with cell cycle regulation. We also detected different DNA methylation changes in early and late stage TMJOA (Rearly=0.68, Rlate=0.47), while the differences between age-matched healthy cartilage were subtle. Strong inverse changes between methylation status and mRNA levels were confirmed in Adamts5, Chad, Cldn11 and Tnf. CONCLUSIONS: Our data reveals dynamic DNA methylation patterns during the progression of TMJOA, with a different host of genes and pathways. The changes of cartilage DNA methylation patterns might contribute to understand the etiologic mechanisms of TMJOA epigenetically.

Multiple complex odontoma of the maxilla and the mandible.

OBJECTIVE: The aim of this study was to present a literature review and case report of multiple odontoma. METHODS: A case of multiple odontoma is presented with a review of the English-language literature. The clinical and radiologic features are summarized. RESULTS: In total, 12 cases of multiple odontoma were retrieved from the literature for analysis. The multiple odontomas were localized or extensive and involved two to four quadrants of the jaws. The histologic types were compound or complex. CONCLUSION: Odontomas can be multiple and involve multiple quadrants of the jaws.