Bacterial leakage in root canals filled with conventional and MTA-based sealers.

AIM: To evaluate bacterial leakage after filling root canals with several endodontic sealers, including MTA-based materials. METHODOLOGY: One hundred and thirty single-rooted extracted human teeth were randomly divided into experimental groups (n = 15) and two control groups (n = 5). Six root canal sealers were namely: AH Plus (AHP), Sealer 26 (S26), Epiphany SE (ESE), Sealapex (SEL), Active GP (AGP), Endofill (EDF), and two MTA-based sealers were namely: Endo CPM Sealer (CPM) and MTA-based sealer (MTAS, MTA Sealer). Teeth in the control groups were either filled with no sealer or made completely impermeable. Root canals were prepared and filled with either gutta-percha and one of the sealers or with Resilon and Epiphany SE. Teeth were sterilized by ethylene oxide prior to the bacterial leakage experiments using Enterococcus faecalis. Leakage was evaluated every 24 h for 16 weeks. Data were analysed by the Kaplan-Meier, Kruskal-Wallis and Dunn tests at 5% significance. RESULTS: Control groups had either immediate leakage or no leakage. During 120 days, significantly more leaking samples were detected for AGP, CPM and MTAS (P < 0.05). The best sealing ability was observed for AH Plus and Sealapex (P < 0.05). CONCLUSIONS: All sealers evaluated allowed bacterial leakage. The MTA-based sealers had the most leakage.

Evaluation of the radiopacity of calcium hydroxide- and glass-ionomer-based root canal sealers.

AIM: To evaluate the radiopacity of calcium hydroxide-based root canal sealers (Acroseal, Sealapex and Sealer 26), a glass-ionomer-based sealer (Activ GP Sealer) and a zinc oxide and eugenol-based sealer (Intrafill). METHODOLOGY: Five disc-shaped specimens (10 x 1 mm) were fabricated from each material, according to the International Organization for Standardization (ISO) 6876/2001 standard. After setting of the materials, radiographs were taken using occlusal films and a graduated aluminum step-wedge varying from 2 to 16 mm in thickness. The dental X-ray unit (GE1000) was set at 50 Kvp, 10 mA, 18 pulses s(-1) and distance of 33.5 cm. The radiographs were digitized and the radiopacity compared with that of the aluminum step-wedge, using WIXWIN-2000 software (Gendex). Data (mm Al) were submitted to ANOVA and Tukey test. RESULTS: Intrafill was the most radiopaque material (7.67 mm Al) followed by Sealer 26 (6.33 mm Al), Sealapex (6.05 mm Al) and Acroseal (4.03 mm Al). Activ GP was the least radiopaque material (1.95 mm Al, P < 0.05). CONCLUSIONS: The sealers evaluated in this study had different radiopacities. However, except for the glass-ionomer-based sealer, all materials had radiopacity values above the minimum recommended by the ISO standard.

Methods of experimental induction of periapical inflammation. Microbiological and radiographic evaluation.

AIM: To evaluate the influence of coronal filling and apical perforation on the induction of periapical inflammation. METHODOLOGY: Fifty-eight root canals in the teeth of dogs were divided into four groups. Groups I and II: root canals were exposed for 180 days; groups III and IV: root canals were exposed for 7 days and then the access cavity filled for 53 days. The root apices of groups I and III were perforated after the coronal opening, whilst those of groups II and IV remained intact. Standard radiographs were taken before and after the experimental periods. Digital images of the radiographs were created and then analysed by three examiners. After induction of periapical inflammation, the root canal contents were collected using paper points. Microbiologic evaluation of the type of microorganism was carried out by culture in different growth media. The radiographic and microbiologic data were statistically analysed using anova at a 5% significance level. RESULTS: There were a greater total number of microorganisms in groups I and II (P < 0.05). The number of anaerobes was greater than the number of aerobes (P < 0.05). The size of the periapical radiolucencies were not significantly different between the experimental groups. CONCLUSIONS: The different methods analysed induced similar areas of periapical radiolucency in dogs with predominantly anaerobic bacteria. However, the time required for induction was less when the method with coronal filling was used.

Effect of different irrigation solutions and calcium hydroxide on bacterial LPS.

AIM: To evaluate the effect of biomechanical preparation with different irrigating solutions and calcium hydroxide dressing in dog root canals containing bacterial endotoxin (lipopolysaccharides; LPS). METHODOLOGY: One hundred and forty premolar roots from seven dogs were filled with Escherichia coli LPS for 10 days (three roots were lost during histological processing). The following irrigating solutions were used for biomechanical preparation: 1% (group I, n = 20), 2.5% (group II, n = 19) and 5% sodium hypochlorite (group III, n = 19), 2% chlorhexidine digluconate (group IV, n = 20) and physiological saline solution (group V, n = 19). In group VI (n = 20), the LPS solution was maintained in the root canal during the entire experiment and in group VII (n = 20), after biomechanical preparation with saline solution, the root canals were filled with a calcium hydroxide dressing (Calen; control). After 60 days, the animals were sacrificed and the following parameters of periapical disease were evaluated: (a) inflammatory infiltrate, (b) periodontal ligament thickness, (c) cementum resorption and (d) bone resorption. Scores were given and data were analysed statistically with the Kruskal-Wallis and Dunn tests (P < 0.05). RESULTS: Histopathological evaluation showed that groups I-VI had more inflammatory infiltrate, greater periodontal ligament thickening and greater cementum and bone resorption (P < 0.05) compared to group VII, which received the calcium hydroxide intracanal dressing. CONCLUSIONS: Biomechanical preparation with the irrigating solutions did not inactivate the effects of the endotoxin but the calcium hydroxide intracanal dressing did appear to inactivate the effects induced by the endotoxin in vivo.