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.     

Evaluation of the effect of a stabilization splint on occlusal force in patients with masticatory muscle disorders

The purpose of this study was to evaluate the effect of stabilization splint therapy on occlusal force in patients with masticatory muscle disorders (MD). Six female patients with myalgia or myofascial pain participated in this study. The occlusal points and load on the dental arch in maximum clenching was measured using the computerized system with Dental Prescale(R) before and after the use of the splint. There were no significant changes in the number of occlusal points, mean occlusal pressure, and asymmetry in occlusal balance between before and after the use of the splint. However, there were significant differences in the extent of the area of occlusion and in the integrated occlusal loads. The integrated occlusal load converged to the normal level with the use of the splint. From the results of this study, it is suggested that the use of the stabilization splint has the effect of normalizing the occlusal force.