Comparison of Flow Characteristics of Irrigants with Two Different Needles

Objectives: To determine the direction of flow of irrigating solutions inside simulated root canals when different irrigation needles are used. To determine whether different needle designs, increases the likelihood of irrigating solution past the anatomical apex of the simulated root canals. Methods: Twenty root canal models that are designed for endodontic technique exercises were used to simulate root canals in teeth. Two types of needles were compared: a standard needle with a bevel and an open-end and the DENTSPLY needle (Rinn's new Maxi-I-Probe) with a side opening and closed rounded tip within the canal and the observations were noted. Results: The larger the gauge of the needle the further it went into the canal. Observations of flow of irigant within the canals indicate that Maxi-I-Probe can be dangerous if the needle gauges are small and they have reached the full length of the canal, as irrigants can be pushed into the periapical area as irrigants flowed past the tip of the needle. However for the standard needle fluid did not go beyond the tip of the needle with minimum irrigating pressure. As the size of canal increased, there was no fluid extruding beyond the tip of both the needles. However if the needles were bound in the canals, then the fluid was forced away from the tip of the needle, and the pressure applied to the syringe was directly proportional to the distance the fluid flowed away from the tip of the needle. Conclusion: The major finding from this study appears to be that both maxi-I-probe and standard needles can be used for irrigation safely and effectively if dynamic (moving the needle up and down inside the canals while irrigating) irrigation is done.