A collagen ‘bio‐molecular film’ex vivo model to evaluate the efficacy of dynamic irrigation using the RinsEndo® system

Abstract

Aim To evaluate the efficacy of three irrigation protocols using a model consisting of a standard collagen film coating the root canal walls of extracted teeth.Methodology Thirty human teeth with single straight canals were randomly allocated to three groups for static (n = 10), manual dynamic (n = 20) or automated dynamic (n = 10) irrigation. The root canals were prepared to apical size 40 with a 0.08 taper. The teeth were split longitudinally to give two halves and stained collagen was applied to the canal surfaces in a standard manner. The re‐assembled teeth were irrigated using one of the protocols. Digital images were taken of the canal surfaces before and after irrigation with 18 mL of NaOCl. Static irrigation consisted of simple placement of an irrigation needle (gauge 30) in a fixed orientation 4 mm or 10 mm short of the working length. Manual dynamic irrigation consisted of push–pull agitation of the placed irrigant with a well‐fitting, tapered gutta‐percha point. Automated dynamic irrigation was carried out using the RinsEndo® system. The percentage canal surface coverage with stained collagen was calculated using a software package (ipWin4®). The data were analyzed using paired‐t tests and GEE linear regression models.Results The area of canal covered with stained collagen was significantly (P < 0.001) less (21% or 16%, respectively) after manual or automated dynamic irrigation compared with static irrigation. However, the RinsEndo® system was significantly (P = 0.037) less effective (5%) than manual dynamic irrigation. The ‘corono‐apical level of canal’ and the ‘depth of needle tip penetration’ emerged as significant factors influencing outcome of irrigation. Residual collagen was least evident in the middle third, followed by apical and then coronal thirds. Deeper penetration of the needle tip resulted in 7.5% (P < 0.001) more effective collagen removal. The orientation of the side‐port of the irrigation needle was not a significant factor (P = 0.051).Conclusions Automated dynamic irrigation using RinsEndo® system was significantly more effective (16%) in removing stained collagen from the root canal than static irrigation. However, it was significantly less effective (5%) than manual dynamic irrigation. Irrigation was more effective (7%) when the needle was placed closer to the apex.