Increased Resistance to Vertical Fracture of MTA-filled Roots

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.

 

Group	1 (MTA-48h)	2 (GP-48h)	3 (C-48h)	4 (MTA-1m)	5 (GP-1m)	6 (C-1m)	7 (MTA-6m)	8 (GP-6m)	9 (C-6m)
F-max (N)	441.8a (135.8)	453.3a (136.0)	434.0a (77.9)	594.4b (90.2)	450.6a (108.1)	445.4a (108.2)	599.4b (99.7)	454.2a (88.5)	403.6a (74.9)

 

 

 

 

Table 1: Mean F-max with standard deviation in parenthesis. Superscripts indicate statistically significant differences at P<0.05