T‐cell independent production of salivary secretory IgA after hematopoietic stem cell transplantation in children

This study examined the recovery of secretory IgA (S‐IgA) in saliva after hematopoietic stem cell transplantation (HSCT) in 35 children and young people between the ages of 3 and 27 years (mean = 13.6), and compared this recovery with that of serum immunologic constituents. Reference values for human salivary S‐IgA in saliva were obtained from 77 healthy control subjects between the ages of 7 and 25 years (mean = 11.4). In the 35 patients, a nadir of secretory IgA concentrations in saliva (S‐IgA) was observed between the 3rd and the 4th month, and a return to normal values 1 year after HSCT. Serum IgA concentrations reached their nadir in the 6th month, and normalized in the 18 months after HSCT. The recovery of T‐helper cells (CD4⁺/3⁺) was also delayed to beyond 18 months. We found a significant correlation between the reconstitution pattern of S‐IgA and that of T‐helper lymphocytes, but no correlation was found between the post‐transplant evolutions of S‐IgA and serum IgA, or between S‐IgA and T‐helper cells. The recovery of S‐IgA was more rapid than that of serum IgA and appeared to be T‐helper cell independent.     

Metabolism of vitamin E acetate by reconstituted human gingival and buccal epithelium

Aim : To demonstrate metabolism of vitamin E acetate to vitamin E by human gingival and buccal reconstituted epithelial cell cultures. Method : Human gingival and buccal reconstituted epithelial cell cultures (SkinEthic, France) were exposed to vitamin E acetate and maintained for up to seven days at 37°C (5% CO₂) in a humidified incubator. Following organic extraction of the cultures, reverse phase HPLC was used to analyse the quantities of vitamin E and vitamin E acetate in the cultures. Results : The ratio of vitamin E to vitamin E acetate increased up to 30 fold more than the solution control in gingival cultures after 7 days. Conclusion : This paper demonstrates that human gingival and buccal epithelial cells can metabolise vitamin E acetate to vitamin E, thus delivering the more active vitamin E species under the control of the activity of endogenous host enzymes.     

The effect of ketoprofen creams on periodontal disease in rhesus monkeys

Ketoprofen creams were evaluated for the treatment of periodontal disease in a placebo-controlled, double-blind study in the rhesus monkeys, Macaca mulatta. Two formulations containing ketoprofen (1%), with or without vitamin E, were evaluated against appropriate controls (8 monkeys per group). Two weeks prior to treatment, the animals received prophylaxis on only the left side of the mouth (spontaneous model). Selected teeth on the right side of the mouth were ligated (ligature model). The creams were administered to the gingiva once daily at a standard dose of 1.8 ml per monkey for 6 months. Clinical assessments were made 2 wk before initiation, at baseline and 1, 2, 3 and 6 months post-treatment. The clinical parameters included plaque formation, gingival redness, edema, bleeding on probing and Ramfjord Attachment Level measurements (RAL). Radiographs were taken at 2 wk before initiation, baseline and at 3 and 6 months post-treatment. Digital subtraction radiography was used to measure vertical linear bone loss along the interproximal root surfaces of the left and right mandibular first molars. Gingival crevicular fluid (GCF) was collected for biochemical assays on PGE₂, TxB₂, LTB₄, IL-1β and TNFα. There were no significant differences among groups with respect to gingival indices. Radiographic data demonstrated significant positive effects on bone activity in both groups treated with ketoprofen formulations with improvement over time in the ligature model (0.01 ≤p≤ 0.04). The placebo group exhibited bone loss of 1.96±0.48 and 1.40±0.56 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream showed an apparent bone gain of 0.28±0.41 and 0.78±0.47 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream containing vitamin E showed a mean bone loss of 0.41–0.48 mm per site at 3 months with improvement to an apparent bone gain of 0.31±0.44 mm per site at 6 months. The biochemical data demonstrated early and significant suppression of GCF-LTB₄ by both ketoprofen formulations at 1 month, which preceded the significant suppression of GCF-PGE₂ at 2 and 3 months in the ligature model (p≤0.003) and at 2 to 6 months in the spontaneous model (p≤0.02). We conclude that ketoprofen at 1% level in suitable topical vehicles can effectively inhibit GCF-LTB₄ and GCF-PGE₂ and positively alter alveolar bone activity in the ligature-induced model of periodontitis in the monkey.     

Competitive adsorption versus surface complexation as models for the simultaneous adsorption of metal complexes and free ligands

A statistical thermodynamical approach to the study of anion-induced adsorption of Cd(II) from halide solutions is presented. The simultaneous adsorption of metal complex and ligand is introduced in the isotherms by considering two possible mechanisms — competitive adsorption and surface complexation. These isotherms have been tested for the system Cd(II) in KBr at several ionic strengths. The experimental surface excesses of Cd(II) calculated from single-step chronocoulometry can be simulated, giving an explanation for the desorption of the metal complex at positive potentials. Also, the change in ligand adsorption promoted by the adsorption of the metal complex has been calculated. Both approaches lead to the conclusion that the anionic tricoordinate metal complex CdBr₃^? and the tetracoordinate CdBr₄^2? are the absorbed species on the electrode surface, with CdBr₄^2? dominating at higher bromide concentrations.     

Measurement of proteases in human subgingival dental plaque by fluorescence polarization

Fluorescence polarization (FP) was examined as a rapid quantitative method to assay the proteases in subgingival plaque. Protease activity was measured by a decrease in FP at 0.5-min intervals over 5 min, using BODIPY®--casein, a protein substrate. To quantitate activity, the least absolute deviation (LAD) slope for each assay was determined. Protease activity increased with the quantity of plaque (r=0.416, P<0.001). Of the 208 subgingival plaque samples, 87 contained detectable protease activity, with a mean of about 4 μg trypsin equivalents above a general background of 1 μg per site. The mean plaque protease activity of 89 paired samples from 15 individuals had decreased by 1.1 μg trypsin equivalents per site when measured at 8 months after tooth scaling and root planing (P<0.01). Most isolates of Porphyromonas gingivalis, Treponema denticola, Prevotella nigrescens, and Prevotella intermedia implicated in the pathogenesis of adult periodontitis exhibited high activity in the FP assay. The assay is rapid, quantitative and requires only one-tenth of the plaque sampled using a single pass with a Gracey curette at a single tooth site.     

The influence of bone mechanical properties and implant fixation upon bone loading around oral implants.

Finite element models were created to study the stress and strain distribution around a solitary BAnemark implant. The influence of a number of clinically relevant parameters was examined: bone-implant interface (fixed bond versus frictionless free contact), bone elastic properties, unicortical versus bicortical implant fixation and the presence of a lamina dura. Bone loading patterns in the vicinity of the implant seem to be very sensitive to these parameters. Hence they should be integrated correctly in numerical models of in vivo behaviour of oral implants. This necessitates the creation of patient-dependent finite element models.     

Variations in the prevalence and extent of periodontitis

A national survey of employed adults showed a decrease in the extent and severity of periodontal disease in comparison with findings from earlier studies. Using data from that survey, this report evaluates the association of socioeconomic factors--race, education, income and dental insurance, as well as most recent dental visit--with the prevalence and extent of periodontal disease. Periodontitis was more prevalent and usually more extensive in persons who are black, have less education or had not seen a dentist in three or more years. Having dental insurance was not associated with better periodontal health.     

In vitro resistance to fracture of porcelain inlays bonded to tooth

To assess the resistance to fracture of ceramic inlays, extracted sound human molars were restored with different ceramic materials and glass-ionomer or composite resin luting cement. Compression forces were applied to the specimens until they fractured, and maximal force developed, extent and location of fractures, and the micromorphology of the fractured surfaces were studied. Inlays made of Vitadur N with aluminum oxide profile and bonded with composite resin demonstrated the highest resistance among the restorative combinations, but their resistance was still lower than that of intact (control) teeth. The extent of fracture increased proportionally to the fracture resistance of the specimens. Scanning electron microscopic observation confirmed the effectiveness of the adhesion between composite resin and etched ceramic and the absence of sufficient micromechanical anchoring between glass-ionomer cement and etched ceramic.