Root Canal Microbiome Associated With Asymptomatic Apical Periodontitis as Determined by High-Throughput Sequencing.

INTRODUCTION: Advanced DNA sequencing technology allows more detailed analysis and description of the endodontic microbiome. This study used the MiSeq high-throughput sequencing platform (Illumina, San Diego, CA) to describe the endodontic microbiome of teeth with primary asymptomatic apical periodontitis with no sinus tract. METHODS: Root canal samples from 25 patients were prepared for DNA sequencing analysis. Bacterial diversity of the microbiome was identified and compared between cases and according to the size of the related apical periodontitis lesions. Statistical analyses of the operational taxonomic unit distribution was performed using principal component analysis with the Bray-Curtis distance and a principal coordinate analysis, 2-way permutational multivariate analysis of variance. The chi-square or Fisher exact test was used to evaluate the prevalence of different operational taxonomic units related to small and large apical periodontitis lesions. RESULTS: Although there was a very high bacterial diversity in the microbiome of teeth with asymptomatic apical periodontitis, 4 phyla dominated the microbiome: Firmicutes (27%), Bacteroidetes (21%), Proteobacteria (21%), and Actinobacteria (12%). There was high variability in species composition between root canal samples with no common species pattern for the cases. Large lesions showed a higher number of species but did not significantly differ from small lesions in bacterial diversity indexes. Bacteroidaceae [G-1] bacterium HMT 272, a previously uncultivated but still unnamed and uncharacterized taxon, was the most prevalent and abundant phylotype. CONCLUSIONS: High-throughput sequencing technology confirmed the complexity of the endodontic microbiome and revealed that microbial heterogeneity is a feature between cases. This indicates that various microbial combinations of the endodontic microbiome are able to illicit periapical inflammatory diseases.

Use of technology in endodontics by undergraduate dental students in a south-eastern state of Brazil.

INTRODUCTION: This study aimed to determine the level of incorporation of current technologies for endodontic treatment in undergraduate dentistry courses in a south-eastern state of Brazil. METHODS: For data collection, a self-assessment-based online questionnaire was created using the "Google Forms" platform, consisting of 12 multiple-choice and a few open-ended questions. The questions were related to the use of current technologies for diagnosis, imaging, use of ultrasonics in endodontics, instrumentation, use of apex locator, microscopy, photodynamic therapy and thermoplastic techniques during endodontic treatment. The questionnaire was sent to 54 dental schools in Minas Gerais. RESULTS: The results show low technological incorporation during the various stages of endodontic treatment by undergraduate students in dentistry courses in Minas Gerais. CONCLUSION: Despite the availability of several technologies to help perform different stages of endodontic treatment, it was observed that most universities do not teach the use of these technologies. Additional studies are needed to correlate how the lack of incorporation of these technologies could impact on the quality of the endodontic learning for undergraduate students.

Pulpal response to sensibility tests after traumatic dental injuries in permanent teeth.

BACKGROUND/AIM: The assessment of pulp vitality is one of the major challenges in dental traumatology due to the temporary loss of sensibility after trauma and because of the limitations of conventional pulp tests. The aim of this study was to evaluate pulpal response to sensibility tests and to determine their accuracy after crown fractures and luxation injuries. MATERIALS AND METHODS: A total of 121 permanent anterior teeth from 78 patients treated at the Dental Trauma Clinic of the Federal University of Minas Gerais were evaluated. Responses to pulp sensibility tests were monitored for a minimum period of 24 months or until the diagnosis of pulp necrosis. RESULTS: At the first appointment, 68 teeth responded positively to sensibility tests, one tooth was necrotic and 52 teeth did not respond to sensibility tests but showed no other signs of necrosis. The initial lack of response was not associated with age (P = 0.18), but was related to the presence of luxation (P < 0.001). At the final appointment, 87 teeth were classified as vital and 31 were classified as non-vital. While a positive response shortly after trauma was a good predictor of vitality, a lack of response was not associated with subsequent necrosis. The final pulpal condition of the teeth that initially did not respond was associated with the type of injury, as displaced teeth tended to develop necrosis (P = 0.008). The accuracy of each sensibility test at the initial and final appointments was, respectively, 55.1% and 67.8% for the heat test, 55.9% and 77.9% for the cold test, and 57.6% and 89% for the electrical test. CONCLUSIONS: A temporary loss of sensibility was a frequent finding during post-traumatic pulpal healing, especially after luxation injuries. All sensibility tests presented low accuracy shortly after trauma. The electrical test provided the best support for pulpal diagnosis after long-term follow up. The clinician must be aware of additional signs of crown discoloration and radiographic changes before initiating endodontic treatment.

In vitro evaluation of the cytotoxicity of two root canal sealers on macrophage activity.

Although some studies have been concerned with the cytotoxicity of endodontic sealers and their components, few have approached the effects of endodontic sealers on macrophage viability and activity. In this study the effect of two zinc oxide-eugenol-based sealers, freshly prepared or after setting for 24 h, was determined on macrophage activity in vitro. Sealers were placed inside a glass capillary tube and added to mouse-elicited macrophage cultures. Sealers did not affect macrophage viability; however, adherence to glass and phagocytosis were impaired. Moreover, nitric oxide production in response to activation with interferon-gamma was diminished, but interleukin-12 production in response to Listeria monocytogenes was not altered. Interestingly, freshly mixed and solid test samples had similar inhibitory activities. In conclusion, the tested sealers did not affect a pro-inflammatory response (interleukin-12 production) but had an inhibitory effect on the effector responses measured (phagocytosis and nitric oxide production).