Comparative Analysis of AH Plus Bond Strength to Root Canal Dentin and Adhesive Interface Quality after Calcium Hydroxide Removal using Different Irrigation Protocols.

INTRODUCTION: To evaluate the push-out bond strength (POBS) of AH Plus sealer to root dentin and the adhesive interface quality after calcium hydroxide (Ca(OH)2) intracanal dressing removal with different final irrigation protocols. METHOD: After root canal instrumentation and irrigation, 40 root canals were filled with Ca(OH)2 and sealed. After 14 days, the specimens were randomly distributed according to the irrigation protocols for Ca(OH)2 removal (n = 10): GH2O (control) - distilled water; GNaOCl - 1% NaOCl; GEDTA - 17% EDTA; GEDTA + NaOCl - 17% EDTA + 1% NaOCl. The root canals were filled with AH Plus sealer and gutta-percha. After 7 days, the roots were sectioned into dentin slices and submitted to POBS test and analysis of the adhesive interface under scanning electron microscope. The POBS data were statistically evaluated (analysis of variance and Tukey test). The Kruskal-Wallis and Mann-Whitney tests were used to analyze the adhesive interface (α = 0.05). RESULTS: GH2O, GNaOCl, and GEDTA + NaOCl had similar POBS values, with higher values on the apical third, in comparison with other thirds (P < .05). A homogeneous and free-of-gaps adhesive interface was observed for GH2O, GNaOCl, and GEDTA + NaOCl, with difference between GH2O and GEDTA (P < .05). GH2O and GEDTA + NaOCl presented higher sealer tags formation (P < .05). CONCLUSION: The final rinse with EDTA for Ca(OH)2 dressing removal had a negative effect on the POBS of the filling material to root dentin. The use of EDTA followed by NaOCl had results similar to the distilled water, providing uniform and free-of-gaps adhesive interface, and a higher number of sealer tags.

Analysis of physicochemical properties of endodontic sealers containing rhodamine B.

The use of fluorescent dyes in microscopy studies is frequent. Therefore, it is important to investigate whether these compounds may alter the physicochemical properties of materials in which they are incorporated to avoid methodological biases. This study evaluated the physicochemical properties of two endodontic sealers containing dry or diluted rhodamine B. Six groups were evaluated: AH Plus and MTA Fillapex in their original composition and mixed with 0.1% dry or diluted rhodamine. Push-out test was applied to assess the bond strength to root dentin. ANSI-ADA No. 57 and ISO No. 6876:2012 specifications were followed to evaluate flowability, setting time, and solubility of the sealers. pH changes were assessed after 24 h, 7, and 30 days. Intergroup comparisons were analyzed by ANOVA complemented by Tukey's post-hoc test; comparisons among periods were analyzed by Wilcoxon and Friedman tests. The incorporation of dry rhodamine decreased the bond strength and prolonged the setting time of AH Plus. The incorporation of diluted rhodamine decreased the setting time and increased the flowability of MTA Fillapex. Diluted rhodamine promoted pH reduction of AH Plus after 24 h and dry rhodamine after 7 days. Rhodamine incorporation promoted pH reduction after 30 days for MTA Fillapex. Solubility was not affected. In conclusion, the incorporation of diluted rhodamine changed the properties of MTA Fillapex, and the incorporation of dry rhodamine changed the properties of AH Plus. Previous dilution of rhodamine did not severely compromise the physicochemical properties of AH Plus and may be suggested to assess its penetrability.

Effect of different periods of calcium hydroxide dressing on the fracture resistance of root dentin.

The aim of this in vitro study was to evaluate the effect of different periods of intracanal calcium hydroxide (Ca[OH]2) dressing application on the compressive strength of root dentin. The roots of 80 human mandibular premolars were prepared via the crown-down technique and randomly distributed into 1 control group (Gc) and 4 experimental groups (n = 16). The experimental groups were based on the length of intracanal Ca(OH)2 dressing use: 7 (G7d), 14 (G14d), 30 (G30d), or 90 (G90d) days. The prepared roots in the control group were left unfilled. The root canals in the experimental groups were dried, filled with the Ca(OH)2 dressing, and radiographed, and then the root canal entrance was sealed. All of the specimens were stored in saline solution at 37°C for the duration of their experimental period. After storage, the roots were sectioned with 2 cuts. The first cut was 1 mm below the cementoenamel junction, and the second was 6 mm apical to the first cut, creating 6-mm-long × 3-mm-diameter cylinders. At each test period, 4 specimens from Gc and all 16 specimens from the appropriate experimental group were submitted to compressive strength testing (1 mm/min). The groups demonstrated the following mean (SD) values of compressive strength: Gc, 174.41 (56.10) MPa; G7d, 161.29 (39.10) MPa; G14d, 130.27 (57.53) MPa; G30d, 167.88 (34.24) MPa; and G90d, 129.62 (31.46) MPa. Statistically significant differences among the groups were found (P = 0.007; analysis of variance and Tukey test, α = 5%), with a significant difference between Gc and both G14d and G90d (P < 0.05). There were no statistically significant differences (P > 0.05) among the mean compressive strength values of the experimental groups (7, 14, 30, and 90 days). The results indicated that the use of Ca(OH)2 as an intracanal medication for periods of 14 and 90 days reduced the fracture resistance of root dentin.

Correlation between Bond Strength to Dentin and Sealers Penetration by Push-Out Test and CLSM Analysis.

This study correlated the bond strength (BS) and dentin penetration of different sealers by push-out test and Confocal Laser Scanning Microscopy (CLSM) analysis. Forty-five root canals were prepared according to the crown-down technique and filled with gutta-percha associated to the following sealers (n=15): Endofill, AH Plus and MTA Fillapex. Five canals of each group were filled with the sealers added with 0.1% Rhodamine B dye. Next, the specimens were transversely sectioned and submitted to the push-out test (n=10) and CLSM analysis (n=5). The BS data showed the following means (MPa) and standard deviation: AH Plus (4.17±1.86); MTA Fillapex (3.13±1.96) and Endofill (2.10±1.03). Statistical analysis (two-way ANOVA, α=0.05) showed significant difference among sealers (p<0.001) and root canal thirds (p<0.001). The BS results of Endofill and MTA Fillapex were statistically similar (p>0.05), however, they were statistically different from AH Plus (p<0.001). The regional analysis of BS showed similarity between middle and apical thirds (p>0.05), and both were different from coronal portion (p<0.001). CLSM analysis verified tags formation in all groups and higher penetration of the specimens filled with AH Plus (p<0.05). The Kendall test (correlation between BS to dentin and sealer penetration into dentinal tubules) and the Pearson test (between failures pattern and sealer penetration into dentinal tubules) did not show correlation between the variables evaluated for all the tested sealers (p>0.05). AH Plus group had higher BS to dentin, and deeper tags formation than the other sealers. There was no significant correlation between BS and intratubular penetration of the tested sealers.

Effect of Bleaching and Ca(OH)2 Dressing on the Bond Strength of Fiberglass Posts to Root Dentine.

OBJECTIVE: The purpose of this study was to evaluate the effect of the intracoronary bleaching and calcium hydroxide (Ca(OH)2) dressing use, on the bond strength (BS) of fiberglass posts to root dentine. MATERIALS AND METHODS: After root canal filling of 40 bovine incisors, a 2-mm thick cervical plug was fabricated 2 mm below the cementum-enamel junction. Seven days later, teeth were randomly distributed into four groups (n = 10), as follows: G1 no bleaching, followed by immediate post cementation; G2 bleaching and immediate post cementation; G3 bleaching, dressing with Ca(OH)2 for 7 days, and post cementation; and G4 bleaching, no dressing, and post cementation after 7 days. The roots were transversally cut into 1-mm thick slices to perform the push-out test (0.5 mm/min). Failure modes were assessed under scanning electron microscopy. STATISTICAL ANALYSIS: The analysis of variance (two-way ANOVA) was performed, followed by the supplementary Tukey multiple comparison test (a = 5%). RESULTS: No significant difference for BS was observed among groups. Considering the different root thirds, G1 had higher BS values for the cervical third in comparison with the apical one (p < 0.05). The most frequent failure modes were adhesive between cement/dentine (G1); cohesive at the post (G2 and G3), and mixed (G4). CONCLUSIONS: The BS of the fiberglass posts to root dentine was not affected by the intracoronary bleaching and the use of Ca(OH)2 dressing.

Influence of Infected Root Dentin on the Bond Strength of a Self-adhesive Resin Cement.

AIM: The aim of this study was to determine the bond strength (BS) of a self-adhesive resin cement to the contaminated root dentin. MATERIALS AND METHODS: The crown and apical third of twenty single-rooted teeth were removed. The root canals were flared and 1-mm-thick root sections were obtained. The sections were rinsed, dried, and sterilized. The control group (n=20) was composed of one section of each third, which remained immersed in sterile trypticase soy broth (TSB) for 2 months. The other sections comprised the experimental group (n = 40) and were immersed in a suspension of Enterococcus faecalis. The culture medium was changed at every 4 days for 2 months. The sections were rinsed with distilled water, dried, and the root canal space was filled with the self-adhesive resin cement RelyX™ U200. After 24 h, the push-out test was performed and the types of interface failure were observed on a stereo microscope. STATISTICAL ANALYSIS: Data were statistically analyzed by the nonparametric Mann-Whitney test (α=5%). RESULTS: A significant reduction was observed in the BS of resin cement to the contaminated dentin compared to the healthy dentin, for both thirds analyzed (P < 0.05). The BS was significantly greater at the cervical third compared to the middle third for specimens in the experimental group (P < 0.05). Adhesive and mixed failures were observed more frequently in specimens contaminated with E. faecalis. CONCLUSION: Bacterial contamination negatively infl uenced the BS of the self-adhesive resin cement to the root dentin, and there was a predominance of adhesive and mixed failures.

Comparison of two observational methods, scanning electron and confocal laser scanning microscopies, in the adhesive interface analysis of endodontic sealers to root dentine.

OBJECTIVES: To compare the accuracy of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) during the analysis of the adhesive interface integrity and intratubular penetration of root canal sealers to radicular dentine. MATERIALS AND METHODS: Twenty roots of human maxillary incisors were prepared and distributed into two groups (n = 10), followed by filling with gutta-percha and Endofill (G1) or AH Plus (G2). After 7 days, roots were sectioned and analyzed under CLSM and SEM. Score systems were used to evaluate the adhesive interface integrity (0-4) and sealer intratubular penetration (0-3). Data were submitted to Wilcoxon-Mann-Whitney and Kendall correlation statistical tests (α = 5%). RESULTS: In the adhesive interface analysis, CLSM was similar (P = 0.157) to SEM for Endofill; however, the results were different for AH Plus (P = 0.029). Intratubular penetration had significant difference between observational methods for both sealers (P < 0.0001). Correlation analysis between SEM and CLSM for adhesive interface was moderate for Endofill and low for AH Plus. Intratubular penetration was low for both sealers. CONCLUSION: SEM and CLSM analysis had similar results when sealers were compared, with a more homogeneous adhesive interface, and greater intratubular penetration for AH Plus. Comparison between observational methods demonstrated low positive correlation for adhesive interface and intratubular penetration analysis. CLINICAL RELEVANCE: A proper interface formed between sealer and dentine is very important for final quality of root canal filling. Observational methods which allow an accurate analysis of this interface must be selected to assess such features.

Intracanal Irrigating Solutions Prior to Calcium Hydroxide Medication and Its Effects on Root Dentin Strength.

The aim of this study was to assess the effects of intracanal irrigation with sodium hypochlorite (NaOCl) and ethylenediaminetetracetic acid (EDTA) prior to calcium hydroxide medication on the compressive strength of root dentin. Forty-eight roots with single and straight canals were instrumented with a crown-down technique using Flexofile files and Gates Glidden burs, under 0.9% sodium chloride (NaCl) irrigation. Root canals were randomly separated into 4 groups (n=12), according to the irrigating solution: Control Group, 0.9% NaCl; GroupNaOCl, 1% NaOCl; GroupEDTA, 17% EDTA; and GroupEDTA+NaOCl, 17% EDTA and 1% NaOCl. Solutions remained for 40 min, renewed every 10 min, except for GroupEDTA+NaOCl, where the solutions were alternated every 10 min. Canals were dried and filled with calcium hydroxide paste, and radiographed. Each canal was sealed and stored at 37 °C for 30 days. After this period, the roots were cut 1 mm below the cementoenamel junction and 6 mm apically from this point in order to obtain 6 mm-long cylinders. The compressive test was conducted with a crosshead speed of 1 mm/min. The means (±SD) (MPa) of compressive strength were: Control Group, 151.23±94.36; GroupNaOCl, 167.50±57.25; GroupEDTA, 108.79±99.88; GroupEDTA+NaOCl, 60.12±92.10. Significant statistical differences among groups were found (ANOVA and Tukey, a=5%, p=0.02). Control Group and GroupNaOCl showed higher means of compressive strength than GroupEDTA+NaOCl. Intracanal irrigation with 17% EDTA and 1% NaOCl produced a significant reduction of dentin compressive strength 30 days after medication with calcium hydroxide.

Intracanal Irrigating Solutions Prior to Calcium Hydroxide Medication and Its Effects on Root Dentin Strength

Abstract The aim of this study was to assess the effects of intracanal irrigation with sodium hypochlorite (NaOCl) and ethylenediaminetetracetic acid (EDTA) prior to calcium hydroxide medication on the compressive strength of root dentin. Forty-eight roots with single and straight canals were instrumented with a crown-down technique using Flexofile files and Gates Glidden burs, under 0.9% sodium chloride (NaCl) irrigation. Root canals were randomly separated into 4 groups (n=12), according to the irrigating solution: Control Group, 0.9% NaCl; GroupNaOCl, 1% NaOCl; GroupEDTA, 17% EDTA; and GroupEDTA+NaOCl, 17% EDTA and 1% NaOCl. Solutions remained for 40 min, renewed every 10 min, except for GroupEDTA+NaOCl, where the solutions were alternated every 10 min. Canals were dried and filled with calcium hydroxide paste, and radiographed. Each canal was sealed and stored at 37 °C for 30 days. After this period, the roots were cut 1 mm below the cementoenamel junction and 6 mm apically from this point in order to obtain 6 mm-long cylinders. The compressive test was conducted with a crosshead speed of 1 mm/min. The means (±SD) (MPa) of compressive strength were: Control Group, 151.23±94.36; GroupNaOCl, 167.50±57.25; GroupEDTA, 108.79±99.88; GroupEDTA+NaOCl, 60.12±92.10. Significant statistical differences among groups were found (ANOVA and Tukey, a=5%, p=0.02). Control Group and GroupNaOCl showed higher means of compressive strength than GroupEDTA+NaOCl. Intracanal irrigation with 17% EDTA and 1% NaOCl produced a significant reduction of dentin compressive strength 30 days after medication with calcium hydroxide.

Resumo O objetivo desse estudo foi avaliar o efeito da irrigação intracanal com hipoclorito de sódio (NaOCl) e ácido etilenodiamino tetracético (EDTA) previamente à medicação de hidróxido de cálcio na resistência à compressão da dentina radicular. Quarenta e oito raízes com canais únicos e retos tiveram os canais instrumentados pela técnica coroa-ápice com limas Flexofile e brocas Gates Glidden sob irrigação com solução salina (NaCl) a 0,9%. Os canais radiculares foram separados em 4 grupos (n=12), de acordo com a solução irrigadora: Grupo Controle, NaCl 0,9%; GrupoNaOCl, NaOCl 1%; GrupoEDTA, EDTA 17%; e GrupoEDTA+NaOCl, NaOCl 1% e EDTA 17%. As soluções permaneceram por 40 min, sendo renovadas a cada 10 min, exceto para o GrupoEDTA+NaOCl, onde as soluções foram alternadas a cada 10 min. Os canais foram secos, preenchidos com pasta de hidróxido de cálcio e radiografados. Cada canal foi selado e mantido a 37 °C por 30 dias. Após esse período, as raízes foram cortadas 1 mm abaixo da junção cemento-esmalte e 6 mm apicalmente a este corte, a fim de obter cilindros de 6 mm de comprimento. O teste de compressão foi realizado com velocidade de cruzeta de 1 mm/min. As médias (±SD) da resistência à compressão em MPa foram: Grupo Controle, 151.23±94.36; GrupoNaOCl, 167.50±57.25; GrupoEDTA, 108.79±99.88; GrupoEDTA+NaOCl, 60.12±92.10. Diferenças estatisticamente significativas foram encontradas entre os grupos (ANOVA e Tukey; a=0,05; p=0,02). O Grupo Controle e o GrupoNaOCl obtiveram maiores médias de resistência à compressão em relação ao GrupoEDTA+NaOCl. A irrigação intracanal com EDTA 17% e NaOCl 1% promoveu redução significativa da resistência à compressão da dentina, após 30 dias de medicação intracanal com hidróxido de cálcio.

Adhesive interface and bond strength of endodontic sealers to root canal dentine after immersion in phosphate-buffered saline.

This study evaluated the bond strength (BS) and the adhesive interface of four endodontic sealers to root canal dentine, before, and after immersion in phosphate buffered saline (PBS) to simulate an in vivo environment. Eighty roots were instrumented using ProTaper rotatory files, under irrigation with 17% EDTA and 1% NaOCl. Posteriorly were divided into four groups (n = 20) according to the sealer used: Endofill, AH Plus, Sealapex, and MTA Fillapex. Each group was divided into two subgroups (n = 10) and stored at 37°C immersed in water for 7 days and in PBS for 60 days. From each subgroup, 1 mm thick sections were obtained. One section of each region (coronal, middle, and apical) was submitted to the push-out test and failures were observed. Twelve sections of each subgroup (four from each region) were evaluated under SEM. Three-way ANOVA evaluation for BS showed significant differences between groups and regions (P < 0.0001), but not between subgroups (P > 0.05). AH Plus had significantly higher BS than the others sealers, regardless of the analyzed subgroup (Tukey's test, P < 0.5). The most common failures were adhesive to dentine and cohesive of the sealer. The SEM evaluation (Kruskal-Wallis, Mann-Whitney) showed homogeneous adhesive interface formed and sealer tags in all groups with significant statistical differences with AH Plus, regardless of PBS immersion. AH Plus was superior to the other sealers for both BS and quality of interface formation. Immersion in PBS did not interfere on BS or adhesive interface of the sealers tested.

Análise ex vivo da influência do preparo cervical na determinação do comprimento de trabalho por três diferentes localizadores apicais eletrônicos / Ex vivo analysis of the influence of cervical preparation in determining the working length by three different apex electronic locators

Introdução: Atualmente uma geração nova de localizadores apicaiseletrônicos (electronic apex locators ? EALs) passou a utilizar correntesalternadas com frequências baixas, em que o efeito do potencial de polarização do eletrodo é evitado, dando mais precisão para os valoresmedidos. Objetivo: O objetivo deste estudo foi avaliar ex vivo a influênciado preparo do terço cervical na eficácia de três localizadores apicaisquando comparados com o exame radiográfico. Material e métodos:Foram utilizados 20 pré-molares inferiores de canais únicos e retos. Osespécimes tiveram inicialmente o comprimento de trabalho estabelecidoa 1 mm do ápice radicular pelo método visual. Na sequência os dentesforam submetidos ao método radiográfico e aos localizadores apicaisRoot ZX, Root ZX II e Novapex, definindo dessa forma dados numéricosdo grupo controle, radiográfico e localizadores apicais. A medição foifeita antes e após o preparo do terço cervical, com o instrumento SXdo sistema Protaper. Resultados: Após a obtenção dos dados, estesforam submetidos a análise estatística, e não se encontrou diferençaestatisticamente significante entre os grupos experimentais estudados.Conclusão: Os localizadores apicais pesquisados provaram ser precisospara a realização da odontometria durante a terapia endodôntica.

Introduction: Currently, a new generation of electronic apex locators(EALs) started to use alternating current at low frequencies, where theeffect of polarization potential of the electrode is avoided, giving moreprecision to the measured values. Objective: The aim of this studywas to evaluate ex vivo the influence of the preparation of the cervicalthird in the effectiveness of three apex locators when compared to theradiographic examination. Material and methods: 20 mandibularpremolars with single straight canals were used. At first the specimenshad the working length established at 1 mm from the apex through thevisual method. Then teeth were submitted to the radiographic methodand to the Root ZX, Root ZX II and Novapex apex locators, therebysetting data in the control group, radiographic and apex locators. Themeasurement was performed before and after the preparation of thecervical third, with the SX instrument of the Protaper system. Results:After obtained, data was submitted to statistical analysis, and nostatistically significant difference was found between the experimentalgroups studied. Conclusion: The apex locators studied proved tobe accurate to perform the root canal measuring during endodontictherapy.