Apical extrusion of bacteria when using reciprocating single-file and rotary multifile instrumentation systems.

AIM: To evaluate ex vivo, apical bacterial extrusion associated with two reciprocating single-file systems (WaveOne and Reciproc) compared with a conventional multifile rotary system (BioRace). METHODOLOGY: Forty-five human single-rooted mandibular incisors were used. Endodontic access cavities were prepared, and root canals were contaminated with an Enterococcus faecalis suspension. Following incubation at 37 °C for thirty days, the contaminated teeth were divided into three groups of 15 specimens each (G1 - Reciproc, G2 - WaveOne and G3 - BioRace). Positive and negative controls consisted of 5 infected teeth and 3 uninfected incisors that were instrumented with one of the tested NiTi systems, respectively. Bacteria extruded from the apical foramen during instrumentation were collected into vials containing 0.9% NaCl. The microbiological samples were taken from the vials and incubated in brain heart agar medium for 24 h. The resulting bacterial titre, in colony-forming units (CFU) per mL, was determined, and these data were analysed by Wilcoxon matched-pairs signed rank test and Kruskal-Wallis H-test. The level of significance was set at α = 0.05. RESULTS: No significant difference was found in the number of CFU between the two reciprocating systems (P = 0.41). The conventional multifile rotary system group was associated with significantly higher CFU than both of the two reciprocating groups (P = 0.01). CONCLUSIONS: All instrumentation systems extruded bacteria beyond the foramen. However, both reciprocating single-file systems extruded fewer bacteria apically than the conventional multifile rotary system.

The ability of the Reciproc R25 instrument to reach the full root canal working length without a glide path.

AIM: To assess the frequency in which the Reciproc instrument reaches the full working length (FWL) of mandibular molar canals without a glide path. METHODOLOGY: From a pool of mandibular molars, 253 root canals were classified as straight (G1) and, 249 root canals as moderately curved (G2) following Schneider's method. A R25 Reciproc instrument (VDW, Munich, Germany) was advanced in the canals without any previous glide path. All cases where Reciproc instruments reached the FWL were classified as 'Reaching the FWL' (RFWL). When the FWL was not reached by the R25, the root canals were classified as 'Not Reaching the FWL' (NRFWL). Pearson's χ(2) test compared (i) the frequency distributions of root canals classified as RFWL and NRFWL for each group and (ii) the frequency distributions of NRFWL canals between the groups. RESULTS: In G1, 9 cases (3.56%) and in G2, 23 canals (9.34%) were classified as NRFWL. The difference between NRFWL and RFWL was significant in both groups (P = 0.00, χ(2) = 217.2 for G1; P = 0.00, χ(2) = 167.8 for G2). The frequency of NRFWL was significantly higher for G2 (P = 0.02, χ(2) = 5.452). CONCLUSION: The R25 Reciproc instrument is able to reach the FWL of straight- and moderate-curved mandibular molar canals without a glide path in a large proportion of cases.

Pharmacokinetic and pharmacodynamic comparison of two "pegylated" interferon alpha-2 formulations in healthy male volunteers: a randomized, crossover, double-blind study.

BACKGROUND: Interferon (IFN) alpha conjugation to polyethylene glycol (PEG) results in a better pharmacokinetic profile and efficacy. The aim of this study was to compare the pharmacokinetic, pharmacodynamic and safety properties of a new, locally developed, 40-kDa PEG-IFN alpha-2b preparation with a reference, commercially available PEG-IFN alpha-2a in healthy male volunteers. METHODS: A randomized, crossover, double-blind study with a 3-weeks washout period, was done. A single 180 micrograms PEG-IFN alpha-2 dose was administered subcutaneously in both groups. Sixteen apparently healthy male subjects were included. Serum PEG-IFN concentration was measured during 336 hours by an enzyme immunoassay (EIA). Other clinical and laboratory variables were used as pharmacodynamic and safety criteria. RESULTS: The pharmacokinetic comparison by EIA yielded a high similitude between the formulations. In spite of a high subject variability, the parameters' mean were very close (in all cases p > 0.05): AUC: 53623 vs. 44311 pg.h/mL; Cmax: 333 vs. 271 pg/mL; Tmax: 54 vs. 55 h; half-life (t1/2): 72.4 vs. 64.8 h; terminal elimination rate (lambda): 0.011 vs. 0.014 h(-1); mean residence time (MRT): 135 vs. 123 h for reference and study preparations, respectively. There were no significant differences with respect to the pharmacodynamic variables either: serum neopterin and beta-2 microglobulin levels, stimulation of 2'5' oligoadenylate synthetase expression, and serum IFN antiviral activity. A strong Spearman's rank order correlation (p < 0.01) between the pharmacokinetic and pharmacodynamic concentration-time curves was observed. Both products caused similar leukocyte counts diminution and had similar safety profiles. The most frequent adverse reactions were leukopenia, fever, thrombocytopenia, transaminases increase and asthenia, mostly mild. CONCLUSIONS: Both formulations are fully comparable from the pharmacokinetic, pharmacodynamic, and safety profiles. Efficacy trials can be carried out to confirm clinical similarity.

Similar expression of through-and-through fluid movement along orthograde apical plugs of MTA Bio and white Portland cement.

AIM: To compare the sealing ability of four hydraulic cements when used as an apical plug in teeth with wide-open apices. METHODOLOGY: A sample of 70 maxillary central incisors were divided into four groups (n = 15) and a further 10 teeth served as controls. An artificial open apex was created in the teeth using Gates Glidden drills numbers 6-1 in a crown-down manner until the size 1 bur passed through the foramen. A divergent open apex was prepared to a size of 1.24 mm at the foramen by retrograde apical transportation using a number 8 (0.60) Profile Series 29 0.4 taper instrument inserted to the length of the cutting blade. In G1, the open apices were repaired with WMTA Angelus whilst in G2, G3 and G4 MTA Bio, Pro-Root MTA and Portland cement was employed respectively. Each root was assembled in a hermetic cell to allow the evaluation of fluid filtration. Leakage was measured by the movement of an air bubble travelling within a pipette connected to the teeth. Measurements of the air bubble movement were made after 10 min at a constant pressure of 50 cm H(2)O. The Kruskal-Wallis H-test was applied to the fluid flow data to detect differences between the experimental groups (P < 0.05). RESULTS: Fluid movement occurred in every sample but was variable in all the experimental groups, ranging from 0.61 to 2.45 microL min(-1). There was no significant difference in mean fluid flow between the experimental groups (P > 0.05). CONCLUSIONS: Fluid movement through teeth with open apices and filled with four hydraulic cements was similar. All cements allowed fluid movement.

Microbiological evaluation of primary endodontic infections in teeth with and without sinus tract.

AIM: To examine the microbiological status of primary endodontic infections in teeth with and without a sinus tract. METHODOLOGY: Samples were collected by means of a size 15 H-type file and two sterile paper points from 30 cases of primary endodontic infections with (n = 15) or without (n = 15) a sinus tract. The presence of 40 bacterial species was determined by the checkerboard DNA-DNA hybridization method. RESULTS: The species found at the highest levels and prevalence were Fusobacterium nucleatum sp. vincentii, Porphyromonas gingivalis, Veillonella parvula, Enterococcus faecalis, Campylobacter gracilis and Neisseria mucosa. Total bacterial counts were similar between teeth with (44 x 10(5)) and without (50 x 10(5)) a sinus tract (t-test: P > 0.05). E. faecalis, Streptococcus anginosus, Capnocytophaga sputigena and Capnocytophaga gingivalis had significantly higher counts in the absence of sinus tract (Mann-Whitney test, P < 0.05). Higher levels of P. gingivalis and Fusobacterium nucleatum sp. nucleatum were observed in cases with a sinus tract. Leptotrichia buccalis (OR = 1.83; CI 95%) and Porphyromonas endodontalis (OR = 2.15; CI 95%) were associated with an increased chance of subjects having a sinus tract. CONCLUSIONS: Primary endodontic infections were associated with a large variety of bacterial species. Specific differences between the composition of the microbiota of primary root canal infections were observed in cases with or without a sinus tract.

Dentine demineralization when subjected to EDTA with or without various wetting agents: a co-site digital optical microscopy study.

AIM: To analyse quantitatively the chelating ability of ethylenediaminetetraacetic acid (EDTA) and three common EDTA-based associations with wetting agents. METHODOLOGY: Twelve maxillary human molars were selected, from which 3 mm thick discs were obtained from the cervical third of the root. Following the creation of standardized smear layer co-site microscopy image sequences of the dentine surface submitted to EDTA, EDTA plus 0.1% cetavlon (Sigma Chemical Co., St Louis, MO, USA), EDTA plus 1.25% sodium lauryl ether sulphate and SmearClear (Sybron Endo, Orange, CA, USA) were obtained after several cumulative demineralization times. Sixteen images were obtained of each dentine sample for each experimental time, at 1000 x magnification. An image processing and analysis sequence was used to measure the area of open tubules for each experimental time. Thus, it was possible to follow the demineralization process and quantitatively analyse the effect of the various substances. The Student's t-test was used to assess differences between experimental groups. Results EDTA solution had the strongest effect at all experimental times whilst the association of EDTA with wetting agents showed a weaker chelating effect and this difference was statistically significant (P < 0.05). CONCLUSIONS: (i) The EDTA solution had the strongest effect at all experimental times (P < 0.05); (ii) the association of EDTA with wetting agents did not improve the chelating power of the solution; (iii) co-site optical microscopy represents a powerful approach to compare directly, longitudinally and quantitatively the ability of the chelating solutions.

Evaluation of the microbiota of primary endodontic infections using checkerboard DNA-DNA hybridization.

BACKGROUND/AIMS: The aim of this study was to evaluate the composition of the microbiota of primary endodontic infections in 111 selected cases of single-rooted teeth with necrotic pulp. METHODS: Samples were collected from the root canals using #15 Hedströen-type files and two sterile paper points, which were introduced 1 mm short of the apical foramen. The presence, levels, and proportions of 40 different bacterial species in each sample were determined using DNA probes and checkerboard DNA-DNA hybridization techniques. RESULTS: The mean number of species per sample was 22. Enterococcus faecalis (89.3%), Campylobacter gracilis (89.3%), Leptotrichia buccalis (89.3%), Neisseria mucosa (87.5%), Prevotella melaninogenica (86.6%), Fusobacterium nucleatum ssp. vincentii (85.7%), Eubacterium saburreum (75.9%), Streptococcus anginosus (75%), and Veillonella parvula (74.1%) were the most prevalent species. The species found in highest mean counts (over 10(5)) were F. nucleatum ssp. vincentii (13.14 x 10(5)), E. saburreum (5.67 x 10(5)), E. faecalis (5.38 x 10(5)), N. mucosa (4.19 x 10(5)), V. parvula (3.63 x 10(5)), C. gracilis (3.46 x 10(5)), Treponema socranskii (3.34 x 10(5)), Porphyromonas endodontalis (2.96 x 10(5)), Porphyromonas gingivalis (2.85 x 10(5)), Micromonas micros (2.81 x 10(5)), Prevotella nigrescens (2.68 x 10(5)) and Fusobacterium nucleatum ssp. nucleatum (2.64 x 10(5)). Most of these species were also found in high proportions. CONCLUSIONS: Our results suggest that several bacterial species considered to be oral pathogens seem to be implicated in the etiology of primary endodontic infections.

The sealing ability of GuttaFlow in oval-shaped canals: an ex vivo study using a polymicrobial leakage model.

AIM: To compare systematically the sealing ability provided by four endodontic cements: AH Plus, Pulp Canal Sealer EWT, RoekoSeal and GuttaFlow. METHODOLOGY: A sample of 100 human mandibular incisors with oval-shaped canals was selected from an initial sampling of two hundred teeth. The root canals in 80 teeth were prepared and filled by the same operator using the cold lateral compaction technique with one of the following four cements (n = 20): G1: AH Plus; G2: Pulp Canal Sealer EWT; G3: RoekoSeal and G4: GuttaFlow. Ten teeth with intact crowns served as negative controls and 10 teeth that were not root filled served as positive controls. All teeth were mounted in a two chamber apparatus and then exposed to human saliva. The number of days over a 9-weeks-period was recorded for the appearance of turbidity in the BHI broth. A Log-rank test was used to analyse the leakage data. RESULTS: Overall, 30% of the samples of the AH Plus group (G1) and 35% of the Pulp Canal Sealer EWT group (G2) were fully contaminated after 9 weeks, whereas 15% of RoekoSeal (G3) and GuttaFlow (G4) groups were fully contaminated. There was a significant difference between (G1/G2) and (G3/G4) (P < 0.05). There was no significant difference between G1 and G2 or between G3 and G4 (P > 0.05). CONCLUSION: The silicone-based sealers revealed the best results throughout the experimental period. Leakage patterns of AH plus and Pulp Canal Sealer were statistically similar.

Co-site digital optical microscopy and image analysis: an approach to evaluate the process of dentine demineralization.

AIM: To introduce and explore the potential of digital optical co-site microscopy and image analysis for the observation of changes in dentine surfaces during demineralization. The effect of ethylenediamine tetraacetic acid (EDTA) was evaluated quantitatively and longitudinally. METHODOLOGY: Three maxillary human molars were sectioned transversely at the cemento-enamel junction, and the crowns discarded. Subsequently, discs approximately 3 mm thick were cut in the cervical third of the root and a standardized smear layer produced. Co-site image sequences of the dentine surface subjected to 17% EDTA were obtained over the experimental period (15, 30, 60, 180 and 300 s). Sixteen images were obtained in each dentine sample for each experimental time, thus, a total of 48 image fields were obtained. For each field, an image analysis routine automatically discriminated open dentine tubules and measured their number, area fraction and minimum diameter, thus allowing the quantification of the demineralization process. The Student t-test was used to analyse the data. RESULTS: The number of open tubules remained essentially constant during the demineralization process. The area fraction increased from 9% to 32%. Tubule minimum diameter increased from 1.5 to 3.0 microm. The changes over time for the area fraction and minimum diameter were significant for comparison between all experimental times (P<0.05). CONCLUSIONS: The methodology developed for longitudinal observation of dentinal surfaces was fast, robust and reproducible. It could be easily extended to other chelating substances, thus contributing to the understanding of the demineralization process and in establishing an optimal time-effect relationship in the clinical application.

The influence of organic load on the antimicrobial activity of different concentrations of NaOCl and chlorhexidine in vitro.

AIM: To evaluate bacterial growth after contact with sodium hypochlorite (NaOCl; 1 and 5%) and chlorhexidine (CHX; 0.12, 0.5 and 1%) in vitro with or without the addition of organic material (bovine serum albumin (BSA) 0.5%). METHODOLOGY: Bacterial samples (American Type Culture Collection (ATCC)) of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis and Fusobacterium nucleatum were kept in contact with each irrigating solution for varying intervals of time: immediately (t0), 5 min (t5), 15 min (t15) and 30 min (t30). Each test was repeated 10 times. In half of the specimens, 0.5% BSA was added as organic material in an attempt to simulate the organic tissue present in the root canal system. Bacterial growth under appropriate condition of incubation was evaluated and compared for each microorganism at all time intervals. RESULTS: A 0.12% CHX solution did not eliminate E. faecalis at any time interval. One percent CHX eliminated all strains, as did both NaOCl concentrations. BSA did not interfere substantially with the antimicrobial activity of any of the irrigating solutions. CONCLUSIONS: Under the condition of this study, a 0.12% CHX solution was ineffective at killing E. faecalis.

Maxillary lateral incisor with two root canals: fusion, gemination or dens invaginatus?

Endodontic retreatment of a maxillary right lateral incisor with two root canals is described. The diagnosis of fusion, gemination or dens invaginatus could not be made, due to conflicting findings, and to previous root canal treatment that erased the original configuration of the pulp chamber.

In vitro action of various carbamide peroxide gel bleaching agents on the microhardness of human enamel.

The authors verified a decrease in human enamel microhardness after application of the following carbamide peroxide gel bleaching agents for 8 hours daily for 1 week: 10% Nite White, 16% Nite White, Opalescence, Karisma Alpha and Perfect Smile. Statistical analysis showed that these agents caused a decrease in enamel microhardness. Nite White (16%) was the most effective in reducing enamel microhardness and Opalescente the least effective. Nite White (10%), Karisma Alpha and Perfect Smile fell into a statistically intermediate position.