Expression Of DSPP, DSP In Gingival Crevicular Fluid Of During Root Resorption Following Orthodontic Tooth Movement

When the force is put on the teeth, it is inevitable the occurrence of different extent of root resorption. Root resorption is one of the most common complications during orthodontic treatment. Now its mechanism is not clear and there are not effective preventive methods. Once root resorption appeared, there are not effective therapeutical methods. Unlike physiological root resorption of deciduous teeth, it is a pathological process of root resorption of permanent teeth involved multi-pathogeny. About root resorption, it is necessary to find a new method to diagnose and detect the development of root resorption.Objective:The objective of this study is to realize approximate moment of the appearance of root resorption and analyse the relationship of different mechanieal forces and period of treatment after exerting different mechanieal forces. At the same time, observing the expression and change of Dentin Sialophosphoprotein (DSPP) and/or Dentin Sialoprotein (DSP) in gingival crevieular fluid (GCF) of human, to study the effect of different forces on the expression of them and discuss the possible effect DSPP/DSP played during tooth movement. Thus, it can look for a new index which might be related to root resorption experimentally.Methods:1) Thirty-six patients were chosen from the orthodontic department as subjects. It was engaged continuous intrusive force (light force - 30g; excessive force - 300g) on the maxillary the first premolar or the second premolar. The teeth were extracted after 1w, 4w, 8w, 12w respectively. The histological sections were made and stained with hematoxylin and eosin (H&E) and Tartrate resistant acid phosphatase (TRAP) to observe the root resorption.2) 30# absorbent paper points were used to collect GCF of experimental teeth. Western blot was used to check the proteins in GCF, and analyze the relationship of the expression of DSPP/DSP and root resorptionResults:1) The establishment of the clinical model of root resorption:â‘ observation on the X-ray film: In the excessive force group, four weeks later, the periapical radiolucent areas appeared; eight weeks later, the radiolucent areas augmented; twelve weeks later, root tips were little shorter than normal teeth. The change was not obvious in the light force group.â‘¡observation on the anatomy morphology: It was found that the root was incomplete with irregular absorbed section in the apex area in the excessive force group.â‘¢observation on the histological sections: It is severer in the excessive force group than the light force group, which the change appeared in the root tip. Furthermore, it was found that a large number of cells with monocytes or polyocytes focused in the area of root resorption.2) The expression of DSPP/DSP in gingival crevicular fluid (GCF): During root resorption, the expression of DSPP/DSPP had statistical significance in gingival crevicular fluid between the excessive force group and the light force group. After the force was applied, the DSPP/DSP in gingival crevicular fluid increased from the second week, and it reached the climax at the seventh-ninth week, and subsequently reduced little by little.Conclusion:1) By the way of continuous intrusive force engagement, the clinicall model of root resorption can be established and the resorption can be found at the fourth week.2) It was suggested that the continuous intrusive force engagement can induce root resorption during the orthodontic treatment.3) The level of DSPP/DSP in GCF changed after light force and excessive force were exerted,it had a time dependent manner. The experiment may provide a new method of inspecting root resorption in clinic.