Objectives: to investigate the vertical root fracture (VRF) resistance of human roots filled with MTA over different time intervals compared with a negative control and gutta percha (GP) filled roots as a gold standard.
Methods: 108 extracted human-teeth with single canals and minimal curvatures were decoronated, instrumented (size 50/.05), irrigated (1%NaOCl) and randomly allocated to one of nine groups (n=12). Groups 1,4&7 were obturated with MTA (White ProRoot MTA, Dentsply, Tulsa, USA), 2,5&8 were filled with GP, and 3,6&9 served as control. Roots were stored in synthetic tissue fluid for 2-days in groups1,2&3, for 1-month in 4,5&6 and for 6-months in 7,8&9. Periodontal ligament was simulated, and vertical loading was carried out with a ball-ended steel cylinder fitted on a universal testing machine at 1mm/min cross-head speed. The maximum force at fracture (F-max) and the fracture mode were recorded for each root.
Results: Data were statistically analyzed using two-way ANOVA and Bonferroni post-hoc tests. The mean and standard deviation values for F-max in each group are listed in Table 1. Two modes of fracture were identified; split and comminuted. The latter resulted in significantly higher mean F-max values (P<0.001). In all groups, split fracture was the most dominant mode apart from groups 4&7.
Conclusions: MTA, when fully set, improves the resistance to VRF of endodontically treated teeth and influences the mode of fracture.
Table 1: Mean F-max with standard deviation in parenthesis. Superscripts indicate statistically significant differences at P<0.05
Keywords: Endodontics and MTA, Root-fracture
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