Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

Statement Of Problem: Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail.

Purpose: The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination.

Material And Methods: Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins.

Thymoma and hypogammaglobulinaemia with and without T suppressor cells.

Patients with acquired hypogammaglobulinaemia usually have near normal numbers of B cells and normal T cell function. When hypogammaglobulinaemia occurs in association with thymoma, then B cell numbers have been reported as low, and distinctive T cells are present which inhibit immunoglobulin production by normal cells. It has been suggested that these T cells are responsible for the observed hypogammaglobulinaemia.

The role of B cell differentiation factors and specific T cell help in the pathogenesis of primary hypogammaglobulinemia.

We have examined the function of T and B cells from patients with late onset primary acquired hypogammaglobulinemia (PHG). T cells from these patients give effective help to normal B cells for antigen-dependent antibody synthesis. PHG mononuclear cells also synthesize normal quantities of B cell differentiation factors, which enhance IgG, IgM and antigen-dependent antibody synthesis by normal lymphocytes.

Non-specific factor enhancement of human in vitro antigen-dependent antibody synthesis: role of B cell activation and T cell help.

Lectin-free supernatants obtained from PWM-stimulated lymphocytes, enable B cells to proliferate and secrete immunoglobulin. Both functions are augmented by the addition of irradiated T cells. In the presence of antigen, these supernatants also enhance specific anti-tetanus toxoid antibody production.