Abstract Chitosan is a natural, biocompatible chelating substance with potential for dental use. This study compared the effects of final canal irrigation with chitosan and EDTA on dentin microhardness, sealer dentin tubules penetration capacity, and push-out strength. Methodology: Fifty canine roots were distributed according to the final irrigation protocol (n=10): G1- 15% EDTA with conventional irrigation; G2- 15% EDTA with Endovac; G3- 0.2% chitosan with conventional irrigation; G4- 0.2% chitosan with Endovac; and G5- without irrigation. Specimens were obturated (AH Plus) and sectioned in 3 slices per root third. The first slice was used for microhardness and sealer penetration assessments under a laser confocal microscope. The second was utilized in a push-out strength test. The third slice was discarded. Data were analyzed using 2-way ANOVA and Tukey's post hoc test (α<0.05). Failure mode was determined at x40 magnification. Results: Microhardness reduction was more significant in groups G2 and G4 (p<0.05). Sealer penetration through dentin was significantly greater in group G2 (p<0.05). There was no significant difference between groups G1, G3, and G4 (p>0.05). In general, all experimental groups presented similar bond resistance (p>0.05) that significantly differed from the control (p<0.001). Mixed type failures were predominant. Conclusions: In general, 0.2% chitosan and 15% EDTA solutions act in a similar manner with regard to the variables studied. The use of Endovac potentiates the effect of these solutions.

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.

Resumo Estudou-se a morfologia, microdureza e permeabilidade dentinária da furca de pré-molares superiores. Dez pré-molares tiveram a porção oclusal da coroa e os terços radiculares médio e apical removidos. Cortou-se longitudinalmente o remanescente e delimitou-se a furca. As hemi-secções foram distribuídas em dois grupos. Num (n=10), mediu-se a microdureza nas regiões vestibular, central e palatina, nas camadas externa, média e interna e nas porções vestibular e palatina adjacentes à furca. Utilizou-se dureza Knoop, carga de 10 g por 15 s. Os dados foram analisados pelo teste ANOVA e Tukey-Kramer (a=0.05). No outro grupo (n=10) utilizou-se microscopia confocal para estudo da morfologia da dentina. Outros 10 espécimes foram instrumentados com Protaper e NaOCl a 1% e imersos em sulfato de cobre a 10% para análise da permeabilidade. Após preparo histológico os espécimes foram analisados em fotomicroscópio. Não houve diferença significante (p>0,05) entre a microdureza das regiões vestibular (39,9±3,1), central (39,5±4,4) e palatina (39,7±5,0), nem entre essas regiões e as adjacentes vestibular (39,1±5,8) e palatina (39,7±5,8) (p>0,05). A camada interna (42,3±3,7) é mais dura que a externa (37,1±3,9) (p<0,05). Há uma tendência dos canalículos calcificarem no sentido da camada externa para a interna. A porcentagem de área corada foi de 12,45±2.0 e restrita à camada externa. As regiões vestibular, central e palatina da furca, bem como as adjacentes vestibular e palatina apresentaram microdureza semelhante entre si. A camada interna apresentou-se mais dura que a externa. Os canalículos dentinários eram sinuosos e se entrelaçaram em direção à camada média. A penetração de corantes se restringiu à camada externa.

Abstract The morphology, microhardness and dentin permeability of the furcation region of maxillary premolars were evaluated. Ten premolars were cut lengthwise and the furcation region was delimited. In one group (n=10) microhardness was measured in the buccal, central and palatal regions, in the outer middle and inner layers of the furcation, and in the buccal and palatal regions adjacent to the furcation. Knoop hardness was tested with 10 g load for 15 s. Data were analyzed statistically by ANOVA and Tukey-Kramer test (a=0.05). In the other group (n=10) confocal microscopy was used to study dentin morphology. Other 10 specimens were instrumented with ProTaper and immersed in 10% copper sulfate for analysis of permeability under light microscopy. About microhardness, there was no significant difference (p>0.05) among the buccal (39.9±3.1), central (39.5±4.4) and palatal (39.7±5.0) regions of the furcation, or between these regions and the adjacent buccal (39.1±5.8) and palatal (39.7±5.8) regions (p>0.05). The inner layer (42.3±3.7) had significantly higher microhardness (p<0.05) than the outer layer (37.1±3.9). There was a tendency of calcification of the dentinal tubules from the outer towards the inner layer. The percentage of stained area was 12.45±2.0%, restricted to the outer layer. The buccal, central and palatal regions of the furcation as well as the buccal and palatal adjacent regions had similar microhardness values. In conclusion, the inner dentin layer is harder than the outer dentin layer. The dentinal tubules are sinuous and intertwine towards the middle layer. Dye penetration is restricted to the outer layer.

Abstract The aim of this study was to evaluate the influence of drying protocols (DP) on the apical sealing (AS) and on the bond strength (BS) of teeth filled with different sealers. The root canals of one hundred and fifty-six roots of maxillary canines were prepared with Reciproc rotary files (R50). The teeth were randomly divided into four groups (n = 39), according to the DP: GI–paper points; GII–70% isopropyl alcohol + aspiration with NaviTip points; GIII–95% ethanol + paper points; GIV–EndoVac + paper points. Each group was divided into subgroups, according to the sealer used: AH Plus, Sealapex and MTA Fillapex, using a single-cone technique. Evaluation of AS and BS was performed with fluid filtration (FF) and push-out (PO) methods, respectively. The PO test consisted of sectioning the roots, and subjecting a single slice from each third to testing and analysis for failure type. The data was submitted to two-way and three-way variance analysis (ANOVA) and Tukey (α = 5%). The AS showed no drying protocol influence. The FF results revealed a statistically significant difference between MTA and Sealapex (p < 0.05) sealers. The BS test values showed that there was no statistical significant difference among the canal thirds (p > 0.05), but that there was such a difference among the sealers (p < 0.05), among the protocols (p < 0.05), and in the interaction between sealers and protocols (p < 0.05). AH Plus revealed the highest BS values among the sealers; the highest BS results for the sealers occurred with the specimens used with isopropyl alcohol, compared with ethanol and EndoVac.

Avaliou-se o efeito das soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% sobre a microdureza da dentina radicular. Foram utilizados 13 incisivos centrais superiores humanos, os quais tiveram suas coroas seccionadas transversalmente e desprezadas. Dez raízes foram incluídas em resina acrílica de rápida polimerização e o bloco formado raiz/resina adaptado à maquina de corte. Desprezou-se o primeiro corte transversal da porção cervical e dividiu-se o segundo, em 4 quadrantes. Cada quarto foi destinado à confecção do corpo-de-prova obtendo-se 4 espécimes para cada raiz, um para cada solução (n=10): EDTA a 15%, ácido cítrico a 10%, quitosana a 0,2% e água destilada (controle). Os espécimes receberam 50 μ L da solução por 5 min, sendo em seguida, lavados com água destilada. Utilizou-se um microdurômetro (dureza Knoop) com carga de 10 g durante 15 s. Os dados foram avaliados por meio do teste ANOVA e Tukey-Kramer (α=0,05). Três incisivos centrais superiores foram instrumentados e irrigados, ao final da biomecânica, com uma das soluções estudadas. Os espécimes foram levados para MEV e posterior análise qualitativa. Todas as soluções avaliadas reduziram a microdureza da dentina radicular de forma semelhante entre si (p>0,05) e estatisticamente diferente do controle (p<0,01). As fotomicrografias mostraram que as 3 soluções removeram a smear layer do terço médio do canal radicular. Concluiu-se que as soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% apresentam efeito semelhante na redução da microdureza dentinária.

The effect of solutions of 0.2% chitosan, 15% EDTA and 10% citric acid on the microhardness of root dentin was evaluated comparatively in this study. Thirteen sound human maxillary central incisors were selected and decoronated at the cementoenamel junction. Ten roots were set into rapid polymerization acrylic resin and the root/resin block was fitted to the cutting machine to obtain slices from the cervical third. The first slice was discarded and the second slice was divided into four quadrants. Each quadrant was used to construct a sample, so that 4 specimens were obtained from each root slice, being one for each chelating solution to be tested: 15% EDTA, 10% citric acid, 0.2% chitosan and distilled water (control). The specimens were exposed to 50 μL of the solution for 5 min, and then washed in distilled water. A microhardness tester (Knoop hardness) with a 10 g load was used for 15 s. Data were analyzed statistically by one-way ANOVA and Tukey-Kramer test (α=0.05). The other 3 roots had the canals instrumented and irrigated at the end of the biomechanical preparation with the test solutions, and then examined by scanning electron microscopy (SEM) for qualitative analysis. All solutions reduced the microhardness of root dentin in a way that was statistically similar to each other (p>0.05) but significantly different from the control (p>0.05). The SEM micrographs showed that the three solutions removed smear layer from the middle third of the root canal. In conclusion, 0.2% chitosan, 15% EDTA and 10% citric acid showed similar effects in reducing dentin microhardness.

A proposta desse estudo foi avaliar o efeito do NaOCl 1% e do ácido etilenodiaminotetracético 17% (EDTA), de forma isolada e alternada, sobre a microdureza dentinária da região da furca de molares inferiores. A superfície oclusal e as raízes de vinte molares inferiores, recém extraídos, foram cortadas transversalmente e descartadas. Os espécimes foram distribuídos em 4 grupos (n=5) de acordo com a solução irrigante utilizada. As soluções empregadas foram EDTA 17% (I), NaOCl 1% (II), NaOCl 1% e EDTA 17% (III), e água destilada (IV) (controle). Os dentes foram incluídos em blocos de resina acrílica e cortados transversalmente. A hemi-secção que melhor representou a furca dental foi lixada e polida para a avaliação da microdureza Knoop. As medidas obtidas foram analisadas utilizando-se teste ANOVA seguido do teste de comparação múltipla de Tukey (α=0,05). Os resultados desse estudo mostraram que todas as soluções, exceto o grupo controle, diminuíram a microdureza dentinária. O EDTA não apresentou diferença estatística significante em relação ao NaOCl/EDTA (p>0,05), mas foi diferente do NaOCl (p<0,01). Os grupos do EDTA e NaOCl/EDTA mostraram a maior redução da microdureza. A solução de EDTA 17%, associada ou não ao NaOCl 1% reduz, significantemente, a microdureza dentinária da furca de molares inferiores.

The aim of this study was to evaluate the effect of irrigation regimens on dentin microhardness at the furcation area of mandibular molars, using sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA), individually and in alternation. The occlusal surface and the roots of 20 non-carious extracted human permanent mandibular molars were cut transversally and discarded. The tooth blocks were embedded in acrylic resin and randomly assigned to 4 groups (n=5) according to the irrigating regimens: 1% NaOCl solution, 17% EDTA solution, 1% NaOCl and 17% EDTA and distilled water (control). Knoop microhardness of dentin at the furcation area was evaluated. Data were analyzed using one-way ANOVA and Tukey's multiple comparison tests (α=0.05). The results of this study indicated that all irrigation solutions, except for distilled water (control), decreased dentin microhardness. EDTA did not show a significant difference with NaOCl/EDTA (p>0.05), but showed a significant difference with NaOCl (p<0.01). EDTA and NaOCl/EDTA showed a maximum decrease in microhardness. The 17% EDTA solution, either alone or in combination with 1% NaOCl reduced significantly dentin microhardness at the furcation area of mandibular molars.

Completo debridamento dos canais radiculares com a remoção da smear layer são medidas essenciais no sucesso do tratamento endodôntico. O objetivo deste estudo foi avaliar os efeitos da quitosana, em diferentes concentrações, na remoção da smear layer e na estrutura da dentina, após 3 e 5 min de aplicação. Doze dentes caninos superiores, recém extraídos, foram instrumentados pela técnica crown-down e irrigados com hipoclorito de sódio 1%. Os espécimes foram distribuídos em seis grupos conforme o tempo e a concentração da solução irrigante final: G1: quitosana 0,1% por 3 min; G2: quitosana 0,2% por 3 min; G3: quitosana 0,37% por 3 min; G4: quitosana 0,1% por 5 min; G5: quitosana 0,2% por 5 min; G6: quitosana 0,37% por 5 min. Todas as amostras foram preparadas para avaliação em MEV. Os resultados mostraram que o G1 apresentou remoção da smear layer, mas não da smear plug. O G2 mostrou túbulos visíveis e abertos com ligeira erosão da dentina peritubular. A limpeza no G3 foi semelhante à do G2, no entanto, o efeito erosivo foi maior. No G4 houve ampliação do diâmetro dos túbulos e no G5 e G6, severa erosão com deterioração da superfície dentinária. Concluiu-se que a quitosana 0,2% por 3 min foi eficiente na remoção da smear layer, ocasionando pequena erosão

Complete debridement with smear layer removal are essential measures for achieving a successful outcome of root canal treatment. The aim of this study was to evaluate the effects of chitosan at different concentrations on the removal of the smear layer and on dentin structure after 3 and 5 min of application. Twelve recently extracted maxillary canine teeth were instrumented using the crown-down technique and irrigated with 1% sodium hypochlorite. The specimens were distributed according to the time and concentration of the final irrigating solution: G1: 0.1% chitosan for 3 min; G2: 0.2% chitosan for 3 min; G3: 0.37% chitosan for 3 min; G4: 0.1% chitosan for 5 min; G5: 0.2% chitosan for 5 min; G6: 0.37% chitosan for 5 min. All samples were prepared for SEM analysis. G1 exhibited removal of the smear layer, but not the smear plugs. G2 showed visible and open tubules with slight erosion of the peritubular dentin. Cleaning in G3 was similar to that in G2, however, the erosive effect was greater. There was expansion of the diameter of the tubules in G4; and in G5 and G6, there was severe erosion with deterioration of dentin surface. In conclusion, 0.2% chitosan for 3 min appeared to be efficient for removing the smear layer, causing little erosion of dentin.

O objetivo do presente estudo foi avaliar a remoção de smear layer por meio da microscopia eletrônica de varredura (MEV) e quantificar a liberação de íons cálcio resultante da irrigação com as soluções quelantes estudadas, por meio da espectrofotometria de absorção atômica. Dezesseis caninos extraídos foram instrumentados com a técnica step-back e divididos em 3 grupos de acordo com a solução irrigadora utilizada: G1: 1 mL de EDTAC a 17% entre cada lima; G2: CDTA a 17%; e G3: EGTA a 17%. As soluções foram coletadas após o uso. Os dentes foram secionados longitudinalmente e as raízes examinadas por MEV para verificação de smear layer nos terços por meio de escores (variando de 1 a 4), e avaliadas por três examinadores calibrados "cegos". Para quantificar a liberação de íons cálcio, as soluções coletadas foram avaliadas por espectrofotometria de absorção atômica. Com relação ao smear layer, o teste de Friedman evidenciou diferença estatisticamente significante (p<0,01) comparando-se o EGTA 17% ao EDTAC 17% e ao CDTA 17%, sendo que os canais irrigados com estas duas soluções apresentaram menor quantidade de smear layer que aqueles irrigados com EGTA. As soluções de EDTAC 17% (70,5±14,2 µg/mL Ca) e CDTA 17% (60,6±20,67 µg/mL Ca) apresentaram maiores quantidades de íons cálcio (p<0,01) quando comparadas ao EGTA 17% (22,8±7,54 µg/mL Ca). Desta forma, pode-se concluir que a associação destas metodologias pode contribuir para o entendimento da ação das soluções quelantes no interior dos canais radiculares.

The purpose of this study was to evaluate, by scanning electron microscopy (SEM), smear layer removal and quantify, by atomic absorption spectrophotometry, the amount of calcium ion present in the chelating solutions after their use. Sixteen extracted canines were instrumented using the step-back technique and were assigned to 3 groups according to the irrigating solution used: G1: 1 mL 17% EDTAC between each file; G2: 1 mL 17% CDTA; G3: 1 mL 17% EGTA. The solutions were collected after use. The teeth were cleaved longitudinally, evaluated under SEM and assessed for smear layer by blinded examiners and scored from 1 to 4. In order to quantify calcium ion release, the collected solutions were examined by atomic absorption spectrophotometry. Freidman's test was used for statistical analysis of SEM values and showed that canals irrigated with 17% EDTAC and 17% CDTA had significantly less smear layer throughout the canals than 17% EGTA (p<0.01). For analysis of the collected solutions, Tukey's test was used and showed that EDTAC and CDTA had a greater amount of calcium ions (22.8±7.54 and 60.6±20.67 µg/mL, respectively) compared to EGTA (70.5±14.2 µg/mL) (p<0.01). The association both methodologies may contribute to the understanding of how these solutions act in the root canal.

Estudou-se o efeito da solução de EGTA (ácido bis(2-aminoetil) etilenoglicol-N,N,N',N'-tetraacético) a 1, 3 e 5% sobre a microdureza da dentina radicular, no terço cervical de dentes humanos. Utilizaram-se 5 incisivos centrais superiores recém-extraídos. Os dentes foram seccionados transversalmente na junção esmalte/cemento e as coroas foram desprezadas. As raízes foram incluídas em blocos de resina acrílica de rápida polimerização, colocadas em uma máquina de corte e seccionadas transversalmente de 1 em 1 milímetro. O segundo corte do terço cervical da raiz de cada dente foi selecionado para o experimento. Cada corte foi dividido em quatro partes sendo que cada parte foi colocada sobre um disco de acrílico, que servia de suporte para a medida de microdureza. Aplicou-se 50 µl da solução teste durante cinco minutos sobre cada superfície de dentina. Água destilada e deionizada foi utilizada como controle. A microdureza da dentina foi medida em um aparelho de dureza Vickers com 50 gramas de carga e 15 segundos de aplicação. A análise estatística dos resultados mostrou que as 3 soluções quelantes reduziram significantemente a microdureza da dentina quando comparado com a água. As soluções de EGTA a 1, 3 e 5% apresentaram-se estatisticamente diferentes entre si.

The effect of 1%, 3% and 5% EGTA (ethylene glycol-bis-(b-amino-ethyl ether) N,N,N´,N´-tetra-acetic acid) on the microhardness of root dentin of the cervical third of human teeth was studied. Five newly extracted maxillary incisors were sectioned transversely at the cementoenamel junction, and the crowns were discarded. The roots were embedded in blocks of high-speed polymerized acrylic resin and cut transversely into 1-mm sections. The second section of the cervical third of the root of each tooth was sectioned and divided into four parts. Each part was placed on an acrylic disc that was used as a base for microhardness measurement. Fifty microliters of 1% EGTA, 3% EGTA, or 5% EGTA were applied to the dentin surface. Deionized and distilled water was used as control. Dentin microhardness was then measured with a load of 50 g for 15 s. Statistical analysis showed that the three concentrations of the chelating solution EGTA significantly reduced dentin microhardness when compared with water (ANOVA, p<0.01), and that there was a statistically significant difference among the three solutions (Tukey test, p<0.05).