Biocompatibility of new nanostructural materials based on active silicate systems and hydroxyapatite: in vitro and in vivo study.

AIM: To evaluate in vitro cytotoxicity and in vivo inflammatory response to new nanostructural materials based on active calcium silicate systems (CS) and hydroxyapatite (HA-CS). METHODOLOGY: Cytotoxicity of eluates of new nanostructural noncommercial materials CS and HA-CS, and MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil) as a control, were tested using the MTT assay on MRC-5 cells. Eluates of set materials were tested in 100% and 50% concentrations, 24 h, 7 days and 21 days post-elution. The pH values were determined for undiluted eluates of set materials. Polyethylene tubes containing the test materials (CS, HA-CS, MTA) were implanted in subcutaneous tissue of Wistar rats. Histopathological examinations were conducted at 7, 15, 30 and 60 days after the implantation. Data were statistically analyzed using three-way and one-way anova Tukey's post hoc test as well as Kruskall-Wallis test with Dunn's post hoc test at α = 0.05. RESULTS: All materials significantly reduced cell viability; especially when undiluted eluates were used (P < 0.001). After 24 h elution, cell viability was 10 ± 1.8%, 49.5 ± 4.2% and 61 ± 7.4%, for MTA, and HA-CS, respectively. However, CS and HA-CS were significantly less toxic than the control material MTA (P < 0.05). Cytotoxicity could be at least partially attributed to pH kinetics over time. Dilution of eluates of all tested materials resulted in better cell survival. Histopathological examination indicated similar inflammatory reaction, vascular congestion and connective tissue integrity associated with CS, HA-CS and MTA at each observation period (P > 0.05). The only significant difference was found for capsule thickness, that is thicker capsule was associated with HA-CS compared to MTA at 60 days (P = 0.0039). HA-CS induced moderately thick capsules (median score 3, score range 2-3), whereas MTA resulted in thin capsule formation (median score 2, score range 1-3). CONCLUSIONS: Evaluation of cytotoxicity and inflammatory response indicated better biocompatibility of CS and HA-CS, in comparison with MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil).

Characterization of antigen-presenting cells in human apical periodontitis lesions by flow cytometry and immunocytochemistry.

AIM: To analyse phenotypic characteristics of antigen-presenting cells (APC), isolated from human periapical lesions by flow cytometry and immunocytochemistry. METHODOLOGY: Sixteen periapical lesions were digested for 15 min with 0.05% collagenase. Mononuclear cells, separated from other inflammatory cells by density centrifugation, were processed for flow cytometry and/or immunocytochemistry. Single and double immunostainings were performed using monoclonal antibodies specific for human CD45, CD3, CD19, CD14, HLA-DR, CD1a, CD83 and CD123. RESULTS: Antigen-presenting cells (HLA-DR(+) cells) represented 32.9 +/- 17.8% of total mononuclear cells. Amongst them, B cells (HLA-DR(+) CD19(+)) were the predominant APC population, followed by activated macrophages (HLA-DR(+) CD14(+)), dendritic cells (DC) (HLA-DR(+) CD14(-) CD19(-) CD3(-)) and activated T cells (HLA-DR(+) CD3(+)). Based on the predominance of T cells (CD3(+)) or B cells and plasma cells (CD19(+) and CD19(lo), respectively) amongst mononuclear cell infiltrates, lesions were divided into T- and B-types. The percentage of DC in T-type lesions (27.1 +/- 6.8% of total HLA-DR(+) cells) was higher, compared with B-type lesions (10.3 +/- 5.2%) (P < 0.01). Within the DC population, the percentages of CD1a (Langerhans cell type) and CD123 (probably plasmacytoid DC type) did not differ significantly between the groups (P > 0.05). However, the percentage of mature DC (CD83(+)) was significantly higher in T-type periapical lesions (P < 0.05). CONCLUSIONS: Flow cytometry and immunocytochemistry are suitable methods for phenotypic analysis of APC after their isolation from human periapical lesions. APC, that were phenotypically heterogeneous, constituted a significant component of infiltrating cells. Lesions with the predominance of T cells were characterized by a higher proportion of mature DC (HLA-DR(+)CD83(+) cells) than lesions with predominance of B cells/plasma cells.

[The epithelium of the periodontal pocket--an electron microscopy analysis]. / Epitel parodontalnog dzepa--analiza elektronskim mikroskopom.

The aim of this study was to examine intra- and intercellular changes that characterize the periodontal pocket epithelian. Biopsy specimens of human gingiva were prepared for an electron microscope study by a routine histological procedure. Results of the histological preparations analyses revealed changes significant for pathogenesis of gingivitis and periodontal disease because they cause destruction of epithelial barrier. Such a damaged periodontal pocket epithelium enables further invasion of harmful noxae and spreading of destructive processes into deeper parts of the periodontium.

Beta 2-microglobulinuria as a predictor of death in a population exposed to Balkan endemic nephropathy.

During the year 1974, urinary beta 2-microglobulin (beta 2mu) was measured at monthly intervals using the first-morning urine sample of randomly selected individuals from the BEN affected village of Petka (416 persons) and from the nearby situated control village of Stubica (216 persons). Initial compliance was complete; over 90% of villagers had at least 10 tests performed. beta 2mu, as assessed by radial immunodiffusion (RID), was repeatedly (at least twice) positive in 12% and 1.4% of the populations of the endemic and control villages, respectively. Over the 15 years of follow-up (1974 to 1988), none from the control village developed BEN, while many medical records of the cohort exposed to BEN contained data suggestive of BEN. Death from/with BEN was used as a measure of outcome. Incidence density of 12 was 3.3 per 1000 person/years of observation (19/5723). A single positive beta 2mu test was a sensitive predictor of BEN death (sensitivity = 89.5%). Selecting two or more positive tests as the cut-off point, the specificity and positive predictive value were considerably increased. Using the sulfosalicylic acid test for detection of significant proteinuria, a similar level of validity indices was reached only by four testings.

Beta 2-microglobulinuria in a population exposed to Balkan endemic nephropathy: inferences from repeated cross-sectional studies.

Baseline data from a study run in 1974, which comprised beta 2-microglobulinuria (beta 2mu) measurements at monthly intervals from 416 members in 112 households from the BEN affected village of Petka, were compared with the results of two subsequent, cross sectional studies. In June 1988, retesting involved 320 available persons from the same households. Another collection of 284 urine specimens took place in October 1989. Prevalence of tubular proteinuria was the same in 1988 and 1989 as it was in 1974, indicating that the level of exposure to nephrotoxic agent did not change over time. Over 94% of the individuals who were always beta 2mu negative in 1974 remained negative in 1988. By contrast, over two thirds (68.7%) of those who were positive two or more times 14 years ago, tested positive upon re-examination in 1988. Particular interest arises from the data on those initially repeatedly positive persons in whom the overt disease did not occur over time; moreover, some appeared to be unaffected in 1988 and 1989 according to our set of laboratory criteria. The results suggest occasional slow progression and even possible reversibility of tubular lesions in individuals living in the BEN affected environment.

Treatment of class II furcation defects using porous hydroxylapatite in conjunction with a polytetrafluoroethylene membrane.

The purpose of the present study was to determine whether the use of a porous hydroxylapatite in conjunction with guided tissue regeneration technique influenced the clinical results in the treatment of Class II furcation defects in humans. Fifteen subjects with a mean age of 39.4 +/- 9.3 years were used in this study. All subjects had Class II furcation defects on the buccal surfaces of 2 lower molars. In each subject one furcation defect was filled with granular porous hydroxylapatite and then a barrier of polytetrafluoroethylene periodontal material was positioned over the furcation. The other furca was treated in the same manner except that no hydroxylapatite was used. The flaps were placed coronally to their presurgical level. Before the surgery and 6 months postsurgery all areas were clinically evaluated using the same clinical parameters. Reentry procedures were used to repeat measurements of the osseous defects made during the initial surgery. At 6 months both surgical procedures resulted in statistically significant reduction in pocket depth and gain in probing attachment level with no significant difference between the two surgical procedures. When porous hydroxylapatite was used in conjunction with a polytetrafluoroethylene membrane, however, less gingival recession and more defect fill were obtained. This study suggests that there is a difference in healing of molar furcations when porous hydroxylapatite is used in conjunction with a barrier membrane. The lesions treated with porous hydroxylapatite gain in clinical attachment and horizontal and vertical bone fill, while the lesions treated with membrane only gain probing attachment with less bony fill.