Yara Teresinha Corrêa Silva-Sousa

Adhesion of Epiphany and AH Plus Sealers to Human Root Dentin Treated with Different Solutions

This study evaluated comparatively the adhesion of Epiphany and AH Plus endodontic sealers to human root dentin treated with 1% NaOCl and 1% NaOCl+17% EDTA, using the push-out test. Sixty root cylinders obtained from maxillary canines had the canals prepared and were randomly assigned to 3 groups (n=20), according to root dentin treatment: GI - distilled water (control), GII - 1% NaOCl and GIII - 1% NaOCl+17% EDTA. Each group was divided into 2 subgroups (n=10) filled with either Epiphany or AH Plus. Bond strength push-out test data (kN) were obtained and analyzed statistically by ANOVA and Tukeys post-hoc test. There was statistically significant difference between sealers (AH Plus: 0.78 +/- 0.13; Epiphany: 0.61 +/- 0.19; p<0.01) and among root dentin treatments (distilled water: 0.58 +/- 0.19; 1% NaOCl: 0.71 +/- 0.12; 1% NaOCl+17% EDTA: 0.80 +/- 0.17; p<0.05). In conclusion, AH Plus sealer presented greater adhesion to dentin than Epiphany, regardless of the treatment of root canal walls.

Antimicrobial activity of Arctium lappa constituents against microorganisms commonly found in endodontic infections

This study evaluated in vitro the antimicrobial activity of rough extracts from leaves of Arctium lappa and their phases. The following microorganisms, commonly found in the oral cavity, specifically in endodontic infections, were used: Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. The agar-diffusion method allowed detection of the hexanic phase as an inhibitor of microbial growth. Bioautographic assays identified antimicrobial substances in the extract. The results showed the existence, in the rough hexanic phase and in its fractions, of constituents that have retention factors (Rf) in three distinct zones, thereby suggesting the presence of active constituents with chemical structures of different polarities that exhibited specificity against the target microorganisms. It may be concluded that the Arctium lappa constituents exhibited a great microbial inhibition potential against the tested endodontic pathogens.

Debris and smear removal in flattened root canals after use of different irrigant agitation protocols

Scanning electron microscopy (SEM) can be used to analyze the presence of debris and smear layer on the internal walls of root canal. This study evaluated the debris and smear removal in flattened root canals using SEM after use of different irrigant agitation protocols. Fifty mandibular incisors were distributed into five groups (n = 10) according to the irrigant agitation protocol used during chemomechanical preparation: conventional syringe irrigation with NaviTip needle (no activation), active scrubbing of irrigant with brush‐covered NaviTip FX needle, manual dynamic irrigation, continuous passive ultrasonic irrigation, and apical negative pressure irrigation (EndoVac system). Canals were irrigated with 5 mL of 2.5% NaOCl at each change of instrument and received a final flush with 17% EDTA for 1 min. After instrumentation, the roots were split longitudinally and SEM micrographs at ×100 and ×1,000 were taken to evaluate the amount of debris and smear layer, respectively, in each third. Data were analyzed by Kruskal–Wallis and Dunns post‐hoc tests (α = 5%). Manual dynamic activation left significantly (p < 0.05) more debris inside the canals than the other protocols, while ultrasonic irrigation and EndoVac were the most effective (p < 0.05) for debris removal. Regarding the removal of smear layer, there was no statistically significant difference (p > 0.05) either among the irrigant agitation protocols or between the protocol–canal third interactions. Although none of the irrigant agitation protocols completely removed debris and smear layer from flattened root canals, the machine‐assisted agitation systems (ultrasound and EndoVac) removed more debris than the manual techniques. Microsc. Res. Tech. 75:781–790, 2012.

Physicochemical Properties of Methacrylate Resin–based Root Canal Sealers

INTRODUCTION This study assessed in vitro the physicochemical properties of 2 methacrylate resin-based sealers (Epiphany SE and Hybrid Root SEAL), comparing the results with a well-established epoxy resin-based sealer (AH Plus). METHODS Five samples of each material were used for each test (setting time, flow, radiopacity, dimensional change after setting, and solubility) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. The samples were assigned to 3 groups: I, AH Plus; II, Epiphany SE; and III, Hybrid Root SEAL. The distilled and deionized water used at the solubility test was submitted to atomic absorption spectrometry to observe the presence of Ca2+, K+, Ni2+, and Zn2+ ions. In addition, the surface morphology of the specimens was analyzed by means of scanning electron microscopy (SEM). Statistical analysis was performed by using one-way analysis of variance and Tukey-Kramer test (P < .05). RESULTS Flow, radiopacity, and solubility of all sealers were in accordance with ANSI/ADA. The setting time of Hybrid Root SEAL did not agree with ANSI/ADA requirements. The dimensional change of all sealers was greater than the values considered acceptable by ANSI/ADA. The spectrometry analysis showed significant Ca(2+) ions release for AH Plus. In SEM analysis, Hybrid Root SEAL presented spherical monomers with inferior size than AH Plus and Epiphany SE. CONCLUSIONS It might be concluded that physicochemical properties of the tested sealers conformed to ANSI/ADA (2000) standardization, except for the setting time of Hybrid Root SEAL and the dimensional change of all sealers, which did not fulfill the ANSI/ADA requirements.

Bond Strength of Epiphany Sealer Prepared with Resinous Solvent

This study evaluated in vitro the bond strength of Epiphany sealer prepared with resinous solvent of Epiphany system (Thinning resin) by using a push-out test. Forty maxillary canines were sectioned transversally below the cementoenamel junction to provide 4-mm-thick dentin disks that were centered in aluminum rings and embedded in acrylic resin. Root canals were prepared with tapered diamond bur. Intraradicular dentin was treated with 1% NaOCl for 30 minutes, 17% ethylenediaminetetraacetic acid for 5 minutes, and flushed with distilled water for 1 minute. The specimens were randomly distributed into 4 groups (n = 10) according to the filling material: GI, Epiphany without photoactivation; GII, Epiphany prepared with solvent without photoactivation; GIII, Epiphany followed by photoactivation; and GIV, Epiphany prepared with solvent followed by photoactivation. After the setting time, the specimens were submitted to the push-out test. The highest mean value (14.91 +/- 2.82 MPa) was obtained with Epiphany prepared with solvent followed by photoactivation (GIV), which was statistically different (P < .01) from the other groups. Groups I (8.15 +/- 2.47 MPa), II (9.46 +/- 2.38 MPa), and III (9.80 +/- 2.51 MPa) had inferior bond strength values and were statistically similar among themselves (P > .01). The resinous solvent of Epiphany system increased the bond strength of Epiphany sealer to dentin walls when followed by photoactivation.

Bond Strength of Fiber Posts to Weakened Roots After Resin Restoration With Different Light-Curing Times

INTRODUCTION This study evaluated the bond strength of translucent fiber posts to experimentally weakened radicular dentin restored with composite resin and polymerized with different light-exposure time. METHODS Roots of 60 maxillary incisors were used. Twenty-four hours after obturation, the filling materials of root canals were removed to a depth of 12 mm, and 4 groups were randomly formed. In 3 groups, root dentin was flared to produce a space between fiber post and canal walls. In the control group, the roots were not experimentally weakened. The flared roots were bulk restored with composite resin, which was light-activated through the translucent post for 40, 80, or 120 seconds. Posts were cemented, and after 24 hours, all roots were sectioned transversely in the coronal, middle, and apical regions, producing 1-mm-thick slices. Push-out test was performed, and failure modes were observed. RESULTS The quantitative analysis showed significant statistical difference only among groups (P < .001). Comparing the weakened/restored groups, composite light-exposure time did not influence the results. Overall, adhesive failures occurred more frequently than other types of failures. Cohesive failures occurred only in the weakened/restored roots. CONCLUSIONS Intracanal root restoration with composite resin and translucent fiber posts provided similar or higher bond strength to dentin than the control group, regardless of the light-exposure time used for polymerization.

Morphometrical analysis of cleaning capacity using nickel-titanium rotary instrumentation associated with irrigating solutions in mesio-distal flattened root canals

Variations in the internal anatomy of root canals may interfere with the success of root canal because tissue remnants may remain in the isthmus, re-entrances and ramifications of flattened root canals making instrumentation more difficult. Successful root canal treatment depends fundamentally on shaping, cleaning, disinfection and obturation. This study verified the quality of cleaning of ProFile .04 rotary technique associated with different irrigating solutions: 0.5% sodium hypochlorite, calcium hydroxide + Tergentol and 2% chlorhexidine in canals with mesio-distal flattening. Twelve human mandibular central incisors were randomly divided into 3 groups and instrumented up to ProFile 0.4 #35 file after cervical preparation, and processed histologically. After optical microscopic evaluation, statistical analysis showed that the percentage of cleaning of the three irrigating solutions was statistically different. Two-by-two comparisons classified the irrigating solutions in increasing order of cleaning: calcium hydroxide + Tergentol < chlorhexidine < 0.5% sodium hypochlorite.

Morphological alterations of radicular dentine pretreated with different irrigating solutions and irradiated with 980‐nm diode laser

Background: The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. Purpose: To evaluate the alterations of dentine irradiated with 980‐nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Study design: Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali‐quatitative way. The scores were submitted to two‐way Kruskal–Wallis and Dunns tests. Results: The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P < 0.05) from the laser‐irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser‐modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. Conclusions: The tested parameters of 980‐nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Microsc. Res. Tech., 2009.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and guttapercha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Students t-test (α=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to guttapercha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Influence of Ultrasound, With and Without Water Spray Cooling, on Removal of Posts Cemented With Resin or Zinc Phosphate Cements

The efficacy of ultrasound, with and without water spray, was evaluated in vitro on the amount of force necessary to dislodge posts cemented with resin or zinc phosphate. Forty-two samples were divided into six groups: groups 1, 2, and 3, posts cemented with zinc phosphate; groups 4, 5, and 6, posts cemented with resin (Panavia F); groups 1 and 4 (controls), no ultrasound; groups 2 and 5, ultrasound without water spray; and groups 3 and 6, ultrasound with water spray. The Instron testing machine was used. Ultrasound without water spray significantly reduced (71%) the force necessary to displace posts cemented with Panavia F (p < 0.01); however, this value was similar to the efficacy of ultrasound with water spray for posts cemented with zinc phosphate (reduction of 75%). We conclude that cooling with ultrasound interferes with the force necessary for post removal, depending on the type of cement used.