1, Root canal filling pastes for primary tooth have to meet more needs than paste for permanent tooth, such as being absorbed with root simultaneously and doing no harm to permanent tooth germ.

2, Objective To investigate the features of primary tooth structure in hypophosphatasia.

3, Conclusion: The ART approach used for the treatment of primary tooth decay and for prevention of secondary caries is effective and acceptable.

4, Conclusion: Bone remodel around the permanent tooth germ resulted from primary tooth orthodontic movement.

5, This review will introduce odontclast and its related signal cascades and the cor-relation of permanent successor with physiological root resorption of primary tooth.