To test the effect of preflaring on tacticle detection of apical constriction
N = 120 root canals
Exclusion criteria: complicated anatomy, external root resorption, severe root curvature
M&M: No pre-op xray shown to operator à #15 or 20 k file used to feel apical constriction à radiograph taken to verify.
Group 1 (68 canals) = no flaring
Group 2(52 canals) = flaring by hedstrom, Gates 2 & 4, ultrasonic
(A)within 1 mm of radiographic apex
(B)(B) short ≥ 1 mm
Preflaring increased tactile ability to detect apical constriction (ss)
- Preflaring can reduce the # of radiographic images needed to determine WL, and reduces the chance of overtension which can cause periapical injury and inflammation.
- Less relevant with use of apex locaters.
- Preflaring helps achieve an accurate working length.