ABSTRACT
The aim of this study was to compare the fracture resistance of over-f/ared root canals of teeth obturated with either MTA or Composite. 104 human extracted lower single rooted premo/ars teeth were allocated, 13 sample were used as positive control group [Group+ve], while the remaining 92 teeth were prepared to the working length, and subsequently over flared, leaving the apical 5mm undisturbed, and randomly allocated into 7 groups of 13 samples each. Negative control group [Group-vej were over prepared and left without obturation, while the remaining 6 groups were obturated with gutta percha-nano HA [Group 1], gutta percha-nano HA + composite [Group 2], gutta percha-nano HA + MTA [Group 3], resilon-epiphany [Group 4], resilon-epiphany + composite [Group 5], and resilon-epiphany + MTA [Group 6] Fracture resistance of all the samples in each group were measured using the Instron machine [Instron 5982, IDR, UK] while 3 samples from each group had the depth of their fracture line measured by Micro CT Scan [Gemini, LEO SUPRA 55VP, Germany]. This In-Vitro study showed that the highest fracture resistance was observed in Group H-ve, followed by Group 3, Group 6, Group 5, Group 4, Group 2, Group 1 with the value of 1721.7[219.6] 1498.5[260.3], 1432.6[205.3], 896.5[59.9], 784.6[154.8], 761.2[303.8], 474.5[262.8] respectively. The lowest fracture resistance was Group-ve, 286.6[80.7]. Statistically, there was a highly significant difference in fracture resistance between all groups P value < .001. Micro CT Scan showed that tooth in the Group +ve has the lowest percentage of tooth fracture. Within the limits of this study, it is concluded that MTA has the ability to withstand heavy vertical forces