Prevention and management of fractured instruments in endodontic treatment

Table 2 The recommended use times of different studies

Year	Ref.	Instruments (rotary)	n	Used times	Operator	Deformation (files)	Separation (files)
2006	Wolcott et al[77]	ProTaper	4652 canals	1 tooth	Experienced		20
				2 teeth	Experienced		12
				3 teeth	Experienced		23
				4 teeth	Experienced		19
				5 teeth	Experienced		39
2009	Shen et al[75]	ProFile 0.04,	1071 files	1 visit	Experienced	8 (0.75%)	0
		ProFile Series 29 0.04	432 files	1 visit	Experienced	0	0
		ProTaper	1895 files	1 visit	Experienced	55 (2.9%)	5 (0.26%)
2009	Inan et al[7]	Mtwo	593 files	4 molar teeth or 2 molar teeth with curved canals	10 trained	58 (9.78%) (unwinding and curve/bend)	95 (16.02%)
2009	Vieira et al[48]	ProTaper Universal	10 sets files	5 molar teeth	Experienced	0	0
2010	Ma et al[74]	ProTaper	432 case	20 canals			27
2012	Shen et al[53]	ProFile Vortex	2023 files	1 visit	Undergraduate students	0	1 (0.04)
2013	Shen et al[76]	HyFlex CM	468 files	3 teeth	9 residents	16 (3.4%)	0
2015	Plotino et al[19]	Reciproc	1696 files	1 tooth		6 (0.35%)	8 (0.47%)