Este estudo teve como objetivo avaliar a eficácia dos cimentos obturadores do sistema de canais radiculares quando submetidos ao desafio ácido em ambiente bucal. Foram utilizadas 55 raízes de incisivos centrais inferiores humanos com comprimento padronizado em 10 mm. Realizou-se o preparo biomecânico dos canais até o instrumento #40.02 e as raízes foram esterilizadas em autoclave. Quarenta e quatro raízes foram obturadas pela técnica de condensação lateral com um dos quatro cimentos de diferentes bases: AH Plus, MTA Fillapex, Sealapex ou Endofill. Nas 11 raízes remanescentes, apenas foi executado o preparo biomecânico dos canais e esterilização (controle negativo). Foram selecionados 11 participantes que atenderam aos critérios de inclusão na pesquisa. Foi realizada a moldagem das arcadas dentais e confecção dos dispositivos acrílicos intra-bucais palatinos com 5 nichos, sendo 4 deles para as raízes correspondentes a cada cimento experimental e 1 nicho para a raiz controle. As raízes foram fixadas com cera e tela para favorecer o acúmulo de biofilme. Durante 14 dias, 11 participantes utilizaram o dispositivo o dia todo e foram orientados a gotejar solução de sacarose 20% sobre as amostras, seis vezes ao dia, simulando alto desafio cariogênico. Após os 14 dias, as raízes foram removidas dos dispositivos, seccionadas em slices e foram realizadas as seguintes análises: perfil de desgaste do material obturador e superfície dentinária antes e após a exposição ao ambiente ácido bucal por microscopia confocal de varredura a laser (MCVL); resistência adesiva (MPa) do material obturador à dentina radicular por teste de push-out e análise qualitativa da morfologia da interface adesiva e desmineralização ao redor do material obturador por MCVL. Os dados do perfil de desgaste foram avaliados pelo teste não-paramétrico de Kruskal-Wallis e teste t (&alpha;=0,05), os dados da resistência adesiva foram avaliados por Análise de Variância a dois critérios (cimentos e terços radiculares) e teste de Tukey (&alpha;=0,05). Verificou-se que não houve diferença estatisticamente significante entre os cimentos (p=0,6190), porém todas as amostras apresentaram desgaste da dentina e material obturador após exposição ao ambiente bucal (p<0,05). As raízes obturadas com o cimento AH Plus apresentaram maior resistência adesiva à dentina (11,40 ± 7,74 a) (p<0,05). Resultados intermediários foram encontrados nas raízes obturadas com o MTA Fillapex (7,22 ± 5,88 ab) e Endofill (7,37 ± 6,75 ab). As raízes obturadas com o Sealapex apresentaram menores valores de resistência adesiva (5,18 ± 4,34 b). Não houve diferença significante para os terços radiculares, nem na interação dos fatores (p>0,05). Houve predomínio de falhas adesivas em dentina nas raízes obturadas com os cimentos AH Plus, MTA Fillapex e Endofill (respectivamente 66%, 75% e 54,2%). Nas raízes obturadas com o Sealapex houve predomínio de falhas mistas (54,2%). Todos os cimentos apresentaram degradação do material obturador e superfície dentinária, além da desmineralização ao redor da obturação, sendo esta última mais intensa nas raízes obturadas com os cimentos Sealapex e Endofill. Nas raízes não obturadas, houve acúmulo intenso de biofilme bacteriano e desmineralização da dentina intrarradicular. Nenhum cimento foi capaz de evitar a degradação da interface adesiva e da dentina. No entanto, nestas situações de alto desafio ácido, os cimentos AH Plus e MTA Fillapex demonstraram desempenho superior aos demais cimentos testados, por apresentarem melhor resistência adesiva do material obturador à dentina, além de degradação e desmineralização ao redor da obturação menos intensa. / This study has the purpose to evaluate the efficacy of root canal sealers following in situ acid challenge. The root canals of 55 human mandibular central incisors with standardized root canals length 10 mm were used. Roots were as submitted to biomechanical preparation up to #40.02 instrument and canals were sterilized in an autoclave. Forty-four roots were filled with one of the four sealers using the lateral condensation technique: AH Plus, Endofill, MTA Fillapex e Sealapex. The remaining 11 roots were only submitted to biomechanical preparation and were sterilized (negative control). Eleven 11 participants that fulfill the inclusion criteria were selected. The impressions of dental arcs were performed and intraoral acrylic devices were done with 5 spaces, being 4 for roots with experimental sealers and 1 for control root. The roots were fixed with wax and screen to promote the accumulation of biofilm. During 14 days, 11 participants were instructed to use the devices every day. Dental biofilm was allowed to accumulate on root and drops of 20% sucrose solution were dripped onto them, simulating a high acidic challenge. After 14 days, the roots were removed from the intraoral devices sectioned in slices and the following analyses were conducted: degradation (wear profile) in the dentin-sealer interface subjected to confocal laser scanning microscope (CLSM); bond strength of filling material (MPa) to root canal (push-out test) and qualitative analysis of adhesive interface morphology and demineralization around filling material by CLSM. The wear profile data were assessed by non-parametric Kruskal-Wallis and t-test (&alpha;=0.05), the bond strength were evaluated by two-way ANOVA (cements and root thirds) and Tukey test (&alpha;=0.05). Statistical analyses were set at 5% significance level. Regarding the surface of the wear profile, it was found that there was no significant statistical difference between sealers (p=0.6190), but all samples showed wear of dentine and filling material after exposure to the oral environment (p <0.05). Roots filled with AH Plus sealer showed the higher bond strength to dentin (11.40 ± 7.74 a) (p<0.05). Intermediate results were found in roots with MTA Fillapex (7.22 ± 5.88 ab) and Endofill (7.37 ± 6.75 ab). The worst result was found in roots with Sealapex (5.18 ± 4.34 b). There were no significant differences in root thirds, neither in the interaction of factors (p>0.05). Adhesive failure were predominant in root canals with AH Plus, MTA Fillapex and Endofill (respectively, 66%, 75% e 54.2%). Root canals with Sealapex presented more mixed failure (54.2%). Qualitative morphological analysis showed that all sealers presented dentin demineralization around root canal filling, being greater when using to Sealapex and Endofill sealers. In unfilled roots, there was intense accumulation of bacterial biofilm and demineralization of intraradicular dentin. After the exposure of roots to oral environment for 14 days, it may be concluded that no sealer was able to prevent degradation of the adhesive interface and dentin. However, in these situations of high acid challenge, AH Plus and MTA Fillapex sealers have shown superior performance than other tested sealers for their high adhesive strength of the filling material to dentin, and less intense degradation and demineralization around the root canal filling.

Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Ions in the soil solution traverse many layers (epidermis, exodermis, central cortex, and endodermis) within the root to reach the stele. The endodermis is present in almost all vascular plants while the exodermis is found only in majority of angiosperm roots tested. The maturation of the exodermis and the death of epidermis alter the plasma membrane surface areas (PMSA) potentially available for ion uptake. Do these changes reduce the ion uptake in proportion to the loss of absorptive surface areas? To answer this question onion (Allium cepa L cv. Wolf) adventitious root segments representing above features: Immature Exodermis Live Epidermis (IEXLEP), Mature Exodermis Live Epidermis (MEXLEP), Mature Exodermis Dead Epidermis (MEXDEP) were excised. Using a compartmental elution technique, radioactive sulphate and phosphate present in various internal compartments were quantified. Quantities of ions moved across the plasma membrane, a summation of quantities in the cytoplasm, ‘vacuole’, and ‘bound’ compartments, indicated that the maturation of the exodermis reduces the uptake of sulphate but not phosphate. In contrast, epidermal death reduced the movement of both ions across the plasma membranes. Although there is a reduction in the available PMSA with the maturation of the exodermis and death of the epidermis, these events do not necessarily reduce the ion movement into the plasma symplast. The endodermal cells of onion roots deposit suberin lamellae as secondary walls. As seen in cross-sections some cells remain without these lamellae and are known as ‘passage cells’. What is the pattern of suberin lamella deposition along the root? Is the suberin lamella a continuous layer? To answer these questions, endodermal layers isolated from onion adventitious roots were used in the present study. These layers were observed using four stains (Sudan Red 7B, Fluorol yellow 088 [Fy], berberine, and Nile red) and three microscopes (compound-white light, compound-epifluorescence and confocal scanning). In differentiating cells with and without suberin lamellae in endodermal layers Sudan Red 7B served the best results for compound-white light microscope, Fy for compound-epifluorescence microscope and Nile for confocal laser scanning microscope (CLSM). Suberin lamellae deposition initiated almost in a random manner; they continued to be deposited resulting in the production of longitudinal files alternating with files with passage cells, and were ultimately deposited in almost all cells at a distance of 255 mm from the tip. The suberin lamellae are perforated with pores, a consistent feature even as far as 285 mm from the tip. These pores may serve as portals for water, ions, and pathogen movement.

Ions in the soil solution traverse many layers (epidermis, exodermis, central cortex, and endodermis) within the root to reach the stele. The endodermis is present in almost all vascular plants while the exodermis is found only in majority of angiosperm roots tested. The maturation of the exodermis and the death of epidermis alter the plasma membrane surface areas (PMSA) potentially available for ion uptake. Do these changes reduce the ion uptake in proportion to the loss of absorptive surface areas? To answer this question onion (Allium cepa L cv. Wolf) adventitious root segments representing above features: Immature Exodermis Live Epidermis (IEXLEP), Mature Exodermis Live Epidermis (MEXLEP), Mature Exodermis Dead Epidermis (MEXDEP) were excised. Using a compartmental elution technique, radioactive sulphate and phosphate present in various internal compartments were quantified. Quantities of ions moved across the plasma membrane, a summation of quantities in the cytoplasm, ‘vacuole’, and ‘bound’ compartments, indicated that the maturation of the exodermis reduces the uptake of sulphate but not phosphate. In contrast, epidermal death reduced the movement of both ions across the plasma membranes. Although there is a reduction in the available PMSA with the maturation of the exodermis and death of the epidermis, these events do not necessarily reduce the ion movement into the plasma symplast. The endodermal cells of onion roots deposit suberin lamellae as secondary walls. As seen in cross-sections some cells remain without these lamellae and are known as ‘passage cells’. What is the pattern of suberin lamella deposition along the root? Is the suberin lamella a continuous layer? To answer these questions, endodermal layers isolated from onion adventitious roots were used in the present study. These layers were observed using four stains (Sudan Red 7B, Fluorol yellow 088 [Fy], berberine, and Nile red) and three microscopes (compound-white light, compound-epifluorescence and confocal scanning). In differentiating cells with and without suberin lamellae in endodermal layers Sudan Red 7B served the best results for compound-white light microscope, Fy for compound-epifluorescence microscope and Nile for confocal laser scanning microscope (CLSM). Suberin lamellae deposition initiated almost in a random manner; they continued to be deposited resulting in the production of longitudinal files alternating with files with passage cells, and were ultimately deposited in almost all cells at a distance of 255 mm from the tip. The suberin lamellae are perforated with pores, a consistent feature even as far as 285 mm from the tip. These pores may serve as portals for water, ions, and pathogen movement.

Pheroid is a patented system comprising of a unique submicron emulsion type formulation. Pheroid vesicles consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful molecules. The aim of this study was to show that a modulation of components and parameters is necessary to obtain the optimum formula to be used in pharmaceutical preparations. Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions (Bjerregaard et al., 2001:23). Careful consideration was given to the apparatus used during the processing along with the ratios of the various components added to the formulation and the storage conditions of the Pheroid vesicles. A preliminary study was performed to optimize the most accurate processing parameters during emulsification. The effect of emulsification rate and time, the temperature of the aqueous phase, the number of days the water phase were gassed, the concentration of the surfactant, cremophor® RH 40, used and the concentration of Vitamin F Ethyl Ester CLR added to the oil phase of the o/w emulsion has been studied. Quantification of the mean particle size, zeta potential, turbidity, pH and current values were used to characterize the emulsions. The samples were characterised after 1, 2, 3, 7, 14, 21 and 28 days of storage. The emulsions were also characterised with confocal laser scanning microscopy (CLSM) to measure the number and size and size distribution of the vesicles. After determination of the processing variables influencing the emulsion stability an accelerated stability test was conducted on a final formula. In the present study, accelerated stability testing employing elevated temperatures and relative humidity were used with good accuracy to predict long-term stability of an o/w emulsion kept at both 5 and 25 OC with 60 % relative humidity and 40 OC with 75 % relative humidity. The results of the stability tests were presented in histograms of the physical properties 24 hours, 1 month, 2 months and 3 months after preparation of the emulsion. It was concluded that Pheroid vesicles demonstrate much potential as a drug delivery system. The high stability of this formula allows its use in a wide variety of applications in the pharmaceutical industry. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Pheroid is a patented system comprising of a unique submicron emulsion type formulation. Pheroid vesicles consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful molecules. The aim of this study was to show that a modulation of components and parameters is necessary to obtain the optimum formula to be used in pharmaceutical preparations. Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions (Bjerregaard et al., 2001:23). Careful consideration was given to the apparatus used during the processing along with the ratios of the various components added to the formulation and the storage conditions of the Pheroid vesicles. A preliminary study was performed to optimize the most accurate processing parameters during emulsification. The effect of emulsification rate and time, the temperature of the aqueous phase, the number of days the water phase were gassed, the concentration of the surfactant, cremophor® RH 40, used and the concentration of Vitamin F Ethyl Ester CLR added to the oil phase of the o/w emulsion has been studied. Quantification of the mean particle size, zeta potential, turbidity, pH and current values were used to characterize the emulsions. The samples were characterised after 1, 2, 3, 7, 14, 21 and 28 days of storage. The emulsions were also characterised with confocal laser scanning microscopy (CLSM) to measure the number and size and size distribution of the vesicles. After determination of the processing variables influencing the emulsion stability an accelerated stability test was conducted on a final formula. In the present study, accelerated stability testing employing elevated temperatures and relative humidity were used with good accuracy to predict long-term stability of an o/w emulsion kept at both 5 and 25 OC with 60 % relative humidity and 40 OC with 75 % relative humidity. The results of the stability tests were presented in histograms of the physical properties 24 hours, 1 month, 2 months and 3 months after preparation of the emulsion. It was concluded that Pheroid vesicles demonstrate much potential as a drug delivery system. The high stability of this formula allows its use in a wide variety of applications in the pharmaceutical industry. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Este estudo teve como objetivo avaliar a eficácia dos cimentos obturadores do sistema de canais radiculares quando submetidos ao desafio ácido em ambiente bucal. Foram utilizadas 55 raízes de incisivos centrais inferiores humanos com comprimento padronizado em 10 mm. Realizou-se o preparo biomecânico dos canais até o instrumento #40.02 e as raízes foram esterilizadas em autoclave. Quarenta e quatro raízes foram obturadas pela técnica de condensação lateral com um dos quatro cimentos de diferentes bases: AH Plus, MTA Fillapex, Sealapex ou Endofill. Nas 11 raízes remanescentes, apenas foi executado o preparo biomecânico dos canais e esterilização (controle negativo). Foram selecionados 11 participantes que atenderam aos critérios de inclusão na pesquisa. Foi realizada a moldagem das arcadas dentais e confecção dos dispositivos acrílicos intra-bucais palatinos com 5 nichos, sendo 4 deles para as raízes correspondentes a cada cimento experimental e 1 nicho para a raiz controle. As raízes foram fixadas com cera e tela para favorecer o acúmulo de biofilme. Durante 14 dias, 11 participantes utilizaram o dispositivo o dia todo e foram orientados a gotejar solução de sacarose 20% sobre as amostras, seis vezes ao dia, simulando alto desafio cariogênico. Após os 14 dias, as raízes foram removidas dos dispositivos, seccionadas em slices e foram realizadas as seguintes análises: perfil de desgaste do material obturador e superfície dentinária antes e após a exposição ao ambiente ácido bucal por microscopia confocal de varredura a laser (MCVL); resistência adesiva (MPa) do material obturador à dentina radicular por teste de push-out e análise qualitativa da morfologia da interface adesiva e desmineralização ao redor do material obturador por MCVL. Os dados do perfil de desgaste foram avaliados pelo teste não-paramétrico de Kruskal-Wallis e teste t (&alpha;=0,05), os dados da resistência adesiva foram avaliados por Análise de Variância a dois critérios (cimentos e terços radiculares) e teste de Tukey (&alpha;=0,05). Verificou-se que não houve diferença estatisticamente significante entre os cimentos (p=0,6190), porém todas as amostras apresentaram desgaste da dentina e material obturador após exposição ao ambiente bucal (p<0,05). As raízes obturadas com o cimento AH Plus apresentaram maior resistência adesiva à dentina (11,40 ± 7,74 a) (p<0,05). Resultados intermediários foram encontrados nas raízes obturadas com o MTA Fillapex (7,22 ± 5,88 ab) e Endofill (7,37 ± 6,75 ab). As raízes obturadas com o Sealapex apresentaram menores valores de resistência adesiva (5,18 ± 4,34 b). Não houve diferença significante para os terços radiculares, nem na interação dos fatores (p>0,05). Houve predomínio de falhas adesivas em dentina nas raízes obturadas com os cimentos AH Plus, MTA Fillapex e Endofill (respectivamente 66%, 75% e 54,2%). Nas raízes obturadas com o Sealapex houve predomínio de falhas mistas (54,2%). Todos os cimentos apresentaram degradação do material obturador e superfície dentinária, além da desmineralização ao redor da obturação, sendo esta última mais intensa nas raízes obturadas com os cimentos Sealapex e Endofill. Nas raízes não obturadas, houve acúmulo intenso de biofilme bacteriano e desmineralização da dentina intrarradicular. Nenhum cimento foi capaz de evitar a degradação da interface adesiva e da dentina. No entanto, nestas situações de alto desafio ácido, os cimentos AH Plus e MTA Fillapex demonstraram desempenho superior aos demais cimentos testados, por apresentarem melhor resistência adesiva do material obturador à dentina, além de degradação e desmineralização ao redor da obturação menos intensa. / This study has the purpose to evaluate the efficacy of root canal sealers following in situ acid challenge. The root canals of 55 human mandibular central incisors with standardized root canals length 10 mm were used. Roots were as submitted to biomechanical preparation up to #40.02 instrument and canals were sterilized in an autoclave. Forty-four roots were filled with one of the four sealers using the lateral condensation technique: AH Plus, Endofill, MTA Fillapex e Sealapex. The remaining 11 roots were only submitted to biomechanical preparation and were sterilized (negative control). Eleven 11 participants that fulfill the inclusion criteria were selected. The impressions of dental arcs were performed and intraoral acrylic devices were done with 5 spaces, being 4 for roots with experimental sealers and 1 for control root. The roots were fixed with wax and screen to promote the accumulation of biofilm. During 14 days, 11 participants were instructed to use the devices every day. Dental biofilm was allowed to accumulate on root and drops of 20% sucrose solution were dripped onto them, simulating a high acidic challenge. After 14 days, the roots were removed from the intraoral devices sectioned in slices and the following analyses were conducted: degradation (wear profile) in the dentin-sealer interface subjected to confocal laser scanning microscope (CLSM); bond strength of filling material (MPa) to root canal (push-out test) and qualitative analysis of adhesive interface morphology and demineralization around filling material by CLSM. The wear profile data were assessed by non-parametric Kruskal-Wallis and t-test (&alpha;=0.05), the bond strength were evaluated by two-way ANOVA (cements and root thirds) and Tukey test (&alpha;=0.05). Statistical analyses were set at 5% significance level. Regarding the surface of the wear profile, it was found that there was no significant statistical difference between sealers (p=0.6190), but all samples showed wear of dentine and filling material after exposure to the oral environment (p <0.05). Roots filled with AH Plus sealer showed the higher bond strength to dentin (11.40 ± 7.74 a) (p<0.05). Intermediate results were found in roots with MTA Fillapex (7.22 ± 5.88 ab) and Endofill (7.37 ± 6.75 ab). The worst result was found in roots with Sealapex (5.18 ± 4.34 b). There were no significant differences in root thirds, neither in the interaction of factors (p>0.05). Adhesive failure were predominant in root canals with AH Plus, MTA Fillapex and Endofill (respectively, 66%, 75% e 54.2%). Root canals with Sealapex presented more mixed failure (54.2%). Qualitative morphological analysis showed that all sealers presented dentin demineralization around root canal filling, being greater when using to Sealapex and Endofill sealers. In unfilled roots, there was intense accumulation of bacterial biofilm and demineralization of intraradicular dentin. After the exposure of roots to oral environment for 14 days, it may be concluded that no sealer was able to prevent degradation of the adhesive interface and dentin. However, in these situations of high acid challenge, AH Plus and MTA Fillapex sealers have shown superior performance than other tested sealers for their high adhesive strength of the filling material to dentin, and less intense degradation and demineralization around the root canal filling.

No description available.

No description available.

The aim of this in vitro study was to analyse the performance of CAD/CAM resin-based composites for the fabrication of long-term temporary fixed dental prostheses (FDP) and to compare it to other commercially available alternative materials regarding its long-term stability. Four CAD/CAM materials [Structur CAD (SC), VITA CAD-Temp (CT), Grandio disc (GD), and Lava Esthetic (LE)] and two direct RBCs [(Structur 3 (S3) and LuxaCrown (LC)] were used to fabricate three-unit FDPs. 10/20 FDPs were subjected to thermal cycling and mechanical loading by chewing simulation and 10/20 FDPs were stored in distilled water. Two FDPs of each material were forwarded to additional image diagnostics prior and after chewing simulation. Fracture loads were measured and data were statistically analysed. SC is suitable for use as a long-term temporary (two years) three-unit FDP. In comparison to CT, SC featured significantly higher breaking forces (SC > 800 N; CT < 600 N) and the surface wear of the antagonists was (significantly) lower and the abrasion of the FDP was similar. The high breaking forces (1100–1327 N) of GD and the small difference compared to LE regarding flexural strength showed that the material might be used for the fabrication of three-unit FDPs. With the exception of S3, all analysed direct or indirect materials are suitable for the fabrication of temporary FDPs.