Mapping the periapex anatomical pattern of teeth involved in sodium hypochlorite accidents: a cross-sectional quasi-experimental study.

AIM: To determine the anatomical reasons for sodium hypochlorite (NaOCl) accidents by testing whether this mishap is likely to occur in cases where the anatomical apex of the teeth fenestrates the overlying buccal cortical alveolar bone, allowing NaOCl to gain direct access to buccal soft tissues. METHODOLOGY: Following a cross-sectional, nonrandomized design, 13 patients who suffered unintentional NaOCl accidents whilst undergoing root canal treatment were included. After remission of symptoms, the root canals were fully irrigated with an innocuous radiopaque solution (saline diluted Claritrast 300) and subsequently CBCT scanned to create a 3D-map of the periapex and tracking of the irrigant pathway throughout the periapical tissues. An extra group of five control patients, who underwent root canal treatment with no NaOCl accident, was also CBCT-scanned after irrigation with the tracking radiopaque solution. The anatomical relationship of the cortical bone and the root apex, as well as the distribution of irrigation solution in the periapical tissue, was associated with patients undergoing a NaOCl accident or not, using a Fisher's exact test. RESULTS: The frequency of teeth with apical cortical fenestration was significantly higher in the NaOCl accident-positive group, compared to the negative (P < 0.001). All 13 accident-positive patients had an anatomical apex in direct contact with the buccal soft tissue via fenestration of the overlying cortical bone and direct contact of the foramen with the soft tissues. The radiopaque solution was distributed in the soft tissue in these cases. In contrast, accident-negative patients had no fenestration of the buccal cortical bone and the anatomical root apex was within the cancellous bone or within a bone-confined periapical lesion. The radiopaque solution was also found in the cancellous bone or the periapical lesion, but patients had no manifestations of a NaOCl accident. CONCLUSION: This quasi-experimental cross-sectional clinical study suggests that, in addition to the presence of the extruded NaOCl solution, a patent foramen that fenestrates the cortical bone merging into the mucosal tissue might constitute a risk for the clinical manifestation of a NaOCl accident. Preoperative 3D scans aid in anticipating when an accident is likely to occur.

Preserving dentine in minimally invasive access cavities does not strength fracture resistance of restored mandibular molars.

AIM: To evaluate the correlation between the volume of dental hard tissues removed and the fracture resistance of mandibular molar teeth with ultraconservative (UltraAC) or traditional (TradAC) access cavity preparations. METHODOLOGY: Sixty recently extracted and intact mandibular first molars were scanned in a microcomputed tomographic (micro-CT) device, anatomically matched and assigned at random to 2 groups (n = 30), according to the access cavity type: UltraAC or TradAC. After access preparation, mesial and distal canals were prepared using Reciproc instruments and a new scan was taken. The volumes of pulp chamber and dental hard tissues in each specimen were measured before and after the experimental procedures, and the percentage volume reduction of hard tissues calculated for the entire tooth and for the crown separately. Teeth were then root filled, restored and subjected to fracture resistance tests in an universal testing machine. The force required to fracture was recorded in Newtons (N). The adherence of the variables to a Gaussian curve was verified using a Shapiro-Wilk test. Skewed data were analysed with nonparametric Wilcoxon signed rank or Spearman correlation tests, whilst the normally distributed data were analysed with a dependent samples Student t-test. Level of significance was set at 5%. RESULTS: Pre-operatively, no difference was observed between groups regarding the volume of pulp canal space or dental hard tissues (P > 0.05). After access preparation, volumes of the removed hard tissues from the entire tooth and from the crown were significantly greater in teeth prepared with TradAC than with UltraAC (P < 0.05). No significant difference was observed in the fracture resistance values between TradAC (902.9 ± 347.8 N) and UltraAC (948.7 ± 405.7 N) groups (P = 0.975). The Spearman test was unable to identify a correlation between fracture resistance and percentage volume of removed dental hard tissues in the entire root (P = 0.525, r = -0.084) or only in the crown (P = 0.152, r = -0.187). CONCLUSION: The volume of hard dental tissues removed, although greater in teeth with TradAC compared to UltraAC, did not correlate with the fracture resistance results, indicating that a minimally invasive access cavity did not increase the resistance of restored mandibular first molars to fracture.

Do pre-existing microcracks play a role in the fracture resistance of roots in a laboratory setting?

AIM: To investigate a potential cause-effect relationship between dentinal microcracks and fracture resistance of mandibular incisors that had not been endodontically treated. METHODOLOGY: Sixty mandibular incisors with circular-shaped canals were selected based on micro-computed tomographic scans to create a homogeneous sample. The cross-sectional images of the specimens were screened to identify and quantify the presence of dentinal microcracks. Then, teeth were embedded in polystyrene resin and subjected to axial compressive loading using a universal testing machine. After fracture, the roots were re-scanned and fractography analysis was performed by inspection of 3D models to verify crack propagation. Spearman's rank correlation was used to assess the correlation between the number of microcracks and force required to fracture. RESULTS: Dentinal microcracks were detected in 79% of the specimens (n = 44). The incidence of microcracks varied between teeth from 6% to 42% of the total slices per sample (average of 14 ± 17%). The number of microcracks per sample varied from 0 to 1605, with an average of 412 ± 484 (median = 221 and IQR 25% = 15/75% = 658). The load at failure values varied from 227 to 924 N, with an average of 560.3 ± 168.1 N (median = 561 and IQR 25% = 458/75% = 694). The Spearman correlation coefficient (rho) equalled 0.065. CONCLUSIONS: There was no cause-effect relationship between the number of dentinal microcracks and the fracture resistance of nonendodontically treated mandibular incisors. The presence and quantity of microcracks did not make these roots more prone to fracture.

Creation of well-balanced experimental groups for comparative endodontic laboratory studies: a new proposal based on micro-CT and in silico methods.

AIM: To introduce a new method to select anatomically matched teeth using micro-computed tomographic (micro-CT) technology. METHODOLOGY: Single-rooted mandibular incisors with a single root canal (n = 60) were selected and distributed into three experimental groups according to the method used for matching 10 pairs of teeth in each group. In group 1, the pairs of mandibular incisors were randomly selected from a pool of teeth. In group 2, teeth were paired based on the measurement of canal width 5 mm from the root apex using radiographs taken from buccolingual and mesiodistal directions. In group 3, teeth were scanned (pixel size of 14.25 µm) and pair-matched based on the anatomical aspects of the root canal, named aspect ratio (AR), volume and three-dimensional canal geometry. After allocating the specimens into groups 1 and 2, the teeth were scanned and the canal morphology evaluated as in group 3. A bivariate Pearson's regression analysis was performed correlating the individual AR values of each pair, and the correlation coefficient was used to estimate the strength of the pair-matching process. One-way anova post hoc Tukey's tests were applied for pairwise comparisons at a significance level of 5%. RESULTS: The micro-CT revealed that 100% of the samples had strong (80%) or very strong (20%) correlations with respect to AR values. Analysis of the radiographic method revealed strong correlation in two pairs (20%), but most of the samples had weak (30%) or negligible (30%) correlation coefficients. The randomization method resulted in three pairs (30%) with very strong correlations, whilst 50% had weak or negligible rates. A significant difference in correlation coefficients was observed in the micro-CT method compared to the other groups (P < 0.05), whilst no difference was detected between radiographic and randomized methods (P > 0.05). Eta-squared (η2 ) calculations demonstrated a very high effect size in the micro-CT group for selecting pairs (0.99) and lower effect sizes in the radiographic (0.67) and randomized (0.66) groups. CONCLUSIONS: Use of Micro-CT was able to provide better control of the confounding effect that anatomical variances in tooth morphology may have on the results in experiments with matched-pair design.

Arrowhead design ultrasonic tip as a supplementary tool for canal debridement.

AIM: To investigate the shaping and cleaning performance of the Clearsonic ultrasonic tip as a supplementary tool during the preparation of long oval-shaped root canals through micro-computed tomographic (micro-CT) imaging technology. The Reciproc M-Wire R40 instrument was used as a reference instrumentation technique for comparison. METHODOLOGY: Twenty mandibular incisors with single, straight and long oval-shaped canals were selected and pair-matched by micro-CT scanning. The root canals were prepared with Reciproc R25 and R40 instruments, scanned again in a micro-CT device and randomly allocated into one of the two experimental groups (n = 10), according to the supplementary debridement protocol used: Clearsonic or Reciproc R40 used in a brushing motion against buccal and lingual walls. Noninstrumented canal areas, accumulation of hard-tissue debris (AHTD) and volume of removed dentine were assessed using micro-CT imaging following the supplementary debridement protocols. Data were analysed statistically in two phases using a t-test with a significance level of 5%. RESULTS: In phase-1, there was a significant similarity between the samples regarding the evaluated micro-CT baseline parameters (P > 0.05), validating the anatomical similarity between the tooth pairs. In phase-2, there was a significant difference between the groups for canal volume, surface area, noninstrumented root canal walls and the amount of removed dentine for both absolute and percentage values (P < 0.05), but not for AHTD (P = 0.759). CONCLUSIONS: The Clearsonic tip outperformed the Reciproc R40 instrument as a supplementary debridement protocol as it was associated with significantly greater reduction of noninstrumented root canals walls and consequently a larger amount of removed dentine. Both groups performed similarly regarding the AHTD.

Dentinal microcracks on freshly extracted teeth: the impact of the extraction technique.

AIM: To evaluate the incidence of root dentinal microcracks after two extraction techniques through micro-computed tomographic (micro-CT) analysis. METHODOLOGY: Thirty pairs of premolars, extracted for orthodontic reasons, were assigned to two experimental groups, following a split-mouth design (n = 30): traumatic technique group (TTG) - teeth extracted following a conventional protocol using forceps, and an atraumatic technique group (ATG) - teeth extracted following an atraumatic technique protocol in which the root was gently detached from the periodontal ligament using a periotome. All teeth were immediately immersed in distilled water and scanned in a micro-CT device within 72 h following the extraction. The assessment of the images was completed on cross-section images by two masked evaluators. The Mann-Whitney test was used to assess the significant differences between the groups regarding the number of cross-sections displaying microcracks whilst the Fischer's exact test was used to assess differences in the frequency of specimens with defects (P < 0.05). RESULTS: A total of 52 750 micro-CT cross-sectional images were evaluated. A total of 352 cross-sections had at least one dentinal defect. Microcracks were observed in five teeth of the TTG group (n = 352 slices) and in two teeth of the ATG group (n = 103 slices). The statistical analysis used was unable to detect a significant difference between the groups in terms of the number of dentinal microcracks (P = 0.233) and in the frequency of teeth displaying microcracks (P = 0.424). CONCLUSION: A small number of sound teeth without endodontic treatment had dentinal microcracks regardless of the extraction technique applied. No difference was noticed between the traumatic and atraumatic techniques in the incidence of microcracks.

Natural vertical infection by dengue virus serotype 4, Zika virus and Mayaro virus in Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus.

Vertical transmission to progeny ensures the maintenance of arboviruses in their natural vectors. This mechanism is largely reported for dengue virus (DENV) and yellow fever virus (YFV). Few studies have addressed this mechanism for Zika virus (ZIKV), Mayaro virus (MAYV) and other arboviruses. The present study investigated the natural infection rate by arboviruses in 4490 Aedes (Stegomyia) aegypti and 296 Aedes (Stegomyia) albopictus (Diptera: Culicidae) reared from eggs collected with ovitraps in Cuiabá, Mato Grosso State, from February to July, 2017. After viral RNA extraction and reverse transcriptase-polymerase chain reaction protocols for 10 flaviviruses and five alphaviruses, nucleotide sequencing and three passages in C6/36 cells, eight pools of Ae. aegypti positive for DENV-4 genotype II, seven for ZIKV Asian genotype and two for MAYV genotype L were found. In addition, two Ae. albopictus pools were positive for DENV-4 genotype II and two were positive for ZIKV Asian genotype. Infection was confirmed by viral isolation in all positive pools for DENV-4 and for MAYV and in eight of nine for ZIKV. This mechanism may contribute to the spread of arboviruses during epidemics and also to their maintenance in natural vectors during interepidemic periods.

Bovine teeth can reliably substitute human dentine in an intra-tooth push-out bond strength model?

AIM: To investigate the reliability of using bovine teeth as an alternative to human teeth in an intra-tooth push-out model by comparing the bond strength of three root canal sealers in both tooth substrates. METHODOLOGY: From human and bovine incisors (12 per group), one 1-mm disc was obtained from each root. On each disc, three standard 0.8-mm-diameter holes were drilled through the dentine. After irrigation, the holes were filled with one of three root canal sealers: AH Plus, MTA Fillapex or Total Fill BC Sealer. Tooth slices were kept in contact with sterile gauze moistened in PBS solution (pH = 7.2) for 7 days at 37 °C, and finally, a push-out load was applied until sealer dislocation. The bonded interface area was calculated to obtain data in MPa. The push-out data for each sealer and the overall push-out data for human and bovine teeth were compared (Mann-Whitney U). Kruskal-Wallis was used to study the sealers behaviour at each of the dental substrates. Multiple comparisons were performed using Mann-Whitney U after Bonferroni correction (P < 0.05). RESULTS: Dentine substrate did not influence the push-out of either individual sealers or overall sealers tested (Mann-Whitney U, P > 0.05). In both human and bovine samples, AH Plus performed better than BC Sealer and MTA Fillapex, whilst BC Sealer also provided a superior push-out compared to MTA Fillapex (Mann-Whitney U, P < 0.05). CONCLUSION: When using an intra-tooth model, bovine teeth did not significantly influence the bond strength of sealers.

Shaping efficiency as a function of time of a new heat-treated instrument.

AIM: To assess the shaping ability of the new XP-endo Shaper instrument after different working times. METHODOLOGY: Ten mesial roots of mandibular molars were scanned in a micro-computed tomographic device and prepared using the XP-endo Shaper instrument up to the working length (WL) according to the manufacturer's recommendation. Then, each specimen was subjected to an extra 15, 30 and 45 s of active instrumentation at the WL. Postoperative scans were performed after canal preparation at each time-point. Then, the registered pre- and postoperative datasets were examined to evaluate the percentages of volume and surface area of the instrumented canal, surface area of noninstrumented canal areas and the volume of removed dentine. Repeated measures general linear model was used to compare the differences in either the increase or the reduction of the parameters amongst the time-points. Alpha-error was set at 5%. RESULTS: Extending the period of XP-endo Shaper active instrumentation at WL significantly influenced several parameters such as volume (P < 0.001) and surface area (P < 0.001) of the instrumented canal, surface area of noninstrumented canal areas (P < 0.001), and volume of removed dentine (P < 0.001). CONCLUSIONS: Extending the activation time of XP-endo Shaper instruments at WL resulted in a more comprehensive root canal preparation, increasing the volume and surface area of root canal preparation and the volume of removed dentine.

XP-endo Finisher R instrument optimizes the removal of root filling remnants in oval-shaped canals.

AIM: To evaluate the performance of XP-endo Finisher R instruments when removing root filling remnants from oval-shaped canals using microcomputed tomographic (micro-CT) imaging as the analytical tool. Passive ultrasonic irrigation (PUI) was used as a reference technique for comparison. METHODOLOGY: Twenty mandibular incisors with oval-shaped canals were matched based on similar anatomic features of the canal (volume, aspect ratio and 3D configuration) after scanning procedures. The canals were prepared with Reciproc R25 instruments, filled with gutta-percha and AH Plus sealer using the single-cone technique and retreated up to a Reciproc R40 instrument. After retreatment procedures, the specimens were rescanned, and the homogeneity between the specimens, the oval-shaped anatomy and the remaining filling material were confirmed. The pair-matched samples were assigned to two experimental groups (n = 10), according to the supplementary approach used: XP-endo Finisher R or PUI. Each sample was scanned after each endodontic procedure. The volume of remaining root filling material was quantified before and after the use of each supplementary approach. This analysis was performed considering the total canal (Student t-test) and also by thirds (anova procedure followed by a Bonferroni correction). Data were analysed statistically with a significance level of 5%. RESULTS: The volume of root filling material at baseline was similar between the groups (t-test, P = 0.787). XP-endo Finisher R removed significantly more root filling material compared to PUI (t-test, P = 0.015), as it removed a mean of ≅32% material compared to 12% for the PUI. There was no difference in the amount of root filling material removed in the root canal thirds after using both supplementary approaches (one-way anova, P = 0.07 for XP-endo Finisher R and P = 0.886 for PUI). CONCLUSIONS: Both supplementary approaches significantly reduced the volume of remaining root filling material from oval-shaped canals. The XP-endo Finisher R instrument removed significantly more root filling material than PUI. None of the supplementary approaches was able to render oval-shaped canals completely free from remaining root filling material.

Root dentinal microcracks: a post-extraction experimental phenomenon?

AIM: To investigate the prevalence, location and pattern of pre-existing microcracks in non-endodontically treated teeth from fresh cadavers. Micro-computed tomography (micro-CT) technology was used as the analytical tool enabling full screening of the root dentine with the teeth retained in their original alveolar socket. METHODOLOGY: As a pilot study and to validate the present method, a series of 4 high-resolution scans were performed on one bone-block specimen with teeth collected post-mortem: (i) entire bone-block including the teeth, (ii) second molar tooth extracted atraumatically from the bone-block, (iii) extracted tooth dehydrated to induce dentinal defects and (iv) entire bone-block following reinsertion of the extracted tooth into its matching alveolar socket. In the main study, forty-two dentoalveolar maxillary and mandibular bone-blocks each containing 3-5 adjacent teeth (a total of 178 teeth) were collected post-mortem and scanned in a micro-CT device. All cross-section images of the 178 teeth (n = 65 530) were screened from the cementoenamel junction to the apex to identify the presence of dentinal defects. RESULTS: In the pilot study, the microcracks observable when the dehydrated tooth was outside the bone-block remained detectable when the entire bone-block plus reinserted tooth was scanned. This means that the screening process revealed the presence of the same microcracks in both experimental situations (the tooth outside and inside the maxillary bone-block). From a total of 178 teeth in the bone-blocks removed from cadavers, 65 530 cross-sectional images were analysed and no dentinal microcracks were detected. CONCLUSIONS: This in situ cadaveric model revealed the lack of pre-existing dentinal microcracks in non-endodontically treated teeth. Thus, the finding of dentinal microcracks observed in previous cross-sectional images of stored extracted teeth is unsound and not valid. It should be assumed that microcracks observed in stored extracted teeth subjected to root canal procedures are a result of the extraction process and/or the post-extraction storage conditions. Therefore, as a consequence, the presence of such dentinal microcracks in stored extracted teeth - observable in cross-sectional images of the roots - should be referred to as experimental dentinal microcracks.

Impact of infected and noninfected human dentine debris on bone healing in rats.

AIM: To evaluate in vivo the bone tissue response of rats to varying amounts of infected and noninfected dentine debris. METHODOLOGY: Bone tissue reactions were evaluated histologically in 42 Wistar rats after 7, 30 and 60 days. For each animal, three surgical cavities were prepared on the femur and filled with varying amounts (5, 10 or 20 mg) of infected or noninfected dentine debris pellets. In the negative control group, the surgical cavities were not filled. At the end of each experimental period, the animals were euthanized. The samples were processed histologically and analysed using a light microscope. The presence and the severity of inflammatory reaction, as well as hard tissue deposition were evaluated. Data were subjected to statistical analysis and the effects of the dependent variables calculated using nonparametric tests Kruskal-Wallis and Mann-Whitney U with due Bonferroni corrections at P = 0.05. RESULTS: At 7 days, the presence of infected debris significantly increased the histopathological scores for neutrophils (P < 0.05), and abscess formation (P < 0.05). Noninfected debris scored significantly higher for lymphocyte infiltrate compared with the control group and infected debris (P < 0.05). Both infected and noninfected debris equally triggered eosinophil cells compared with no-dentine (P < 0.05). As for giant cells and macrophages, no difference was detected amongst the dentine groups (P > 0.05). Hard tissue deposition was similar regardless of the presence or the bacteriological status of the dentine (P = 1.00). None of the above histopathological parameters was significantly influenced by the amount of debris (P > 0.05). For all parameters evaluated, at 7 days of analysis, the inflammatory response was significantly more intense compared with 30 and 60 days (P < 0.05). Inflammatory parameters were scored similarly for the evaluated groups after 30 and 60 days (P > 0.05). However, hard tissue deposition has significantly increased after 30 days (P < 0.05). No difference was seen between 30 and 60 days of analysis (P = 1.00) for all histological parameters evaluated. CONCLUSION: The assumption that the amount of extruded debris may negatively affect the inflammatory response of bone tissue was not validated in the present in vivo animal study. Infected dentine may trigger acute inflammatory parameters especially during the first 7 days of contact with the tissue; however, in the long term, these negative effects are mitigated.

Anatomical danger zone reconsidered: a micro-CT study on dentine thickness in mandibular molars.

AIM: To investigate the smallest dentine thickness in mesial canals of mandibular molars along the cervical and middle thirds of the root by means of a micro-computed tomographic (micro-CT) technology and digital image analysis. METHODOLOGY: Fifty mesial roots of mandibular molars having two independent canals (mesiobuccal and mesiolingual), in the coronal and middle levels, were selected and scanned in a micro-CT device. After reconstruction procedures, approximately 468 slices per root covering the 7 mm below the furcation area of the mesial root were analysed to measure the smallest dentine thickness (danger zone [DZ]) in each slice from both distal and mesial regions of the mesial canals by an automatic segmentation process. RESULTS: The DZ values in the mesiobuccal canals varied from 0.67 to 1.93 mm, with an average of 1.13 ± 0.21 mm. For the mesiolingual canals, the DZ varied from 0.77 to 1.89 mm with an average of 1.10 ± 0.21 mm. There was no correspondence in the DZ between the mesiobuccal and mesiolingual canals at the same cross-sectional level in 71% of the specimens. Moreover, the smallest dentine thickness was towards the mesial region of the roots in 22% and 18% of the mesiolingual and mesiobuccal canals, respectively. (Figs 1 and 2 CONCLUSIONS: The smallest dentine thickness was on the mesial plane of the roots in about 40% of the canals. The vertical location of the DZ in relation to the furcation area was in the middle third of the root.

Effectiveness of XP-endo Finisher and XP-endo Finisher R in removing root filling remnants: a micro-CT study.

AIM: To evaluate the efficacy of filling material removal from oval-shaped canals after the use of supplementary files (XP-endo Finisher and XP-endo Finisher R) through microcomputed tomographic (micro-CT) analysis. METHODOLOGY: The root canals of twenty maxillary single-rooted teeth were prepared with Reciproc R25 files and filled with gutta-percha and AH Plus sealer using the continuous wave of condensation technique. The root canals were then retreated using Reciproc R25 and R40 instruments. After this, the specimens were assigned to two groups according to the supplementary cleaning approach, using XP-endo Finisher and XP-endo Finisher R. The surface area and volume of removed filling material was assessed using micro-CT imaging before and after the use of the XP-endo instruments. Data were analysed statistically with a significance level of 5%. RESULTS: Removal of filling material at 66.8% and 59.4% in volume and 67.3% and 61.4% in surface area was seen for the XP-endo Finisher and the XP-endo Finisher R files, respectively. The amount of filling material removed by both supplementary files was highly significant (P = 0.000). No significant difference in the percentage of removed filling material was detected for the XP-endo instruments (P = 0.636 for volume and P = 0.667 for surface area). CONCLUSIONS: Both XP-endo files were equally effective in the removal of remaining filling material from straight oval-shaped canals. None of the instruments were able to remove all the residual filling material.

Micro-CT assessment of the shaping ability of four root canal instrumentation systems in oval-shaped canals.

AIM: To compare the shaping ability of four root canal instrumentation systems in oval-shaped canals using micro-computed tomographic analysis. METHODOLOGY: Forty anatomically matched mandibular incisors were scanned and assigned to four groups (n = 10), according to the canal preparation protocol: BioRace, Reciproc, Self-Adjusting File (SAF) and TRUShape systems. After canal instrumentation, the specimens were rescanned, and the registered pre- and postoperative datasets were examined to evaluate the percentages of accumulated hard-tissue debris, untouched canal walls and dentine removed. Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni correction were used to compare the variables in the groups (α = 5%). RESULTS: The preparation techniques did not affect the percentage of accumulated hard-tissue debris (P = 0.126). The percentage of untouched canal areas was significantly higher for BioRace (32.38%)compared to Reciproc (18.95%) and SAF (16.08%) systems (P < 0.05). Reciproc removed significantly more dentine (4.18%) than BioRace (2.21%) and SAF (2.56%) (P < 0.05). The TRUShape system had intermediate results for both untouched canal walls (19.20%) and dentine removed (3.77%), with no significant difference compared to BioRace, Reciproc and SAF systems. CONCLUSIONS: The preparation techniques resulted in the same level of accumulated hard-tissue debris. Compared to the other tested systems, BioRace was associated with more untouched canal walls and Reciproc produced the greatest amount of removed dentine. Although it touched more of the root canal walls, the SAF system removed less dentine, whereas TRUShape had intermediate results for these same parameters. None of the systems tested were able to provide optimal shaping ability in oval-shaped canals.

A NodD-like protein activates transcription of genes involved with naringenin degradation in a flavonoid-dependent manner in Herbaspirillum seropedicae.

Herbaspirillum seropedicae is an associative, endophytic non-nodulating diazotrophic bacterium that colonises several grasses. An ORF encoding a LysR-type transcriptional regulator, very similar to NodD proteins of rhizobia, was identified in its genome. This nodD-like gene, named fdeR, is divergently transcribed from an operon encoding enzymes involved in flavonoid degradation (fde operon). Apigenin, chrysin, luteolin and naringenin strongly induce transcription of the fde operon, but not that of the fdeR, in an FdeR-dependent manner. The intergenic region between fdeR and fdeA contains several generic LysR consensus sequences (T-N11 -A) and we propose a binding site for FdeR, which is conserved in other bacteria. DNase I foot-printing revealed that the interaction with the FdeR binding site is modified by the four flavonoids that stimulate transcription of the fde operon. Moreover, FdeR binds naringenin and chrysin as shown by isothermal titration calorimetry. Interestingly, FdeR also binds in vitro to the nod-box from the nodABC operon of Rhizobium sp. NGR234 and is able to activate its transcription in vivo. These results show that FdeR exhibits two features of rhizobial NodD proteins: nod-box recognition and flavonoid-dependent transcription activation, but its role in H. seropedicae and related organisms seems to have evolved to control flavonoid metabolism.

Molecular characterisation of Salmonella strains isolated from outbreaks and sporadic cases of diarrhoea occurred in Paraná State, South of Brazil.

A total of 46 strains of Salmonella isolated from patients with sporadic diarrhoea or involved in foodborne outbreaks were analysed by PCR for genus identification and serotyping. Subtyping was performed using pulsed-field gel electrophoresis (PFGE) and multiple amplification of phage locus typing (MAPLT) for seven variable loci. Bacteria were identified as belonging to serotype Enteritidis (33 strains; 71·7%) or Typhimurium (13 strains; 28·3%). A high similarity coefficient (94·6%) was observed in the Salmonella Enteritidis group for which were found three related PFGE profiles and only one MAPLT; strains representing profile PA/P1/MI were prevalent (27; 81·8%). Two Salmonella Typhimurium isolates were untypeable by PFGE. The remaining 11 strains had eight PFGE and three MAPLT profiles. The discriminatory power of MAPLT was lower than that of PFGE. Salmonella Enteritidis of clonal nature is predominant in Paraná State, with the most prevalent profile PA/P1/M1 associated with sporadic diarrhoea and with seven of nine reported outbreaks. In conclusion, PFGE shows higher discriminatory power among Salmonella strains.

Exploring the genomic diversity of black yeasts and relatives (Chaetothyriales, Ascomycota).

The order Chaetothyriales (Pezizomycotina, Ascomycetes) harbours obligatorily melanised fungi and includes numerous etiologic agents of chromoblastomycosis, phaeohyphomycosis and other diseases of vertebrate hosts. Diseases range from mild cutaneous to fatal cerebral or disseminated infections and affect humans and cold-blooded animals globally. In addition, Chaetothyriales comprise species with aquatic, rock-inhabiting, ant-associated, and mycoparasitic life-styles, as well as species that tolerate toxic compounds, suggesting a high degree of versatile extremotolerance. To understand their biology and divergent niche occupation, we sequenced and annotated a set of 23 genomes of main the human opportunists within the Chaetothyriales as well as related environmental species. Our analyses included fungi with diverse life-styles, namely opportunistic pathogens and closely related saprobes, to identify genomic adaptations related to pathogenesis. Furthermore, ecological preferences of Chaetothyriales were analysed, in conjuncture with the order-level phylogeny based on conserved ribosomal genes. General characteristics, phylogenomic relationships, transposable elements, sex-related genes, protein family evolution, genes related to protein degradation (MEROPS), carbohydrate-active enzymes (CAZymes), melanin synthesis and secondary metabolism were investigated and compared between species. Genome assemblies varied from 25.81 Mb (Capronia coronata) to 43.03 Mb (Cladophialophora immunda). The bantiana-clade contained the highest number of predicted genes (12 817 on average) as well as larger genomes. We found a low content of mobile elements, with DNA transposons from Tc1/Mariner superfamily being the most abundant across analysed species. Additionally, we identified a reduction of carbohydrate degrading enzymes, specifically many of the Glycosyl Hydrolase (GH) class, while most of the Pectin Lyase (PL) genes were lost in etiological agents of chromoblastomycosis and phaeohyphomycosis. An expansion was found in protein degrading peptidase enzyme families S12 (serine-type D-Ala-D-Ala carboxypeptidases) and M38 (isoaspartyl dipeptidases). Based on genomic information, a wide range of abilities of melanin biosynthesis was revealed; genes related to metabolically distinct DHN, DOPA and pyomelanin pathways were identified. The MAT (MAting Type) locus and other sex-related genes were recognized in all 23 black fungi. Members of the asexual genera Fonsecaea and Cladophialophora appear to be heterothallic with a single copy of either MAT-1-1 or MAT-1-2 in each individual. All Capronia species are homothallic as both MAT1-1 and MAT1-2 genes were found in each single genome. The genomic synteny of the MAT-locus flanking genes (SLA2-APN2-COX13) is not conserved in black fungi as is commonly observed in Eurotiomycetes, indicating a unique genomic context for MAT in those species. The heterokaryon (het) genes expansion associated with the low selective pressure at the MAT-locus suggests that a parasexual cycle may play an important role in generating diversity among those fungi.

A quality assessment of randomized controlled trial reports in endodontics.

AIM: To assess the quality of the randomized clinical trial (RCT) reports published in Endodontics between 1997 and 2012. METHODOLOGY: Retrieval of RCTs in Endodontics was based on a search of the Thomson Reuters Web of Science (WoS) database (March 2013). Quality evaluation was performed using a checklist based on the Jadad criteria, CONSORT (Consolidated Standards of Reporting Trials) statement and SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials). Descriptive statistics were used for frequency distribution of data. Student's t-test and Welch test were used to identify the influence of certain trial characteristics upon report quality (α = 0.05). RESULTS: A total of 89 RCTs were evaluated, and several methodological flaws were found: only 45% had random sequence generation at low risk of bias, 75% did not provide information on allocation concealment, and 19% were nonblinded designs. Regarding statistics, only 55% of the RCTs performed adequate sample size estimations, only 16% presented confidence intervals, and 25% did not provide the exact P-value. Also, 2% of the articles used no statistical tests, and in 87% of the RCTs, the information provided was insufficient to determine whether the statistical methodology applied was appropriate or not. Significantly higher scores were observed for multicentre trials (P = 0.023), RCTs signed by more than 5 authors (P = 0.03), articles belonging to journals ranked above the JCR median (P = 0.03), and articles complying with the CONSORT guidelines (P = 0.000). CONCLUSIONS: The quality of RCT reports in key areas for internal validity of the study was poor. Several measures, such as compliance with the CONSORT guidelines, are important in order to raise the quality of RCTs in Endodontics.

Micro-CT assessment of dentinal micro-cracks after root canal filling procedures.

AIM: To evaluate the frequency of dentinal micro-cracks after root canal filling procedures with GuttaCore (GC), cold lateral compaction (CLC) and warm vertical compaction (WVC) techniques in mandibular molars using micro-computed tomographic analysis. METHODOLOGY: Thirty mesial roots of mandibular molars, with a type II Vertucci's canal configuration, were prepared to working length with a Reciproc R40 instrument and randomly assigned to one of the three experimental groups (n = 10), according to the technique used for root filling: GC, CLC or WVC. The GC group was filled with a size 40 GC obturator, whilst CLC and WVC groups used conventional gutta-percha cones. AH Plus sealer was used in all groups. The specimens were scanned at an isotropic resolution of 14.25 µm before and after root canal preparation and after root filling. Then, all pre- and postoperative cross-sectional images of the roots (n = 41 660) were screened to identify the presence of dentinal defects. RESULTS: Overall, 30.75% (n = 12 810) of the pre- + post-filling images displayed dentinal defects. In the GC, CLC and WVC groups, dentinal micro-cracks were observed in 18.68% (n = 2510), 15.99% (n = 2389) and 11.34% (n = 1506) of the cross-sectional images, respectively. All micro-cracks identified in the post-filling scans were also observed in the corresponding post-preparation images. CONCLUSION: Root fillings in all techniques did not induce the development of new dentinal micro-cracks.