A Study On The Experimental Molar Caries Of Rats And Its Relationship To Two Different Ligation Wires

Object: To compare the different caries effect of the rats'molars round by two kinds of steel-wires, and to explore the relationship between the surface area of steel-wire contacting with the molars and the caries of teeth. Method: Thirty wistar rats were randomly devided into 3 groups, subsequently inoculated with the mixture of Streptococcus mutans and Streptococcus sobrinus in the oral cavity. In the first week, all rats were fed with normal food not including sucrose . The second week from the beginning of the experiment, the upper second maxillary molars were extracted , at the same time , the neck of the upper first maxillary molars were ligatured with different steel-wires, one with circular cross section and the other with flat one. The rats were then fed with caries-inducing diet 2000#. The rats were sacrificed at 9, 11, 13 weeks from the beginning of experiment, and heating the rat head under the condition of high pressure and high temperature to get the bone and teeth. The upper first maxillary molars were sectioned along the median line of the mesio distal direction, then the teeth sections were observed under microscope. The sum of caries scores were assessed by the procedure of Keyes. Result:There were no differences between the cariogenicity of the rats ligationed with two kinds of steel-wires at 9 ,11,13 weeks, (P>0.05).While there were differences between the caries scores at different periods,and the teeth caries become more seriously with ligation time. Conclusion:The experiment indicates that there are no different...