Different biomechanical preparation protocols on the penetration and bond strength of the filling material to dentin.

The aim of this study was to evaluate the influence of different instruments and mechanisms of agitation of the irrigating solution on the penetration by confocal laser scanning microscopy (CLSM), and the bond strength (BS) of the filling material to the dentin by push-out test. Human premolars were distributed in two experimental groups (n=30), according to the instrumentation system: ProTaper Next (PN) or XP-endo Shaper (XS) and three irrigation protocol (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). The 2.5% NaOCl and 17% EDTA were the irrigating solutions used. The filling was performed using a lateral condensation technique, with AH Plus added to 0.1% rodhamine B. The roots were sectioned, obtaining 2 slices for each third of the root. The first slice was submitted to the sealer penetration analysis and the push-out test. The second slice was submitted to qualitative analysis (SEM) of the union interface. For the penetration (%) Tukey showed that PNXF (82.38±13.48), PNPUIXF (82.48± 12.02), XSXF (82.24±11.28) and XSPUIXP (86.23±10.45) presented the highest values, different (p<0.05) from PNNv (68.29±15.12) and XSNv (71.41±16.50). The BS (MPa) test evidenced that in the cervical third, PNPF (4.92±1.04) and XPSPF (5.03±0.70) obtained the highest values differing from the others groups (p<0.05). CSLM and SEM showed greater penetration of the sealer on the entire length of the root canal when the irrigation solution was stirred. In conclusion that the association PUI and XP-endo Finisher favored the penetration and bond strength of the filling material to the root dentin.

Removal of filling material using rotating or reciprocating systems with or without solvent: microCT analysis.

This study evaluated by the efficacy of rotary and reciprocating systems to remove filling material by micro-CT. Sixty human canines were instrumented up to F3 by ProTaper Universal system and filled with AH Plus/ gutta-percha. Specimens were submitted to 1,200 thermal cycles, scanned by microCT SkyScan 1176 and randomly distributed in groups according to the filling material removal protocol (n = 10): ProTaper Universal, ProTaper Universal/xylol, ProTaper Next, ProTaper Next/xylol, Reciproc and Reciproc/xylol. After filling removal, specimens were analyzed by microCT to separately verify the presence of gutta-percha and sealer remnants. The data (mm3) were analyzed by two way ANOVA and Tukey´s test (5%). For the remaining gutta-percha, the use of xylol provided the highest values for Reciproc (7.60 ± 0.73), which was statistically different from the other groups (p < 0.05) that presented lower values and were statistically similar to each other (p > 0.05). For the remaining sealer, xylol provided the highest values (21.25 ± 6.94) different (p < 0.05) from the use of instruments alone (11.47 ± 9.45). ProTaper Next presented the lowest values (8.16 ± 1.37) for the remaining sealer, different (p < 0.05) from that of Reciproc (24.67 ± 6.32). The qualitative analysis revealed that all groups presented some remaining root filling material, with the highest volumes presented by Reciproc and Reciproc/xylol. In conclusion the rotary systems provided greater removal of filling material regardless of the use of xylol. The use of xylol negatively interfered with the action of the reciprocating system in the removal of the gutta-percha and sealer.

Different biomechanical preparation protocols on the penetration and bond strength of the filling material to dentin

Abstract The aim of this study was to evaluate the influence of different instruments and mechanisms of agitation of the irrigating solution on the penetration by confocal laser scanning microscopy (CLSM), and the bond strength (BS) of the filling material to the dentin by push-out test. Human premolars were distributed in two experimental groups (n=30), according to the instrumentation system: ProTaper Next (PN) or XP-endo Shaper (XS) and three irrigation protocol (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). The 2.5% NaOCl and 17% EDTA were the irrigating solutions used. The filling was performed using a lateral condensation technique, with AH Plus added to 0.1% rodhamine B. The roots were sectioned, obtaining 2 slices for each third of the root. The first slice was submitted to the sealer penetration analysis and the push-out test. The second slice was submitted to qualitative analysis (SEM) of the union interface. For the penetration (%) Tukey showed that PNXF (82.38±13.48), PNPUIXF (82.48± 12.02), XSXF (82.24±11.28) and XSPUIXP (86.23±10.45) presented the highest values, different (p<0.05) from PNNv (68.29±15.12) and XSNv (71.41±16.50). The BS (MPa) test evidenced that in the cervical third, PNPF (4.92±1.04) and XPSPF (5.03±0.70) obtained the highest values differing from the others groups (p<0.05). CSLM and SEM showed greater penetration of the sealer on the entire length of the root canal when the irrigation solution was stirred. In conclusion that the association PUI and XP-endo Finisher favored the penetration and bond strength of the filling material to the root dentin.

Resumo O objetivo neste estudo foi avaliar a influência de diferentes instrumentos e mecanismos de agitação da solução irrigadora na penetração e resistência de união (RU) do AH Plus à dentina. Pré molares humanos foram distribuídos em dois grupos experimentais (n=30), de acordo com o sistema de instrumentação: ProTaper Next (PN) ou XP-endo Shaper (XS) e de acordo com três protocolos de irrigação (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). A irrigação do canal radicular foi realizada com NaOCl 2,5% e EDTA 17%. A obturação foi realizada por meio da técnica da condensação lateral, com AH Plus acrescido de rodhamina B 0,1%. As raízes foram seccionadas, obtendo-se 2 slices de 2,0 mm para cada terço radicular. O primeiro slice foi submetido a análise da penetração do cimento e ao teste de push-out e o segundo slice submetido a MEV para análise da interface de união. Para penetração (%) Tukey evidenciou que PNXF (82,38±13,48), PNPUIXF (82,48±12,02), XSXF (82,24±11,28) e XSPUIXF (86,23±10,45) apresentaram os maiores valores, diferentes (p<0,05) de PNC (68,29±15,12) e XPSC (71,41±16,50). Na RU (MPa) foi evidenciado que PNPF (4,92±1,04) e XPSPF (5,03±0,70), no terço cervical, obtiveram os maiores valores diferentes dos demais (p<0,05). MCVL e MEV evidenciaram maior penetração do cimento em toda extensão da parede do canal radicular inclusive nas regiões polares, quando foi realizada a agitação da solução irrigadora. Concluiu-se que a associação PUI e XP-endo Finisher favoreceu a penetração e resistência de união do material obturador à dentina radicular.

Effect of epigallocatechin-3-gallate and thermal cycling on the bond strength of resin cements to the root dentin.

This study evaluated the effect of epigallocatechin-3-gallate (EGCG) solution and thermal cycling on the bond strength (BS) of fiber posts to the root dentin using two different resin cements (conventional or self-adhesive). One hundred and forty-four bovine roots were endodontically treated. After post space preparation, specimens were randomly divided into six groups (n = 24) according to dentin pretreatment [distilled water, 0.05% EGCG solution or 2% chlorhexidine (CHX) solution] and resin luting agent used for fiber post cementation (RelyX ARC or RelyX U200-3 M ESPE). Then, the samples were separated into two subgroups (n = 12): storage in distilled water at 37 °C for 24 h and thermal cycling (5 °C/55 °C, dwell time 30 s-12,000 cycles) during 6 months. After that, the specimens were subjected to the pull-out BS test (Universal Testing Machine-0.5 mm/min) and the failures pattern was analyzed in a stereomicroscope. According to the BS results (three-way ANOVA, Tukey's test, α = 0.05), the highest values were reported in the group EGCG + RelyX U200, showing significant statistical differences compared to all the other experimental groups. For Control and CHX groups BS values, there was no significant difference (p > .05) between the resin cements. For conventional resin cement, there was no significant difference among treatment solutions (p > .05). The thermal cycling did not influence the BS results (p > .05). As reported by the failure mode analysis, adhesive failure was predominant in all groups. EGCG solution improved the bond strength of self-adhesive resin cement to root dentin.

Influence of Ultrasonic Activation on the Physicochemical Properties of Calcium Silicate-Based Cements.

PURPOSE: To evaluate the influence of ultrasonic activation on the physicochemical properties of setting time (ST), flow (FL), dimensional change (DC), and solubility (SL) of the cements: MTA, MTA Repair HP, and Biodentine®. MATERIALS AND METHODS: Two experimental groups were formed according to the cement activation protocol: without ultrasonic activation and with ultrasonic activation. Cements were manipulated according to the manufacturers' instructions. Ultrasonic activation group was performed with an E1 insert at power 3 (24-32 kHz) for 30 s directly in the center of the cement mass. The molds for analysis of the physicochemical properties were filled out and evaluated according to specification No. 57 from ANSI/ADA. The results were analyzed using the ANOVA test (two-way), complemented by Tukey's test (α = 0.05). 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 analyzed by means of a scanning electron microscope (SEM). RESULTS: For the ST, ultrasonic activation reduced the values of MTA, MTA Repair HP, and Biodentine (P < 0.05). For the FL, ultrasonic activation did not alter the flow of MTA (P > 0.05); however, it increased the flow MTA Repair HP and Biodentine (P < 0.05). For the DC, the percentage values of dimensional change were higher when there was ultrasonic activation in all repair cements (P < 0.05). For SL, there was a reduction in the percentage of the values in MTA and MTA Repair HP (P < 0.05); however, there was no change in the values of Biodentine (P > 0.05). Ultrasonic activation favored the release of calcium ions from all cements. The SEM analysis showed, in general, that the ultrasonic activation reduced and altered the particle shape of the cement. CONCLUSIONS: The ultrasonic activation interfered in the ST, DC, FL, ultrastructural morphology, and calcium release of the repair cements. However, it did not affect the solubility of Biodentine®.

Calcium hydroxide paste removal strategies and bond strengths of epoxy- and silicate-based sealers.

This study evaluated the syringe/needle (SN), passive ultrasonic irrigation (PUI) and XP-endo Finisher (XP) in the removal of Ca(OH)2 -based paste and the bond strength (BS) values of an epoxy resin (AH Plus) and silicate (MTA)-based sealers to root dentin. Eighty lower premolars were assigned: control group (CT), SN, PUI and XP, and subdivided according to the sealer (n = 10) for BS. SN has the lowest removal followed by PUI and XP. AH Plus had higher BS for CT compared with SN in all root thirds. CT and XP presented similar BS in the apical and middle thirds and higher than SN and PUI. For MTA, similar BS was observed in the cervical and apical thirds, and in the middle third, CT, PUI and XP presented similar values and higher than SN. PUI and XP methods presented higher efficiency in the Ca(OH)2 removal, and the residual Ca(OH)2 provides a reduction in BS of the AH Plus.

Removal of filling material using rotating or reciprocating systems with or without solvent: microCT analysis

Abstract This study evaluated by the efficacy of rotary and reciprocating systems to remove filling material by micro-CT. Sixty human canines were instrumented up to F3 by ProTaper Universal system and filled with AH Plus/ gutta-percha. Specimens were submitted to 1,200 thermal cycles, scanned by microCT SkyScan 1176 and randomly distributed in groups according to the filling material removal protocol (n = 10): ProTaper Universal, ProTaper Universal/xylol, ProTaper Next, ProTaper Next/xylol, Reciproc and Reciproc/xylol. After filling removal, specimens were analyzed by microCT to separately verify the presence of gutta-percha and sealer remnants. The data (mm3) were analyzed by two way ANOVA and Tukey´s test (5%). For the remaining gutta-percha, the use of xylol provided the highest values for Reciproc (7.60 ± 0.73), which was statistically different from the other groups (p < 0.05) that presented lower values and were statistically similar to each other (p > 0.05). For the remaining sealer, xylol provided the highest values (21.25 ± 6.94) different (p < 0.05) from the use of instruments alone (11.47 ± 9.45). ProTaper Next presented the lowest values (8.16 ± 1.37) for the remaining sealer, different (p < 0.05) from that of Reciproc (24.67 ± 6.32). The qualitative analysis revealed that all groups presented some remaining root filling material, with the highest volumes presented by Reciproc and Reciproc/xylol. In conclusion the rotary systems provided greater removal of filling material regardless of the use of xylol. The use of xylol negatively interfered with the action of the reciprocating system in the removal of the gutta-percha and sealer.

Comparative Effect of Rotary Microbrush Combined with Different Chemical Irrigants on Root Dentin Microhardness, Roughness and Bond Strength to an Epoxy-based Sealer.

PURPOSE: This study evaluated the effect of 17% EDTA, 10% citric acid (CA), and 2% chlorhexidine (CHX) activated with a rotary microbrush (CanalBrush) on root dentin microhardness, roughness, and epoxy-based sealer bond strength. MATERIALS AND METHODS: One hundred sixty single-rooted bovine incisors were instrumented and divided into 8 groups according to treatment: 1. 17% EDTA; 2. 17% EDTA+2% CHX; 3. 10% CA; 4. 10% CA+2% CHX; 5. 17% EDTA with CanalBrush; 6. 17% EDTA+2% CHX with CanalBrush; 7. 10% CA with CanalBrush; and 8. 10% CA+2% CHX with CanalBrush. Ten roots in each group were split into halves and submitted to microhardness and roughness analyses (n = 10). Following endodontic filling with AH Plus sealer, 10 roots in each group underwent push-out bond strength testing (n = 10). Data were analyzed using two-way ANOVA and Tukey's tests (α = 0.05). RESULTS: All groups had similar microhardness values (p > 0.05) which was higher in the apical third than in the middle and cervical thirds (p < 0.05). The CanalBrush groups had higher roughness than the no-activation groups (p < 0.05), with significantly higher roughness in the cervical third than in the apical third (p < 0.05). All groups exhibited similar bond strength (p > 0.05), with the cervical third being higher, followed by the middle and apical thirds (p < 0.05). CONCLUSIONS: Microbrush activation had a direct impact on dentin roughness and did not influence the dentin microhardness or the retention of epoxy-based sealer to the root canal.

Push-out bond strength of different tricalcium silicate-based filling materials to root dentin.

The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10): MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80) was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01). MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

Push-out bond strength of different tricalcium silicate-based filling materials to root dentin

Abstract: The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10): MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80) was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01). MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

Influence of Root Canal Filling Techniques on Sealer Penetration and Bond Strength to Dentin

Abstract The influence of root canal filling techniques on the penetration of AH Plus into dentinal tubules was evaluated using confocal laser scanning microscopy (CLSM) and the impact on the bond strength of the filling material on the root dentin was evaluated using the push-out test. Roots of the maxillary central incisors (n=40) were prepared with ProTaper Universal and assigned to four groups: lateral condensation, vertical compaction, modified Tagger hybrid and single cone. After root canal filling with gutta-percha and AH Plus, along with the addition of 0.01% fluorescein, the roots were cut into 2-mm slices. CLSM was performed on the first slice of each root third, followed by the push-out test. The second slice was analyzed under SEM. ANOVA demonstrated a statistically significant difference between the root canal filling techniques and the root thirds (p<0.05). For percent penetration, Tukey's test showed that the vertical compaction (91.77±13.51), lateral condensation (89.18±10.91) and modified Tagger hybrid (87.53±15.42) presented the highest values, which significantly differed (p<0.05) from those of the single cone (78.19±22.46). For bond strength (MPa), lateral condensation (3.42±0.54) and vertical compaction (3.47±0.53) had the highest values (p<0.05), while the modified Tagger hybrid (2.19±0.41) and single cone (0.54±0.21) had the lowest. In conclusion, the lateral condensation, vertical compaction and Modified Tagger's hybrid techniques resulted in greater penetration and bond strength to the intra-radicular dentin.

Resumo Avaliou-se a influência da técnica obturadora na penetração do cimento AH Plus nos túbulos dentinários, por meio de microscopia confocal de varredura a laser (MCVL), e o impacto na resistência de união do material obturador à dentina, por meio do teste de push out. Raízes de incisivos centrais superiores (n=40) foram preparadas com ProTaper Universal e distribuídas em 4 grupos: Condensação lateral, Compactação vertical, Híbrida de Tagger Modificada e Cone único. Após obturação com guta percha e AH Plus acrescido de fluoresceína 0,01%, as raízes foram seccionadas em slices de 2,0 mm. O primeiro slice de cada terço foi submetido à MCVL e, posteriormente, ao teste de push out. O segundo slice foi analisado em MEV. ANOVA demonstrou diferença estatisticamente significante para as técnicas obturadoras e terços radiculares (p<0,05). Para o percentual de penetração, Tukey evidenciou que compactação vertical (91,77±13,51), Condensação lateral (89,18±10,91) e Híbrida de Tagger Modificada (87,53±15,42) apresentaram os maiores valores, estatisticamente diferentes (p<0,05) da Cone único (78,19±22,46). Na resistência de união (MPa), Condensação lateral (3,42±0,54) e Compactação vertical (3,47±0,53) obtiveram os maiores valores, diferentes (p<0,05) da Híbrida de Tagger Modificada (2,19±0,41) e da Cone único (0,54±0,21), que teve os menores valores. Concluiu-se que as técnicas obturadoras Condensação lateral, Compactação vertical e Híbrida de Tagger Modificada propiciaram maior penetração e resistência de união à dentina intrarradicular.

Influence of solvents on the bond strength of resin sealer to intraradicular dentin after retreatment.

This study evaluated the removal of filling material with ProTaper Universal Rotary Retreatment system (PTR) combined with solvents and the influence of solvents on the bond strength (PBS) of sealer to intraradicular dentin after canal reobturation. Roots were endodontically treated and distributed to five groups (n = 12). The control group was not retreated. In the four experimental groups, canals were retreated with PTR alone or in combination with xylol, orange oil, and eucalyptol. After filling material removal, two specimens of each group were analysed by SEM and µCT to verify the presence of filling remnants on root canal walls. The other roots were reobturated and sectioned in 1-mm-thick dentin slices that were subjected to the push-out test. Data were analysed by two-way ANOVA and Tukey's test (α = 0.05). SEM and µCT analysis revealed that all retreatment techniques left filling remnants on canal walls. The control group (3.47 ± 1.21) presented significantly higher (p < 0.05) PBS than the experimental groups. The groups retreated with PTR alone (2.59 ± 0.99) or combined with xylol (2.54 ± 0.77) and orange oil (2.32 ± 0.93) presented similar bond strength (p > 0.05), and differed significantly from the group with eucalyptol (1.89 ± 0.63). The solvents reduced the PBS of the sealer to dentin and no retreatment technique promoted complete removal of filling material.

Influence of Root Canal Filling Techniques on Sealer Penetration and Bond Strength to Dentin.

The influence of root canal filling techniques on the penetration of AH Plus into dentinal tubules was evaluated using confocal laser scanning microscopy (CLSM) and the impact on the bond strength of the filling material on the root dentin was evaluated using the push-out test. Roots of the maxillary central incisors (n=40) were prepared with ProTaper Universal and assigned to four groups: lateral condensation, vertical compaction, modified Tagger hybrid and single cone. After root canal filling with gutta-percha and AH Plus, along with the addition of 0.01% fluorescein, the roots were cut into 2-mm slices. CLSM was performed on the first slice of each root third, followed by the push-out test. The second slice was analyzed under SEM. ANOVA demonstrated a statistically significant difference between the root canal filling techniques and the root thirds (p<0.05). For percent penetration, Tukey's test showed that the vertical compaction (91.77±13.51), lateral condensation (89.18±10.91) and modified Tagger hybrid (87.53±15.42) presented the highest values, which significantly differed (p<0.05) from those of the single cone (78.19±22.46). For bond strength (MPa), lateral condensation (3.42±0.54) and vertical compaction (3.47±0.53) had the highest values (p<0.05), while the modified Tagger hybrid (2.19±0.41) and single cone (0.54±0.21) had the lowest. In conclusion, the lateral condensation, vertical compaction and Modified Tagger's hybrid techniques resulted in greater penetration and bond strength to the intra-radicular dentin.

Influence of root dentin treatment on the push-out bond strength of fibre-reinforced posts

Abstract This study evaluates the influence of root dentin treatment with NaOCl alone and combined with EDTA, with and without ultrasound activation, on the push-out bond strength (BS) of fiber-reinforced posts in weakened roots, cemented with RelyX or Panavia. The root canals of 42 maxillary canines were instrumented with Reciproc and 2.5% NaOCl. In the coronal 12mm of all canals, experimental weakening of the roots was produced by reducing dentin thickness with 2.44mm diameter diamond burs. The roots were assigned to 3 groups (n = 14) according to root dentin treatment: 2.5% NaOCl; 2.5% NaOCl + 17% EDTA; and 2.5% NaOCl + 17% EDTA, with solutions agitated using passive ultrasonic irrigation. After cementation of the fiber-reinforced posts the roots were divided in thirds. The first slice of each third was used for the push-out BS test, the second slice for confocal laser scanning microscopy and dentin microhardness (Knoop) analysis. Data were analysed by a two-way ANOVA and Tukey test (a = 0.05). NaOCl + EDTA provided highest BS values than NaOCl (p < 0.0001). Specimens cemented with Panavia presented significantly higher BS than those with RelyX in the three root thirds (p < 0.0001). The highest BS values occurred in the cervical third (p < 0.001). Ultrasound-activated NaOCl + EDTA promoted the greatest reduction in dentin microhardness, followed by NaOCl/EDTA and NaOCl. Ultrasonic activation of NaOCl and EDTA reduced root dentin microhardness, but did not improve the push-out BS of resin-based cements. Panavia presented higher BS than RelyX. RelyX was not influenced by the root dentin treatment protocols.

Influence of solvents on the bond strength of resin sealer to intraradicular dentin after retreatment

Abstract This study evaluated the removal of filling material with ProTaper Universal Rotary Retreatment system (PTR) combined with solvents and the influence of solvents on the bond strength (PBS) of sealer to intraradicular dentin after canal reobturation. Roots were endodontically treated and distributed to five groups (n = 12). The control group was not retreated. In the four experimental groups, canals were retreated with PTR alone or in combination with xylol, orange oil, and eucalyptol. After filling material removal, two specimens of each group were analysed by SEM and µCT to verify the presence of filling remnants on root canal walls. The other roots were reobturated and sectioned in 1-mm-thick dentin slices that were subjected to the push-out test. Data were analysed by two-way ANOVA and Tukey’s test (α = 0.05). SEM and µCT analysis revealed that all retreatment techniques left filling remnants on canal walls. The control group (3.47 ± 1.21) presented significantly higher (p < 0.05) PBS than the experimental groups. The groups retreated with PTR alone (2.59 ± 0.99) or combined with xylol (2.54 ± 0.77) and orange oil (2.32 ± 0.93) presented similar bond strength (p > 0.05), and differed significantly from the group with eucalyptol (1.89 ± 0.63). The solvents reduced the PBS of the sealer to dentin and no retreatment technique promoted complete removal of filling material.

Zinc Oxide Nanoparticles Enhance Physicochemical Characteristics of Grossman Sealer.

INTRODUCTION: Metallic antibacterial nanoparticles have been shown to provide distinct antibacterial advantage and antibiofilm efficacy when applied in infected root canals. The purpose of this study was to evaluate the influence of incorporating zinc oxide nanoparticles (ZnO-Np) on the physicochemical properties of Grossman sealer. METHODS: Grossman sealer was prepared according to its original formula. Additionally, 4 experimental sealers were prepared by replacing the zinc oxide component of the powder with ZnO-Np (average size of 20 nm) in different amounts (25%, 50%, 75%, and 100%). Characterization of the setting time, flow, solubility, dimensional changes, and radiopacity were performed according to American National Standards Institute (ANSI)/American Dental Association (ADA) Specification 57. Scanning electron microscopic and energy-dispersive X-ray spectroscopic analyses were conducted to assess the ultrastructural and chemical characteristics of experimental sealers subjected to the solubility test. Statistical analyses were performed with analysis of variance and post hoc Tukey-Kramer tests with a significance level of 5%. RESULTS: A statistically significant difference in the setting time was observed among groups (P < .05), but only 25% ZnO-Np sealer complied with ANSI/ADA requirements. There was a significant difference in the flow characteristics between the control and 25% and 75% ZnO-Np experimental sealers (P < .05), but all sealers conformed to ANSI/ADA standardization; 25% ZnO-Np sealer showed significantly less solubility (1.81% ± 0.31%) and dimensional change (-0.34% ± 0.12%) than other sealers (P < .05). All sealers showed ultrastructural changes with increasing solubility. CONCLUSIONS: ZnO-Np decreased the setting time and dimensional changes characteristic of Grossman sealer; 25% ZnO-Np improved the physicochemical properties of Grossman sealer in accordance with ANSI/ADA requirements.

Influence of Sealer and Light-Curing Units on Push-Out Bond Strength Of Composite Resin to Weakened Roots.

The aim of this study was to assess the influence of sealer and light-curing unit on regional bond strength of resin composite to the weakened roots. Ninety roots of incisors were experimentally weakened, subjected to biomechanical preparation and filled with either Endofill, AH Plus or MTA Fillapex The roots were desobturated e reinforced with resin composite and fiber post light-activated with one of the light sources: halogen at 600 mW/ cm2 (QTH-600), LED at 800 mW/ cm2 (LED-800) and LED at 1500 mW/ cm2 (LED-1500). The roots were sectioned in slices from cervical, middle and apical root-reinforcement regions and analyzed by push out test, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Bond strength data were analyzed using three-way ANOVA and Tukey´s test (α=0.05). Specimens filled with AH Plus had higher bond strength, followed by MTA Fillapex and Endofill (p<0.05). For light-curing unit, LED-1500 presented superior bond strength than LED-800, which was higher than QTH-600 (p<0.05). The cervical region had the greatest mean values (p<0.05) while apical part showed the lowest bond strength (p<0.05). CLMS revealed remaining filling material in the dentinal tubules for all groups. The eugenol-containing sealer (Endofill) compromised the push-out bond strength of composite resin to the root dentin. Bond strength was favored in the cervical region, and when LED-1500 was used.

1064-nm Nd:YAG and 980-nm Diode Laser EDTA Agitation on the Retention of an Epoxy-Based Sealer to Root Dentin.

Root canal irrigants are used to minimize the negative effects of smear layer on endodontic sealer retention. The aim of this study was to evaluate the efficacy of agitation of 17% ethylenediaminetetraacetic acid (EDTA) with ultrasonic, 1064-nm Nd:YAG and 980-nm diode laser on the retention of an epoxy-based sealer to the root canal walls. Forty single-rooted bovine teeth were instrumented with ProTaper rotary system and divided into four groups according to the final irrigation protocol (n = 10): (1) 17% EDTA (control); (2) 17% EDTA with 50-s ultrasonic agitation; (3) 17% EDTA with 50-s diode laser (2-W) agitation; and (4) 17% EDTA with 50-s Nd:YAG (1.5-W) laser agitation. After endodontic filling with gutta-percha F5 master cone and Sealer 26, the roots were sectioned at the cervical, middle, and apical root thirds to obtain 1.5-mm slices. Push-out tests were performed using a universal testing machine at a 1 mm/min crosshead speed. Data were analyzed using two-way ANOVA and Tukey's tests (α=0.05). Apical root thirds had significant higher retention values than cervical and middle thirds (p < 0.05). EDTA with 1064-nm Nd:YAG or 980-nm diode laser presented the highest retention values and was significantly different from EDTA with ultrasonic agitation and EDTA only (p < 0.05). Adhesive failures were predominant to EDTA only group. Mixed failures were predominant to all agitation groups. 1064-nm Nd:YAG and 980-nm diode laser EDTA agitation enhanced the retention of the epoxy-based sealer to the root canal walls compared with that due to EDTA only or EDTA with ultrasonic agitation.

Influence of Sealer and Light-Curing Units on Push-Out Bond Strength Of Composite Resin to Weakened Roots

Abstract The aim of this study was to assess the influence of sealer and light-curing unit on regional bond strength of resin composite to the weakened roots. Ninety roots of incisors were experimentally weakened, subjected to biomechanical preparation and filled with either Endofill, AH Plus or MTA Fillapex The roots were desobturated e reinforced with resin composite and fiber post light-activated with one of the light sources: halogen at 600 mW/ cm2 (QTH-600), LED at 800 mW/ cm2 (LED-800) and LED at 1500 mW/ cm2 (LED-1500). The roots were sectioned in slices from cervical, middle and apical root-reinforcement regions and analyzed by push out test, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Bond strength data were analyzed using three-way ANOVA and Tukey´s test (α=0.05). Specimens filled with AH Plus had higher bond strength, followed by MTA Fillapex and Endofill (p<0.05). For light-curing unit, LED-1500 presented superior bond strength than LED-800, which was higher than QTH-600 (p<0.05). The cervical region had the greatest mean values (p<0.05) while apical part showed the lowest bond strength (p<0.05). CLMS revealed remaining filling material in the dentinal tubules for all groups. The eugenol-containing sealer (Endofill) compromised the push-out bond strength of composite resin to the root dentin. Bond strength was favored in the cervical region, and when LED-1500 was used.

Resumo O objetivo neste estudo foi avaliar a influência do cimento endodôntico e da fonte de luz fotoativadora na resistência de união (RU) regional da resina composta às raízes fragilizadas. Noventa raízes de incisivos foram experimentalmente fragilizados, submetidos ao preparo biomecânico e obturadas com Endofill, AH Plus ou MTA Fillapex. Os canais foram desobturados e reforçados com pinos de fibra de vidro e resina composta fotoativada com uma das fontes de luz: halógena a 600 mW/cm2 (QTH-600), diodo emissor de luz a 800 mW/cm2 (LED-800) e LED a 1500 mW/cm2 (LED-1500). As raízes foram seccionadas em slices provenientes dos terços cervical, médio e apical das regiões da raiz reforçada e analisadas por meio do teste de push out, microscopia eletrônica de varredura (MEV) e microscopia confocal de varredura a laser (MCVL). Os dados de resistência de união foram analisados por ANOVA a três critérios e teste de Tukey (α=0,05). Os espécimes obturados com AH Plus apresentaram maior resistência de união, seguido do MTA Fillapex e do Endofill (p<0,05). Para fonte de luz fotoativadora, LED-1500 apresentou resistência de união superior ao LED-800 que foi maior que QTH-600 (p<0,05). A região cervical obteve as maiores médias (p<0,05), enquanto que a região apical apresentou a menor resistência de união (p<0,05). MCVL revelou remanescente de material endodôntico nos túbulos dentinários para todos os grupos. O cimento contendo eugenol (Endofill) comprometeu a resistência de união da resina composta à dentina radicular. A resistência de união foi favorecida na região cervical, e quando o LED-1500 foi empregado.

1064-nm Nd: YAG and 980-nm Diode Laser EDTA Agitation on the Retention of an Epoxy-Based Sealer to Root Dentin

Abstract Root canal irrigants are used to minimize the negative effects of smear layer on endodontic sealer retention. The aim of this study was to evaluate the efficacy of agitation of 17% ethylenediaminetetraacetic acid (EDTA) with ultrasonic, 1064-nm Nd:YAG and 980-nm diode laser on the retention of an epoxy-based sealer to the root canal walls. Forty single-rooted bovine teeth were instrumented with ProTaper rotary system and divided into four groups according to the final irrigation protocol (n = 10): (1) 17% EDTA (control); (2) 17% EDTA with 50-s ultrasonic agitation; (3) 17% EDTA with 50-s diode laser (2-W) agitation; and (4) 17% EDTA with 50-s Nd:YAG (1.5-W) laser agitation. After endodontic filling with gutta-percha F5 master cone and Sealer 26, the roots were sectioned at the cervical, middle, and apical root thirds to obtain 1.5-mm slices. Push-out tests were performed using a universal testing machine at a 1 mm/min crosshead speed. Data were analyzed using two-way ANOVA and Tukey's tests (α=0.05). Apical root thirds had significant higher retention values than cervical and middle thirds (p < 0.05). EDTA with 1064-nm Nd:YAG or 980-nm diode laser presented the highest retention values and was significantly different from EDTA with ultrasonic agitation and EDTA only (p < 0.05). Adhesive failures were predominant to EDTA only group. Mixed failures were predominant to all agitation groups. 1064-nm Nd:YAG and 980-nm diode laser EDTA agitation enhanced the retention of the epoxy-based sealer to the root canal walls compared with that due to EDTA only or EDTA with ultrasonic agitation.

Resumo Irrigantes para canais radiculares são usados para minimizar os efeitos negativos da camada de smear na retenção do cimento obturador. O objetivo deste estudo foi avaliar a eficácia da agitação do ácido etilenodiaminotetracético a 17% (EDTA) com ultrassom, Nd:YAG 1064-nm e laser diodo 980-nm na retenção de um cimento obturador à base de resina epóxica nas paredes do canal radicular. Quarenta dentes bovinos unirradiculares foram instrumentados com o sistema rotatório ProTaper e divididos em quatro grupos de acordo com o protocolo de irrigação final (n = 10): (1) EDTA 17% (controle); (2) EDTA 17% com agitação ultrassônica por 50-s; (3) EDTA 17% com agitação com laser diodo (2-W) por 50-s; e (4) EDTA 17% com agitação com laser Nd:YAG (1,5-W) por 50-s. Após obturação endodôntica com cone principal F5 e cimento Sealer 26, as raízes foram seccionadas nos terços radiculares cervical, médio e apical para obtenção de slices de 1,5-mm. Testes de push-out foram realizados utilizando uma máquina universal de ensaios com velocidade de carga de 1 mm/min. Os dados foram analisados utilizando os testes two-way ANOVA e Tukey's (α=0,05). Os terços radiculares apicais tiveram força de adesão significantemente maior que os terços cervical e médio (p<0,05). EDTA com Nd:YAG 1064-nm ou laser diodo 980-nm apresentaram os maiores valores de força de adesão e foram significantemente diferentes do EDTA com agitação ultrassônica e EDTA apenas (p < 0,05). Falhas adesivas foram predominantes apenas no grupo EDTA. Falhas mistas foram predominantes em todos os grupos de agitação. A agitação do EDTA com Nd:YAG 1064-nm e laser diodo 980-nm aumentou a força de adesão do cimento à base de resina epóxica às paredes do canal radicular comparado com a obtida com EDTA apenas ou EDTA com agitação ultrassônica.