Protease-active extracellular protein preparations from Porphyromonas gingivalis W83 induce N-cadherin proteolysis, loss of cell adhesion, and apoptosis in human epithelial cells

BACKGROUND: The protease-induced cytotoxicity of P. gingivalis may partly result from alteration of the extracellular matrix and/or surface receptors that mediate interaction between the host cells and their matrix. While P. gingivalis-induced degradation of E-cadherin has been documented, there is no information on the effects of P. gingivalis proteases on other members of this family of cell adhesion proteins. METHODS: Human epithelial KB cells were exposed to protease-active extracellular protein preparations from isogenic mutants of P. gingivalis. Quantification of apoptosis was performed by visualization of nuclei stained with 4,6'-diamidino-2-phenylindole. Alteration of cell adhesion proteins was examined by immunoblotting of cell lysates using monoclonal antibodies to those proteins. RESULTS: Treated cells exhibited loss of cell adhesion properties with apoptotic cell death subsequently observed. These effects correlated with the different levels of cysteine-dependent proteolytic activities of the isogenic mutants tested. Cleavage of N-cadherin was observed in immunoblots of lysates from detached cells. There was a direct correlation between the kinetics of N-cadherin cleavage and loss of cell adhesion properties. Loss of cell adhesion, as well as N-cadherin cleavage, could be inhibited by preincubation of P. gingivalis protease active extracellular protein preparations with the cysteine protease inhibitor TLCK. In control experiments, the cleavage of N-cadherin was detected after treatment of KB cells with trypsin but not after cell dissociation by a non-enzymatic method. CONCLUSIONS: These results suggest that extracellular proteases from P. gingivalis can induce degradation of N-cadherin, which could have implications for the pathogenicity of this bacterium.     

Metastatic transitional cell carcinoma of the urinary bladder presenting as a mandibular gingival swelling

Oral cavity metastases mostly originate from the breasts, lungs, or kidneys. Transitional cell carcinoma (TCC), the most frequent malignant tumor of the urinary bladder, rarely metastasizes to the jaws. To the best of our knowledge, only 8 cases of bladder carcinoma have been reported in the English literature to metastasize to the jawbones. A new case of mandibular metastasis of urinary bladder TCC with extension to the gingiva is presented in a 64-year-old white man. The patient was referred for a periodontal infection of the upper right first molar. The clinical examination also showed a gingival swelling located in the lower left premolar region with a hypoasthesia of the left side of the lower lip. The gingival mass was biopsied, and the microscopy showed a mandibular metastatic TCC of the urinary bladder extending to the gingiva. Periodontists should be aware that, although gingival metastases are rare, when they occur they may mimic other local benign pathological conditions.     

Clinical and radiographic evaluation of pulpotomies performed under intrapulpal injection of anaesthetic solution

AIM: The purpose of this study was to evaluate clinically and radiographically pulpotomies carried out under intrapulpal injection of anaesthetic solution. METHODOLOGY: Forty-one permanent mandibular molar teeth presenting with deep carious lesions and/or exposed pulps, with or without periapical changes on radiographic examination, were treated with pulpotomy and dressed with calcium hydroxide. The teeth were divided into three groups. Group A consisted of 15 teeth, where intrapulpal anaesthesia was administered by a slow injection of lidocaine hydrochloride 2%. Group B, with 14 teeth, where intrapulpal anaesthesia was obtained with lidocaine hydrochloride 2% with adrenaline 1:100,000. Group C consisted of 12 teeth in which anaesthesia was performed with a mandibular block using prilocaine hydrochloride 3% with felypressin 1: 100,000. Healing was evaluated using clinical and radiographic criteria: dentine barrier formation, absence of clinical symptoms and resolution of periapical involvement. RESULTS: After an observation time of 6-8 weeks (postoperative control) and 24-32 weeks (intermediate control), healing occurred in 13 teeth from group A (87%), in 11 teeth from group B (79%) and in 10 teeth from group C (83%). No statistical difference was demonstrated between the three groups (Fisher's exact test). CONCLUSIONS: Based on the methodology adopted, intrapulpal injection of anaesthetic solution did not impair healing in pulpotomized teeth.     

Ranking dental aesthetics and thresholds of treatment need: a comparison between patients, parents, and dentists

The aims of the present study were to compare rankings of dental aesthetics and the threshold at which orthodontic treatment would be sought among patients, parents, and dentists. A prospective cross-sectional study was designed to address these aims. The study sample comprised 100 patients and parents and 23 dental specialists. The patients were equally divided between males and females and their mean age was 14.7 years (standard deviation 2.3 years). The aesthetic component (AC) of the Index of Orthodontic Treatment Need (IOTN) represented impairment of dental aesthetics. The 10 numbered photographs of the AC were cut into equal-sized rectangles and subjects were asked to arrange them from 'the one that looks best' to 'the one that looks worst'. The subjects were then presented with the 10 photographs of AC in sequence and asked to identify the cut-off point between 'teeth that need orthodontic treatment' and 'no treatment'. Statistical analysis was undertaken with a Mann-Whitney test. The results showed that median rankings of dental aesthetics were similar among the three groups (P > 0.05). The median ranking of photographs 1, 2, 3, 4, and 10 were identical to the AC of IOTN. The photographs representing IOTN AC 7 and 8 were allocated the same median rank of 7 and AC 5 and 9 were allocated corresponding median ranks of 6 and 8, respectively. There were no significant differences in median cut-off points for treatment need among the three groups of subjects (P > 0.05), indicating that the mean threshold at which treatment would be sought was AC 4.     

Jaw clenching: muscle and joint forces, optimization strategies

Realistic masticatory muscle and temporomandibular joint forces generated during bilateral jaw clenching are largely unknown. To determine which clenching directions load masticatory muscles and temporomandibular joints most heavily, we investigated muscle and joint forces based on feedback-controlled electromyograms of all jaw muscles, lines of action, geometrical data from the skull, and physiological cross-sectional areas acquired from the same individuals. To identify possible motor control strategies, we applied objective functions. The medial pterygoid turned out to be the most heavily loaded muscle for all bite directions. Biting with accentuated horizontal force components provoked the highest loading within the medial and lateral pterygoids. The largest joint forces were also found for these bite directions. Conversely, the lowest joint forces were detected during vertical biting. Additionally, joint forces with a clear posterior orientation were found. Optimization strategies with the elastic energy as objective function revealed the best fit with the calculated results.     

Use of a composite pedicled muscle flap and rhBMP-7 for mandibular reconstruction

The aim of this study was to investigate the feasibility of reconstructing critical size continuity osteoperiosteal defects of the mandible using a composite of recombinant BMP-7 contained in a bovine type-1 collagen carrier wrapped in a pedicled sterno-occipitalis muscle flap. At 3 months following surgery, bridging of the surgical defect was noted in three subjects (60%). Histologically, the induced bone regenerate showed maturation from woven to lamellar bone. Islands of cartilage were distributed throughout the defect. Replacement ossification of the degenerated muscle was a common feature in all specimens. Microradiography showed a gradual increase in the calcification of mineralized tissue from the margin to the centre of the newly generated bone. This research represents a proof of the concept that bone can be satisfactorily formed within a muscular scaffolding at the site of the created defect in a one-stage procedure.     

Oral health care system in Chinese Mainland

The purpose of this review is to describe the training of dental professionals and to give an overview of the oral health care system in Mainland China. It may be of interest and importance for American readers to become aware that there are alternative practice structures and the world is getting smaller.     

The working practices and career satisfaction of dental therapists in New Zealand

OBJECTIVE: To describe the working practices and level of career satisfaction of dental therapists in New Zealand. DESIGN: Postal survey of dental therapists identified from the New Zealand Dental Council's dental therapy database. One mailing with one follow-up. PARTICIPANTS: Questionnaires were sent to 683 registered dental therapists. Replies were received from 566 (82.9%). OUTCOME MEASURES: Current working practice, career breaks, continuing education, career satisfaction. RESULTS: Respondents had a high career satisfaction, but were much less satisfied with their remuneration. After controlling for age and income satisfaction, therapists who felt that they were valued members of the dental community had over four times the odds of having higher overall job satisfaction. There were no differences in the mean career satisfaction scale score by age, but respondents aged 45 and over had a lower mean income satisfaction scale score than their younger counterparts (p<0.05). Older respondents were more likely to report regularly placing fissure sealants (p<0.05), participating in peer review (p<0.05), and playing a role in team management/coordination (p<0.05) than younger respondents. Most therapists (412; 82.2%) had taken at least one career break, usually for child rearing. A mean of 6.5 years (SD 5.9; range six weeks to 25 years) had been taken in career breaks. Younger therapists were more interested in moving into private practice than their older colleagues (p<0.05). More than half of respondents planned to retire from dental therapy within 10 years. CONCLUSION: Urgent action is required to improve the recruitment and retention of dental therapists in the New Zealand School Dental Service. Measures to reduce the time taken in career breaks could increase the productivity of this workforce. Remuneration and career progression are key issues; therapists need to feel that they are valued members of the dental profession.     

Antibacterial effect of chlorhexidine- containing glass ionomer cement in vivo: a pilot study

This in vivo pilot study was carried out to test the antibacterial effect of glass ionomer containing chlorhexidine (test group) in comparison to conventional glass ionomer (control group). Fifty 6- to 11-year-old children with one occlusal lesion in a molar were randomly allocated to test and control groups in a parallel-group design. The cavity walls and one half of the floor were cleaned and restored with one of the materials without dentine conditioning. The restorations were removed after 7 days. Dentine samples were taken from the cleaned (affected dentine) and noncleaned area (infected dentine) at baseline and at day 7. Samples were anaerobically and aerobically cultivated for mutans streptococci, lactobacilli and total viable bacterial count (TVC) following common laboratory procedures. ANCOVA was used to test for treatment effects. Seven days after treatment, a significant decrease in anaerobic and aerobic bacterial counts (p = 0.0001) was shown. Lower numbers of anaerobic lactobacilli (p = 0.02), TVC (p = 0.008) and aerobic lactobacilli and TVC (p = 0.03), but not of mutans streptococci, were indicated in the test group compared to the control group. A significant reduction in aerobic lactobacilli from infected dentine treated with the glass ionomer containing chlorhexidine (p = 0.05) was observed whereas in affected dentine, anaerobic mutans streptococci, lactobacilli and TVC and aerobic TVC and mutans streptococci were significantly lower in the test group 7 days after treatment (p = 0.01). We conclude that the present pilot study revealed lower microorganism counts in chlorhexidine-containing glass ionomers than in conventional glass ionomers for both affected and infected dentine over a 7-day period.     

Antimicrobial activity of endodontic sealers on Enterococcus faecalis

Enterococcus faecalis has been shown to be highly resistant once established in the root canal system and may play an important role in endodontic failures. The purpose of this study was to evaluate the antimicrobial activity of four root canal sealers on E. faecalis. Seventeen blood-agar plates were inoculated with E. faecalis using the Lawn technique. Five discs were placed on each plate, four with sealers--Sealapex, Roth 811, Kerr EWT, and AH-Plus--and an ampicillin disc as the control. The plates were incubated at 37 degrees C. The zones of inhibition were measured at 24 and 48 h. Analysis using a one-way ANOVA and Tukey test showed a statistically significance difference (p < 0.05) between all four groups of sealers. Roth 811 showed the largest zone of inhibition (1.1 mm), followed by Sealapex (0.8 mm) and Kerr EWT (0.5 mm), whereas AH-Plus had no antimicrobial activity. There was no difference in the zones of inhibition between the 24- and 48-h time periods.