The effects of cementum on the permeability of the root canal wall

doi:10.3969/j.issn.1002-7386.2018.10.016

Abstract：Objective To investigate the effects of cementum on the permeability of root canal wall.Methods The 140 anterior teeth,140 premolars,140 molars were randomly divided into 2 groups,respectively,which were group A1,A2,B1,B2,C1,C2,with 70 teeth in each group.The cementum located 4 ～ 10 mm from root apex was removed by hand-held hoe to expose the dentin in group A1,group B1 and group C1.However the cementum of teeth in group A2,B2 and C2 was not treated to keep the cementum integrity.All in vitro teeth root apex 4 mm area was evenly coated with two layers of nail polish.Then these teeth root apex 10 mm area was immersed into 2％ methylene blue solution in eppendorf tube,and 10 teeth were selected from each group at an interval of 24 hours,and the teeth were cleavaged along the long axis of the tooth to observe the methylene blue infiltration status into the dentinal tubules for continuous 7 days.Results In group A 1,B 1,C 1,methylene blue penetration into dentine could be observed at the first day,and the penetration distance limited outer 1/3 layer and middle 1/ 3 layer of dentin ofthe root canal.However methylene blue penetration could be found in inner 1/3 layer of dentin at the third day,moreover,which could be observed at the forth day in allthe groups.There was significant difference at 1 d,2d,3d,4d,5 d,6d,7d between group AI and group A2,between group B1 and group B2 and between group CI and group C2 (P ＜ 0.05).Conclusion The permeability of the root canal wall is increased significantly after cementum being destroyed,and leakage oriented from peridontal tissue to pulp can be observed.