| Objective:Human teeth in vitro for the study, to evaluate the lateral loading conditions, the study of teeth if after root canal therapy should taken the line core crown, and compare the influence of amount of tooth structure remaining on the fiber post and composite resin core restorations against off performance for different clinical deficits of residual crown and root, select the appropriate way to reference repair.Methods:Select group of teeth that in January 2010 to June 2010, That in First Affiliated Hospital of Xinjiang Medical University, Thirty six recently extracted single rooted lower premolars from orthodontic patients were divided into 4 groups(groupl of crown transverse defects, completely missing ferrule; group2 of crown mesial-distal oblique defects, missing parts of dentin ferrule; group3 of crown transverse defects, with the integrity of the dentin 2mm ferrule; group4 of the control group) 9 teeth each. All the teeth were restored with fiber post-core system. The specimens were loaded with loading direction at 135 degree to the tooth axis and crosshead speed of 0.2mm/min. For each specimen, we recorded the load to fracture (in Newtonand) the fracture type of the fiber posts. All the results were analyzed by ANOVA, with the use of SPSS 17.0 software package.Results:The median fracture values of the four groups were as follows:The fracture resistance of first group (796.56±118.94N) and second group (961.09±101.49N) was significantly lower than that inthe third group (1316.44±77.94N) and the control group(1433.94±95.92N)(P<0.05).Conclusion:The fracture resistance ability rises with the increase of the amount of residual tooth in the full crown restoration with fiber post and composite resin core. So in order to get the best repair effect, we must retain more tooth tissue. |
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