Physicochemical Properties and Dentin Bond Strength of a Tricalcium Silicate-Based Retrograde Material

Abstract The aim of this study was to evaluate the physicochemical properties and the apical dentin bond strength of the tricalcium silicate-based Biodentine in comparison to white MTA and zinc oxide eugenol-based cement (ZOE). Setting time and radiopacity were evaluated according to ISO 6876:2012 specification. Final setting time, compressive strength and pH were also assessed. Material’s bond strength to the apical root canal dentin was measured by the push-out assay. Data were analyzed by ANOVA and Tukey-Krammer post-hoc test. Biodentine presented the shortest initial (16.2±1.48 min) and final setting time (35.4±5.55 min). Radiopacity of Biodentine (2.79±0.27 mmAl) does not agree with ISO 6876:2012 specifications. On the other hand, Biodentine showed higher compressive strength after 21 days (37.22±5.27 MPa) and higher dentin bond strength (11.2±2.16 MPa) in comparison to white MTA (27.68±3.56 MPa for compressive strength and 2.98±0.64 MPa for bond strength) (p<0.05). Both MTA and Biodentine produced an alkaline environment (approximately pH 10) (p>0.05) compared to ZOE (pH 7). It may be concluded that Biodentine exhibited faster setting, higher long-term compressive strength and bond strength to the apical dentin than MTA and ZOE.

Resumo O objetivo deste estudo foi avaliar as propriedades físico-químicas e a resistência de união à dentina apical do cimento Biodentine em comparação ao MTA branco e cimento à base de óxido de zinco e eugenol (OZE). O tempo de presa e a radiopacidade foram avaliados de acordo com as especificações ISO 6876:2012. O tempo de presa final, a resistência à compressão e o pH também foram avaliados. A resistência de união dos materiais à dentina apical do canal radicular foi avaliada por meio do ensaio push-out. Dados foram analisados por ANOVA e teste complementar de Tukey-Krammer. Biodentine apresentou o menor tempo de presa inicial (16,2±1,48 min) e final (35,4±5,55 min). Os valores de radiopacidade do Biodentine (2,79±0,27 mmAl) não estão de acordo com as especificações ISO 6876:2012. Por outro lado, este material apresentou maior resistência à compressão após 21 dias (37,22±5,27 MPa) e maiores valores de adesão à dentina (11,2±2,16 MPa) em comparação ao MTA branco (27,68±3,56 MPa de resistência à compressão e 2,98±0,64 MPa de resistência de união) (p>0.05). Ambos os materiais produziram ambiente alcalino (aproximadamente 10) (p>0.05) em comparação ao OZE (pH 7). Pode-se concluir que o Biodentine demonstrou endurecimento mais rápido e apresentou maior resistência à compressão e resistência de união à dentina apical do que MTA e OZE.

Influence of the gutta-percha taper and finger spreader on lateral condensation effectiveness

Introduction: Lateral condensation effectiveness may be influenced by the gutta-percha and finger spreader taper used during root canal obturation. Objective: To evaluate the penetration ability of finger spreader into simulated root canals prepared using MTwo rotary system and filled with different gutta-percha and finger spreader tapers. Material and methods: Resin blocks with curved root canals had the apical diameter enlarged up to #25.06 and distributed into groups (n = 6) according to the gutta-percha taper (#25.02, #25.04, and #25.06) and the finger spreader (#30 and #35 NiTi, and stainless steel B) used to perform cold lateral condensation. After applying a load of 1.5 Kg over the finger spreaders' head, the distance between the finger spread tip and the apical limit of the root canal preparation were obtained. The data were submitted to Anova and Tukey-Krammer's test, with 5% of significance. Results: The gutta-percha cones with 0.02 taper enabled higher finger spreader penetration when compared to 0.04 and 0.06 tapers (p < 0.05), which were similar between each other (p > 0.05), regardless of the type and diameter of the finger spreader used. When different finger spreaders were compared among themselves, stainless steel B showed higher penetration ability (p < 0.05). Conclusion: It was concluded that the stainless-steel finger spreaders showed superior penetration ability and gutta-percha with lower tapers enabled a more effective lateral condensation at the apical third.

Propriedades físico-químicas e mecânicas, potencial bioativo e caracterização da interface dentina-cimento de cimentos endodônticos experimentais à base de cimento Portland associados à radiopacificadores micro e nanoparticulados / Physicochemical and mechanical properties, bioactivity potential and characterization of the dentin-sealer interface of experimental root sealers based on Portland cement with micro and nano particulate radiopacifiers

O cimento Portland é constituído por silicato de cálcio e a associação com aditivos e veículos conferem características que podem viabilizar seu uso como cimento endodôntico. No entanto, o cimento Portland não apresenta radiopacidade própria, o que torna necessário a adição de um agente radiopacificador à mistura para ser utilizado como material dentário. O objetivo deste estudo foi avaliar as propriedades físico-químicas e mecânicas, o potencial bioativo e caracterizar a interface dentina-cimento de cimentos endodônticos experimentas à base de cimento Portland (ES) contendo nano ou micro partículas de óxido de zircônio ou óxido de nióbio. O tempo de presa, resistência à compressão, escoamento, espessura de filme, radiopacidade, solubilidade e estabilidade dimensional foram avaliadas de acordo com a norma ISO 6876:2012, enquanto que a liberação de fomaldeído foi avaliada por meio de cromatografia gasosa. A resistência de união dentinária foi avaliada por meio de teste push-out e tanto a caracterização da microestrutura dos cimento quanto a análise do potencial bioativo foram realizadas utilizando energia dispersiva de raios-x, difractometria e espectroscopia infravermelha. A interface dentina-cimento foi avaliada com relação à penetração de microesferas fluorescentes e examinada em microscopia confocal e microscopia eletrônica de varredura associada à escaneamento por energia dispersiva de raios-x linear. Os dados foram submetidos aos testes ANOVA e Tukey (p < 0,05). Com exceção da radiopacidade, os ES apresentaram propriedades físico-químicas de acordo com as especificações ISO 6876, adequada resistência de união à dentina, potencial bioativo e promoveram selamento coronário e interação química com a dentina.

Portland Cement is composed by calcium silicate and the association with additives or vehicles, may confer characteristics to enable the use of this cement as root canal sealer. However, Portland cement lacks in radiopacity which requires the addition of a radiopacifying agent to the mixture to be used as dental material. The purpose of this study was to assess the physicochemical and mechanical properties, the bioactivy potential and to characterize the dentin-sealers interfaces of Portland-based experimental root canal sealers (ES) containing nano or micro particles of zirconium oxide or niobium oxide. Setting time, compressive strength, flow ability, film thickness, radiopacity, solubility and dimensional stability were evaluated according to ISO 6876:2012 standards, whereas formaldehyde realease was investigated using gas-cromatography. Dentin bond strength was evaluated by push-out test and the sealer's microestruture and bioactivity potential were perfomed using X-ray energy espectroscopy, Xray diffractometry and infrared spectroscopy. Dentin-sealers interface was assessed with respect to fluorescent microspheres penetration and it was also examined using confocal microscope and scanning electron microscope coupled to X-ray energy dispersive line scans. Data were analyzed by ANOVA and Tukey post-hoc test (p < 0.05). With the exception of radiopacity, ES showed physicochemical properties according to ISO 6876:2012 specifications, adequate dentin bond strength, great bioactivity potential and promoted coronal sealing and chemical interaction with dentin

Repercussões periapicais em dentes com necrose pulpar / Periapical repercussion of pulpal necrosis

As doenças da polpa dental são consequências da ação de fatores químicos, físicos e principalmente bacteriológicos. O resultado desta ação pode se manifestar a curto ou longo prazo, produzindo sinais e sintomas característicos de cada doença. A necrose pulpar ocorre quando as funções vitais da polpa são interrompidas, iniciando-se um processo de degeneração que, se não tratado precocemente, levará a disseminação bacteriana ao osso alveolar produzindo lesões ósseas periapicais. Estas lesões periapicais associadas à necrose pulpar resultam dos mesmos fatores etiológicos, contudo apresentam características clínico-radiográficas peculiares e diversificadas sintomatologias, importantes no diagnóstico diferencial, que conduzem o tratamento. De acordo com o exame clínico e radiográfico, as lesões periapicais podem ser classificadas em: Pericementite Apical; Abscesso Periapical; Granuloma Periapical; Cisto Periapical e Osteíte Condensante. Este estudo tem como objetivo expor e discutir, a partir da literatura, a etiologia e as características histológicas, clínicas e radiográficas das doenças periapicais resultantes da necrose pulpar.

Dental pulp illnesses are a consequence of the actions of mainly bacteriological, but also chemical and physical factors. The results of these actions can be reveled after short or long time periods, showing characteristic signals and symptoms of each pathology. Pulp necrosis occurs when the pulp?s vital functions are interrupted, starting a degenerative process. If this degenerative process is not promptly treated it will result in bacterial dissemination into the alveolar bone producing periapical bone lesions. These periapical lesions related to pulp necrosis result from the same etiologic factors, but they present particular clinical and radiographical features and diverse symptoms that are important to differentiate the diagnosis that will determine the treatment. According to the clinical and radiographical features, the periapical lesions can be classified as follows: Apical pericementitis, Periapical Abscess, Periapical Granuloma, Periapical Cyst and Condensing Osteitis. The objective of this study was to expose and discuss, through a review, the etiological factors and histological, clinical and radiographical features of the periapical illnesses resulting from necrosis.

Effect of different restorative procedures on the fracture resistance of teeth submitted to internal bleaching

The aim of this study was to evaluate the influence of different restorative procedures on the fracture resistance of endodontically treated teeth submitted to intracoronal bleaching. Fifty upper central incisors were distributed into 5 groups: GI - healthy teeth; GII - endodontically treated teeth sealed with Coltosol; GIII - endodontically treated teeth bleached and sealed with Coltosol; GIV - endodontically treated teeth bleached and restored with composite resin; and GV - endodontically treated teeth bleached and restored with a fiberglass post and composite resin. In the bleached specimens, a cervical seal was made prior to bleaching with 38% hydrogen peroxide. The gel was applied on the buccal surface and in the pulp chamber, and was then light-activated for 45 s. This procedure was repeated three times per session for four sessions, and each group was submitted to the restorative procedures described above. The specimens were submitted to fracture resistance testing in a universal testing machine. There were statistically significant differences among the groups (p < 0.05). The mean value found for GIII was the lowest (0.32 kN) and was significantly different from the values found for GI (0.75 kN), GII (0.67 kN), GIV (0.70 kN), and GV (0.72 kN), which were not significantly different from each other (p > 0.05). The restorative procedures using composite resin were found to successfully restore the fracture resistance of endodontically treated and bleached teeth.

Evaluation of physico-chemical properties of Portland cements and MTA

The purpose of this study was to evaluate the hydrogenionic potential and electrical conductivity of Portland cements and MTA, as well as the amount of arsenic and calcium released from these materials. In Teflon molds, samples of each material were agitated and added to plastic flasks containing distilled water for 3, 24, 72 and 168 h. The results were analyzed with a Kruskal-Wallis non-parametric test for global comparisons and a Dunn-Tukey test for pairwise comparisons. The results revealed no significant differences in the pH of the materials (p > 0.05). The electrical conductivity of the cements were not statistically different (p > 0.05). White non-structural cement and MTA BIO released the largest amount of calcium ions into solution (p < 0.05), while arsenic release was insignificant in all of the materials (p > 0.05). The results indicated that the physico-chemical properties of Portland cements and MTA were similar. Furthermore, all materials produced an alkaline environment and can be considered safe for clinical use because arsenic was not released. The electrical conductivity and the amount of calcium ions released into solution increased over time.

Comparação de duas modalidades de apicectomia seguidas de retropreparo no selamento marginal de retrobturações / Comparison of two modalities of apicoectomy followed by root-end cavity preparation on marginal sealing of retrofllings

Este estudo avaliou in vitro a infltração apical após apicectomia e retrobturação, variando o ângulo de corte radicular e a técnica de preparo da cavidade retrógrada. Vinte e quatro dentes humanos unirradiculares foram tratados endodonticamente e obturados pela técnica de condensação lateral da guta-percha com cimento Endo-Fill, sendo distribuídos em dois grupos experimentais (n = 10): GI - apicectomia perpendicular ao longo eixo radicular, seguida do preparo das cavidades retrógradas com ponta ultrassônica lisa 12/90; GII - apicectomia com corte inclinado em 45° para vestibular e preparo retrógrado com broca esférica carbide em baixa rotação. Todas as retrocavidades foram seladas com cimento à base de óxido de zinco e eugenol (IRM). Os grupos experimentais foram imersos por 48 horas em solução de Rodamina B a 0,2% tamponada em ambiente com vácuo. A seguir, as raízes foram seccionadas longitudinalmente e a infiltração de corante analisada em microscópio de mensuração. O teste de U de Mann-Whitney evidenciou diferença signifcante em nível de 1% entre os grupos, com menores níveis de infiltração no grupo em que as cavidades retrógradas foram realizadas com ponta ultrassônica lisa 12/90. Pode-se concluir que a apicectomia perpendicular ao longo eixo do dente, seguida de retrocavidade confeccionada com ponta ultrassônica lisa, reduziu a infiltração apical após retrobturação com cimento a base de óxido de zinco e eugenol.

This in vitro study has evaluated the apical leakage after apicoectomy and root-end filling varying the bevel cut and the root-end cavity preparation technique. Twenty four single root human teeth were submitted to endodontic treatment and obtured by lateral condensation techique with gutta-percha points and Endo Fill cement. The teeth were distributed into two experimental groups (n = 10): Group I - perpendicular apicoectomy to root axis followed by root-end preparation performed with 12/90 smooth ultra-sonic tip. Group II - 45° buccal side inclined apicoectomy and root-end preparation performed with spherical carbide burn in low speed. All root-end cavities were sealed with zinc oxide-eugenol based cement (IRM). The experimental groups were immersed in rhodamine B dye for 48 hours and stored in vacuum environment. After that, the roots were separated longitudinally and the dye infiltration was analyzed under optical microscope. Mann-Whitney test showed signifcant difference between the groups (P < 0.01) with lowest levels of leakage in the Group I. It was concluded that the perpendicular apicoectomy followed by retrograde cavity preparation with ultra-sonic smooth tips decreases the marginal leakage in root-end cavities sealed with zinc oxide-eugenol cement.