Effects of Calcium Hydroxide Paste in Different Vehicles on Bacterial Reduction during Treatment of Teeth with Apical Periodontitis.

INTRODUCTION: This clinical study evaluated the antibacterial effects of calcium hydroxide associated with different vehicles during the treatment of infected teeth with apical periodontitis. METHODS: Bacteriologic samples were taken from 90 necrotic root canals of teeth with apical periodontitis before (S1) and after preparation with a rotary nickel-titanium instrument system and 2.5% sodium hypochlorite irrigation (S2). The teeth were distributed in 3 groups according to the intracanal medication used, which consisted of a calcium hydroxide paste in glycerin, camphorated paramonochlorophenol/glycerin (CHPG), or 2% chlorhexidine for 1 week, and then another sample was taken (S3). The frequency of bacteria-positive cases and the reduction of bacterial counts were evaluated by quantitative real-time polymerase chain reaction. RESULTS: Substantial intracanal bacterial reduction was observed after preparation in the 3 groups (P < .001). After calcium hydroxide paste in glycerin medication, the number of bacteria-positive cases decreased from 20/29 (69%) to 17/29 (59%); however, the mean bacterial counts increased 8.4% from S2 to S3. Medication with CHPG reduced the number of bacteria-positive cases from 17/29 (59%) to 15/29 (52%), with a significant mean S2-S3 reduction of 71% (P < .05). In the chlorhexidine group, the number of bacteria-positive cases decreased from 21/30 (70%) to 17/30 (57%) after medication, with a mean S2-S3 reduction of 55%, which, however, was not statistically significant (P > .05). Intergroup comparisons showed no significant differences (P > .05). CONCLUSION: Comparison between the 3 calcium hydroxide pastes showed no significant differences in antibacterial effectiveness in the main root canal. However, only the CHPG paste showed a significant reduction in bacterial counts when postpreparation and postmedication samples were compared.

AQR1 gene (ORF YNL065w) encodes a plasma membrane transporter of the major facilitator superfamily that confers resistance to short-chain monocarboxylic acids and quinidine in Saccharomyces cerevisiae.

We report results on the functional analysis of Saccharomyces cerevisiae ORF YNL065w, predicted to code for a protein belonging to the poorly characterized major facilitator superfamily (MFS) of transporters that are involved in multidrug resistance (MDR). YNL065w is important for a moderate increase of yeast tolerance to ketoconazole and to the cationic dye crystal violet; it protects the cell against short-chain monocarboxylic acids (C(2)-C(6)), but not against highly liposoluble acids such as octanoic acid or the phenoxyacetic-acid herbicides 2,4-D and MCPA; it is also a determinant of resistance to the antiarrhytmic and antimalarial drug quinidine. The encoding ORF was, thus, denominated the AQR1 gene. Results obtained using an AQR1-lacZ fusion indicate that gene expression is very low and it is not stimulated under weak acid stress. The encoded putative transporter was localized in the plasma membrane by fluorescence microscopy observation of the overproduced Aqr1-GFP fusion protein distribution.