Er:YAG Laser for 3-Dimensional Debridement of Canal Systems: Use of Photon-Induced Photoacoustic Streaming
DiVito E, Lloyd AAsepsis of root canal systems has long been the goal of endodontic treatment. The historic use of chemotherapeutic agents to disinfect intracanal tissue has not been realized, and the efficacy of the medicament is based on the ability to reach infected pulpal tissues in complex anatomy (Figure 1) where no instrument is capable of shaping; and secondly, the toxicity the agent possesses will also have an effect on the viable periradicular tissues it contacts, should it pass through any portals of exit.
Using conventional side-vented irrigation needles, the critical factors in determining elimination of biofilm, organic tissue, and canal cleanliness are depth of needle penetration and volume of irrigant.1,2 A computational fluid dynamic model found an apical "dead water zone" beyond the irrigating needle tip whereby no fluid movement occurred leaving the apical third unaffected.3 The parameters that would enable fluid interchange at this level include apical matrix size, taper and needle gauge. A recent investigation found apical enlargement to size/taper 40/.04 enabled optimum volume of irrigant to flow at the desired apical depth using a negative pressure irrigation system.4 The curvature of complex root canal systems may not, however, permit these preparation sizes without compromising the integrity of the tooth and iatrogenically damaging the canal.
Regardless of the ability to create enlarged canal spaces to accommodate irrigating needles, intracanal medicaments cannot reach aberrant anatomy and, therefore, do not come into contact with the infected pulp or microbes. A system that would remove the impediments to cleaning throughout the root canal system down to the tubular dentin level and eliminate biofilm would result in total canal sterilization, something that has been unobtainable thus far.
