No abstract

There was no NaOCl extrusion in nine specimens in P1, but all of these teeth had irrigant extrusion in P2. The 5.25% NaOCl used as an endodontic irrigant showed great capacity to extrude beyond both intact and small-sized apical foramina of MB root canals of maxillary first molars.

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- The pH values of the external aqueous medium, relative to the roots of 41 human premolar teeth filled with Ca(OH)2 in to several vehicles, were evaluated in the present study. After root canal biomechanical preparation and smear-layer removal, the teeth were stored individually, immersed in flasks containing 800 ml of ultra-pure deionized water for a period of 118 days. A pH meter was used to analyse the pH values as a function of time. The measurements were divided into phase 1: dissolution, in which all canals remained empty and open in the absence of medicament for 48 days, and phase 2: diffusion, in which the specimens were divided into 10 groups which consisted of three control groups: group 1, water control; group 2, sealing control; and group 3, opened canal dissolution control, and seven experimental groups, with five teeth each, whose canals were filled with Ca(OH)2 paste associated with the following vehicles: group 4, saline solution; group 5, polyethylene glycol (Calen); group 6, glycerin and parachlorophenol (PMCC); group 7, PMCC; group 8, glycerin; group 9, glycerin and formo cresol (FC); and group 10, anesthetic solution. This phase lasted for 70 days. A total of 1058 measurements of the pH values were made. Regression analysis was used for statistical evaluation. The results show that all groups containing polyol in the composition of the paste had a trend to acidification in the interval between filling and 14 days later (therapeutic period) and, at the end of the experiment (1687 h to 70 days after canal filling), the pH was slightly alkaline. We conclude that polyhydroxy alcohol (glycerin and polyethylene glycol, Calen) diffusion enhances acidification of the aqueous medium.

Using high-performance liquid chromatography (HPLC), small amounts of liquid samples in which 25 premolar human teeth were immersed were evaluated. Each tooth was immersed separately in 800-ml flasks with distilled ultra-pure deionized water and remained there for 1678 h after the filling of their canals with Ca(OH)2 associated with different vehicles: group 1: polyethylene glycol and colophon (Calen); group 2: glycerin and camphorated paramonochlorophenol; group 3: camphorated paramonochlorophenol; group 4: glycerin and tricresol formol; and group 5: anesthetic solution (Citanest). Five polyethylene tubes were filled with each of these pastes and placed unsealed in similar flasks. At the end of this period, HPLC analyses of the aqueous medium related to each group were performed to detect other substances that had diffused from the pastes used in the canals of the teeth other than calcium and hydroxyl ions. Although the groups presented different maximum peaks when there was no barrier, they all showed higher values than when the tooth was present. At least 15 substances other than Ca2+ and OH- were detected in the aqueous medium of group 4. Analyzing the HPLC graphs, we concluded that not only Ca2+ and OH-, but also a considerable quantity of other components of the pastes diffused through the dentine and reached the external root surface.