312 research outputs found
Assessment of smear layer removal protocols in curved root canals
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Previous issue date: 2014This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1mL of 17% ethylenediaminetetraacetic acid (EDTA)), 5EDTA (syringe irrigation with 5mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1mL of 17% EDTA+pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5mL of 17% EDTA+pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1mL of 17% EDTA+EndoActivator) and 5EDTA-EA (syringe irrigation with 5mL of 17% EDTA+EndoActivator). Final rinsing was carried out over 3min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P<0.05). The combination of 5mL of 17% EDTA and 3mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.[Raldi, Denise Pontes] Universidade de Taubaté (Unitau), Dept Dent, Sao Paulo, Brazil[Cunha, Rodrigo Sanches; Mello, Isabel] Univ Manitoba, Fac Dent, Dept Restorat Dent, Winnipeg, MB R3E 0W2, Canad
Treatment Options for Teeth with Open Apices and Apical Periodontitis
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Previous issue date: 2009Three clinical cases involving teeth with open apices and apical periodontitis were treated using different protocols. The first case was managed with intracanal calcium hydroxide paste for 12 months before obturation with gutta-percha and sealer. In the second case, an apical plug of mineral trioxide aggregate (MTA) was used before obturation with gutta-percha and sealer and treatment was completed during 2 appointments. In the third case, the tooth, which had a divergent root canal system, was completely obturated with MTA and treatment was also completed over 2 appointments. In all 3 cases, signs of bone healing were observed after treatment.[Raldi, Denise Pontes; Habitante, Sandra Marcia; Lage-Marques, Jose Luiz] Universidade de Taubaté (Unitau), Div Endodont[Mello, Isabel] Univ Manitoba, Div Endodontol, Winnipeg, MB R3E 0W2, Canada[Coil, Jeffrey] Univ British Columbia, Fac Dent, Dept Oral Biol & Med Sci, Vancouver, BC V5Z 1M9, Canad
Study of the effects of high power laser irradiation and materials for endodontic purpose on simulated external root resorptions
No full textEste estudo avaliou, por meio de cultivo celular e MEV, a capacidade de adesão de fibroblastos e as alterações estruturais ocorridas na superfície dentinária de reabsorções radiculares externas simuladas, após tratamento com hidróxido de cálcio, MTA e/ou radiação com laser de diodo de alta potência e laser Er:YAG. Após a hemisecção das raízes de 31 dentes unirradiculares, foram realizadas cavidades padronizadas no terço cervical de cada secção, obtendo-se 62 amostras que foram divididas em 9 grupos: grupo1 - irradiação com laser Er:YAG (42 mJ/pulso, 10 s, 10 Hz e 38 J/cm2 ); grupo 2 - irradiação com laser de diodo de alta potência (1 W, 10 s, 796 W/cm2); grupo 3 - preenchimento da cavidade com hidróxido de cálcio e irradiação com laser Er:YAG; grupo 4 - preenchimento da cavidade com hidróxido de cálcio e irradiação com laser de diodo; grupo 5 - preenchimento da cavidade com MTA e irradiação com laser de Er:YAG; grupo 6 - preenchimento da cavidade com MTA e irradiação com laser de diodo; grupo 7 - preenchimento da cavidade com hidróxido de cálcio; grupo 8 - preenchimento da cavidade com MTA e grupo 9 (controle) - nenhum tratamento. Após a esterilização dos espécimes foi realizado o subcultivo celular com fibroblastos gengivais da linhagem FMM1, o plaqueamento dos fragmentos (5 x 104 células por fragmento) e o preparo para análise em MEV. A contagem das células aderidas evidenciou que a adesão celular foi em ordem decrescente: G1 (Er:YAG) > G2 (diodo) > G9 (controle) > G8 (MTA) > G5 (MTA+Er:YAG) > G6 (MTA+diodo) > G4 (CaOH2+diodo) > G3 (CaOH2+Er:YAG) > G7(CaOH2). Observou-se diferença estatisticamente significante entre a maioria dos grupos experimentais, exceto entre os grupos: G9 x G8; G8 x G5; G8 x G4; G5 x G6; G4 x G3; G3x G7. Na análise em MEV, observou-se nas amostras irradiadas com laser Er:YAG microrugosidades na superfície dentinária, ausência de smear layer e túbulos dentinários abertos. As irradiadas com laser de diodo apresentaram superfície dentinária mais lisa, maior quantidade de smear layer e os túbulos dentinários fechados. Não foram observadas zonas de carbonização nos grupos irradiados com laser. Nos grupos nos quais se associou a radiação laser com os materiais de uso endodôntico, foram observadas zonas de derretimento e fusão nas superfícies do hidróxido de cálcio e do MTA. Diante dos resultados obtidos foi possível concluir que: a irradiação com os lasers Er:YAG e de diodo, nos arâmetros utilizados neste experimento, provocaram alterações morfológicas nas superfícies dentinárias das reabsorções simuladas que favoreceram a adesão celular; o uso do MTA nas reabsorções radiculares simuladas permitiu a adesão celular, enquanto que o hidróxido de cálcio a inibiu e a associação dos materiais de uso endodôntico com os lasers Er:YAG e de diodo resultou em alterações morfológicas na superfície do MTA, assim como, na do hidróxido de cálcio, que interferiram, de forma discreta, na adesão celular.The present study, utilizing cell culture and SEM, evaluated the adhesion of fibroblasts, and the structural changes on the dentinal surface of simulated external root resorptions, after treatment with calcium hydroxide, MTA and/or high power diode laser radiation and Er:YAG laser radiation. After splitting the roots of 31 single rooted teeth, standardized cavities were done on the coronal third of each section, resulting in 62 samples which were divided into 9 experimental groups: group 1 ? Er:YAG laser irradiation (42 mJ/pulse, 10 Hz, 10 s, 38 J/cm2); group 2 ? high power diode laser irradiation (1 W, 10 s, 796 W/cm2); group 3 ? cavity filling with calcium hydroxide and Er:YAG laser irradiation; group 4 ? cavity filling with calcium hydroxide and irradiation with diode laser; group 5 ? cavity filling with MTA and Er:YAG laser irradiation; group 6 - cavity filling with MTA and irradiation with diode laser; group 7 - cavity filling with calcium hydroxide; group 8 - cavity filling with MTA and group 9 (control) ? not treated. After the specimens were sterilized, a subculture was done with gingival fibroblasts from cell line FMM1. The fragments were plated (5 x 104 per fragment) and then prepared for SEM analyzis. The counting of adhered cells showed that the cells? adhesion was in decreasing order: G1 (Er:YAG) > G2 (diode) > G9 (control) > G8 (MTA) > G5 (MTA+Er:YAG) > G6 (MTA+diode) > G4 (CaOH2+diode) > G3 (CaOH2+Er:YAG) > G7(CaOH2). Significant statistical differences were observed among most of the experimental groups, except among the following groups: G9 x G8; G8 x G5; G8 x G4; G5 x G6; G4 x G3; G3 x G7. At the SEM analyzis of the samples irradiated with Er:YAG laser, roughness on the dentinal surface, no smear layer and open dentinal tubules were observed. The samples irradiated with diode laser exhibited a smooth surface, more smear layer and closed dentinal tubules. No carbonization zones were observed at the groups irradiated with both lasers. In the groups where laser irradiation was associated with endodontic materials, melting zones and fusion on the calcium hydroxide and MTA surfaces were observed. Based on the results it may be concluded that: irradiation with Er:YAG and diode lasers, in the parameters utilized in this experiment, caused morphologic changes on the dentinal surfaces of the simulated resorptions that favored cell adhesion; the MTA used on the simulated root resorptions allowed cell adhesion while calcium hydroxide inhibited it; and, the association of the endodontic materials to Er:YAG and diode lasers resulted in morphologic changes on the MTA and on the calcium hydroxide surface, which interfered subtly with the cell adhesion
Alpha-interferon enhances non-T cell cytotoxicity for autologous hepatocytes in acute and chronic HBV infection.
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Tooth discolouration and internal bleaching after the use of triple antibiotic paste
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Previous issue date: 2015AimTo assess the discolouration of teeth with closed and open apices after placement of triple antibiotic paste (TAP, ciprofloxacin, metronidazole and minocycline) in the pulp chamber and whether discolouration could be reversed by internal bleaching procedures. MethodologyTwenty extracted human mandibular premolars were divided into 2 groups (n=10): teeth with closed apices (CA) and teeth with open apices (OA). After conventional access, the TAP was sealed in the pulp chamber for 3weeks. The paste was removed by a rinse with sodium hypochlorite (NaOCl) and a mixture of sodium perborate and distilled water was sealed in the pulp chamber for 1, 2 and 3weeks. The shade was measured by a spectrophotometer at six time periods: baseline (T0), after 3weeks of placement of TAP (T1), after removal of TAP with a NaOCl rinse (T2) and after 1 (T3), 2 (T4) and 3 (T5) weeks of internal bleaching with sodium perborate paste. Data were collected based on the CIELAB-CIE1976 (L*a*b*) system and analysed using t-tests and anova. ResultsA significant decrease in the mean values of L* (lightness) was observed after treatment with TAP (T1, P<0.05). Considerable increases in these values after bleaching with sodium perborate (T3<T4<T5) were found in both groups. The only significant difference in the intergroup analysis was between T1 and T2, in which E values in the OA group were higher (P=0.04). ConclusionsTAP discoloured the tooth structure, but discolouration could be reversed with sodium perborate paste. In general, teeth with closed and open apices had the same rates of discolouration and bleaching.[Kirchhoff, A. L.] Pontificia Univ Catolica Parana, Div Endodont, Curitiba, Parana, Brazil[Raldi, D. P.] Universidade de Taubaté (Unitau), Dept Dent[Salles, A. C.] Univ Manitoba, Coll Dent, Div Pediat Dent, Winnipeg, MB, Canada[Cunha, R. S.] Univ Manitoba, Coll Dent, Div Endodont, Winnipeg, MB, Canada[Mello, I.] Dalhousie Univ, Fac Dent, Div Endodont, Halifax, NS B3H 4R2, Canad
Regulatory items: a study applied to the Brazilian electricity tariff regulation
No full textAs empresas com tarifas reguladas, de maneira geral, fornecem bens públicos. Muitas delas atuam em atividades que são prerrogativas, diretas ou indiretas, do estado. A regulamentação tarifária se justifica pelo fato de essas empresas não atuarem em condições de mercado. A tarifa é definida de maneira a fornecer uma remuneração justa, pelo risco assumido pelo investidor e, concomitantemente, um custo razoável para os consumidores. Existem dois modelos extremos de regime tarifário: cost-plus (pelo custo) ou fixed-price (pelo preço). O primeiro repassa todos os custos incorridos e mais uma margem às tarifas. Por outro lado, os regimes pelo preço fixam a tarifa máxima, que não está necessariamente associada aos custos incorridos. A diferença fundamental entre os dois regimes está no estímulo à eficiência, inexistente nos regimes pelo custo. Na prática, muitos regimes são considerados como híbridos, ou seja, somente alguns custos têm sua recuperação garantida. Nesses regimes, é necessária a existência de algum mecanismo de repasse dos custos recuperáveis. No Brasil, o setor elétrico adotou um modelo no qual a tarifa garante a recuperação dos custos não gerenciáveis (a chamada \"parcela A\"), e os custos gerenciáveis são fixados com base em níveis considerados como eficientes (a chamada \"parcela B\"). Por meio da portaria interministerial MF/MME nº 025/2002, o poder concedente cria um mecanismo para garantir a recuperação dos custos não gerenciáveis - a chamada conta de Compensação da Variação dos Custos da Parcela A (CVA). Segundo esse mecanismo, a diferença entre os custos que compõem essa parcela e o efetivamente incorrido é repassada no próximo reajuste tarifário anual. Caso o saldo não seja integralmente recuperado dentro de um ano, o resíduo é contemplado nos próximos reajustes anuais. O saldo da CVA é atualizado pela SELIC, da data de sua ocorrência até a data de sua liquidação. Com a adoção das normas internacionais de contabilidade, os itens regulatórios foram eliminados das demonstrações contábeis societárias. Devido às suas funções regulatórias, a agência nacional de energia elétrica (ANEEL) decidiu criar a contabilidade regulatória, na qual, entre outras exigências, o reconhecimento da CVA é obrigatório. O presente estudo analisa se a regulamentação tarifária fornece suporte para o reconhecimento contábil dos itens regulatórios, bem como, especificamente o da CVA. O estudo se suporta pela teoria da regulação e pela teoria contábil, com ênfase na estrutura conceitual para elaboração e divulgação de relatório contábil-financeiro (IFRS FOUNDATION, 2010). A pesquisa pode ser rotulada como qualitativa. Conclui-se que os itens regulatórios somente podem ser reconhecidos quando existe um recurso econômico ou uma obrigação econômica presente. Por consequência, apenas devem ser contabilizados os itens regulatórios cuja recuperação ou devolução for garantida. Especificamente para a CVA, não existem evidências objetivas de que seu saldo possa ser recuperado de outra maneira que não seja pela tarifa de fornecimento de energia, não devendo, portanto, ser reconhecido nas demonstrações contábeis societárias.Rate-regulated companies generally provide public goods. Many of them carry out activities that are prerogative, direct or indirect, of the State. Rate regulations are justified by the fact that these companies do not operate under free market conditions. Rates are set in order to provide a fair return to the risk taken by the investor and concomitantly a reasonable cost to consumers. There are two broad regulatory regimes: cost-plus and fixed-prices. Regimes based on cost allow the recovery of all incurred costs, plus a margin. On the other hand, regimes based on price set a maximum rate, which is not necessarily associated with the incurred costs. The key difference between regimes is the efficiency stimulus, not present in cost regimes. In practice, many regimes are considered hybrid, in other words, just some costs have their recovery guaranteed. Under these regimes, it is necessary a pass-through mechanism for the recoverable costs. In Brazil, the energy sector adopted a model in which the rate allows the recovery of non-manageable cost (called \"Parcel A\"), while manageable costs are recovered based on efficiency levels (called \"Parcel B\"). Through the Portaria Interministerial MF/MME no 025/2005, the grantor creates a mechanism that allows the recovery of non-manageable costs, the so-called \"Conta de Compensação de Variação dos Custos da Parcela A (CVA). By this mechanism, the difference between the costs that are included in \"Parcel A\" and those actually incurred is considered in the next annual rate reset. In the case that it is not wholly recovered within one year, the remainder will be contemplating in the next annual rate resets. The CVA balance is indexed by the SELIC from the date of its occurrence to its settlement. With the International Accounting Standards adoption, the regulatory items are derecognized from the corporate financial statements. Due to its regulatory duties, ANEEL decided to create the Regulatory Accounting, in which amongst other requirements, the recognition of the regulatory items is mandatory. The present study analyses if the rate regulation provides support for the recognition of regulatory items, more specifically, the CVA. The study is based on the Regulation Theory and Accounting Theory with emphasis in the Conceptual Framework for Financial Reporting (IFRS FOUNDATION, 2010). The research can be labelled as qualitative. It was concluded that regulatory items shall only be recognized when there are a present economic resource or a present economic obligation. Consequently, only the regulatory items which the recovery or the devolution is guaranteed can be booked. Specifically for CVA, there are no objective evidences that its balance can be recovery by other mean different than energy supply rate. Therefore, it shall not be recognized in the corporate financial statements
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