Table 4.

Characteristics of the included studies evaluating voids

Author (Year)	Sample size (N)	Groups	System of preparation/ Apical size	Filling material/ Obturation technique	PSP method	Measurement	Time of immediate PSP	Time of delayed PSP	Outcome
Kataia1 et al. (2020)	56	GA1: penetrating drill/ GA2: heated plugger & EXACTO bur SubGroups: single cone, System-B Minor SubGroups: imm, 1W	ProTaper Universal System/ F5	GP/AH Plus sealer /single cone, System-B	penetrating drill, heated plugger & EXACTO bur	By micro-CT scanner; % voids	Immediately	7 days	Delay > Immediate single cone > System-B penetrating drill > heated plugger & EXACTO bur
Long et al (2019) [5]	40	GA: single cone, imm/ GB: CWC, imm/ GC: single cone , 1W/ GD: CWC, 1W	M3 Rotary system/ 30.04	GP/ iRoot SP sealer/ single cone or CWC/	heated plugger	By micro-CT imaging; % volume	Immediately	7 days	immediate-delay CWC - single cone
Dhaded et al. (2013) [72]	80	G1:AH Plus, imm/ G2:AH Plus, 1W/ G3:Resilon/Epiphany, imm/ G4:Resilon/Epiphany, 1W	Protaper universal/ #40	GP+ AH Plus, Resilon + Epiphany/ CLC	peeso reamer	SEM analysis; mm/ stereomicroscope	Immediately	7 days	Delay > immediate immediately: AH Plus-Resilon + Epiphany delayed: AH Plus >Resilon/Epiphany

CLC cold lateral compaction, CWC continuous wave of condensation, G groups, GP gutta percha, imm Immediate, PSP post space preparation, W week, - ; similar outcome.