Push-out strength of methacrylate resin-based sealers to root canal walls

P>Aim To assess the push-out strength of Epiphany SE, Epiphany and Hybrid Root SEAL to the dentine walls of root canals. Methodology Sixty roots of canines were prepared and distributed to six groups (n = 10) according to the filling material: GI - Epiphany SE, GII - Epiphany primer and sealer, GIII - Epiphany primer, sealer and resinous solvent, GIV - Clearfil DC Bond and Epiphany sealer, GV - Clearfil, Epiphany sealer and solvent and GVI - Hybrid Root SEAL. Resilon cones were used in all groups. Roots were sectioned transversally to obtain three slices from each third. One slice was subjected to the push-out test (MPa), and results were analysed by anova and Tukey`s test (P < 0.05). The other two slices were prepared for scanning electron microscopy (SEM). Failure mode was also analysed. Results A statistically significant difference (P < 0.05) occurred between Hybrid Root SEAL (5.27 +/- 2.07) and the other materials, GI (0.40 +/- 0.23), GII (0.78 +/- 0.45), GIII (0.57 +/- 0.28), GIV (0.40 +/- 0.24) and GV (0.50 +/- 0.41), which did not differ significantly from each other (P > 0.05). Adhesive failures predominated in groups I, II, IV and V, whilst mixed and cohesive failures were the most frequent in groups III and VI, respectively. There were gaps in the adhesive interface of GI and GII, continuity areas of the filling material with dentine in GIV and GV and good adaptation of the interface of GVI. Conclusion Hybrid Root SEAL had greater push-out strength to root canal dentine than Epiphany SE and Epiphany. The use of primer, solvent and adhesive system did not influence the adhesion of Epiphany.

Effect of erbium:yttrium-aluminum-garnet laser energies on superficial and deep dentin microhardness

This study evaluated the microhardness of superficial and deep dentin irradiated with different erbium:yttrium-aluminum-garnet (Er:YAG) laser energies. Seventy-two molars were bisected and randomly assigned to two groups (superficial dentin or deep dentin) and into six subgroups (160 mJ, 200 mJ, 260 mJ, 300 mJ, 360 mJ, and control). After irradiation, the cavities were longitudinally bisected. Microhardness was measured at six points (20 A mu m, 40 A mu m, 60 A mu m, 80 A mu m, 100 A mu m, and 200 A mu m) under the cavity floor. Data were submitted to analysis of variance (ANOVA) and Fisher`s tests (alpha = 0.05). Superficial dentin presented higher microhardness than deep dentin; energy of 160 mJ resulted in the highest microhardness and 360 mJ the lowest one. Values at all points were different, exhibiting increasing microhardness throughout; superficial dentin microhardness was the highest at 20 A mu m with 160 mJ energy; for deep dentin, microhardness after irradiation at 160 mJ and 200 mJ was similar to that of the control. The lowest energy increased superficial dentin microhardness at the closest extent under the cavity; deep dentin microhardness was not altered by energies of 160 mJ and 200 mJ.

Laboratory evaluation of the physicochemical properties of a new root canal sealer based on Copaifera multijuga oil-resin

Aim To compare a new root canal sealer based on Copaifera multijuga oil-resin (Biosealer) using three other established sealers (Sealer 26 (R), Endofill (R) and AH plus (R)) in terms of their physicochemical properties. Methodology The study was carried out according to the requirements of Specification Number 57 of the American Dental Association (ADA) and consisted of the following tests: setting time, flow, film thickness, dimensional stability, radiopacity and solubility/disintegration. Data were analysed statistically using anova and Tukey`s test for multiple comparisons. The significance level was set at 5% for all analyses. Results Sealer 26 (R) and AH Plus (R) had the longest setting time (P < 0.05). All materials presented flow in with the ADA`s guidelines. Regarding film thick-ness, Sealer 26 (R) did not have a satisfactory performance, as it had a higher mean value than the maximum allowed by the ADA (0.05 mm), being significantly different from the other materials (P < 0.05), which had mean values for film thickness in accordance with the ADA`s recommendations. Regarding the solubility and disintegration, only Endofill (R) did not meet the ADA`s specifications and presented the worst results of all materials (P < 0.05). Sealer 26 (R) presented the greatest dimensional changes and differed significantly from all other sealers (P < 0.05). Biosealer had the lowest radiopacity values and was significantly different from the other sealers (P < 0.05). Conclusion The experimental sealer based on Copaifera multijuga oil-resin presented satisfactory results in the physicochemical tests required by the ADA.

A comparative study of physicochemical properties of AH Plus, Epiphany, and Epiphany SE root canal sealers

P>Aim To assess the physicochemical properties and the surface morphology of AH Plus, Epiphany, and Epiphany SE root canal sealers. Methodology Five samples of each material were employed for each test according to ANSI/ADA specification 57. The samples were assigned to four groups: (i) AH Plus; (ii) Epiphany; (iii) Epiphany + Thinning Resin; (iv) Epiphany SE. The distilled water used during the solubility test was submitted to spectrometry to verify the release of calcium ions. The morphologies of the external surface and the cross-section of the samples were analysed by means of a scanning electron microscope (SEM). Statistical analysis was performed by using One-Way anova and post hoc Tukey-Kramer tests with the null hypothesis set as 5%. Results Setting time, flow and radiopacity results were in accordance with ANSI/ADA requirements whereas the dimensional change of all sealers and solubility of Epiphany did not fulfil ANSI/ADA protocols. AH Plus and Epiphany SE were similar in terms of flow, radiopacity, solubility and dimensional change. The spectrometry test revealed significant calcium ion release from Epiphany with and without the thinning resin. SEM analysis revealed essentially a homogeneous surface with compact layer and some rough areas. Conclusions Setting time, flow, and radiopacity tests conformed to ANSI/ADA standardization. The dimensional change in all groups and the solubility of Epiphany were greater than values considered acceptable, with higher amounts of calcium ion release. Epiphany SE revealed more organized, compacted, and homogeneous polymers in a reduced resin matrix when compared with the other groups.

Bond strength of Epiphany (TM) Sealer combined with different adhesive systems photo-activated with LED and QTH

The Epiphany (TM) Sealer is a new dual-curing resin-based sealer and has been introduced as an alternative to gutta-percha and traditional root canal sealers. The canal filling is claimed to create a seal with the dentinal tubules within the root canal system producing a `monoblock` effect between the sealer and dentinal tubules. Therefore, considering the possibility to incorporate the others adhesive systems, it is important to study the bond strength of the resulting cement. Forty-eight root mandibular canines were sectioned 8-mm below CEJ. The dentine discs were prepared using a tapered diamond bur and irrigated with 1% NaOCl and 17% EDTA. Previous the application Epiphany (TM) Sealer, the Epiphany (TM) Primer, AdheSE, and One Up Bond F were applied to the root canal walls. The LED and QTH (Quartz Tungsten Halogen) were used to photo-activation during 45 s with power density of 400 and 720 mW/cm(2), respectively. The specimens were performed on a universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The force was recorded and the debonding values were used to calculate Push-out bond strength. The analysis of variance (ANOVA) and Tukey`s post-hoc tests showed significant statistical differences (P < 0.05) to Epiphany (TM) Sealer/Epiphany (TM) Primer/QTH and EpiphanyTM Sealer/AdheSE/QTH, which had the highest mean values of bond strength. The efficiency of resin-based filling materials are dependent the type of light curing unit used including the power density, the polymerization characteristics of these resin-based filling materials, depending on the primer/adhesive used.

Evaluation of several protocols for the application of ultrasound during the removal of cast intraradicular posts cemented with zinc phosphate cement

To evaluate several protocols for the application of ultrasound during removal of cast posts with varying core configurations cemented with zinc phosphate. Sixty maxillary canines were distributed into three groups (n = 20): group 1 - core with 5 mm diameter/height and post diameter of 1.3 mm; groups 2 and 3 - core with the same diameter as the post (1.3 mm) and heights of 5 mm and 3 mm, respectively. Posts/cores were cemented using a standard technique with zinc phosphate cement. Each group was divided into two subgroups according to the ultrasonic vibration mode: point vibration - ultrasonic vibration applied to the core surface for 5 s, on each face totalling 25 s; alternate vibration - intermittent application of ultrasonic vibration for 10 s to the labial and lingual surfaces, 10 s to the mesial and distal surfaces and 5 s to the incisal surface, totalling 25 s. The specimens were submitted to the tensile test using an Instron machine (1 mm min(-1)) and results were analysed by anova and t-test. The failure type was also analysed. Statistical analysis showed significant differences between groups relating to the core preparations (P < 0.05). The lowest mean values of traction force were obtained for group 3 (46.1 +/- 7.7 N), followed by group 2 (89.0 +/- 2.7 N) and group 1 (160.4 +/- 7.5 N). Regarding ultrasonic vibration, the lowest mean was observed with alternate vibration (81.1 +/- 10.1 N), which was significantly lower than the point vibration (115.9 +/- 9.5 N) (P < 0.05). Cohesive failure occurred in all cases. A reduction in core diameter/height and intermittent ultrasonic application improved the removal of cast posts cemented with zinc phosphate.

Effect of a 10% carbamide peroxide on wear resistance of enamel and dentine: In situ study

Objectives: This triple-blind, 2 x 2 crossover in situ study, was undertaken to verify whether the wear resistance of enamel and root dentine would be affected by bleaching with a 10% carbamide peroxide agent and a placebo agent. Methods: Thirty slabs of each. substrate (2 mm x 3 mm x 2 mm) were selected for each phase, after flattening and polishing procedures and microhardness test. After a 7-day lead-in period, one specimen of each substrate was randomly bonded on the facial surface of each one of 30 subject`s upper second premolars. The volunteers received instructions on how to perform toothbrushing and application of gel in the tray. Fifteen volunteers bleached their maxillary arch with a 10% carbamide peroxide bleaching agent for a 2-week period, while the remainders used a placebo agent. After a 1-week washout period, a new set of enamel and root dentine slabs were bonded to the premolars and volunteers were crossed over to the alternate agent for 14 days. The resistance of enamel and root dentine to wear following bleaching, toothbrushing and intraoral exposure was measured with a profilometer, using reference areas. Results: For enamel, ANOVA did not demonstrate significant difference between wear provided by placebo and bleaching agent (p = 0.3713), but higher wear depth was observed for bleached root dentine (p = 0.0346). Conclusions: While overnight bleaching caused no alteration in wear resistance of enamel, root dentine showed increased tissue loss. (C) 2008 Elsevier Ltd. All rights reserved.

IN VITRO FRACTURE RESISTANCE OF GLASS-FIBER AND CAST METAL POSTS WITH DIFFERENT LENGTHS

Statement of problem. Dental fractures can occur in endodontically treated teeth restored with posts. Purpose. The purpose of this study was to evaluate the in vitro fracture resistance of roots with glass-fiber and metal posts of different lengths. Material and methods. Sixty endodontically treated maxillary canines were embedded in acrylic resin, except for 4 mm of the cervical area, after removing the clinical crowns. The post spaces were opened with a cylindrical bur at low speed attached to a surveyor, resulting in preparations with lengths of 6 mm (group 6 mm), 8 mm (group 8 mm), or 10 mm (group 10 mm). Each group was divided into 2 subgroups according to the post material: cast post and core or glass-fiber post (n=30). The posts were luted with dual-polymerizing resin cement (Panavia F). Cast posts and cores of Co-Cr (Resilient Plus) crowns were made and cemented with zinc phosphate. Specimens were subjected to increasing compressive load (N) until fracture. Data were analyzed with 2-way ANOVA and the Tukey-Kramer test (alpha=.05). Results. The ANOVA analysis indicated significant differences (P<.05) among the groups, and the Tukey test revealed no significant difference among the metal posts of 6-mm length (26.5 N +/- 13.4), 8-mm length (25.2 N +/- 13.9), and 10-mm length (17.1 N +/- 5.2). Also, in the glass-fiber post group, there was no significant difference when posts of 8-mm length (13.4 N +/- 11.0) were compared with the 6-mm (6.9 N +/- 4.6) and 10-mm (31.7 N +/- 13.1) groups. The 10-mm-long post displayed superior fracture resistance, and the 6-mm-long post showed significantly lower mean values (P<.001). Conclusions. Within the limitations of this study, it was concluded that the glass-fiber post represents a viable alternative to the cast metal post, increasing the resistance to fracture of endodontically treated canines. (J Prosthet Dent 2009;101:183-188)

Quantitative 3D profilometry and SEM analysis of the adaptation of root-end filling materials placed under an optical microscope

P>Aim To evaluate by 3D profilometry and scanning electron microscopy (SEM), the marginal adaptation of mineral trioxide aggregate (MTA) and Sealer 26 placed in root-end cavities with direct vision or under an optical microscope. Methodology The root ends of 52 root filled canine teeth were filled with MTA or Sealer 26 under direct vision or optical microscope (n = 13). In each group, eight specimens were analysed by profilometry for measurement of the area and depth of gaps. In the other five specimens, gap area was measured using SEM to verify marginal adaptation and surface characteristic. Data were analysed by parametric (anova and Tukey) and non-parametric (Kruskal-Wallis and Dunn) tests. Results The assessment of the adaptation of both materials to dentine was not influenced by the mode of visualization, which was confirmed by both profilometry and SEM observations. The voids measured with profilometry for Sealer 26 under direct vision were significantly wider and deeper than those for MTA under direct vision (P < 0.05). In SEM, significantly larger gap areas were observed with Sealer 26 (P < 0.05). Conclusion Root-end cavities filled with MTA had smaller gaps and better marginal adaptation than Sealer 26.

Potential effect of sodium bicarbonate-containing dentifrice in controlling enamel erosion in situ

Purpose: To assess, by a crossover 2 x 2 in situ study, the speculated protective role of a sodium bicarbonate-containing toothpaste in controlling erosive lesions. Methods: Bovine enamel slabs were sterilized, and submitted to baseline Knoop microhardness measurements. After a 3-day lead-in period, 14 volunteers wore palatal acrylic appliances containing six enamel slabs (three on each side), for 4 consecutive days. On the first day, appliances with contained specimens were placed in the oral cavity to allow salivary pellicle formation. On the subsequent days, half of the enamel slabs were immersed extraorally in a lemonade-like soft drink for 90 seconds, twice daily. On both of these occasions, the appliance was dipped in toothpaste slurry of either a sodium bicarbonate-containing toothpaste or a regular counterpart for 60 seconds. Following a 3-day washout period, a new set of enamel slabs were mounted and the volunteers started the second period using the alternate dentifrice. Results: ANOVA (alpha = 0.05) showed no statistically significant difference between enamel treated with regular and sodium bicarbonate-based dentifrices, regardless of whether specimens were eroded or not (P=0.8430). Acid-challenged specimens revealed lower microhardness values than uneroded samples. (Am J Dent 2008;21:300-302).

Bond strength of AH Plus and Epiphany sealers on root dentine irradiated with 980 nm diode laser

Aim To evaluate the bond strength of AH Plus and Epiphany sealers to human root canal dentine irradiated with a 980 nm diode laser at different power and frequency parameters, using the push-out test. Methodology Sixty canine roots were sectioned below the cementoenamel junction to provide 4-mm-thick dentine discs that had their root canals prepared with a tapered bur and irrigated with sodium hypochlorite, ethylenediaminetetraacetic acid and distilled water. The specimens were assigned to five groups (n = 12): one control (no laser) and four experimental groups that were submitted to 980 nm diode laser irradiation at different power (1.5 and 3.0 W) and frequency (continuous wave and 100 Hz) parameters. Half of specimens in each group had their canals filled with AH Plus sealer and half with Epiphany. The push-out test was performed and data (MPa) were analysed statistically by ANOVA and Tukey`s test (P < 0.05). The specimens were split longitudinally and examined under SEM to assess the failure modes after sealer displacement. Results The specimens irradiated with the diode laser and filled with AH Plus had significantly higher bond strength values (8.69 +/- 2.44) than those irradiated and filled with Epiphany (3.28 +/- 1.58) and the nonirradiated controls (3.86 +/- 0.60). The specimens filled with Epiphany did not differ significantly to each other or to the control (1.75 +/- 0.69). There was a predominance of adhesive failures at Epiphany-dentine interface (77%) and mixed failures at AH Plus-dentine interface (67%). Conclusions The 980 nm diode laser irradiation of root canal dentine increased the bond strength of AH Plus sealer, but did not affect the adhesion of Epiphany sealer.

Influence of endodontic sealers on the bond strength of carbon fiber posts

Objective: The aim of this study was to verify the influence of endodontic sealers on the bond strength of an adhesive system and a resin cement used for carbon posts cementation. Methods: Thirty extracted human premolars were instrumented and randomly divided into three groups according to the tested sealer: EndoFill, Sealapex, or EndoREZ. Specimens were stored at 37 degrees C. After 48 h, half of specimens were prepared to receive the post and the others after 7 days. The posts were cemented with Adper Single Bond/Rely X ARC and stored in distilled water at 37 degrees C for 7 days. After this period, the specimens were sectioned in three slices (coronal, middle, and apical). The push-out test was performed in a universal machine and the debonded area was examined in a stereomicroscope. Results: Data were submitted ANOVA and Tukey test (alpha = 0.05). The EndoFill showed lower bond strength than other sealers (p < 0.01). The EndoREZ sealer was statistically greater than other groups for coronal and middle portions and similar for apical portion (P > 0.05). Coronal and middle portions showed the best results for all groups, mainly when the canal preparation was performed after 48 h (p < 0.01). Mixed failure occurs with more frequency (55.6%) followed by failure in adhesive-dentin interface (34.4%) and adhesive-post interface (10.0%). Conclusion: The use of EndoREZ sealer promoted higher bond strength in root coronal and middle portions when carbon post was fixed with a resin cement. (C) 2007 Wiley Periodicals, Inc.

Influence of different endodontic filling materials on root fracture susceptibility

Objective: To evaluate the influence of different endodontic materials on root fracture susceptibility. Methods: Seventy-two mandibular incisors were sectioned 1 mm below the cementoenamel junction to obtain roots of 12 mm length. Roots were submitted to chemomechanical preparation with the rotary instruments of Profile system. The obturation of root canals were performed with the following filling materials (n = 12): GI, unfilled teeth (control); GII, Endofill + gutta-percha; GIII, Sealer 26 + gutta-percha; GIV, AH Plus + gutta-percha; GV, Epiphany + gutta-percha; GVI, Epiphany + Resilon. After the sealers setting time, each root was embedded in acrylic resin. The specimens were then submitted to fracture resistance test using an Instron testing machine at 1 mm/min. Results: The ANOVA test showed no significant statistical difference (p > .05) among GI (162.16 +/- 41.4N), GII (168.46 +/- 37.5N), GIII (164.83 +/- 35.7N), GIV (168.29 +/- 38.7N), GV (172.36 +/- 20.6N) and GVI (193.11 +/- 42.8N). Conclusion: The core materials (gutta-percha or Resilon) combined with the tested endodontic sealers are not able to increase the root fracture resistance in canals submitted to chemomechanical preparation. (c) 2007 Elsevier Ltd. All rights reserved.

Study on the potential inhibition of root dentine wear adjacent to fluoride-containing restorations

The purpose of this in vitro study was to determine whether the vicinity of root dentine that had been restored with fluoride-releasing materials was at reduced risk for erosive/abrasive wear compared to root dentine restored with a non-fluoride-containing material. According to a randomized complete block design, standardized cavities prepared on the surface of 150 bovine root dentine slabs were restored with glass-ionomer cement, resin-modified glass ionomer, polyacid-modified resin composite, fluoride-containing or conventional composite. Specimens were coated with two layers of an acid-resistant nail varnish exposing half of the dentine surface and half of the restoration. Subsequently, specimens were either eroded in an acidic drink or left uneroded, then exposed to artificial saliva and abraded in a toothbrushing machine. Wear depth in the vicinity of restorations was quantified by a stylus profilometer, based on the nonabraded areas surrounding the erosion/abrasion region. Two-way ANOVA did not demonstrate significant interaction between restoratives and eroded-uneroded dentine (p = 0.5549) nor significant difference among restorative materials (p = 0.8639). Tukey`s test ascertained that the wear depth was higher for eroded than for uneroded groups. Fluoride-releasing materials seemed to negligibly inhibit wear in the vicinity of restored root dentine subjected to erosive/abrasive challenges.

Shear Bond Strength and Ultrastructural Interface Analysis of Different Adhesive Systems to Bleached Dentin

Background: It remains unclear as to whether or not dental bleaching affects the bond strength of dentin/resin restoration. Purpose: To evaluated the bond strength of adhesive systems to dentin submitted to bleaching with 38% hydrogen peroxide (HP) activated by LED-laser and to assess the adhesive/dentin interfaces by means of SEM. Study design: Sixty fragments of dentin (25 mm(2)) were included and divided into two groups: bleached and unbleached. HP was applied for 20 s and photoactivated for 45 s. Groups were subdivided according to the adhesive systems (n = 10): (1) two-steps conventional system (Adper Single Bond), (2) two-steps self-etching system (Clearfil standard error (SE) Bond), and (3) one-step self-etching system (Prompt L-Pop). The specimens received the Z250 resin and, after 24 h, were submitted to the bond strength test. Additional 30 dentin fragments (n = 5) received the same surface treatments and were prepared for SEM. Data were analyzed by ANOVA and Tukey`s test (alpha = 0.05). Results: There was significant strength reduction in bleached group when compared to unbleached group (P < 0.05). Higher bond strength was observed for Prompt. Single Bond and Clearfil presented the smallest values when used in bleached dentin. SEM analysis of the unbleached specimens revealed long tags and uniform hybrid layer for all adhesives. In bleached dentin, Single Bond provided open tubules and with few tags, Clearfil determined the absence of tags and hybrid layer, and Prompt promoted a regular hybrid layer with some tags. Conclusions: Prompt promoted higher shear bond strength, regardless of the bleaching treatment and allowed the formation of a regular and fine hybrid layer with less deep tags, when compared to Single Bond and Clearfil. Microsc. Res. Tech. 74:244-250, 2011. (C) 2010 Wiley-Liss, Inc.