ABSTRACT
This study aimed to evaluate the maximum compressive strength, the modulus of elasticity, pH variation, ionic release, radiopacity and biological response of an experimental endodontic repair cement based on 45S5 Bioglass®. An in vitro and in vivo study with an experimental endodontic repair cement containing 45S5 bioactive glass was conducted. There were three endodontic repair cement groups: 45S5 bioactive glass-based (BioG), zinc oxide-based (ZnO), and mineral trioxide aggregate (MTA). In vitro tests were used to evaluate their physicochemical properties: compressive strength, modulus of elasticity, radiopacity, pH variation, and the ionic release of Ca+ and PO4. An animal model was used to evaluate the bone tissue response to endodontic repair cement. Statistical analysis included the unpaired t-test, one-way ANOVA and Tukey's test. BioG showed the lowest compressive strength and ZnO showed the highest radiopacity among the groups, respectively (p < 0.05). There were no significant differences in the modulus of elasticity among the groups. BioG and MTA maintained an alkaline pH during the 7 days of evaluation, both at pH 4 and in a pH 7 buffered solutions. PO4 was elevated in BioG, peaking at 7 days (p < 0.05). Histological analysis showed less intense inflammatory reactions and new bone formation in MTA. BioG showed inflammatory reactions that decreased over time. These findings suggest that the BioG experimental cement had good physicochemical characteristics and biocompatibility required for bioactive endodontic repair cement.
Subject(s)
Zinc Oxide , Animals , Glass , Acrylic Resins , Oxides , Materials TestingABSTRACT
Objetivo: avaliar a resistência máxima à flexão (MFS), módulo de elasticidade (E), microdureza Knoop (KHN) e rugosidade de superfície (Ra) da dentina radicular tratada com solução de clorexidina a 2% (CHX). Métodos: foram selecionados 50 incisivos bovinos com ápice fechado, e trinta raízes foram cortadas em barras de dentina (DB) e divididas em três grupos (n = 10): Controle (sem tratamento), G1 (NaOCl 2,5% + EDTA 17%) e G2 (CHX 2% + H2O). As DB foram submetidas ao ensaio de resistência flexural de três pontos, para se obter os valores de MFS e E. Vinte raízes foram cortadas longitudinalmente ao meio e inseridas em resina acrílica; as superfícies pulpares foram lixadas e polidas e, em seguida, irrigadas de acordo com o grupo (G1 ou G2; n = 20 metades por grupo) e submetidas aos testes de KHN e Ra. Foi realizada análise de MEV. Os dados foram analisados por meio dos testes de ANOVA de um e dois critérios, seguidos do teste de Tukey (α = 0,05). Resultados: os valores de MFS (p < 0,05) e E (p < 0,01) foram maiores para G2. A KHN foi reduzida após o tratamento com cada irrigante endodôntico (p < 0,001), sem diferenças entre eles (p = 0,115). A Ra foi maior para o G1 (p < 0,001). Conclusões: a solução de clorexidina a 2% melhora as propriedades mecânicas de MFS, E e Ra da dentina radicular. (AU)
Objective: To evaluate the maximum flexural strength (MFS), elastic modulus (E), Knoop microhardness (KHN), and surface roughness (Ra) of root dentin treated with 2% chlorhexidine (CHX) solution. Materials and methods: Fifty bovine incisors with closed apex were selected. Thirty roots were cut into dentin bars (DB) and divided into three groups (n=10): control (no treatment), G1 (2.5% NaOCl + 17% EDTA) and G2 (2% CHX + H2O). The DB were submitted to the three-point flexural strength test to obtain the MFS and E. Twenty roots were cut longitudinally into two half-halves and placed in acrylic resin. The pulp surfaces were sanded and polished. They were rinsed according to the group (G1 or G2; n = 20 per group) and subjected to the KHN and Ra tests. SEM analysis was made. Data were analysed by one- and two-way ANOVA and Tukey post hoc test (a = 0.05). Results: The values of MFS (P < 0.05) and E (P < 0.01) were higher for G2. The KHN reduced after both endodontic irrigation treatments (P < 0.001), with no differences between them (P = 0.115). Ra was higher for G1 (P < 0.001). Conclusions: 2% CHX improved the mechanical properties of MFS, E and Ra of root dentin (AU).
Subject(s)
Chlorhexidine , Dental Pulp Cavity , Dentin , Sodium HypochloriteABSTRACT
Purpose. To evaluate the mineral ion loss of root dentine after treatment with 2% chlorhexidine solution (CHX) and to compare its yield and flexural strength (fs) after exposure to calcium hydroxide [Ca(OH)2]. Materials and Methods. Dentine bars (DB) were made from 90 roots of bovine incisors and randomized into three groups: GControl: distilled/deionized water (DDW), GNaOCl: 2.5% sodium hypochlorite + 17% EDTA, and GCHX: CHX + DDW. The release of phosphate (PO4) and calcium (Ca) ions was measured by spectrophotometry. The DB were exposed to Ca(OH)2 paste for 0, 30, 90, and 180 days. DB were subjected to the three-point bending test to obtain yield and fs values. The fracture patterns were evaluated (20x). Data were analyzed using Kruskal-Wallis and Dunn's post hoc tests or one- and two-way ANOVA followed by Tukey's post hoc test (α = 0.05). Results. GCHX showed lower PO43- and Ca2+ ionic release than GNaOCl (p < 0.001). For yield and fs, GCHX > GNaOCl in all periods (p < 0.001), except for yield strength values on 90 days (p = 0.791). A larger frequency of vertical fractures was observed in GNaOCl and that of oblique fractures in GCHX (p < 0.05). Conclusions. CHX prevented PO43- and Ca2+ loss and showed a tendency to preserve the yield and fs of root dentine over time following exposure to Ca(OH)2 paste.
ABSTRACT
Uma adesão satisfatória pode ser dificultada na presença de agentes dessensibilizantes, como nas cavidades do tipo Classe V. Este estudo teve como objetivo investigar a influência de dois agentes dessensibilizantes na resistência de união de um sistema adesivo autocondicionante quando aplicados previamente ao sistema adesivo. Foram utilizadas 30 coroas de incisivos bovinos, sendo incluídos em buchas de redução de PVC pré-fabricadas, com auxílio de resina acrílica. A superfície vestibular foi preparada, deixando a dentina exposta e os 30 conjuntos foram divididos em três grupos: G1 (adesivo + resina), G2 (oxagel + adesivo + resina) e G3 (G.H.F + adesivo + resina). Então, cilindros de resina composta (4 mm de diâmetro e 4 mm de altura) foram confeccionados. Decorridas 24 horas, os espécimes foram submetidos ao ensaio de cisalhamento e velocidade do atuador de 0,5 mm/min. Os dados foram submetidos ao teste de análise de variância de um fator (Anova - one way), complementados pelo teste de Tukey. Houve diferença estatística significante entre os tratamentos (G2 - 2,49 < G1 - 11,01 = G3 - 10,1). Assim, conclui-se que a resistência de união do sistema adesivo autocondicionante na dentina pré-tratada com agentes dessensibilizantes é prejudicada pelo uso do produto à base de oxalato.
A satisfactory bonding may be hampered in the presence of desensitizers agents, such as class V cavities. The aim of this study was to compare the effect of two different desensitizers on shear bond strength of a self-etch adhesive system. Thirty crowns of bovine incisors were mounted in pre-fabricated acrylic PVC using acrylic resin. The vestibular surface was prepared exposing the dentin and the crowns were divided into three groups: G1 (adhesive + resin), G2 (oxagel + adhesive + resin), and G3 (GHF + adhesive + resin). Resin composite cylinders (4 mm in diameter and 4 mm in height) were then placed. After 24 hours, shear bond strengths were measured using a circular knife-edge and crosshead speeds of 0.5 mm/minute. One-way ANOVA and Tukeys tests were used to compare the different conditions for bonding system. There was a statistically significant difference between treatments (G2 2.49 < G1 11.01 = G3 10.1). It was concluded that the shear bond strength of the self-etch adhesive system on dentin pre-treated with desensitizing agents is decreased by the use of the product based on oxalate
