Table 2.

Median performance of each cohort

Performance metrics	Novices	Inter-mediates	Experts	p-valuea
Tip–apex distance (mm)	47	28	24	0.006
Cut-out rate (%)	55	4.7	2.6	0.007
Procedural time (s)	190	206	222	0.6
No. of radiographs (n)	16	26	28	0.03
No. of guide-wire retries (n)	0	1	2	0.2

^aKruskal–Wallis