Some factors associated with open gingival embrasures following orthodontic treatment

Open gingival embrasures or "black triangles" can be an undesirable outcome of adult orthodontic treatment. The aims of the present study were to determine the prevalence of open gingival embrasures in a group of orthodontic patients, and to determine if open gingival embrasures were related to: age at the start of treatment, the severity of pretreatment crowding of the mandibular incisors, the duration of treatment or changes in alveolar bone height. The subjects were 80 orthodontic patients (33 males, 47 females) between 15 and 31 years of age. Open gingival embrasures were found in 43.7 per cent of all subjects, while in subjects over 20 years of age the prevalence was 66.7 per cent. In relation to the amount of crowding 42.8 per cent of the subjects with less than 4 mm crowding had open gingival embrasures, 41.2 per cent of those with between 4 and 8 mm crowding had open gingival embrasures, and 50 per cent of those with more than 8 mm crowding had open gingival embrasures. The groups were not significantly different. Approximately 42 per cent of the subjects in the shorter treatment group had open gingival embrasures, and 44.4 per cent of those whose treatment took longer than 3 years had open gingival embrasures. This difference was not statistically significant. Cephalometric measurements of mandibular alveolar bone height indicate that open gingival embrasures were more likely to be due to resorption of the alveolar crest rather than extrusion of the mandibular incisors. In conclusion, open gingival embrasures were more frequently found in patients over 20 years of age than in younger patients, and were associated with resorption of the alveolar crest.     

Heat shock protein of Mycoplasma salivarium and Mycoplasma orale strains isolated from HIV-seropositive patients

It has been suggested that infection by some mycoplasma species can act as possible cofactors in the acceleration of immunodeficiency in HIV-infected patients. The present study was designed to examine infections by oral mycoplasma species in HIV-seropositive (HIV(+)) patients. Mycoplasma salivarium and Mycoplasma orale were isolated from 59.5% and 16.7% of 42 HIV(+) patients, respectively. Non-M. salivarium and non-M. orale species were isolated from 40.5% of saliva samples from the HIV(+) group and 20.8% of those from 24 HIV-seronegative (HIV(-)) subjects, respectively. Although the production of superantigen by human peripheral lymphocytes in the isolated mycoplasma species from HIV(+) and HIV(-) subjects was evaluated, none of the examined mycoplasma strains, including ATCC strains of M. salivarium, M. orale, Mycoplasma buccae and Mycoplasma penetrans, were found to produce superantigen. Production of heat shock proteins (HSPs) by isolated mycoplasma strains was examined by immunoblotting using monoclonal antibodies against Helicobacter pylori HSP60. It was found that all the strains of M. salivarium, M. orale, and unidentified mycoplasma species isolated from HIV(+) and HIV(-) groups produced heat shock proteins. HSP production by oral mycoplasma may play a role in the immunomodulation of HIV(+) patients.     

Effect of evaporation of primer components on ultimate tensile strengths of primer-adhesive mixture.

OBJECTIVE: The purpose of the present study was to evaluate the effect of evaporation of primer components on the ultimate tensile strength (UTS) of primer-adhesive mixtures. METHODS: The UTSs of 1:3 by weight primer-adhesive mixtures and of the pure adhesives (controls) were measured after 0-, 2-, 5-min and 24-h storage in a 37 degrees C oven for the three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE (Kuraray). RESULTS: Evaporation of primer components increased with time for both adhesives investigated. OptiBond FL showed a higher evaporation of primer components than Clearfil SE at the 2-, 5-min and 24-h storage time. As compared to the pure adhesive, the UTS of the primer-adhesive mixture was lower after 0- and 2-min storage for OptiBond FL and after 0-, 2- and 5-min storage for Clearfil SE. The UTS of OptiBond FL was higher than that of Clearfil SE at the 0- and 2-min storage time, though there was no difference at the 5-min and 24-h storage time. SIGNIFICANCE: The degree of evaporation of primer components depended largely on the primer solvents employed. The significant decrease in UTS of adhesive resin when mixed with primer must be attributed to incomplete evaporation of primer components. Complete evaporation of solvents is hard to achieve, even by thorough air drying.     

A standardized method of X-ray CT for sagittal splitting osteotomy of the mandibular ramus

A useful standardized method of X-ray computed tomography (CT) was proposed for the preoperative examination of sagittal splitting osteotomy of the mandibular ramus. In our assessment conducted for cases of mandibular prognathism operated on by a modified technique, the most informative CT image of the mandibular ramus was provided by the scans between the upper and lower dentitions in the open mouth position at which the scan-plane angulation was given as parallel to the dentition in each jaw. These sections enabled preoperative assessment on the mesio-lateral thickness of the marrow space and the positional relationship between the ramal cortices and the mandibular canal together with other geography of the ramal bone structure. Using these CT images, the plane of sagittal osteotomy is predictable. A technique for obtaining standardized CT slice is proposed in this report.     

Detection of Epstein–Barr virus in saliva by real‐time PCR

The purpose of this investigation was to assess the salivary levels of Epstein–Barr virus (EBV) in patients with periodontitis using real‐time PCR. EBV was detected in 16 out of 33 (48.5%) periodontitis patients and in 3 out of 20(15%) healthy subjects. The baseline mean values for bleeding on probing in EBV‐positive patients were significantly higher than those in EBV‐negative patients. A significant decrease in EBV levels was observed after initial periodontal treatment. Our findings indicate that levels of EBV in saliva may reflect the status of periodontal inflammation.     

Pulmonary granulomas caused experimentally in mice by a recombinant trigger-factor protein of Propionibacterium acnes

Etiology of sarcoidosis remains unknown. A trigger factor from Propionibacterium acnes causes a cellular immune response in some sarcoid patients but not in nonsarcoid subjects. We examined whether experimentally induced hypersensitivity to the trigger factor gives rise to granulomas. Female C57BL/6 mice primed intravenously with P. acnes or not were sensitized with recombinant-protein RP35, a fragment of P. acnes trigger factor, and complete Freund's adjuvant. In controls, RP35 was replaced with P. acnes or one of two control proteins. In primed and unprimed mice, pulmonary granulomas were found in some of the mice sensitized with RP35 or P. acnes but in no control-protein-sensitized mice. Detection of pulmonary granulomas (25-57%) did not differ significantly between mice sensitized with RP35 or P. acnes, primed or not. No difference in popliteal lymph-node-cell reactivity and serum antibodies to these two antigens was found between mice with and without pulmonary granulomas. P. acnes was cultured from the lungs of 8 (33%) of 24 untreated mice. The recombinant trigger-factor protein of P. acnes caused pulmonary granulomas in primed and unprimed mice sensitized with the protein and adjuvant. Sarcoid granulomas may form during hypersensitivity to antigens of P. acnes indigenous to the affected organ.     

Noncariogenicity of erythritol as a substrate.

Erythritol is a sugar alcohol produced by Aureobasidium sp. from glucose. It is 75-80% as sweet as sucrose and is also nonhygroscopic. The aim of this study was to evaluate this sugar substitute from a cariological point of view. Erythritol was neither utilized as a substrate for the lactic acid production nor for plaque formation of mutans streptococci (serotypes a-h) and certain oral microorganisms. It was not utilized for water-insoluble glucan synthesis or cellular adherence by glucosyltransferase from Streptococcus mutans PS-14 (c) and Streptococcus sobrinus 6715 (g). Finally, a significantly lower caries score (3.1 +/- 0.5; mean +/- SEM) was observed in specific pathogen-free rats infected with S. sobrinus 6715 and fed with a diet containing 26% erythritol, as compared to control rats fed with a diet containing 26% sucrose (60.5 +/- 2.0). Also, rats provided a diet containing 56% erythritol chocolate (23.8% erythritol) and challenged with S. mutans PS-14 exhibited a significantly lower caries score (6.7 +/- 0.8) compared to the sucrose chocolate group (82.8 +/- 2.8). The main conclusion from this study is therefore that erythritol is a promising sugar substitute from a cariological point of view.     

Pulpal responses to bacterial contamination following dentin bridging beneath hard-setting calcium hydroxide and self-etching adhesive resin system

Abstract –  To evaluate the pulp healing to bacterial contamination beneath a hard-setting calcium hydroxide (DY: Dycal, L.D. Caulk Co.) and a self-etching adhesive resin (2V: Clearfil Liner Bond 2V, Kuraray Medical Inc.) following dentin bridge formation. Class V cavities were prepared on 30 monkey teeth, and the pulps were exposed with a carbide bur through the cavity floor. Each exposed pulp was capped with either DY or 2V. The cavities were restored with a hybrid resin composite. The resin composite was removed at 180 days after capping, and then cavities were left open to the oral environment for 2 weeks to obtain bacteria contamination DY (BDY) and 2V (B2V; n  = 10). A non-bacterial-contaminated group capped with DY was used as control. After bacterial challenges, inflammatory cell infiltration, incidence and differentiation of dentin bridges were evaluated histologically. There were significant differences in the presence of inflammatory cell infiltration among all groups ( P  < 0.05). No moderate or severe inflammatory reaction was found in Group DY. Group BDY showed moderate or severe inflammatory cell infiltration in 50%, and showed four necrotic specimens. Although no statistically significant difference was found in the formation and differentiation of dentin bridges among all groups, tunnel defects in dentin bridges were detected in 70% (DY), 80% (BDY), and 50% (B2V). Group B2V showed a significantly lower presence of inflammatory cell infiltration than Group BDY ( P  < 0.05). Bonding agent is supposed to seal the exposure site, and the remaining bonding agent on the cavities was effective as the barrier in the dentin bridges after bacterial challenges.