Effect of apical preparation on different needle depth penetration

Aim: Shaping should be complemented by antiseptic solution. These are often delivered using a needle and syringe. But apical penetration of the irrigation solution is of only 1 mmbeyond its tip. The aim of our study was to evaluate the influence of the apical preparation on the penetration depth of some needles. Methodology: 24 teeth were divided randomly into two groups and prepared in continuous rotation (350 rpm) with Revo-S1 or ProTaper1 to sizes AS 30, 35 and 40 and F1, F2 and F3 respectively. Four types of endodontic needles were used. Three sizes of stainless steel needles: 25, 27 and 30 gauge and one of nickel—titanium needle: 30 Gauge. Each needle was inserted and its length of penetration measured before the root canal preparation and after the finishing files. Results: Multivariate analysis of variance showed significant differences for the finishers (p<0.0001) and the kind of needle (p<0.0001). The PLSD Fisher’s test can highlight the differences between the six types of apical shaping used (independently of the needle type). The same differences were observed between the four types of needle (independently of the apical finish) (p=0.0232). Variance analysis between the four different needles is statistically significant for each apical shaping (p<0.00016). Variance analysis among the six types of finish is statistically significant for each type of needle (p<0.00014). Conclusions: This study shows that the apical preparation influences the penetration depth of needles. The 27 gauge needles reach the last millimetre only with the Revo-S1 system shaped with AS 40. Finally, the 30 gauge needles reach it for all finishers except the ProTaper1 F1.