E. T. Pinheiro

Microbial Analysis of Canals of Root-filled Teeth with Periapical Lesions Using Polymerase Chain Reaction

The objective of the present study was to investigate the presence of nine bacterial species in root-filled teeth associated with periapical lesions using a polymerase chain reaction analysis and to correlate these species with clinical features of the cases. DNA was extracted from 45 canal samples of root-filled teeth with periapical lesions. A PCR assay using species-specific primers of 16S rDNA and the downstream intergenic spacer region was used for microbial detection. Enterococcus faecalis was the most prevalent species, detected in 77.8% of the study teeth, followed by Peptostreptococcus micros, detected in 51.1%. Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, and Prevotella nigrescens were detected in 35.6%, 22.2%, 11.1%, and 11.1% of the sampled teeth, respectively. Moreover, PCR detected Filifactor alocis in 26.7%, Treponema denticola in 24.4%, and Tannerella forsythia in 4.4% of the samples. T. denticola and P. micros were statistically associated with tenderness to percussion (p < 0.05). P. nigrescens was associated with the presence of spontaneous pain and abscess (p < 0.05). P. endodontalis and P. nigrescens were associated with purulent exudates (p < 0.05). Synergistic relationship was also observed between some species. The results of this study indicated that E. faecalis was the most frequently identified test species by PCR in teeth with failing endodontic treatment.

Bacteriological study of root canals associated with periapical abscesses

OBJECTIVE The aim of this study was to identify microorganisms from root canals with periapical abscesses and to ascertain the susceptibility of Peptostreptococcus prevotii and Fusobacterium necrophorum to antimicrobials. Study design Thirty root canals were microbiologically sampled by using sterile paper points. The concomitant microorganisms were identified through the use of established methods. The susceptibility of P prevotii and F necrophorum to antimicrobials was evaluated by using the E test method. RESULTS A total of 117 different bacterial strains were recovered, including 75 strict anaerobes or microphilic species. The most frequently isolated strict anaerobes were P prevotii, Peptostreptococcus micros, and F necrophorum. Facultative bacteria such as Gemella morbillorum and Streptococcus mitis were also found, albeit less frequently. The data revealed that P prevotii and F necrophorum were susceptible to the tested antibiotics. CONCLUSIONS Gram-positive anaerobic bacteria predominate in the mixed microbiota of root canals with periapical abscesses. Moreover, P prevotii and F necrophorum are susceptible to the tested antibiotics.

Gemella morbillorum in primary and secondary/persistent endodontic infections

OBJECTIVE To investigate the presence of Gemella morbillorum by culture or nested PCR in primary and secondary/persistent endodontic infections. STUDY DESIGN Microbial samples were taken from 50 cases with primary and 50 cases with secondary/persistent endodontic infections. Microbiologic techniques were used for culture and identification. The DNA extracted from the samples was analyzed for the presence of the target species using species-specific primers. RESULTS Culture and polymerase chain reaction (PCR) identified the species in 23 and 77, respectively, of 100 root canals. Culture yielded the test organism in 19 of 50 (38%) of root canal samples from primary and in 4 of 50 (8%) from secondary/persistent infections. PCR yielded the test organisms in 41 of 50 (82%) and 36 of 50 (72%) of the, respectively, primary and secondary/persistent root canal infections studied. CONCLUSION Gemella morbillorum was identified more frequently in primary endodontic infections than in secondary/persistent ones. A higher frequency of the target species was detected by PCR than by culture.

Thickness of dentine in mesial roots of mandibular molars with different lengths

AIM To measure the minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots of mandibular first molars with different lengths. METHODOLOGY The mesial roots of 285 mandibular first molars were allocated into three groups according to their length: group I - long (24.14 mm +/- 0.85), group II - medium (22.10 mm +/- 0.65) and group III - short (19.97 mm +/- 0.75). The minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots 2 mm below the furcation was measured. The distance between the buccal and lingual canals, and the depth of concavity in the distal surface of the mesial roots were also measured. anova and Tukey-Kramer were used to test for significant differences among the groups. RESULTS The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < 0.05) between group I (long) and III (short), with long teeth having the smallest mean values. No significant difference was found in the thickness of the distal wall of the mesiolingual canal among the groups studied (P > 0.05). The shortest distance between the mesiobuccal and the mesiolingual canals was observed in group III (P < 0.05). The distal (furcal) concavity was deeper in group I (P < 0.05) when compared with the other groups. CONCLUSION There was a significant difference in the minimum thickness of the distal (furcal) root wall of the mesiobuccal canal of mandibular first molars 2 mm below the furcation between group I (long) and group III (short) teeth. The thinnest walls were found in the longest teeth. The deepest concavities in the distal (furcal) walls of the mesial roots were found in the longest roots.