Alterations of energy metabolism and glutathione levels of HL-60 cells induced by methacrylates present in composite resins

OBJECTIVES

Methacrylic compounds such as 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA) and bisphenol A glycerolate (1 glycerol/phenol) dimethacrylate (Bis-GMA) are largely present in auto- or photopolymerizable composite resins. Since the polymerization reaction is never complete, these molecules are released into the oral cavity tissues and biological fluids where they could cause local adverse effects. The aim of this work was to verify the hypothesis that the biological effects of HEMA, TEGDMA and Bis-GMA - at a non-cytotoxic concentration - depend on the interaction with mitochondria and exert consequent alterations of energy metabolism, GSH levels and the related pathways in human promyelocytic cell line (HL-60).

METHODS

The biological effects of methacrylic monomers were determined by analyzing the following parameters: GSH concentration, glucose-6-phosphate dehydrogenase (G6PDH) and glutathione reductase (GR) activity, oxygen and glucose consumption and lactate production along with cell differentiation and proliferation.

RESULTS

All monomers induced both cellular differentiation and decrease in oxygen consumption. Cells treated with TEGDMA and Bis-GMA showed a significant enhancement of glucose consumption and lactate production. TEGDMA and HEMA induced GSH depletion stimulating G6PDH and GR activity.

CONCLUSIONS

All the monomers under study affect the metabolism of HL-60 cells and show differentiating activity. Since alterations in cellular metabolism occurred at compound concentrations well below cytotoxic levels, the changes in energy metabolism and glutathione redox balance could be considered as potential mechanisms for inducing clinical and sub-clinical adverse effects and thus providing useful parameters when testing biocompatibility of dental materials.

Bone remodelling in THA: A comparative DXA scan study between conventional implants and a new stemless femoral component. A preliminary report

Periprosthetic bone loss is a major cause for concern in patients undergoing total hip arthroplasty (THA). There are many different factors that may determine the pattern of bone loss and bone remodelling following THA, such as the quality of the bone before the hip replacement, skeletal bone mass at the time of the operation, material and method of fixation and implant design. Recent developments in dual-energy X-ray absorptiometry (DXA) have made it possible to quantify bone mineral density (BMD) to evaluate changes around the prosthesis and to measure bone stock and bone density redistribution after a total hip replacement. In this cross-sectional multicentre clinical study the DXA method was used to compare bone mass after uncemented THA of a custom-made stemless design with five groups of conventional cementless implants (Alloclassic, Mayo, CFP, IPS, ABG). The adaptive bone changes of the proximal femur three years after implantation were evaluated. Periprosthetic BMD was measured in 130 subjects in the seven regions of interest (ROI) based on Gruen zones. Significant differences were found between the stemless implant and the other five groups in zones 1, 4 and 7. The CFP, IPS, and ABG groups showed decreased BMD in ROI 1, and the Mayo, IPS and Alloclassic in ROI 7. An increased BMD in ROI 4 was observed in the Mayo, IPS, ABG and Alloclassic groups. The results of the present study suggest that a conservative stemless implant with complete proximal load transfer produces a homogeneous and more physiological redistribution of bone density, allowing maintenance of proximal periprosthetic bone stock.