Objective:The aim of this study was to investigate in vivo microorganisms detected in root-filled teeth with post-treatment apical periodontitis and quantify colony-forming units (CFU) during endodontic retreatment.Materials and Methods:Fifteen root-filled teeth had their previous gutta-percha removed and were randomly instrumented before being divided into three groups and medicated with either [Ca(OH)2 + 2% CHX gel], [Ca(OH)2 + 0.9% NaCl] or 2% CHX gel. Samples were taken after removal of gutta-percha (S1), after chemomechanical preparation using 2% CHX gel (S2), and after inter-appointment dressing (S3) for 7 or 14 days later. Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of culture and PCR assay (16S rDNA). Quantitative data were statistically analyzed by using Mann-Whitney test in which pairs of groups were compared (P < 0.05).Results:CFU counts decreased significantly from S1 to S2 (P < 0.05). No significant difference was found between S2 and S3 (P = 0.3093) for all three experimental groups. Chemomechanical preparation and intra-canal dressing promoted significant median reductions of 99.61% and 99.57%, respectively, in the number of bacteria compared to S1 samples. A total of 110 cultivable isolates were recovered by culture technique from 32 different species and 7 different genera. Out of the 13 target species-specific primer of bacteria analyzed, 11 were detected during endodontic retreatment.Conclusion:The great majority of taxa found in post-treatment samples were Gram-positive bacteria, although Gram-negative bacteria were found by molecular methods. Moreover, our results showed that gutta-percha removal and chemomechanical preparation are effective for root canal disinfection, whereas additional intra-canal dressing did not improve disinfection.

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This clinical study was conducted to quantify cultivable bacteria and endotoxin in root canals with post-treatment apical periodontitis by correlating their levels with clinical features and to evaluate the effect of chemo-mechanical preparation (CMP) with 2 % chlorhexidine gel + 17 % EDTA on bacterial and endotoxin removal/elimination. Moreover, target strict Gram-negative anaerobic bacteria were investigated by polymerase chain reaction (PCR). Fifteen teeth with post-treatment apical periodontitis were sampled before (s1) and after (s2) CMP. Culture techniques determined the number of colony-forming units (CFU). PCR (16S rDNA) and limulus amebocyte lysate (LAL) assay were used for bacterial and endotoxin detection, respectively. Prevotella nigrescens (4/15), Prevotella intermedia (2/15), and Tannerella forsythia (2/15) were the most frequently detected species. Endotoxin was recovered in 100 % of the samples. At s1, bacteria and endotoxin were detected at a median value of 5.14 × 10(3) CFU/mL and 3.96 EU/mL, respectively. Higher levels of endotoxin were related to a larger size of radiolucent area (>5 mm) (p < 0.05). CMP was more effective in reducing bacteria (99.61 %) than endotoxin (60.6 %) (both p < 0.05). Our findings indicated that the levels of endotoxin found in infected root canals were related to a larger size of radiolucent area in the periapical region. Moreover, CMP was effective in reducing both bacterial and endotoxin contents in post-treatment apical periodontitis.

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The randomly amplified polymorphic DNA (RAPD) technique was used to analyse the genetic differentiation of 13 strains of Aeromonas salmonicida subsp. salmonicida, and seven strains of Aer. hydrophila. Reproducible profiles of genomic DNA fingerprints were generated by polymerase chain reaction (PCR) using a single randomly designed primer. The RAPD profiles of all the non-motile aeromonads, Aer. salmonicida subsp. salmonicida were identical. However, profiles of the motile aeromonads, Aer. hydrophila differed between isolates. These findings reveal genomic homogeneity in Aer. salmonicida subsp. salmonicida and genetic variety in Aer. hydrophila strains.

Objective:This study aimed to identify possible associations of the presence or absence of posttrauma sequelae with the factors inherent to the traumatized tooth and treatment.Materials and Methods:This retrospective study was performed through the evaluation of records and radiographs of a center of reference for dental trauma between January 2008 and December 2014. The factors were analyzed and associated with posttrauma sequelae, such as pulp necrosis and root resorption.Statistical Analysis Used:A binomial logistic regression model was fit (P < 0.05).Results:In luxations, it was possible to observe 37% pulp necrosis, 16% inflammatory root resorption, and 8% replacement resorption. The binomial logistic regression revealed that male gender (P = 0.0392, odds ratio [OR] = 2.79), avulsion injury (P = 0.0009, OR = 12.27), and elapsed time >16 days between the time of trauma to the beginning of the endodontic treatment (P = 0.0450, OR = 7.53) showed a greater chance of presenting a posttrauma complication.Conclusions:Gender, type of injury, stage of root development, and time after trauma until the beginning of the endodontic intervention were related to the appearance of sequelae.

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