| Objective:To study corresponding relations between decalcification time and calcium cintent of demineralized bone matrix(DBM).To study influence of calcium cintent on DBM- bone induction activitiesMethods:1.Corresponding relations between decalcification time and calcium content of demineralized bone matrix(DBM)were studied as follows:chose 12 Zelanian rabbits and took 90 15mm-length bones from each radius and ulna after they were killed,then divided them into 15 groups that were timed separately for decalcification,by which DBM samples of different degrees of decalcification were derived.Each sample was digested afterwards by mixed solution of MOS(Metal-Oxide-Semicon-ductor) nitric acid and hydrochloric acid,and then continuum source atomic absorption spectrometry was used to determine the samples' calcium content.2.Influence of calcium content on DBM- bone induction activities was studied as follows:first,prepared DBM samples with calcium percentage at respectively 24.05%(not decalcified),12.05%(3 hours of decalcification),2.00% (8 hours of decalcification)and 0.00%(24 hours of decalcification).Then chose Zelanian rabbits to set up segmental bone-defect models,meantime a blank control group was also established.The DBM samples with calcium percentage at respectively 24.05%(not decalcified),12.05%(3 hours of decalcification),2.00% (8 hours of decalcification)and 0.00%(24 hours of decalcification)were separately implanted.Gross observations,X-ray afterwards,Goldner's histological test and fluorescent labeling were carried out separately in the fourth week,eighth week and twelfth week.Gross observation,X-ray and Goldner's histological test provided an intuitive representation of new bones' growth,while fluorescent labeling showed the daily regeneration pace of the demineralized bones.Results:1.The study on corresponding relations between decalcification time and calcium content of DBM reveals that calcium content is 24.05±1.01%in normal Zelanian rabbits,and given gradually elongated time of decalcification,calcium content in the samples reduced gradually nonetheless in a growingly slow way.2. The study on the influence of calcium content on DBM-bone induction activities show:in the fourth week,gross observations,X-ray,Goldner's histological test and fluorescent labeling reveals that the group with Calcium content at 2.00% group showed the most exuberant bone regeneration,and the group with Calcium content at 24.05 percent lower than other components of the three groups;the Mineral Apposition Rate(MAR)of Fluorescent labeling measurements showed that MAR of 2.00 percent was the highest group(P＜0.05),12.05 percent one followed by(P＜0.05),0.00 percent one again(P＜0.05),and 24.05 percent one the lowest(P＜0.05).In the eighth week,the qualitative observations indicate that the calcium content of 2.00 percent group was the most active one,and the calcium content of 24.05 percent group's activity lower than the other components of the three groups.MAR of calcium content measurements showed that MAR of 2.00 percent was the highest group(p＜0.05),and there was no difference between 12.05 percent and 0.00 percent one(p＞0.05),and 24.05 percent one was the lowest(P＜0.05).In the twelfth week,the qualitative observations indicate that the difference between the groups with calcium content of 2.00 percent,calcium content of 2.00%,of calcium content of 0.00 percent was not obvious,while the calcium content of 24.05 percent showed slightly lower than the other three groups of bone regeneration activity;Calcium content of 2.00 percent showed higher MAR than the calcium content of 12.05 percent,and one between the group of 12.05%and 0.00%calcium content,the other between the groups of 2.00%and 0.00%calcium content,showed little statistical significance(P＜0.05).calcium content 24.05%group's MAR is the lowest(P＜0.05).Conclusion:1.During the process of decalcification,calcium content in the samples reduced gradually while in a growingly slow way.2.The group with 2.00% calcium content retained higher bone induction activities than other groups in the process of repair bone defect.3.non-decalcified bones showed less bone induction activities than demineralized bone matrix.
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