Model for quantitative immunohistochemical assessment of pulpal response to biomaterials.

The purpose of this study was to propose a new method for quantitative evaluation of the pulpal inflammation to restorative materials using immunohistochemistry and image analysis. Class V cavities were prepared and filled with different restorative materials in 20 healthy premolars to be extracted for orthodontic reasons. Teeth were extracted at different time intervals, fixed, demineralized, and embedded in paraffin. Six-micrometer-thick sections were cut serially and mounted on slides and every fifth section was stained using hematoxylin and eosin or Masson's trichrome, and served to localize the inflammatory reaction. The slides corresponding to the bulk of the inflammatory reaction were then used for immunohistochemical detection of the inflammatory cells using monoclonal antibodies: CD15 (granulocytes and histiocytes), CD45RO (T lymphocytes and monocytes), Pan-B cell (B lymphocytes, macrophages, and a subpopulation of T lymphocytes), CD45RA (B lymphocytes and monocytes), and EMA (plasma cells). The slides were observed and submitted to computerized image analysis using a SAMBA 2000 system for counting of the cells. The CD15, CD45RO, Pan-B-cell, and CD45RA antibodies positively stained the target cells, which could be counted with the computer. The EMA antibody did not permit staining of cells. These results indicate that polymorphonuclears, T lymphocytes, and B lymphocytes are present in inflamed human dental pulp. The immunologic detection of inflammatory cells followed by computerized image analysis allows an accurate characterization of pulpal pathology, and could be useful for the study of pulp reactions to restorative biomaterials.

Influence of criteria on the results of in vitro evaluation of microleakage.

OBJECTIVES: The aim of this study was to compare and explain the statistical methods employed to evaluate the in vitro sealing efficiency of adhesive restorative systems. METHODS: Two hundred and sixty sound freshly extracted human premolars were randomly divided into 13 groups. Standardized cavities were prepared, and the teeth were restored with 13 restorative systems. The teeth were thermocycled, immersed in dye, embedded in resin and sectioned. Five evaluation criteria were recorded: mean, median and mode of the data measured on each tooth, maximum dye penetration measurements on each tooth, and percentage of teeth in each group without any dye penetration. For each parameter, one-way ANOVAs and Duncan a posteriori tests were used to compare the 13 systems. RESULTS: The number of non-statistically different subgroups, pointed out by Duncan tests, was greater when the selected criterion was the maximum dye penetration (6 subgroups) or the percentage of teeth without any penetration (5 subgroups) than when the criterion was the median (3 subgroups), the mode or the mean (4 subgroups). The positioning of the 13 adhesive restorative systems established from the five criteria was different. Equivalent adhesion strategies revealing different experimental results indicate that other factors contribute to the final effectiveness of a particular system: clinical approach with respect to the formation of an elastic bonding layer, and shrinkage, physical and rheological properties of resin composite. SIGNIFICANCE: The results of these in vitro studies of dye penetration must be considered as comparisons and not as absolute conclusions. The maximum dye penetration measured on each tooth, which complies with the aim of the in vitro evaluation of sealing efficiency defined by Pashley (1990) and allows powerful statistical analysis of results, seems to be the best evaluation criterion.