The Effects Of Root Canal Preparation And Tampering On The Mechanical Characters Of Tooth Root.

Objective: In recent years,root canal therapy has been a effective technique for pulposis, periodontal disease and periodontic endodontic lesion. But excessive root canal preparation and tamping can result in tooth canal slit in pulpless tooth and cause therepy failure. Comparing common clinical methods for root canal preparation and taper, the experiment is to analyze the effects of root canal preparation and tampering on the mechanical characters of tooth root.Methods: 104 extracted human mandibular first premolars were randomly divided into the control group and experiment groups which consists A, B, C, D treated by different methods. All of the crowns were sectioned. Experimental group A was prepared 0. 02 taper treated with stainless steel K一files 30# and obturated with lateral condensation technique ; groups B were prepared 0.02 taper30#, 0.04 taper30# and 0.06 taper30# respecively under NI-TI一files by the same plugging; groups C and D were treated by the same files into the same tapers as group B, except that groups C were obturated with vertical condensation technique and thermoplastic gutta pertscha but groups D were experimented with lateral condensation technique and AH-plus gutta pertscha. Measured and calculated the area, all the tooth were embeded in the column superanhydrite with 4cm diameter and thickness. Then, they were put in universal mechanical experimental machine and loaded with regular speed of 1mm/min until the tooth roots were fractured. The overall load were noted and the maximal load on per area were calculated and compared. T test was used for correlation analyse. The probability was considered as 0.05. Results:1)The stress of control group and experiment group was significantly differented (P<0.05);2 )There was no significant difference between group A and groups B, C, D (P>0.05);3) There were no significant differences between group B and group C; group B and D; group B and C group (P>0.05).Conclusions: The whole resistance to fracture of tooth root can be weakened by root canal therapy, but there is no significant difference between different root canal preparation and tampering within 0. 06 taper.