A relatively wide range of bacteria have been isolated from root canals using standard culture techniques. However, only 50% of the bacteria in the oral cavity are cultivable (S. S. Socransky et al., Arch. Oral Biol. 8:278-280, 1963); hence, bacterial diversity in endodontic infections is underestimated. This study used a PCR-based 16S rRNA gene assay, followed by cloning and sequencing of 16S rRNA amplicons from a small subset of samples to assess the diversity of bacteria present in infected root canals. A total of 41 clinical samples from 15 de novo and 26 refractory cases of endodontic infections were assessed. Of these samples, 44% were positive by culture and 68% were positive by PCR. Eight samples were selected for further analysis. Of these, the two de novo cases yielded sequences related to those of the genera Enterococcus, Lactobacillus, Propionibacterium, and Streptococcus and two clones were related to previously uncultivated bacteria, while the sinus-associated, de novo case yielded sequences related to those of the genera Lactobacillus, Pantoea, Prevotella, and Selenomonas. The five refractory cases produced clones which were related to the genera Capnocytophaga, Cytophaga, Dialister, Eubacterium, Fusobacterium, Gemella, Mogibacterium, Peptostreptococcus, Prevotella, Propionibacterium, Selenomonas, Solobacterium, Streptococcus, and Veillonella and two clones representing previously uncultivated bacteria. The phylogenetic positions of several clones associated with the Clostridiaceae and Sporomusa subgroups of the Firmicutes grouping are also shown. This study demonstrates that molecular techniques can detect the presence of bacteria in endodontic infections when culture techniques yield a negative result and can be used to identify a wider range of endodontic-infection-related bacteria including the presence of previously unidentified or unculturable bacteria.

There was no significant difference in intracanal bacterial reduction when Ni-Ti GT rotary preparation with NaOCl and EDTA irrigation was used with or without apical enlargement preparation technique. It may therefore not be necessary to remove dentine in the apical part of the root canal when a suitable coronal taper is achieved to allow satisfactory irrigation of the root canal system with antimicrobial agents.

The objective of this study was to evaluate radiographically the technical quality of root canal fillings performed by dental students at the School of Dentistry, University of the West Indies. The school's database between 2000 and 2004 was investigated for patients with completed root canal treatment. The final sample consisted of 198 patients with 288 root-filled teeth and 460 canals. The length, presence of voids, taper, curvature of canal and fractured instruments were recorded and scored. Chi-squared analysis was used to determine statistically significant differences between the technical quality of root fillings and tooth type. Sixty-three per cent, 27.6% and 72.2% of root-filled canals had adequate length, density and taper respectively. The overall acceptability of root fillings having adequate length and taper, absence of voids and no fractured instruments was found in 10.9% of canals. Changes in teaching methods may be required to improve the technical quality of root canal treatment done by dental students.

This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials-Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram-by utilizing microhardness measurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirtytwo extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surface to receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student's t-test. Significance level was set at 5%. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (±17.4) and Variolink II = 228.1 (±36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher values compared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.