Effect of extracellular zinc on osteoclastic resorption in dental mineralized tissues / 北京大学学报(医学版)

ABSTRACT

Objective:To investigate the bone resorption caused by osteoclasts and modulating functions of zinc ion on dental slices.Methods:Osteoclasts were separated from long-limb bones of neonatal rabbits,cultured with de-activated human tooth slices and glass slices.The cells in the experiment group were treated with 1?10~(-14)mol/L-1?10~(-4)mol/L zinc+10%(volume fraction) fetal calf serum(FCS)+?MEM,while those in the control group were grown in 10%FCS+?MEM.Osteoclasts on glass slices were stained by TRAP staining.The absorption pits on tooth slices were observed by inverted phase contrast microscope.The resorbing activity was evaluated with the concentration of calcium in the supernatant liquid of osteoclasts.The ratio between the concentration of calcium in the experiment group and that of the control group was termed the resorption index.Results: The isolated cells were multinuclear and showed positive in cytoplasma by TRAP staining.Usually,osteoclasts resorbed tooth slices first on the cementum and dentin,which had lower content of mineralized tissue.Compared with those on bone slices,the lacunae on the dental slices appeared less in amount,less in area and shallower in depth.They often showed shallow pits in a large area.Microscopy showed that the number and area of absorption pits formed on treated tissues were less than those on the control tissues.The content of calcium in the supernatant liquid increased at the concentrations of 1?10~(-4)-1?10~(-14)mol/L zinc,especially in the group of 1?10~(-8)mol/L,1?10~(-10) mol/L,1?10~(-14)mol/L zinc on the 3~(rd) day(P