The reagents were 2 mmol/L APMA (MMP activator), 2 mmol/L EDTA, 100 mmol/L EDTA, 200 mmol/L EDTA, 0.2% and 0.02% chlorhexidine(MMP inhibitor),and the blank artificial salival was taken as control.

• 100、200mmol/L乙二胺四乙酸(EDTA)组,0·2%25、0·02%25醋酸氯己定组(MMP抑制剂); 以空白人工唾液作对照组。