The joint with the open root crack
was analyzed, the crack lengths being considered in arithmetic progression, with the ratio 0.5 mm.
However, determined different values of stress intensity factors for both crack sizes suggest that these three gear pairs do not have the same resistance to tooth root crack
(27,29,34) Root canal preparation alone significantly weakened roots, especially when the working length is longer than optimal, and may create apical root cracks. (31) Thus, the screw-in forces by some active rotary NiTi files, especially used by inexperienced operators, may have a higher chance to go over the apical foramen and may increase the risk of apical crack formation.
(45,48) reported that, with regard to the potential risk of root cracks from the file system, WaveOne instruments induced the least number of cracks and exhibited the greatest resistance to fracture compared with ProTaper files whether used in reciprocating or rotating motions.
Wu, "Incidence of apical root cracks
and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths," Journal of Endodontics, vol.
a rapid 79 not out as England beat New Zealand by eight wickets in the second one-day international, in Napier, as the tourists tied the series and set up a decider in Auckland on Saturday.
Exclusion criteria included root caries, root cracks
, root resorption or other anatomical defects, teeth with incomplete apical development and those too small to produce the test specimen (about 10 mm in length).
The claw of the toothkey was clamped onto the rotten tooth, then twisted until the root cracked
and parted company from the jaw.