Apical vapor lock effect in conservative Ni-Ti instrumentation using V-taper rotary system

Aim: The presence of apical vapor lock during irrigation has been shown to have a negative impact on debris and smear layer removal. The aim of this study was first, to compare apical vapor lock formation during positive pressure syringe irrigation following conventional, ProTaper Gold and conservative, V-taper nickel-titanium instrumentation. The second aim was to evaluate effectiveness of apical vapor lock elimination by sonic, ultrasonic and manual dynamic agitation, once established. Methods: Thirty-six single rooted teeth were instrumented with either ProTaper Gold F2 (25/0.08) or V-taper (25/0.06). In the first part of the study, incidence of apical vapor lock formation was evaluated radiographically following irrigation with sodium hypochlorite and cesium chloride (contrast agent). In the second part, apical vapor lock elimination was evaluated using manual dynamic agitation with 50 strokes of a well-fitting gutta-percha cone. Sonic agitation was performed with the EndoActivator, while ultrasonic agitation was carried out using a piezoelectric unit and a ISO size 15 U-File. Results: Following positive pressure irrigation, apical vapor lock was detected radiographically in 75.0% of total cases, specifically 72.2% and 77.8% of samples instrumented with V-taper and ProTaper Gold, respectively. Manual dynamic agitation eliminated apical vapor lock in 92% of samples, significantly more effective when compared to sonic and ultrasonic agitation. Conclusion: Apical vapor lock was equally detected after conservative and conventional rotary instrumentation using V-taper and ProTaper Gold, respectively. Manual dynamic agitation was effective at eliminating apical vapor lock.Dentistry, Faculty ofGraduat