The mean fracture resistances were ( 762.49 84.91 ) N for group A , ( 794.26 72.61 ) N for group B , ( 517.69 80.30 ) N for group C , ( 543.50 62.88 ) N for group D , ( 219.91 43.20 ) N for group E , and ( 196.16 41.08 ) N for group F.