Table 2. Incidence of mishaps (n[%]) according to tested variables; tooth position, instrumentation technique, operator, number of canals, and root curvature.

	Tooth position		Instrumentation technique		Operator		Number of canal(s)				Root curvature
	Anterior	Posterior	Hand	Rotary	4th year	5th year	1 canal	2 canals	3 canals	4 canals	Mild	Moderate	Severe
Ledge	4[2.9]	16[4.7]	17[4.6]	3[2.8]	9[4.3]	11[4.2]	9[3.4]	4[4.6]	6[6.3]	1[3.8]	7[2.5]	10[6.9]	3[5.5]
Zipping	4[2.9]	13[3.8]	13[3.6]	4[3.7]	8[3.8]	9[3.4]	8[3]	3[3.4]	6[6.3]	0[0]	9[3.3]	7[4.8]	1[1.8]
Perforation	44[32.4]	125[36.9]	135[36.9]	34[31.2]	76[36.2]	93[35.1]	86[32.3]	29[33.3]	43[44.8]	11[42.3]	94[34.2]	57[39.3]	18[32.7]
Instrument separation	0[0]	13[3.8]	10[2.7]	3[2.8]	2[1]	11[4.2]	0[0]	5[5.7]	5[5.2]	3[11.5]	2[0.7]	3[2.1]	8[14.5]
Overall instrumentation mishaps	52[38.2]	156[46]	166[45.4]	42[38.5]	92[43.8]	116[43.8]	102[38.3]	39[44.8]	55[57.3]	12[46.2]	111[40.4]	70[48.3]	27[49.1]
Overall obturation mishaps	58[42.6]	160[47.2]	177[48.4]	41[37.6]	100[47.6]	118[44.5]	118[44.4]	46[52.9]	40[41.7]	14[53.8]	124[45.1]	65[44.8]	29[52.7]