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.

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.

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 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.

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.

Effect of root canal filling techniques on the bond strength of epoxy resin-based sealers

Abstract The aim of this study was to evaluate the effects of different root canal filling techniques on the bond strength of epoxy resin-based sealers. Sixty single-rooted canines were prepared using ProTaper (F5) and divided into the following groups based on the root filling technique: Lateral Compaction (LC), Single Cone (SC), and Tagger Hybrid Technique (THT). The following subgroups (n = 10) were also created based on sealer material used: AH Plus and Sealer 26. Two-millimeter-thick slices were cut from all the root thirds and subjected to push-out test. Data (MPa) was analyzed using ANOVA and Tukey's test (α = 0.05). The push-out values were significantly affected by the sealer, filling technique, and root third (p < 0.05). AH Plus (1.37 ± 1.04) exhibited higher values than Sealer 26 (0.92 ± 0.51), while LC (1.80 ± 0.98) showed greater bond strength than THT (1.16 ± 0.50) and SC (0.92 ± 0.25). The cervical (1.45 ± 1.14) third exhibited higher bond strength, followed by the middle (1.20 ± 0.72) and apical (0.78 ± 0.33) thirds. AH Plus/LC (2.26 ± 1.15) exhibited the highest bond strength values, followed by AH Plus/THT (1.32 ± 0.61), Sealer 26/LC (1.34 ± 0.42), and Sealer 26/THT (1.00 ± 0.27). The lowest values were obtained with AH Plus/SC and Sealer 26/SC. Thus, it can be concluded that the filling technique affects the bond strength of sealers. LC was associated with higher bond strength between the material and intra-radicular dentine than THT and SC techniques.

Effect of thermoplastic filling techniques on the push-out strength of root sealing materials

This study evaluates the effect of two thermoplastic obturation systems (MicroSeal and Obtura II) on bond strength of different sealers to intraradicular dentin. Sixty root canals of human canines were prepared using ProTaper rotary files (crown-down technique) and irrigated with 2.5% sodium hypochlorite and 17% EDTA. The root canals were filled by MicroSeal, Obtura II, or lateral compaction techniques using AH Plus and Epiphany SE. 1.5 mm thick root slices were subjected to the push-out test. ANOVA and Tukey's test showed that the bond strength values (MPa) observed in the groups obturated with MicroSeal (2.96 ± 2.72) and Obtura II (2.68 ± 2.18) did not significantly differ from each other (p > 0.05) but were significantly higher than that observed in the group obturated with lateral condensation (2.01 ± 1.48; p < 0.05). There were no statistically significant differences in strength (p > 0.05) among the root canal thirds (cervical: 2.44 ± 2.03; middle: 2.50 ± 2.27; and apical: 2.70 ± 2.34). Adhesive failures were predominant (60%) in all groups. In conclusion, MicroSeal and Obtura II techniques, using AH plus sealer, increased the resistance to displacement of the filling material, when compared with lateral compaction. Moreover, when used with Epiphany SE, these obturation systems did not affect the bond strength of the material to root dentin.

New Methodology to Evaluate Bond Strength of Root-End Filling Materials

This study evaluated the bond strength of root-end filling materials to root-end cavities using a new methodology. Twenty maxillary central incisors were subjected to biomechanical preparation (#80 hand file) and sectioned transversally 2 mm short of the apex and 4 mm coronally to this point. The root cylinders were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. Two groups (n=10) were formed according to the root-end filling material: MTA and Super EBA. A gutta-percha cone (#80) was tug-backed at the limit between the canal and the root-end cavity. The cavity was filled and the gutta-percha cone was removed after complete setting of the sealer. 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 run at a crosshead speed of 1.0 mm/min for pushing out the root-end filling material. Data were analyzed by ANOVA (α=5%). Super EBA (6.03±1.31) presented higher bond strength (MPa) than MTA (1.81±0.45) (p>0.05). There was a predominance of cohesive failures for Super EBA and mixed for MTA. The protocol of specimen preparation is effective and introduces a specific methodology for assessing bond strength of root-end filling materials to dentin. Among the materials, Super EBA presented the highest bond strength.

Este estudo avaliou a resistência de união de materiais retrobturadores a cavidades retrógradas, usando uma nova metodologia. Vinte incisivos centrais superiores foram submetidos ao preparo biomecânico (lima manual #80) e seccionadas transversalmente a 2 mm do ápice e a 4 mm do primeiro corte. Os cilindros de raízes foram incluídos em resina acrílica e posicionado a 45° em relação ao plano horizontal para confecção das retrocavidades com ponta ultrassônica diamantada. Dois grupos (n = 10) foram formados de acordo com os cimentos utilizados: MTA e Super EBA. Um cone de guta-percha (#80) foi travado no limite da retrocavidade com o canal radicular. A retrocavidade foi preenchida e, após o tempo de endurecimento do cimento utilizado, o cone de guta-percha foi removido. Os espécimes foram fixados na máquina universal de ensaios Instron com a retrobturação voltada para baixo. A haste empregada para pressionar o cimento retrobturador no teste de push-out foi inserida no espaço anteriormente ocupado pela guta-percha e acionada com velocidade de cruzeta de 1,0 mm/min, para extrusão do material retroburador. Os dados foram analisados por meio do teste ANOVA (α=5%). O cimento Super EBA (6,03 ± 1,31) apresentou maior resistência de união (MPa) comparado ao cimento MTA (1,81 ± 0,45) (p> 0,05). Houve predomínio de falhas coesivas para o cimento Super EBA e falhas mistas para o MTA. O protocolo de preparação das amostras é eficaz e apresenta uma metodologia específica para avaliação da resistência de união de materiais retrobturadores à dentina. Dentre os materiais testados, o cimento Super EBA apresentou a maior resistência de união.

Effects of various irrigation/aspiration protocols on cleaning of flattened root canals

This study aimed to evaluate, by means of scanning electron microscopy (SEM), the cleaning of flattened root canals, varying irrigation/aspiration protocols during biomechanical preparation. Thirdy human mandibular incisors were distributed into three groups (n = 10) according to the aspiration/irrigation protocols: conventional, conventional + brush, and apical negative pressure irrigation. Irrigation procedure was performed with 5 mL of 1% NaOCl at each change of instrument; final irrigation was conducted with 17% EDTA for 5 min. After biomechanical preparation, the roots were sectioned and prepared for SEM analysis. The images obtained were evaluated under 35× and 1,000× magnification by three calibrated examiners, following a double-blind design. All data were analyzed using Kruskal–Wallis and Dunn’s post hoctests (α = 0.05). Canals wherein the conventional method and apical negative pressure irrigation were employed revealed less debris, statistically different from the conventional + brush group (p < 0.05). Regarding the presence of smears, apical negative pressure irrigation was more effective in cleaning, showing lowest scores (p < 0.05), compared with the other tested protocols. Comparing each root canal third revealed that the apical portion was difficult to clean as all the tested protocols showed similar high scores (p > 0.05), both for the presence of debris and smear layer. In conclusion, although none of the studied irrigation/aspiration protocols have completely cleaned flattened root canals, apical negative pressure irrigation was more effective in smear layer removal, whereas the conventional + brush protocol was the least effective in removing the debris and smear layer.

Quantitative Assessment of Root Canal Roughness with Calcium-Based Hypochlorite Irrigants by 3D CLSM

Chemical solutions play important roles in endodontic treatment and promote ultrastructural changes in dentin surface. The aim of this study was to quantify root canal roughness at different concentrations of calcium hypochlorite (Ca(OCl)2) and sodium hypochlorite (NaOCl) by confocal laser scanning microscopy (CLSM). Fifty-two human mandibular premolars were sectioned and randomly organized into thirteen groups (n=8): saline (control); 1%, 2.5% and 5% NaOCl; 1%, 2.5% and 5% Ca(OCl)2; the hypochlorite groups were further divided into with or without EDTA. The chlorine concentrations of the different solutions were measured by iodine titration (%). The superficial roughness (Sa) was quantified by CLSM. Ca(OCl)2 presented substantial decrease in chlorine concentration that differed from the package indication, but without compromising the dentin ultrastructure changes. There were no significant differences in dentin roughness between Ca(OCl)2 or NaOCl at all studied concentrations. The combination with EDTA provided similar roughness values among the solutions (p>0.05). The 5% Ca(OCl)2 and NaOCl solutions significantly increased dentin roughness and did not differ from the EDTA association (p>0.05). Ca(OCl)2 promoted similar dentin roughness as the NaOCl at the same concentrations and combined with EDTA. It may be concluded that Ca(OCl)2 modified the root canal dentin roughness similarly to NaOCl, at the same concentrations and EDTA combinations used in this study. Ca(OCl)2 and NaOCl, both at 5%, significantly altered dentin roughness, overcoming EDTA association, thus Ca(OCl)2 concentrations ranging from 1% to 2.5% may be suitable solutions for root canal irrigation protocols.

Soluções químicas são fundamentais para o tratamento endodôntico; entretanto, promovem alterações ultraestruturais na superfície dentinária. O objetivo deste estudo foi quantificar a rugosidade da dentina radicular com diferentes concentrações de hipoclorito de cálcio (Ca(OCl)2) e hipoclorito de sódio (NaOCl) utilizando microscopia confocal à laser (CLSM). Foram utilizados 52 premolares humanos inferiores e aleatoriamente divididos em treze grupos (n=8): Soro fisiológico (controle); NaOCl a 1%, 2,5% and 5%; Ca(OCl)2 a 1%, 2,5% and 5%; os grupos de hipoclorito foram subdivididos pela associação ou não ao ácido etilenodiaminotetracético (EDTA). A concentração de cloro ativo foi avaliada para diferentes soluções utilizando titulação iodométrica (%). A rugosidade superficial (Sa) foi quantificada por CLSM. Ca(OCl)2 apresentou perda substancial de cloro ativo e que foi distinta da condição descrita pelo fabricante, sem entretanto comprometer as alterações no substrato dentinário. Não houve diferenças significantes na rugosidade dentinária produzida pelos Ca(OCl)2 e NaOCl em todas as concentrações estudadas e associação com EDTA. A associação ao EDTA produziu rugosidade semelhante entre as soluções (p>0.05). O Ca(OCl)2 e NaOCl na concentração de 5% aumentaram significativamente a rugosidade dentinária e não apresentaram diferenças dos valores obtidos com a associação de EDTA (p>0.05). O Ca(OCl)2 alterou a rugosidade da dentina radicular de forma semelhante ao NaOCl, nas concentrações e associações utilizadas neste estudo. Como a concentração de 5% de Ca(OCl)2 e NaOCl, apresentou maior rugosidade dentinária, independente da associação ao EDTA, pode-se concluir que Ca(OCl)2 nas concentrações de 1% e 2,5% pode ser considerado uma solução adequada para a irrigação de canais radiculares.

Effect of Light Sources on the Bond Strength of Resin Material to Thin-walled Roots

The aim of this study was to evaluate the bond strength to the dentin of an adhesive material used for root reinforcement light activated with different sources. Roots were divided into 4 groups (n=15) according to the light source used to activate the resin reinforcement: GI, non-weakened roots (control); GII, halogen light (H) 600 mW/cm2; GIII, LED 800 mW/cm2 and GIV, LED 1500 mW/cm2. The reinforcement was done with adhesive, composite resin and fiberglass posts. After 24 h, the specimens were sectioned and the first slice of each post region was used in the push out test in a universal testing machine with a crosshead speed of 0.5 mm/min. Failure modes of the debonded specimens were examined. Data (MPa) were analyzed by ANOVA and Holm-Sidak test (=0.05). The second slice from each region was analyzed by scanning electron microscopy (SEM). LED-1500 (4.69 ± 1.74) provided bond strength similar to the control group (5.05 ± 2.63) and statistically different from H-600 (1.96 ± 0.94) and LED-800 (2.75 ± 1.90), which were similar to each other (p<0.05). Cervical (4.16 ± 2.32) and middle (4.43 ± 2.32) regions showed higher bond strength than the apical (2.25 ± 1.50) (p<0.05). There was a prevalence of adhesive failures in H-600 and LED-800 and cohesive failures in LED-1500. SEM showed the formation of long, numerous and fine tags. It was concluded that LED-1500 provided higher bond strength of resin reinforcement to the dentin.

O objetivo deste estudo foi avaliar a resistência de união à dentina de uma resina utilizada para reforço de raiz, ativada com diferentes fontes de luz. De acordo com a fonte de luz utilizada as raízes foram divididas em 4 grupos (n = 15): GI, raízes não fragilizadas (controle); GII, luz halógena (H) 600 mW/cm2; GIII, LED 800 mW/cm2 e GIV, LED 1500 mW/cm2. O reforço foi feito com adesivo, resina composta e pino de fibra de vidro. Após 24 h, os espécimes foram seccionados e o primeiro slice de cada região utilizado para o teste de união push out, na máquina de ensaios universais com 0,5 mm/min, e o tipo da falha avaliada. Os dados obtidos (MPa) foram analisados utilizando os testes de ANOVA e Holm-Sidak (=0.05). O segundo slice de cada região foi analisado por microscopia eletrônica de varredura (MEV). O LED-1500 (4.69 ± 1.74) proporcionou resistência a união similar ao controle (5.05 ± 2.63) e estatisticamente diferente do H-600 (1.96 ± 0.94) e LED-800 (2.75 ± 1.90), que são similares entre si (p<0.05). As regiões cervical (4.16 ± 2.32) e média (4.43 ± 2.32) apresentaram alta resistência à união quando comparadas à região apical (2.25 ± 1.50) (p<0.05). Houve uma predominância de falhas adesivas com as fontes de luzes H-600 e LED-800 e coesivas com o LED-1500. A análise em MEV demonstrou a formação de longos tags resinosos. Desta forma, pode-se concluir que o LED-1500 proporcionou maior resistência à resina utilizada para o reforço da dentina radicular.

Bond strength of dentin submitted to bleaching and restored with different materials

Introduction: The use of adhesive composite resin with fluoride and with greater fluidity can be favorable to the restoration of the palatal/lingual face of teeth submitted to internal bleaching. Objective: This study evaluated the bond strength of adhesive systems and composite resins to bleached dentin. Material and methods:Forty maxillary canines were sectioned to obtain 40 blocks (5 x 5 mm) of intracoronary dentin. The fragments were included and bleached with 37% carbamide peroxide. After 7 days, the specimens were divided into two groups according to the adhesive system: with (Optibond Solo Plus) and without (Single Bond) fluoride and subdivided into 2 subgroups (n = 10) according to the composite resin: microhybrid (Z250) and flowable (Z350). The restoration was carried out through a bipartite matrix. After 24 hours, the specimens were subjected to shear bond strength test. The data (MPa) were analyzed by ANOVA and Tukey test (a = 0.05). Results: The best results (p < 0.05) were obtained for fluoridated adhesive (7.44 ± 2.35) compared with that without fluoride (5.36 ± 2.01); flowable resin (7.76 ± 2.23) performed better than microhybrid resin (5.03 ± 1.72). When the two variables were associated, the highest results were obtained for the specimens restored with fluoridated adhesive and flowable resin (9.04 ± 1.92). Lower results were observed for non-fluoridated adhesive + microhybrid resin - control (4.24 ± 1.59), without statistically significant differences when compared with the fluoridated adhesive + microhybrid resin (5.83 ± 1.52). Conclusion: The combination with fluoridated adhesive and flowable resin increases the shear bond strength of bleached dentin.

Bond strength of dual-cured resin cements to root canal dentin

Introduction: The bonding of dental posts to the root canal walls depends on the resin cement Objective:This in vitro study assessed the bond strength of resin cements used for post cementation to different root regions. Material and methods: Thirty canine roots were endodontically treated and prepared to receive dental posts which were luted with different resin cements (n = 10): Enforce (Dentsply), Panavia F (Kuraray Dental Co) and RelyX ARC (3M ESPE). The cements were light-cured for 20 s. After cementation, slices from cervical, middle and apical post/root regions were submitted to the push out test in a universal testing machine. The data (MPa) were analyzed using ANOVA and Tukey’s test (a = 0.05). Results: RelyX ARC (3.24 ± 1.49) and Enforce (3.45 ± 1.42) showed higher bond strength than Panavia (0.95 ± 0.39) (p < 0.05), without statistically significant difference between each other (p > 0.05). The bond strength values at the cervical (3.37 ± 1.47) were higher than middle (2.62 ± 1.94) and apical (1.65 ± 0.99) regions (p < 0.05), which were similar between them (p > 0.05). Conclusion: The resin cements RelyX ARC and Enforce presented greater bond strength than Panavia and the bond strength was higher at the cervical region.

Bond strength of endodontic sealers after intracanal surface pretreatment with CO2 laser

Introduction: The aim of this study was to evaluate in vitro the bonding of AH Plus and Endofill sealers to intraradicular canal walls after different dentin surface treatments. Material and methods: Sixty canines were sectioned obtaining dentin discs with 4-mm thickness and were embedded in acrylic resin. The canals were prepared with diamond burs. The specimens were divided into two groups (n = 30): GI - AH Plus and GII - Endofill and were subdivided into three groups based on the dentin surface treatment (n = 10): A - distilled and deionized water (control), B - 17% EDTA, C - CO2 laser with 3W in continuous mode for 10s. The specimens were submitted to push out test in a universal testing machine. Results: Tukey test revealed that the IB (AH Plus/17% EDTA) (17.59 ± 6.04) and IC (AH Plus/CO2 laser) (21.69 ± 4.93) subgroups had the highest values, which were statistically similar between each other (p > 0.05) and different from the other subgroups (p < 0.05). IIC subgroup (Endofill/CO2 laser) (7.25 ± 1.59) had intermediate values, which were statistically similar to (p > 0.05) IA subgroup (AH Plus/water) (10.99 ± 2.63), IIA subgroup (Endofill/water) (3.16 ± 0.83) and IIB subgroup (Endofill/ 17% EDTA) (5.31 ± 3.61), which had the smallest values (p < 0.05). Conclusion: The treatment of superficial intracanal dentin with CO2 laser and EDTA favored the adhesion of AH Plus and Endofill sealers.

Physicochemical properties of endodontic sealers of different bases

OBJECTIVE: To assess the setting time (ST), flow (FL), radiopacity (RD), solubility (SB) and dimensional change following setting (DC) of different sealers (AH Plus®, Polifil, Apexit Plus®, Sealapex®, Endométhasone® and Endofill®) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. MATERIAL AND METHODS: Five samples of each material were used for each test. For ST, cast rings were filled with sealers and tested with a Gilmore needle. For FL, the sealer was placed on a glass plate. After 180 s, another plate with 20 g and a load of 100 g were applied on the material, and the diameters of the discs formed were measured. In RD, circular molds were filled with the sealers, radiographed and analyzed using Digora software. For SB, circular molds were filled with the sealers, a nylon thread was placed inside the material and another glass plate was positioned on the set, pressed and stored at 37°C. Samples were weighed, placed in water, dried and reweighed. The water used for SB was analyzed by atomic absorption spectrometry. For DC, circular molds were filled with the sealers, covered by glass plates and stored at 37°C. Samples were measured and stored in water for 30 days. After this period, they were dryed and measured again. RESULTS: Regarding ST, AH Plus®, Apexit® and Endofil® sealers are in accordance with ANSI/ADA standards. Endométhasone's manufacturer did not mention the ST; Polifil is an experimental sealer and Sealapex® did not set. Considering RD, SB and DC, all sealers were in accordance with ANSI/ADA. The spectrometric analysis showed that a significant amount of K+ and Zn2+ ions was released from Apexit Plus® and Endofill®, respectively. CONCLUSION: Except for DC, all other physicochemical properties of the tested sealers conformed to ANSI/ADA requirements.

Flexural properties, morphology and bond strength of fiber-reinforced posts: influence of post pretreatment

The aim of this study was to assess the influence of surface pretreatments of fiber-reinforced posts on flexural strength (FS), modulus of elasticity (ME) and morphology of these posts, as well as the bond strength (BS) between posts and core material. Fifty-two fiber posts (smooth and serrated) were assigned to 4 groups (n=13): no treatment (control), 10% hydrogen peroxide (HP) for 10 min (HP-10), 24% HP for 1 min (HP-24) and airborne-particle abrasion (Al2O3). To evaluate FS and ME, a 3-point bending test was performed. Three posts of each group were examined by scanning electron microscopy. Composite resin was used as the core build-up and samples were sectioned to obtain microtensile sticks. Data were analyzed by ANOVA and Tukey's test (α=0.05). For FS, significant differences were observed between posts type and surface pretreatment (p<0.05), with the highest means for the smooth posts. Al2O3 provided higher FS than HP-24. Al2O3 promoted higher ME than HP-24 and control. SEM images revealed partial dissolution of the resin matrix in all treated groups. The smooth posts had higher BS and FS than serrated posts (p<0.05). Mechanical properties of the glass fiber posts and the bond strength between posts and composite material were not altered by the surface treatments, except for airborne-particle abrasion that increased the post elastic modulus.

O objetivo deste estudo foi avaliar a influência do pré-tratamento de superfície dos pinos de fibra de vidro na resistência à flexão (RF), módulo de elasticidade (ME) e morfologia, bem como a resistência de união (RU) entre os pinos e o núcleo de preenchimento. Cinqüenta e dois pinos de fibra de vidro (lisos e serrilhados) foram divididos em 4 grupos (n=13): sem tratamento (controle), peróxido de hidrogênio a 10% por 10 min (HP-10), peróxido de hidrogênio 24% por 1 min (HP-24) e jato de óxido de alumínio (Al2O3). Para avaliar a RF e ME, o ensaio de flexão de 3 pontos foi realizado. Três pinos de cada grupo foram examinados em MEV. Resina composta foi utilizada como núcleo de preenchimento e as amostras foram seccionadas para obter palitos de microtração. Os dados foram analisados por ANOVA e teste de Tukey (α=0,05). Na RF, observou-se diferença estatisticamente significante entre os pinos e tipo de pré-tratamento de superfície (p<0,05), com as maiores médias para os pinos lisos. Al2O3 proporcionou maior RF que HP-24. Al2O3 promoveu maior ME que HP-24 e grupo controle. MEV revelou dissolução parcial da matriz de resina em todos os grupos tratados. Os pinos lisos tiveram a maior RU (p<0,05). Os pinos lisos apresentaram RF e RU superior aos pinos serrilhados (p<0,05). As propriedades mecânicas dos pinos de fibra de vidro e a resistência de união entre os pinos e o material resinoso não foram alterados pelos tratamentos de superfície, com exceção do jato de óxido de alumínio que aumentou o módulo de elasticidade dos pinos.

Biocompatibility of sealers used in apical surgery: a histological study in rat subcutaneous tissue

The aim of this study was to evaluate the biocompatibility of sealers used in apical surgery in rat subcutaneous tissue. Sterile polyethylene tubes were filled with the following sealers: Sealapex, Sealapex with addition of zinc oxide, Sealer 26, Sealer 26 with thicker consistency (greater powder-to-resin ratio) and White MTA. The tubes were implanted in the dorsum of male rats and after 7, 21 and 42 days, the animals were killed, obtaining 5 specimens for each sealer in each evaluation period. The lateral surface of the tube was used as negative control. The inflammatory reaction to contact with the sealers was classified as absent, mild, moderate and severe. At 7 days, all sealers caused similar inflammatory reactions in the connective tissue of the animals, with most specimens presenting a moderate to intense chronic inflammatory reaction, with presence of multinucleated giant cells. At 21 days, Sealer 26 and Sealer 26 with thicker consistency presented more intense inflammatory reaction (p=0.004), whereas after 42 days, the inflammatory reaction ranged from absent to mild with statistically similar results for both materials (p=0.08). Except for MTA, all sealers presented foreign-body granulomatous reaction at 42 days. All sealers but Sealapex presented a statistically significant decrease of the inflammatory reaction over time. In conclusion, all sealers caused moderate to severe inflammation in the earlier evaluation period. However, Sealer 26 and Sealer 26 with thicker consistency caused more intense inflammatory reactions after 21 days of contact with the tissues and no granulomatous reaction was observed for MTA at the final period of analysis.

O objetivo deste estudo foi avaliar a biocompatibilidade de cimentos utilizados em cirurgia apical, em tecidos subcutâneos de ratos. Tubos de polietileno esterilizados foram preenchidos com os seguintes cimentos: Sealapex, Sealapex acrescido de óxido de zinco, Sealer 26, Sealer 26 espessado (maior proporção pó:resina) e MTA branco. Os tubos foram implantados no dorso de ratos machos e após 7, 21 e 42 dias, os animais foram mortos, obtendo 5 amostras por cimento em cada período analisado. A superfície lateral do tubo foi utilizada como controle negativo. A reação inflamatória em contato com os cimentos foram classificadas como ausente, leve, moderada e severa. Aos 7 dias, todos os cimentos induziram reações inflamatórias similares no tecido conjuntivo dos animais, com a maioria dos espécimes apresentando reação inflamatória crônica de moderada a intensa, com presença de células gigantes multinucleadas. Aos 21 dias, Sealer 26 e Sealer 26 espessado apresentaram reação inflamatória mais intensa (p=0,004), enquanto após 42 dias, a reação inflamatória variou de ausente a leve, com resultados estatisticamente semelhantes para ambos materiais (p=0,08). Com exceção do grupo MTA, todos os cimentos apresentavam reação granulomatosa de corpo estranho após 42 dias. Todos os grupos, exceto o Sealapex, apresentaram redução estatisticamente significante dos índices inflamatórios ao longo do tempo. Conclui-se que todos os cimentos induziram reação inflamatória de moderada a intensa no período inicial de análise. Entretanto, Sealer 26 e Sealer 26 espessado apresentaram reação inflamatória mais intensa após 21 dias de contato com os tecidos e reação granulomatosa não foi observada no grupo MTA no período final de análise.