Īpplying ultrasound for passive irrigation seems more advantageous. Ultrasonic energy cannot be considered as an alternative to conventional manual instrumentation. Because of the difficulty in controlling dentin removal and subsequently the final shape of the canal, the first method is almost discarded in the clinical practice. Ultrasonic devices can be utilized in two manners simultaneous combination of ultrasonic irrigation/instrumentation and passive ultrasonic irrigation (PUI). Using ultrasonic energy in endodontic treatment has improved treatment quality in many aspects, including access to root canal entry holes, cleaning, shaping and filling the canals, eliminating the obstructions and intracanal materials and endodontic surgery. Įffects of ultrasonic irrigation in endodontics The other advantage is the piston-like linear movement of tip in piezoelectric units from back to front which is ideal for endodontic treatment. One major advantage of piezoelectric units over magnetostrictive devices are production of more cycles per second (40 in piezoelectric vs. First they have elliptical movement and oscillate in a figure-eight manner and second, they generate heat, so adequate cooling is required. Magnetostrictive units have two major drawbacks for endodontic application. Therefore, without producing heat, the crystal undergoes mechanical oscillation. The second method works according to the piezoelectric principle and uses a crystal which changes in size by applying electrical charge. First is magnetostriction that converts the electromagnetic energy into mechanical energy. There are two basic methods for producing an ultrasonic wave. Ultrasonic tips have an important advantage over hand and rotary instruments because they do not rotate, thereby deliver safety and control while maintaining high cutting efficacy. Ultrasound is a vibration or acoustic wave with similar nature as sound but with a frequency higher than the highest frequency detectable by the human ear (approximately 20000 Hz). In well-shaped canals, fluid activation has a critical role in cleaning and disinfection of the canal irregularities by facilitating the fluid penetration through all aspects of the root canal system. On the other hand, active irrigation initiates dynamics and flow within the fluid and thus improves root canal disinfection. Passive irrigation has limitations because the static reservoir of irrigant restricts the penetration, circulation and cleansing potential of the irrigation solution of a root canal system. To achieve deeper and more effective placement, smaller gauged needles should be chosen. In order to allow the irrigant to reflux and move the debris coronally, the needle should be loose in the canal. Passive irrigation is conducted by slow dispensing of the irrigant of choice into a canal through a variety of different gauged needles. faecalis) can penetrate the dentinal tubules of root canal walls up to 800-1000 µm deep, whereas the maximum depth of 6% NaOCl penetration into the dentinal tubules is reported to be 300 µm after 20 min at 45 ☌. In the absence of cementum and during a three-week incubation, Enterococcus faecalis ( E. One of the major drawbacks of NaOCl is the high surface tension, which affects the tubular penetration and thus antibacterial ability of NaOCl. Sodium hypochlorite (NaOCl) is the most common root canal irrigation solution. The aim of root canal irrigation is to remove the pulp tissue remnants and microorganisms (in either planktonic or biofilm forms), eliminate the smear layer (SL) and extirpation of dentine debris during root canal treatment. Therefore, irrigation and chemical debridement are essential parts of root canal treatment as it allows for cleaning beyond the root canal instruments. , only 40% of the root canal walls in the apical area of oval canals can be contacted by rotating instruments. Due to the complex anatomy of the root canal system, and presence of intra-canal irregularities such as oval extensions, isthmi and apical deltas, it is difficult if not impossible to sterile the root canal system.
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