The mean strength that has traditionally been taken as a measurement of the strength of a material does not reflect the true strength, and therefore it cannot be used as a design parameter. This explains why many brittle materials fail at unpredictable stress, either below or above the mean strength. By using Weibull statistics, the prediction and assessment of strength can be made more sensibly. The performance of a material can be predicted by considering a stress at a lower level of failure probability.

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Beta₂-microglobulin (β₂-m) is a low-molecular-weight protein which has been suggested to play an important role in immune functions. The aim of this study was to determine β₂-m levels in serum and saliva from patients with juvenile periodontitis (JP) and to compare them with those of periodontally healthy subjects. The study was performed on 11 patients with JP and 10 periodontally healthy controls (C). Clinical measurements were recorded and serum and saliva samples were obtained from the individuals. β₂-m levels were determined using the ELISA technique. Serum β₂-m levels were significantly higher in the JP group than in the control group. In saliva, no significant difference in β₂-m levels between the groups was found. The higher, β₂-m levels in serum in the JP group suggest that β₂-m may play a role as a systemic factor in the etiology and pathogenesis of JP.

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Mean levels of myeloperoxidase (MPO) activity were determined in samples of gingival crevicular fluid (GCF), whole saliva and peripheral blood neutrophils from patients with rapidly progressive periodontitis (RPP) and adult periodontitis (AP) using a spectrophotometric method. The mean neutrophil MPO activity in the RPP group was 563.1±137.05 U/1×10⁶/ ml, that in the AP group was 483.3±88.81 U/1×10⁶/ml, and that in the control group was 220.6±26.7 U/1×10⁶/ml. The mean GCF MPO activity in the RPP group was 15.13±2.34 U/mg, which was significantly higher than in the other two groups. The mean whole saliva MPO activity in the RPP group was 0.14±0.04 U/ml, that in the AP group was 0.11±0.02 U/ml, and that in the control group was 0.05±0.06 U/mi. MPO activity detected in the samples was significantly increased in the patient groups when compared to the healthy subjects. The highest MPO activity was found in the RPP group. The present findings suggest a relationship between MPO activity and the pattern and severity of periodontal breakdown. Also the increased MPO activity in periodontally diseased patients can be attributed to the increased number of neutrophils, the degranulation of these cells and also their hyperactive state in the presence of chronic antigenic stimulation.

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The levels of natural antibody against Thomsen-Friedenreich (TF) antigen in sera of patients with various cancers and infectious diseases were examined by an enzyme-linked immunosorbent assay (ELISA) and compared with those of healthy donors. The levels of antibody against TF antigen in sera of patients with adenocarcinomas such as gastric, pancreatic and colorectal cancers were lower than those of patients with hepatoma, pyelonephritis and pneumonia. These findings may reflect the expression of TF-antigen in adenocarcinoma tissues.

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A series of studies has been conducted on the synthesis of radiopaque monomers and the development of a composite resin having these monomers.
Using octachlorocyclotetraphosphazene, P₄N₄Cl₈ (4PNC), three kinds of radiopaque cyclophosphazene monomers, 4PN (Br₃Ph) _1-3- (EMA) _7-5, were synthesized by reacting 1-3 mols of tribromophenol (Br₃Ph) and 7-5 mols of 2-hydroxyethyl methacrylate (HEMA).
As the monomer for an organic composite filler, 70% (wt) synthesized monomer was used with silica (OX-50) treated with silane mixed at 30% and ground after heat-polymerization and then run through a 325-mesh sieve after polymerization.
As a base monomer, 25% urethane monomer (U-2TH) was mixed in 25% synthesized monomer and photosensitizer was added. The composite resin was prepared by mixing 50% organic composite filler with 50% base monomer, and polymerized with a Dentacolor XS (Kulzer) visible light-curing apparatus by irradiation for 90 s on each side, 180 s in total.
Mechanical properties did not vary with the increase in the number of tribromophenol replacements. Compressive yield strength was more than 120 MPa in all cases. Transverse strength was 60-75 MPa and hardness was HK 26-30. However, the aluminum equivalent increased with the increase in the number of tribromophenol replacements. In the case of 4PN- (Br₃Ph) ₃, the value was 8.8 mm, whereas in the case of commercial composite resin, it was 0.4-10.4 mm.

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Five currently available glass ionomer cements (BASE CEMENT, DENTIN CEMENT, HY-BOND GLAS IONOMER-F, KETAC CEM, TOKUSO IONOMER) were studied with regard to the relationship between thermal properties and powder-liquid ratio (P/L ratio). The experiments were performed using five different P/L ratio of 0.8, 0.9, 1.0, 1.1 and 1.2 (P/L =1.0 : manufacturer's instruction) and measured with a xenon flash thermal-constant measuring device.
Thermal diffusivity of the glass ionomer cements ranged from 0.212 to 0.303×10^-2 cm² s^-1; it increased according to the increase in the P/L ratio. The specific thermal capacity of the glass ionomer cements ranged from 1.011 to 1.369 Jg^-1K^-1; it decreased with the increase in the P/L ratio. Thermal conductivity of the glass ionomer cements ranged from 0.505 to 0.712 Wm^-1K^-1, it increased according to the increase in the P/L ratio.

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Bone proteins in alveolar bone of mandibles from young adult rabbits (3-month-old) were extracted with 4.0 M guanidine hydrochloride (GuHCl), followed by 0.5 M ethylenediaminetetraacetate, and again with 4.0 M GuHCl (G2-ext). The proteins in the G2-ext were fractionated on a gel-filtration column, followed by an anion-exchange column in the presence of 7.0 M urea. A 28-kDa protein was isolated from the G2-ext. The purified 28-kDa protein showed intense staining with silver on SDS-PAGE slab-gel under reducing conditions. This protein was digested with bacterial collagenase, and a 19-kDa fragment appeared on the gel. However, the protein was not susceptible to reduction with cyanogen bromide. The protein did not bind to hydroxyapatite crystals in the presence of 7.0 M urea, and also did not bind to some lectins. On SDS-PAGE under non-reducing conditions, the protein migrated as two bands; a new band appeared at approximately the 85-kDa region in addition to the original 28-kDa band. The amino acid compositions of the protein were similar to those of the α1-pN-propeptide of type I procollagen obtained from other tissues.

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Concentrations of lomefloxacin in serum, the wall and fluid of radicular cyst, gingiva, and jawbone following single or multiple oral administration were measured. The highest concentrations of lomefloxacin in serum, cyst wall, cyst fluid, gingiva, and jawbone occurred at 3 h after multiple administration, and were 2.31μg/ml, 4.06μg/g, 1.54μg/ml, 4.72μg/g and 2.79μg/g, respectively. The mean concentration ratios of wall/serum, fluid/serum, fluid/wall, gingiva/ serum, and jawbone/serum at the highest concentrations were 1.74, 0.73, 0.47, 2.52 and 1.20, respectively. Although most lomefloxacin concentrations in cyst and oral tissues following single oral administration did not exceed the MICs for 80% of clinically isolated strains of a-hemolytic streptococci, Staphylococcus aureus and Neisseria spp., most of those obtained after multiple oral administration exceeded the MICs except in the case of fluid.

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