Effect of the time-point of acid etching on the persistence of sealer residues after using different dental cleaning protocols

Abstract: Endodontic sealer residues remaining within the pulp chamber dentin after root canal obturation and cleaning with various solvents may compromise the appearance and the durability of dental restorations. Acid etching is routinely performed prior to application of dentine adhesive systems, but is effect on residual sealer material and the optimal time-point for performing etching, are unknown. Here, we evaluated the effect of acid etching on the dentin surface when performed either immediately or 7 days after removal of the endodontic sealer with two solvents, i.e., 95% ethanol or xylol. Forty crowns fragments from bovine incisors were impregnated with sealer and divided into 4 groups (n = 10 each), according to the dentin cleaning protocol and to the acid etching time-point: G1, 95.0% ethanol and immediate acid etching; G2, xylol and immediate acid etching; G3, 95.0% ethanol and acid etching after 7 days; and G4, xylol and acid etching after 7 days. Scanning electron microscopy (SEM) images (2000 ×) were obtained from each specimen and the number of open dentinal tubules counted and compared. Another 40 fragments were similarly prepared, and SEM images were obtained (500 ×) to score and compare the persistence of sealer residues on the dentin. G4 showed the most open dentinal tubules and the least epoxy resin-based sealer residues on the dentin surface (p < 0.05). The least epoxy resin-based sealer residues was obtained when acid etching, using 37% phosphoric acid, was performed after 7 days after cleaning the dentin with xylol.

Effects of calcium hydroxide addition on the physical and chemical properties of a calcium silicate-based sealer

Recently, various calcium silicate-based sealers have been introduced for use in root canal filling. The MTA Fillapex is one of these sealers, but some of its physicochemical properties are not in accordance with the ISO requirements. Objective: The aim of this study was to evaluate the flowability, pH level and calcium release of pure MTA Fillapex (MTAF) or containing 5% (MTAF5) or 10% (MTAF10) calcium hydroxide (CH), in weight, in comparison with AH Plus sealer. Material and Methods: The flowability test was performed according to the ISO 6876:2001 requirements. For the pH level and calcium ion release analyses, the sealers were placed individually (n=10) in plastic tubes and immersed in deionized water. After 24 hours, 7 and 14 days, the water in which each specimen had been immersed was evaluated to determine the pH level changes and calcium released. Flowability, pH level and calcium release data were analyzed statistically by the ANOVA test (α=5%). Results: In relation to flowability: MTAF>AH Plus>MTAF5>MTAF10. In relation to the pH level, for 24 h: MTAF5=MTAF10=MTAF>AH Plus; for 7 and 14 days: MTAF5=MTAF10>MTAF>AH Plus. For the calcium release, for all periods: MTAF>MTAF5=MTAF10>AH Plus. Conclusions: The addition of 5% CH to the MTA Fillapex (in weight) is an alternative to reduce the high flowability presented by the sealer, without interfering in its alkalization potential. .

Resistência de união á dentina do canal radicular de cimentos endodônticos, em função da medicação intracanal com hidróxido de cálcio / Bond strength evaluation of endodontic sealers after use of calcium hydroxide intracanal dressing

Este estudo foi dividido em dois capítulos, tendo como objetivo comparar, através do teste de push-out, a resistência de união do cimento MTA Fillapex (Angelus, Londrina, PR, BR), Sealapex (SybronEndo, Orange, CA, USA) e AH Plus (Dentsply De Trey Gmbh , Konstanz, GE) às paredes do canal radicular de dentes humanos extraídos, após o uso prévio de três tipos de medicação intracanal contendo hidróxido de cálcio: Calen (SS White, São Paulo, SP, BR), Pasta HPG (hidróxido de cálcio, paramonoclorofenol canforado e glicerina) e Ca(OH)2 + água (hidróxido de cálcio + água). Foram utilizados 60 dentes unirradiculares, que tiveram suas coroas seccionadas na junção amelocementária. As raízes foram incluídas em resina epóxi e cortadas transversalmente em fatias de 2 mm dos terços cervical, médio e apical das raízes. Em seguida, utilizando uma fresa tronco-cônica acoplada em micromotor, devidamente adaptado em um delineador, os canais foram preparados, padronizados e submetidos à irrigação com o EDTA a 17%. No primeiro estudo (Capítulo 1), os espécimes foram divididos em seis grupos: G1- MTA Fillapex; G2-Sealapex; G3-AH Plus, após o uso prévio das respectivas medicações com hidróxido de cálcio, por 21 dias. Após este período, os espécimes foram irrigados com NaOCl a 2,5% e EDTA a 17%, sendo então preenchidos com um dos cimentos em estudo, mantendo os corpos de prova por 7 dias, a 37˚C e 95% de umidade. Nos grupos 4, 5 e 6 foram utilizados os mesmos cimentos, sem uso da medicação intracanal, respectivamente. No segundo estudo (Capítulo 2), os espécimes foram distribuídos por grupos e os canais radiculares obturados com: G1- MTA Fillapex e G2-Sealapex. Cada grupo foi subdividido em três sub-grupos, em função da associação da medicação intracanal com hidróxido de cálcio previamente empregada: A - sem medicação; B - Ca(OH)2 + água destilada e C - Ca(OH)2 + glicerina/paramonoclorofenol canforado. Nos estudos dos dois capítulos, após 7 dias da obturação, os espécimes foram submetidos ao teste de push-out em máquina de ensaio mecânico. Os dados foram submetidos ao teste ANOVA e Tukey (α = 5). O tipo de falha foi analisado em estereomicroscópio (S8APO; Leica Microsystems, Wetzlar, Germany) com aumento de 20X, para avaliação do padrão de fratura: adesiva, coesiva ou mista. No primeiro estudo, o AH Plus apresentou maior resistência de união que os demais cimentos, independentemente do terço radicular (P < 0,05) e nos terços cervical e apical, a medicação intracanal interferiu negativamente (P < 0,05). O MTA Fillapex e Sealapex apresentaram resultados similares, independentemente do terço radicular (P > 0,05) e a medicação intracanal não interferiu na adesão. Entre os grupos houve diferente incidência de tipo de fratura. A adesão do AH Plus foi superior a do MTA Fillapex e Sealapex, que não diferiram entre si. O hidróxido de cálcio interferiu negativamente apenas na adesão do AH Plus, nos terços cervical e apical radicular. A fratura mista e adesiva foi mais frequente para o AH Plus e MTA Fillapex, respectivamente. No segundo estudo, a adesão proporcionada pelo MTA Fillapex foi afetada negativamente pelas associações somente no terço cervical (p < 0,05), sendo a fratura adesiva a de maior ocorrência. A resistência de união do Sealapex na dentina sofreu interferência negativa da combinação com água destilada nos terços médio e apical (p < 0,05), ocorrendo maior incidência de fratura adesiva. A associação glicerina/paramonoclorofenol canforado interferiu negativamente apenas no terço apical (p < 0,05), com similares padrões de fratura adesiva e mista. A composição dos resíduos da medicação intracanal com hidróxido de cálcio interfere na resistência de adesão dos cimentos MTA Fillapex e Sealapex, dependendo do terço radicular avaliado

The aim of this study, divided in two chapters, was to evaluate and to compare the push-out bond strength of three root canal sealers to the root canal walls of human extracted teeth: MTA Fillapex (Angelus, Londrina, PR, BR), Sealapex (SybronEndo, Orange, CA, USA) and AH Plus (Dentsply De Trey Gmbh, Konstanz, GE), after the previous use with three calcium hydroxide compositions with intracanal medication: Calen (SS White, São Paulo, SP, BR), HPG paste (Calcium hydroxide, Paramonoclorofenol canforado and Glycerin) and Calcium hydroxide with water paste. Sixty unirradicular teeth were sectioned transversally below the cement-enamel junction. The roots were included in epoxy resin and cut transversally, obtained 2 mm-thick cross-section slices of cervical, middle and apical radicular thirds. In sequence, using a conic drill adjusted in a low electric piece adapted in a pararelometer , the canals were prepared, standardized and submitted to irrigation with EDTA to 17%. In the first study (Chapter 1), the specimens were divided into six groups: G1-MTA Fillapex; G2-Sealapex; G3-OH Plus, after the prior use of calcium hydroxide intracanal medication, by 21 days. After, were irrigated with the 2.5% NaOCl and then filled with one of the materials, stored at 37˚C, for 7 days and 95% of relative humidity. In groups 4, 5 and 6 were used the same cement, without intracanal medication, respectively. In the second study (Chapter 2), the specimens weredivided and the canals obturated with: G1- Fillapex MTA and G2-Sealapex. Each group was subdivided into three sub-groups, depending of the calcium hydroxide intracanal medication composition, previously used: A-without medication; B- distilled water and C- Glycerin/camphorate paramonochlorophenol . After 7 days, the specimens were submitted to the push-out test in mechanical testing machine. The data were analyzed with ANOVA and Tukey test (α = 5%). In sequence,the specimems were analyzed in stereomicroscope (S8APO; Leica Microsystems, Wetzlar, Germany) with increase of 20X, to evaluation of failure modes: adhesive, cohesive or mixed. In the first study, the bond strength of AH Plus presented greater values then the other cements, regardless of the radicular third (P < 0,05), and in cervical and apical thirds intracanal medication interfere negatively (P < 0,05). The MTA Fillapex and Sealapex showed similar results, regardless of the radicular third (P > 0,05) and the intracanal medication did not interfere in the bond strength. Among the groups there was different type of failure modes. The bond strength of AH Plus was higher then MTA Fillapex and Sealapex, that not differed amongst themselves. Calcium hydroxide interfered negatively only in the bond strength of AH Plus, in cervical and apical radicular thirds. Mixed and adhesive fracture was more frequent for AH Plus and MTA Fillapex, respectively. In the second study, the bond strength provided by MTA Fillapex was affected negatively only in the cervical third associations (p < 0,05), being the adhesive fracture the greater occurrence. The bond strength of Sealapex in dentin suffered negative interference of distilled water combination in the middle and apical thirds (p < 0,05), occurring higher incidence of adhesive fracture. Glycerin/camphorate paramonochlorophenol interfered negatively only in the apical third (p < 0,05), with similar adhesive and mixed failure modes. The composition of the calcium hydroxide intracanal medication interferes in the bond strength of MTA Fillapex and Sealapex cements depending on the root third evaluated