Platelet responses and anaphylaxis-like shock induced in mice by intravenous injection of whole cells of oral streptococci

Intravenous injection of lyophilized whole cells of various oral streptococcal strains into muramyldipeptide (MDP)-primed C3H/HeN mice induces rapid anaphylactoid shock. Here we examined the mechanism underlying this shock. In non-primed mice, Streptococcus intermedius K-213K (SiK213) and Streptococcus constellatus T21 (ScT21) produced little or no sign of shock. In MDP-primed mice, SiK213 caused lethal shock, while ScT21 only had a weak effect. SiK213 induced decreases in blood platelets and 5-hydroxytryptamine (5HT) preceding the shock, while the effects of ScT21 were weak. The SiK213-induced 5HT decrease and shock were reduced by a complement-C5 inhibitor. These results suggest that (i). streptococcal bacterial cells can induce rapid platelet responses, (ii). complement-dependent degradation of platelets may be involved in streptococcus-induced shock, (iii). the streptococcus-induced platelet degradation or degranulation may occur largely in the systemic circulation, and (iv). platelets may play a role not only in infectious diseases caused by gram-negative bacteria, but also in diseases caused by gram-positive bacteria.     

Novel mutations in the cathepsin C gene in patients with pre-pubertal aggressive periodontitis and Papillon-Lefèvre syndrome

Aggressive periodontitis (AP) in pre-pubertal children is often associated with genetic disorders like Papillon-Lefèvre syndrome (PLS). PLS is caused by mutations in the cathepsin C (CTSC) gene. We report a novel CTSC mutation (c.566-572del) in an otherwise healthy AP child and two novel compound heterozygous mutations (c.947T>G, c.1268G>C) in a PLS patient. We conclude that at least a subset of pre-pubertal AP is due to CTSC mutations and therefore may be an allelic variant of PLS.     

Clinical and radiographic evaluation of a resin-based root canal sealer

PURPOSE: To conduct a preliminary clinical and radiographic evaluation of a resin-based root canal sealer used in conjunction with gutta percha. METHODS: In a retrospective study on 180 patients who were seen for root canal therapy, a total of 295 root canals were treated with laterally condensed gutta-percha cones in conjunction with a methacrylate-based endodontic sealer (EndoRez). Root canal therapy had been carried out in one visit using standardized techniques. The results were assessed clinically and radiographically 14-24 months postoperatively and a comparison to baseline radiographs was made. 145 patient records were available for a follow-up examination. Success of root canal treatment was based on absence of clinical symptoms, a normal or slightly widened periodontal ligament and reduction of periapical radiolucencies with an absence of pain in patients that had pre-existing lesions associated with pain. RESULTS: The overall success rate was 913%. Root canals had been adequately filled to the working length in 110 teeth (75.7%), short from the working length in six cases (4.1%) and flush in 19 teeth (13.1%). Extruded sealer occurred in 10 (6.9%) instances. 49 teeth out of 55 (89.1%) that had preoperative apical radiolucencies revealed partial or total healing at the 14-24 months recall evaluation. 83 teeth out of 90 (92.2%), without preoperative radiolucencies, showed no radiographic changes. At the 14-24 months recall all patients reported being comfortable. 13 (9.0%) cases were judged failures.     

Fluoride and magnesium concentrations in human dental calculus obtained from Japanese and Chinese patients

Calculus deposited on a total of 68 permanent teeth from patients 30-60 years old from Nagoya in Japan and Beijing in China was investigated. An abrasive microsampling method was used to examine the fluoride (F) and magnesium (Mg) distribution, using a fluoride ion-specific electrode and atomic absorption spectrophotometry, respectively. F concentrations decreased from the surface towards the interior of the calculus. Mg concentrations, however, gradually rose towards the innermost surface adjacent to the tooth. In all parts of the depth profiles, the average concentrations of both magnesium and fluoride were higher in the Japanese than in the Chinese calculus. Towards the inner surface of the calculus, F and Mg concentrations were also much higher in the Japanese than in the Chinese group. A greater intake of sea foods and greater use of fluoride dentifrices are possible reasons for the higher F and Mg concentrations in the Japanese individuals.     

Effects of low-energy CO2 laser irradiation and the organic matrix on inhibition of enamel demineralization

In the past two decades, accumulated evidence has clearly demonstrated the inhibitory effects of laser irradiation on enamel demineralization, but the exact mechanisms of these effects remain unclear. The purpose of this study was to investigate the effects of low-energy CO2 laser irradiation on demineralization of both normal human enamel and human enamel with its organic matrix removed. Twenty-four human molars were collected, cleaned, and cut into two halves. One half of each tooth was randomly selected and its lipid and protein content extracted. The other half of each tooth was used as the matched control. Each tooth half had two window areas. All the left windows were treated with a low-energy laser irradiation, whereas the right windows served as the non-laser controls. After caries-like lesion formation in a pH-cycling environment, microradiographs of tooth sections were taken for quantification of demineralization. The mean mineral losses (with standard deviation) of the enamel control, the lased enamel, the non-organic enamel control, and the lased non-organic enamel subgroups were 3955 (1191), 52(49), 4565(1311), and 1191 (940), respectively. A factorial ANOVA showed significant effects of laser irradiation (p = 0.0001), organic matrix (p = 0.0125), and the laser-organic matrix interaction (p = 0.0377). The laser irradiation resulted in a greater than 98% reduction in mineral loss, but the laser effect dropped to about 70% when the organic matrix in the enamel was removed. The results suggest that clinically applicable CO2 laser irradiation may cause an almost complete inhibition of enamel demineralization.     

Collagenases in different categories of peri-implant vertical bone loss

The loosening of dental implants is associated with peri-implant vertical bone loss. The mechanisms and mediators of this bone destruction are not known. To test the hypothesis that collagenase-2 and collagenase-3 might be markers or maybe even mediators in this process, we measured collagenase-2 (time-resolved immunofluorometric assay) and collagenase-3 (quantitative immunoblot) in peri-implant sulcus fluid in 49 implant sites in 13 patients. Vertical bone loss was graded as being < 1 mm, from 1 to 3 mm, or > 3 mm. The severity of inflammation, as rated according to Gingival Index, did not correlate with the category of bone loss (p > 0.05). Collagenase-2 and collagenase-3 were higher (p < 0.05) in the group which had lost > 3 mm of bone than in the two other groups. Gingival Index is not a clinically important marker for bone loss, but collagenase-2 and collagenase-3 in peri-implant sulcus fluid are. They might participate in peri-implant osteolysis.     

A study of the bond strength and color of ultralow-fusing porcelain

PURPOSE: The purpose of this study was to investigate the effects of different bonding agents, surface roughness, and acid pickling on the bond strength and color of ultralow-fusing porcelain fused to gold alloy. MATERIALS AND METHODS: Porcelain-metal specimens were made to 25 mm x 3 mm x 0.5 mm with a 1-mm porcelain thickness. A 3-point bending test was used to evaluate the bond strength. The color of the porcelain was measured using a dental chromameter, and the data were processed in the CIE Lab system. The color difference (delta E*) was calculated for the tested groups. RESULTS: Good bond strength and color could be achieved regardless of the use and type of bonding agent. Surface roughness and acid pickling had more effect on the bond strength than on color. CONCLUSION: The type of the bonding agent, surface roughness, and acid pickling influenced the bond strength but had minimal effects on the color of ultralow-fusing porcelain. This ultralow-fusing porcelain could produce a color closer to the Vita shade than the conventional low-fusing porcelain.     

Margin quality of titanium and high-gold inlays and onlays--a clinical study.

OBJECTIVES: Unalloyed titanium may be an economical substitute for gold alloys. The purpose of this study was to evaluate the suitability of unalloyed titanium as an alternative to gold alloys for posterior inlay and onlay restorations. METHODS: Fifty-four patients received 99 titanium restorations, 56 patients 96 gold alloy restorations. All titanium restorations were cast in a vacuum-pressure casting machine. Two weeks after insertion the clinical margin integrity was evaluated by replica technique. The maximum marginal gaps were assessed under the optical measuring microscope. The two tailed t-test for independent samples was used for statistical analysis. RESULTS: Accuracy of fit was significantly better in gold alloy than in titanium restorations. Mean maximum marginal gap between restoration margin and tooth structure were 72 +/- 18 microns (mean +/- S.D.) for titanium and 64 +/- 18 microns (mean +/- S.D.) for gold restorations. SIGNIFICANCE: Though marginal gap widths in titanium restorations did not yet match the gold standard, the data justify the use of titanium as an alternative to gold alloy for inlay and onlay restorations.     

Radionuclide skeletal imaging and single photon emission computed tomography in suspected internal derangements of the temporomandibular joint

Fifty one subjects who had pain involving the temporomandibular joint were evaluated using multidirectional tomography, arthrography, conventional nuclear scanning, and single photon emission computed tomography (SPECT) to assess the association of arthritis of the temporomandibular joint with internal derangements related to meniscal dysfunction. Five (56%) of the nine subjects who had normal arthrograms and normal multidirectional tomograms had SPECT scans that were positive for osseous changes. Twenty-two subjects (27 temporomandibular joints) were diagnosed by arthrography to have meniscal displacement with reduction. Multidirectional tomograms of the 27 joints were positive for osseous changes in five (18%) joints, whereas SPECT scans were positive in nine (70%) joints. Twenty subjects (20 temporomandibular joints) had an arthrographic diagnosis of meniscal displacement without reduction. Multidirectional tomograms of the 20 joints were positive for osseous changes in 14 (70%) joints, and SPECT scans were positive in 16 (80%) joints (P less than 0.001 vs control group). Initial observations with SPECT indicate it is a promising imaging method for detecting and staging osseous disease of the TMJ related to meniscal dysfunction.     

The effect of root planing and citric acid applications on flap healing in humans. A histologic evaluation

Four human teeth and their facial gingival attachment were removed en block 3 months after periodontal flap therapy and citric acid root conditioning and then prepared for histologic evaluation. At the time of periodontal surgery, and prior to citric acid application, the facial root surface was grooved at midline and citric acid was applied only to one-half of each root surface. Tissues were decalcified and histologically prepared as horizontally oriented, step serial sections from the level of the gingival margin to the level of the facial crest. The gingival margins demonstrated reformation of a crevice. The corium at this level showed a mild inflammatory infiltrate. Apical to this level, junctional epithelium adhered to both sides of the root surface and to the central groove. Further apically, supracrestal fiber groups were encountered. No new cementum was noted in these areas. Fiber attachment was present apical to this level. Since no new cementum was seen at this area of attachment, it may represent collagen attachment present prior to periodontal surgery. In the four specimens examined, no differences were seen in the soft tissue closures between the root-planed citric acid-treated root surfaces and root surfaces which received root planing alone.