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ePaper created 2017-09-12, 09:26:18 | version 1.38.0
root canal preparation technique | Fig. 1b: Sleiman-Iandolo testing. Demonstrating the airlock eliminated with the use of the negative pressure irrigation system (NB: other means such as further PUI or use of lateral-vented needle were not helpful in overcoming the vapor lock—once produced, the gas bubble remained in place). Investigating irrigation today The fact that during root canal shaping the system may get blocked by debris led to the question of how to best conduct the chemical preparation so that the dentinal tubules remain open to allow for a better cleaning and, consequently, sealing of the system. Drawing from clinical experience and improved out- comes, Jaramillo et al. have formulated an experi- mental irrigation sequence based on Sleiman’s 2005 suggestions, and added a negative pressure device to see if it may have added benefits.7 Scanning electron microscopy used to evaluate the cleanliness of dentinal tubules at three different levels of the canals demonstrated that our experi- mental sequence—alternating the use of 6 % NaOCl and 17 % EDTA with water in between—had shown a significantly better ability to keep the entrances of dentinal tubules open and avoid the blockage of dentinal tubules by the smear layer and debris during the cleaning and shaping procedure compared with the use of 6 % NaOCl or 17 % EDTA alone. The results emphasised the importance of the early use of 17 % EDTA and not only as a final rinse. Fig. 1b This sequence allows us to use the standard endo- dontic irrigants during chemical root canal prepara- tion and prevents any chemical interaction between them thanks to the use of distilled water at strategic times. Depending on the pH levels and the nature of the solutions, such chemical interactions may have a variety consequences, from brown (and in some in- stances, carcinogenic) precipitation to dentine mod- ification, potentially affecting general health and/or quality of the dentine inside the root canal system, which, in turn, may influence the longevity of the link between the sealer and the dentine, thus changing the outcome of the root canal treatment in general. Another finding of the study that echoed positive clinical outcomes related to the use of negative pres- sure in combination with the experimental irrigation sequence; the irrigation protocol that included both the Sleiman sequence (alternating between sodium hypochlorite, water, and EDTA) and a negative pres- sure irrigation device was proven to be the most effi- cient in opening dentinal tubules and maintaining them open. It may be posited that the negative pres- sure allows for a formation of a temporary partial vacuum force, which first draws the liquids from the Fig. 2a: Sleiman-Iandolo testing. Freshly extracted premolar dyed with methylene blue in a centrifuge. Note the deep penetration of the dye, especially in the coronal part. Fig. 2b: Sleiman-Iandolo testing. Results of the dye removal with manual dynamic activation (left) and side-vented needle (right). Note the poor results of the cleaning. Fig. 2a Fig. 2b roots 3 2017 33