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Objective: To investigate the regulatory mechanisms of integrin α5 and β1 in osteoblast in the process of gingipains-induced apoptosis., Methods: Gingipains were isolated and purified from supernatants of Porphyromonas gingivalis W83 which was cultured under standard anaerobic conditions. MC3T3-E1 was challenged with or without 8.3480 U/L gingipains for 48 h and apoptosis was examined by transferase-mediated deoxyuridine triphosphate-biotin nick end labeling-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride (TUNEL-DAPI) staining. The expression of integrin α5 and β1 was analyzed by Western blotting after MC3T3-E1 was treated under different conditions., Results: Arginine-specific proteinases(Rgp) activity was (41.74 ± 2.11) U/L and lysine-specific proteinase(Kgp) was (1.02 ± 0.25) U/L.Gingipains induced MC3T3-E1 cells apoptosis after 48 h. Compared with control group, expression of integrin α5 and β1 was down-regulated by gingipains in a time-dependent manner within short periods ( ≤ 72 h), integrin α5 and β1 relative expression was (0.485 ± 0.039),(0.504 ± 0.002) at 48 h,(0.398 ± 0.058),(0.179 ± 0.001) at 72 h respectively (P < 0.05). After 72 h, integrin α5 expression in MC3T3-E1 cells was stable compared with control group while integrin β1 was still lower(control group:1.000 ± 0.000, 96 h:0.604 ± 0.003, 120 h: 0.357 ± 0.002) (P < 0.05). Proteinase inhibitor tosyl- L- lysine-chloromethyl-ketone(TLCK) effectively blocked the activity of gingipain and inhibited down-regulation of integrin α5 and β1 induced by gingipains from (0.398 ± 0.058,0.179 ± 0.001 ) to (0.781 ± 0.012, 0.857 ± 0.060) (P < 0.05). TLCK alone did not have any effect on integrin α5 and β1(P > 0.05). Gingipains also decreased integrin α5 and β1 in a dose-dependent manner.When cells were treated with 20.8700 U/L gingipains, integrin α5 and β1 relative expression reached to the lowest(0.105 ± 0.004,0.020 ± 0.000) (P < 0.05)., Conclusions: Gingipains inhibited the expression of integrin α5 and β1 in a time- and dose- dependent manner in osteoblasts in the process of apoptosis, which may not be mediated by direct proteolytic effect.

Objective: To establish osteoblast apoptosis model induced by gingipains, and to examine the expression of pro-apoptotic protein Bcl-2 interacting mediator (Bim), Bcl-2 associated X protein (Bax) and Bcl-2 antagonist/killer (Bak)., Methods: Gingipain and gingipain acticity were extracted and measured. Mouse osteoblast cell line MC3T3-E1 cells were cultured in the presence of 0.453, 0.906, 1.812 U/L gingipains for 0, 16, 24 and 48 h. Apoptosis was examined by 4',6-diamidino-2-phenylindole (DAPI) staining or annexin V/propidine iodide (PI) staining.Protein expression of Bim, Bax and Bak was determined by Western blotting after osteoblasts were cultured with 1.812 U/L gingipain for 0, 4, 8, 16, 24 and 48 h. Osteoblasts were cultured with 1.812 U/L gingipain which had been inhibited with N-alpha-tosyl L-lysyl-chlorom ethylketone (TLCK). Western blotting was used to detect Bim expression and DAPI staining to measure apoptosis., Results: Arginine-specific proteinases (Rgp) activity was (18.11 ± 2.11) U/L and specific proteinases (Kgp) was (1.02 ± 0.25) U/L. Percentage of osteoblast apoptosis induced by 1.812 U/L gingipain rose to (6.31 ± 0.37)% after 16 h, and reached (11.20 ± 0.35)% at 24 h and (10.80 ± 0.46)% after 48 h with DAPI staining. Annexin V/PI staining supported the result from DAPI staining.Bim protein level increased during osteoblast apoptosis, the relative fold rose to (0.31 ± 0.03) after 4 h (about 2 fold compared to control), peaking at 24 h (0.57 ± 0.05, 3-4 fold compared to control). Proteinase inhibitor TLCK effectively blocked the activity of gingipain and inhibited up-regulation of Bim induced by gingipains from (0.58 ± 0.04) to (0.14 ± 0.03). The percentage of osteoblast apoptosis decreased from (11.20 ± 0.35)% to (4.31 ± 0.38)% in the presence of TLCK. Expression of Bax remained unchanged when cells were cultured with or without gingipains. Bak was under the detectable level in MC3T3-E1., Conclusions: 1.812 U/L gingipains induced osteoblast apoptosis. Protein expression of Bim was up-regulated during cell apoptosis and was down-regulated when gingipain inhibited with TLCK, suggesting that Bim was involved in osteoblast apoptosis induced by gingipain. Inhibition of Bim protein expression protected osteoblast from apoptosis.

Objective: To compare the effective radiation dose levels of cone beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning the same maxillofacial regions., Methods: The effective doses of 2 CBCT (NewTom 9000 and DCT Pro) and 1 MSCT (bright speed edge select 8 slice) scanners were calculated using thermoluminescent dosimeters (TLD) that were placed in a head and neck phantom, and expressed according to the International Commission on Radiation Protection (ICRP) 2007 guidelines., Results: Effective dose values ranged from 41.8 to 249.1 µSv for CBCT. The doses of MSCT scanning for maxilla, mandible and maxilla + mandible were 506.7, 829.9 and 1066.1 µSv, respectively. Dose levels of scanning only for maxilla or mandible were significantly lower than those for maxilla + mandible., Conclusions: When scanning the same maxillofacial regions, the dose levels for NewTom 9000 and DCT Pro CBCT images were lower than those for Bright speed edge select 8 slice MSCT images. Dose levels reduction could be obtained when smaller regions were scanned.

Objective: To evaluate the diagnostic accuracy of the cone beam computed tomography (CBCT) in judging the relationship between the impacted mandibular third molar (IMTM) and the inferior alveolar canal (IAC)., Methods: Sixty IMTM superimposing on the canal partially or touching the canal in line on panoramic radiograms were examined by CBCT. All CBCT images of these cases were observed by two dentists respectively. Then, all these IMTM were extracted by minimally invasive surgery, and the conditions of the IMTM sockets were observed. Two dentists observed the CBCT images independently and reached a consensus. Diagnosis test was performed in this study., Results: Eight IMTM sockets were bleeding during the extracted operation, and whether the IAC wall was broken could not be judged. The other 52 IMTM sockets were clear and the walls of IAC were broken in 29 IMTM extractions. The sensitivity, specificity, Youden index, positive predictive value and negative predictive value of CBCT were 82.8%, 87.0%, 88.9% and 80.0% respectively. The diagnostic accuracy judged by the two dentists and Kappa coefficient were calculated as 84.6% and 0.800., Conclusions: The CBCT examination had good authenticity and reliability, and it was very helpful in predicting the actual relationship between the IMTM and IAC.

Objective: To investigate the types of disc position of the temporomandibular joint (TMJ) and their relationship with age and gender in asymptomatic volunteers by magnetic resonance imaging (MRI)., Methods: A total of 100 asymptomatic volunteers were divided into 5 groups (11-, 21-, 31-, 41-, 51 - 60 years old), 10 male and 10 female were included in each group. A total of 200 TMJs were scanned with Siemens Trio Tim 3.0T MRI system oblique-sagittally at closed- and open-mouth positions. Visual evaluation of MR images were performed on 3 neighbour slices of each TMJ (lateral, central, medial)., Results: There was a normal disc-condyle relationship in 59 of the 100 asymptomatic subjects. The normal disc position, anterior disc displacement and insidious anterior disc displacement (IADD) were observed in 140 (70.0%), 14(7.0%) and 46(23.0%)joints respectively, which showed no significant differences among different age groups or between genders (P > 0.05). The maximum mouth opening of the 100 asymptomatic volunteers was (46.3 +/- 5.5) mm, with no significant difference among the various types of disc position (P > 0.05)., Conclusions: Disc displacement does exist in the asymptomatic volunteers, however, its occurrence is not associated with age and gender. IADD is the main type of the disc displacement in asymptomatic volunteers. There is no close relationship between the imaging manifestation of the disc displacement and clinical symptoms.

Objective: To investigate the activity and expression of Ca(2+)-Mg(2+)-ATPase in irradiated rat masseter muscle., Methods: The rats were irradiated locally with a single dose of 20 Gy X-ray. The activities of Ca(2+)-Mg(2+)-ATPase were measured with colorimetric method. The protein expression of Ca(2+)-Mg(2+)-ATPase was determined by Western blotting and immunohistochemistry., Results: The activities of Ca(2+)-Mg(2+)-ATPase in masseter muscle decreased by approximately 20% and 40% in irradiated rats on days 3 and 30 postirradiation. There was significant difference in the expression of Ca(2+)-Mg(2+)-ATPase protein between irradiated and nonirradiated rats on day 30 postirradiation. Ca(2+)-Mg(2+)-ATPase protein was found in the cytoplasm of masseter muscle., Conclusions: The decrease of ATPase activity played an important role in the cause of radiation-induced skeletal muscle injury, while there was no significant reduction in the expression of Ca(2+)-Mg(2+)-ATPase protein in irradiated rat masseter muscle.

Objective: To evaluate the shaping ability of hand-used ProTaper on curved canals using Endodontic Cube., Methods: Fifty-four curved root canals in vitro were selected and divided into three groups according to the curved degree (alpha), group A: 0 degrees < or = alpha < 25 degrees , group B: 25 degrees < or = alpha < 40 degrees , group C: 40 degrees < or = alpha < 55 degrees . Endodontic Cube was assembled, and each sample was sectioned perpendicular to the axis of the tooth into four sections with Isomer-Buhler in low speed. Then the root canals were prepared with hand-used ProTaper. Before and after shaping, photograph of all the sections were taken under a stereomicroscope. Statistical analyses were performed., Results: The dentin cutting quantity of the whole canal prepared with ProTaper in group B and C was larger than that of group A. The deviation distance of the whole canal prepared by ProTaper in group C was significantly larger than that in group A, and the deviation distance in middle portion larger than that in group B. The maintaining ability in the middle portion of group C by ProTaper was worse than that of group A and B., Conclusions: The curvature of root canal may increase the cutting quantity of the -dentin and reduce the ability of remaining original canal shape prepared by ProTaper.

Objective: To investigate the actual relationship between the impacted mandibular third molars (IMTM) and the mandibular canals on panoramic radiographs and cone beam computed tomography (CBCT)., Methods: A cross-sectional study design was used and panoramic radiographs of 390 patients (645 sides developed IMTM) were included in the present study. The relationship between the IMTM and the mandibular canal on panoramic radiographs was defined in three types: 'untouched', 'touching in point', and 'superimposition or line touching'. The IMTM superimposing and line touching with mandibular canals on panoramic radiographs were examined by CBCT., Results: The relationship types on panoramic radiographs were as follows: 'untouched' type 441 IMTM (68.4%), the type of 'touching in point' 149 IMTM (23.1%) and the type of 'superimposition and line touching' 55 IMTM (8.5%). CBCT showed that 25 (50%) of 50 IMTM of superimposition and line touching type impinged on the mandibular canals., Conclusions: More than 90% of IMTM which do not have intimate relationship with the mandibular canals can be screened out by panoramic radiographs. The IMTM which belong to the line touching and superposition type on panoramic radiographs should be examined by CBCT.

Objective: To investigate the prevalence of dental erosion and associated drinks in 12-year-old adolescence of Beijing., Methods: A random sample of 12-year-old adolescence of Beijing (n=844) was examined for dental erosion and required to fill a questionnaire of acidic drink intake. The grade criteria suitable for the survey of the dental erosion was used in the study., Results: The prevalence of dental erosion was 61.8%, of which mild enamel was 74.1%, severe enamel erosion 24.9% and dentine erosion 1.0%. Statistic analysis showed that a large amount of intake of carbonated drink or juice were risk factors., Conclusions: Attention should be paid to the prevalence of dental erosion among Chinese adolescence.

Objective: To investigate the ultrastructure character of sclerotic dentin surface conditioned by the Er, Cr: YSGG laser and acid etching., Methods: Sixteen human teeth with sclerotic dentin were randomly assigned to 4 groups, and conditioned with acid etching (Group A), laser irradiation (Group B), laser irradiation after acid etching (Group C), or acid etching after laser irradiation (Group D) respectively. The characters of surface ultrastructure were observed using scanning electron microscope (SEM)., Results: In Group A, the majority of dentin tubules were blocked by sclerotic rods. In Group B, the honeycomb-like change was found on the sclerotic dentin surface. The surface structure of Group C was similar to that of Group B. In group D etching wiped off the honeycomb-like structure., Conclusions: The sclerotic dentin surface treated with laser irradiation turns into uniform honeycomb-like structure. The rough surface may be beneficial to bonding strength on sclerotic dentin after laser irradiation.

Objective: To evaluate the clinical use of cone beam dental CT in the diagnosis of temporomandibular joint osteoarthrosis., Methods: Forty-eight cases diagnosed as temporomandibular joint osteoarthrosis (OA) and disk displacement with or without reduction accompanied by OA changes were included, and a total of 96 joints received both trans-pharyngeal radiography and cone beam CT (CBCT) examination. The detectable rate for OA radiographic changes was compared between the two examinations., Results: The radiographic appearances of osteoarthrotic condyle included six types: loss of the lamina dura density of condyle surface (type I), destructive and erosive bone changes (type II), flattening of the articular surface (type III), sclerosis (type IV), osteophytes (type V), and false cyst change (type VI). The detectable ratio of CBCT for all types of osteoarthrosis was 65.63%, 37.50%, 27.08%, 31.25%, 28.13%, 1.04%, respectively, and the detectable ratio of trans-pharyngeal radiographs was 52.08%, 19.79%, 32.29%, 23.96%, 12.50%, 2.08% respectively. Intraobserver and interobserver reproducibility for type I and type II was in good agreement with both the trans-pharyngeal radiographs and CBCT, Kappa > 0.60., Conclusions: CBCT had higher detectable rates for pathological changes of osteoarthrosis, and could show the exact location, size, and the types of pathological changes. CBCT may be used as a measure in evaluating disease severity and progression, and in clinical trials of disease treatment.

Objective: To evaluate the feasibility of cone beam computed tomography (CBCT) for the evaluation of trabecular bone structure in mandibular condyle and to investigate the distribution of the trabecular bone structure within mandibular condyle., Methods: Eighty condyles from 40 healthy young volunteers (aged 20-32) were scanned by CBCT. A coronoid image was acquired of each condyle and divided into 8 regions where regions of interest were specified. After CBCT images were binarized, four morphological parameters including bone volume fraction, trabecular thickness, trabecular number and trabecular separation were computed., Results: All parameters were significantly different between the superior zone and middle/inferior zone of the condyle (P < 0.05). Superior zone showed the largest bone volume fraction (52.2%), the highest trabecular number (1.33 mm(-1)), the thinnest trabecular thickness (393.48 microm), and the smallest trabecular separation (361.59 microm). Inferior zone showed the smallest bone volume fraction (49.64%). These results were not significantly different between bilateral sides of the condyles (P > 0.05)., Conclusions: Trabecular bone structure was inhomogeneous within the condyle, but symmetrical between bilateral sides of the condyles. CBCT combined with image processing is a feasible tool in evaluating trabecular bone structure of human mandibular condyle.

Objective: To investigate the relationship of temporomandibular disorders (TMD) related pain with age, sex and imaging changes of osteoarthrosis (OA)., Methods: All the patients were grouped based on age, sex, imaging changes of OA and TMD related pain. Craniomandibular index (CMI) was calculated for all the patients., Results: TMD related pain was common in females. Significant differences of CMI were existed in all groups under the age of 45 years old. The occurrence of imagine changes of OA was higher in females than in males (P < 0.001)., Conclusions: TMD related pain and imaging changes of OA were more common in females, especially in 16 - 30 years old females.

Objective: To investigate the patterns of condylar fractures associated with temporomandibular joint ankylosis (TMJA) and treatment methods and results based on the different types of ankylosis., Methods: Forty-two joints of ankylosis in 31 patients with were categorized to four groups according to Sawhney's classification and undergone surgical treatment as follows: a joint release and disc reposition for Type I ankylosis, a dissection of bony block and disc reposition for Type II; a dissection of full-joint and employment of the temporal myofascial flap as interposition for Type III; a radically dissection of full joint followed by ramus distraction osteogenesis and genioplasty for Type IV. All of patients were followed up for 9 to 54 months with an average of 30 months. The range of mouth opening and temporomandibular joint (TMJ) function were assessed. Condylar fractures were retrospectively investigated on the patterns and the course of ankylosis development. Macroscopical visualization on the osseously ankylosed sites and disc displacement were analyzed in comparison with the radiological findings., Results: Condylar sagittal and comminuted fractures were most susceptible to TMJA. Early fibrous ankylosis occurred usually at the 4th or 5th month post-traumatically with an average month opening of 18.3 mm. The articular discs were found displaced in all cases and early bony bridge formed at a limited area where there was no disc as cushion. During fellow-up, considerable improvement in mandibular movement was attained with a stable joint function and mouth opening range of over 30 mm except for two cases in which ankylosis relapsed., Conclusions: Condylar sagittal and comminuted fractures are most likely to cause ankylosis. Early surgical intervention could reduce the disc and avoid the later ankylosis.

Objective: Functional magnetic resonance imaging (fMRI) was used to detect the cerebral cortical somatotopy during maximum voluntary clenching with and without soft splint in patients with hemimasticatory spasms (HMS) and the central mechanisms of HMS and the rule of the splint therapy., Methods: Four HMS patients were selected and the spasms sides were right in two cases and left in the other two cases. FMRI images were obtained on Elscint/GE 2.0 Tesla MR system. Block design was used and the movement pattern was the onset of spasms after maximum voluntary clenching with and without soft splint. The fMRI data were analyzed by SPM99 software., Results: With the onset of spasms after maximum voluntary clenching, the activation of motor cortex in 3 HMS patients was found lateral dominance on the left side, and the other one showed bilateral activation. All the 4 patients were found activation in cingulate area. With the onset of spasms after maximum clenching wearing soft splints, the activation of motor cortex showed no lateral dominance on the left side, and 3 patients were not found activation in cingulate area., Conclusions: The changes of the activation in motor cortex and cingulate area during the onset of spasms after clenching with and without soft splint might be the central mechanisms of the rule of splint therapy, through which the soft splint might function in alleviating muscle pain.

Objective: To evaluate levels of psychosocial incapacity in patients with temporomandibular disorders (TMD) by using the Symptom Checklist 90 (SCL-90)., Methods: Three hundred and thirty-eight patients who came to the Center for TMD and Orofacial Pain of Peking University School of Stomatology, from March to September of 2004 were included in the present study. All of them were evaluated by SCL-90. The one-sample t-test and multivariate analysis of variance were performed to find the psychological difference between the normal and TMD groups., Results: (1) There was a statistically significant difference (P < 0.05) in the scores of Symptom Checklist 90 between healthy controls and TMD group, and TMD patients got higher scores on somatization, obsessive compulsive, anxiety, hostility, phobic anxiety, psychoticism. (2) Twenty-three percent of 338 TMD patients had some psychological symptoms. (3) All patients were evaluated by analysis of reliability, and the reliability coefficients was 0.958., Conclusions: The psychological problems of TMD patients should be emphasized and SCL-90 instrument was also suitable to screen the psychological symptoms of TMD patients in China.

Objective: To elaborate on the angiographic classification of central arteriovenous malformations (AVMs) in jaws, and to evaluate the correlation between this classification and treatment options., Methods: X-ray films and angiograms of 25 cases with AVMs in the jaw were retrospectively reviewed to evaluate the appearance of radiolucency, feeding arteries, nidus of the malformations and draining veins. Based on the findings a classification of angioarchitecture was recommended. Furthermore, the treatment results of these cases were reviewed to assess the correlation between this classification and treatment options., Results: The angiographic pictures of 25 cases with central AVMs could be divided into five types: type I (n = 5) was with merely diffused micro-arteriovenous fistulas (AVFs); type II (n = 8) demonstrated a large venous pouch, all the feeding arteries drained into it; type III (n = 7) had a large venous pouch together with diffused micro-AVFs (I + II); type IV (n = 2) had multiple venous pouches; type V (n = 3) had multiple venous pouches and diffused micro-AVFs (I + IV). The angioarchitecture corresponded well to the radiographic appearance in all except one case. With respect to the treatment, type II, III, IV AVMs gained clinical cure in 100% of cases, whereas type I and type V AVMs obtained clinical cure only in 3 of 5 and 1 of 3 cases respectively., Conclusions: Central AVMs in jaws exhibited variant patterns of angioarchitecture, which could be divided into five types. Elaboration of this classification was helpful for decision-making on choosing appropriate therapy.

Objective: To compare the clinical appearances of TMD patients between acute and chronic anterior disc displacement without reduction., Methods: Successive one hundred TMD patients with fully recorded documents diagnosed as anterior disc displacement without reduction (ADDw/oR) were included, 45 acute and 55 chronic ADDw/oR patients. Clinical appearances including signs and symptoms, maximal mouth opening, Fricton's craniomandibular index, condylar bone changes on radiograms, findings on arthrograms and MRI were compared., Results: The main reason for asking treatment was joint pain in chronic, instead of limited mouth opening in acute patients. Clinical symptoms such as pain and limited mandibular movement showed improvement in chronic patients. Fricton's joint dysfunction index was higher in acute than in chronic patients, but muscle palpation index was higher in chronic than in acute patients, but Fricton's craniomandibular index was not significantly different between chronic and acute patients. The destructive bone changes of condyle on radiograms, the damage of stretched disc attachment on arthrograms and the morphological deformed disc on MRI were more frequently found in chronic than in acute patients., Conclusions: In acute patients there is a great likelihood that tissues are healthy and not morphologically changed, we suggest that early and efficacious intervention should be made to reposition the anterior displaced disc that may block the progress of pathological impairment to both the disc and the condyle of TMJ.

Objective: To study the characteristics of cellular metabolism of mandibular condylar chondrocytes in repairing state of osteoarthrosis and investigate its role in the pathogenesis of the disease., Methods: Temporomandibular joint osteoarthrosis model of rabbits was created by the partial resection of joint disc and confirmed with histological diagnosis. The chondrocytes were harvested from osteoarthritic condylar cartilage in the repairing state and cultured in vitro under the monolayer culture condition. The cellular expression of cartilaginous matrix protein, collagenase and growth factors between the osteoarthritic chondrocytes and the normal controls were measured with RT-PCR technique to outline the basic feature of the osteoarthritic cells., Results: The cultured cells were confirmed as chondrocytes with their ability of expression of collagen type II and Aggrecan. In the reactive repairing state of osteoarthrosis, the chondrocytes showed the imbalance of expression of ECM proteins, and increased expression of collagenase and endogenous growth factors such as IGF-1 and TGF-beta1., Conclusions: This study found the active anabolism of the chondrocytes within the osteoarthritic condylar cartilage and the imbalance synthesis of cartilage matrix. These repairing attempts by the osteoarthritic chondrocytes may be impossible to restore the primary homeostasis within the condylar cartilage.

Objective: To investigate the usefulness of electromyogram (EMG) in the diagnosis of the patients with hemimasticatory spasm (HMS)., Methods: Four cases with HMS were reported. All the 4 patients were undertaken needle and surface electrode EMG examination., Results: Needle electrode EMG of the 4 patients with HMS showed grouped potentials synchronously with the onset of the spasm, which indicated abnormal excitatory electrical activities of the trigeminal nerve resulting in involuntary masticatory muscle movements., Conclusion: It is very important to use EMG for the diagnosis of HMS.

Objective: Temporomandibular joint sideways and rotational disc displacement was assessed by arthrography with dental volumetric computerized tomography., Methods: The study was conducted retrospectively on 119 joints of 109 patients (87 females, 22 males, mean age 31.1 years), who had undergone arthrography with dental volumetric CT in the sagittal and coronal planes. The disc displacements were subdivided into 5 types; condylar abnormalities were subdivided into 4 types., Results: Complete anterior disc displacement was the commonest (70.6%) and medial the rarest (0.8%); anterolateral and anteromedial displacements were 18.5% and 10.1% respectively. The types of disc displacements were not correlated with bone lesions. A higher prevalences of bone lesions were found in the lateral poles of condyles., Conclusions: Arthrography using dental volume CT can be taken in the sagittal and coronal planes, so the sideways and rotational disc displacements, perforations and bone lesions can be evaluated. It's superior to conventional arthrography.