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Fernando Antônio De ,medeiros - One of the best experts on this subject based on the ideXlab platform.
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Estudo fitoquímico e biológico de espécies amazônicas: Pradosia huberi (Ducke) Ducke (Sapotaceae) e Licania macrophylla Bent. (Chrysobalanaceae)
Universidade Federal da Paraíba, 2008Co-Authors: Fernando Antônio De ,medeirosAbstract:O uso das plantas como recurso terapêutico tem ganhado destaque e tornado modismo no mundo. No Brasil não é diferente, e nos últimos anos alguns estados da federação vem implantando a fitoterapia como alternativa terapêutica para o sistema único de saúde. Porém algumas dificuldades são encontradas, entre elas a falta de informações científicas que subsidie o conhecimento tradicional de determinadas espécies. A espécie Licania macrophylla Benth pertence a família Chrysobalanaceae e é conhecida popularmente por anauera ou anuera . As cascas do caule dessa espécie é usada no estado do Amapá como antidiarréica e amebicida. A espécie Pradosiahuberi Ducke, pertence à família Sapotaceae, e é designada popularmente de casca doce ou pau doce , suas cascas do caule são usadas pelos povos amazônicos como auxiliar no tratamento de problemas gástricos e má digestão. No entanto o uso das cascas do caule dessas espécies na preparação de fitoterápico ou mesmo em preparações caseiras é uma prática predatória, pois a recuperação do dano causado pela retirada das cascas leva anos para sua reconstituição, quando não elimina o espécime. O objetivo deste trabalho foi realizar o estudo fitoquímico e biológico das espécies Licania macrophylla Benth e Pradosia huberi (Ducke) Ducke e comparar a composição química entre folhas e cascas do caule das duas espécies, de forma a sugerir se é possível substituir o uso das cascas do caule pelas folhas, e assim contribuir com a conservação das espécies em discussão. As espécies estudadas foram coletadas no município de Porto Grande Amapá Brasil e exsicatas estão depositadas no Herbário Amapaense HAMAB do IEPA. O estudo fitoquímico das cascas do caule da espécie L. macrophyla Benth (Chrysobalanaceae) levou ao isolamento de (-)- 4 -O-metil-epigalocatequina-3 -O-α-L-raminosídeo (Lm-1), (-)-4 -metil-epigalocatequina (Lm-2), enquanto das folhas foram isoladas feofitina A (Lm-3), 132-hidroxi-(132-S)- feofitinaA (Lm-4), feofitina B (Lm-5), β-sitosterol (Lm-6a), estigmasterol (Lm-6b), β-Oglicosídeo- sitosterol (Lm-7), álcool betulínco (Lm-8) e ácido oleanólico (Lm-9), sendo o primeiro não relatado na literatura. Da espécie Pradosiahuberi foi isolado 2,3- dihidromiricetina-3-α-L-O-raminosídeo (Ph-1) e das folhas éster graxo do eritrodiol (Ph- 2), éster graxo do ácido oleanólico (Ph-3), éster graxo do ácido betulínco (Ph-4) e espinasterol (Ph-5), todas identificadas através de técnicas de RMN de 1H e 13C uni e bidimensionais e comparações com a literatura. A avaliação da atividade antidiarréica do extrato metanólico das cascas do caule (EMC) de L. macrophylla mostrou que esse não interfere nos parâmetros intestinais: modulação da defecação normal; diarréia induzida por agente catártico e trânsito intestinal estimulado. Porém EMC apresentou-se ativo frente à Staphylococcus aureus ATCC 25928, Pseudomonas aeruginosa ATCC 25853 e Escherichia coli ATCC 10536, resultado semelhante ao obtido com Lm-1. O extrato metanólico das folhas (EMF) de L. macrophylla mostrou-se ativo frente as doze cepas bactérianas testadas, resultado semelhante ao observado com Lm-4 e Lm-9. No que se refere aos constituintes químicos isolados das cascas do caule e folhas nas duas espécies pode-se afirmar que não são semelhantes. Já em relação a atividade antimicrobiana do EMC e EMF esses apresentaram-se semelhantes, sugerindo que se a atividade antidiarréica fica comprovada que se deve apenas a ação antimicrobiana pode-se haver substituição do uso das cascas do caule pela folhas.The use of plants as a treatment method has gained prominence and became fashionable in the world. In Brazil is not different. In recent years some brazilian states has been implementing phytotherapy as an alternative therapy for the public health. However there are some drawbacks as the lack of scientific information that supporting traditional knowledge of some species. The Licania macrophylla Benth species belongs to the Chrysobalanaceae family and is known popularly as "anauera" or "anuera." The stem bark of this species is used in the state of Amapá like amebicide as antidiarrheal. The Pradosia huberi Ducke species belongs to the Sapotaceae family, and is popularly called "fresh bark" or "stick candy ' and its stem bark is used by Amazonian peoples to assist in the treatment of stomach problems and indigestion. However the use of the stem bark of these species in the preparation of herbal formulation or even home preparation is a predatory practice, because recovery of the damage caused by removal of the bark takes years to rebuild, if not eliminates the specimen. The aim of this work was the phytochemical and biological study of the Licania macrophylla Benth and Pradosia huberi (Ducke) Ducke species and compare the chemical composition of leaves and stem bark of both species, so as to suggest that you can replace the use of shells stem by the leaves, and thus contribute to the conservation of the species under discussion. The species studied were collected at Porto Grande - Amapá - Brazil and specimens are deposited in the Herbarium Amapaense HAMAB IEPA. The phytochemical study of the stem bark of the L. macrophyla Benth (Chrysobalanaceae) species led to the isolation of (-)-4'-O-methyl-epigallocatechin-3'-O-α- L-raminosídeo (LM-1), (-)-4'-methyl-epigallocatechin (Lm -2), while the leaves were isolated pheophytin A (Lm-3), 132-hydroxy-(132-S) pheophytin A (Lm-4), pheophytin B (Lm-5), β-sitosterol (Lm-6a ), stigmasterol (Lm-6b), β-sitosterol-O-glycoside (Lm-7), alcohol betulínco (Lm-8) and oleanolic acid (Lm-9), the first not reported in the literature. From species was isolated Pradosia huberi 2,3-dihidromiricetina-3-α-LO-raminosídeo (Ph-1) and leaves the fatty ester erythrodiol (Ph-2), ester of fatty oleanolic acid (Ph-3) fatty ester betulínco acid (Ph-4) and espinasterol (Ph-5), all identified by techniques 1H NMR and 13C single and two-dimensional and comparisons with published literature. Evaluation of antidiarrhoeal activity of the methanol extract of the stem bark (EMC) of L. macrophylla showed that this does not interfere with intestinal parameters: modulation of normal defecation, cathartic agent-induced diarrhea and intestinal transit stimulated. But EMC had to be active against Staphylococcus aureus ATCC 25928, Pseudomonas aeruginosa ATCC 25853 and Escherichia coli ATCC 10536, a result similar to that seen with Lm-1. The methanol extract of leaves (EMF) of L. macrophylla was active against the twelve bacterial strains tested, a result similar to that observed with Lm-4 and Lm-9. Regarding the chemical constituents isolated from the stem bark and leaves in two species can state that are not similar. Regarding the antimicrobial activity of EMC and EMF were similar, suggesting that the activity is antidiarrhoeal proven that one should only antimicrobial can be no substitution of the stem bark of the leaves
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Estudo fitoquímico e biológico de espécies amazônicas: Pradosia huberi (Ducke) Ducke (Sapotaceae) e Licania macrophylla Bent. (Chrysobalanaceae)
'Portal de Periodicos UFPB', 2008Co-Authors: Fernando Antônio De ,medeirosAbstract:The use of plants as a treatment method has gained prominence and became fashionable in the world. In Brazil is not different. In recent years some brazilian states has been implementing phytotherapy as an alternative therapy for the public health. However there are some drawbacks as the lack of scientific information that supporting traditional knowledge of some species. The Licania macrophylla Benth species belongs to the Chrysobalanaceae family and is known popularly as "anauera" or "anuera." The stem bark of this species is used in the state of Amapá like amebicide as antidiarrheal. The Pradosia huberi Ducke species belongs to the Sapotaceae family, and is popularly called "fresh bark" or "stick candy ' and its stem bark is used by Amazonian peoples to assist in the treatment of stomach problems and indigestion. However the use of the stem bark of these species in the preparation of herbal formulation or even home preparation is a predatory practice, because recovery of the damage caused by removal of the bark takes years to rebuild, if not eliminates the specimen. The aim of this work was the phytochemical and biological study of the Licania macrophylla Benth and Pradosia huberi (Ducke) Ducke species and compare the chemical composition of leaves and stem bark of both species, so as to suggest that you can replace the use of shells stem by the leaves, and thus contribute to the conservation of the species under discussion. The species studied were collected at Porto Grande - Amapá - Brazil and specimens are deposited in the Herbarium Amapaense HAMAB IEPA. The phytochemical study of the stem bark of the L. macrophyla Benth (Chrysobalanaceae) species led to the isolation of (-)-4'-O-methyl-epigallocatechin-3'-O-α- L-raminosídeo (LM-1), (-)-4'-methyl-epigallocatechin (Lm -2), while the leaves were isolated pheophytin A (Lm-3), 132-hydroxy-(132-S) pheophytin A (Lm-4), pheophytin B (Lm-5), β-sitosterol (Lm-6a ), stigmasterol (Lm-6b), β-sitosterol-O-glycoside (Lm-7), alcohol betulínco (Lm-8) and oleanolic acid (Lm-9), the first not reported in the literature. From species was isolated Pradosia huberi 2,3-dihidromiricetina-3-α-LO-raminosídeo (Ph-1) and leaves the fatty ester erythrodiol (Ph-2), ester of fatty oleanolic acid (Ph-3) fatty ester betulínco acid (Ph-4) and espinasterol (Ph-5), all identified by techniques 1H NMR and 13C single and two-dimensional and comparisons with published literature. Evaluation of antidiarrhoeal activity of the methanol extract of the stem bark (EMC) of L. macrophylla showed that this does not interfere with intestinal parameters: modulation of normal defecation, cathartic agent-induced diarrhea and intestinal transit stimulated. But EMC had to be active against Staphylococcus aureus ATCC 25928, Pseudomonas aeruginosa ATCC 25853 and Escherichia coli ATCC 10536, a result similar to that seen with Lm-1. The methanol extract of leaves (EMF) of L. macrophylla was active against the twelve bacterial strains tested, a result similar to that observed with Lm-4 and Lm-9. Regarding the chemical constituents isolated from the stem bark and leaves in two species can state that are not similar. Regarding the antimicrobial activity of EMC and EMF were similar, suggesting that the activity is antidiarrhoeal proven that one should only antimicrobial can be no substitution of the stem bark of the leaves.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESO uso das plantas como recurso terapêutico tem ganhado destaque e tornado modismo no mundo. No Brasil não é diferente, e nos últimos anos alguns estados da federação vem implantando a fitoterapia como alternativa terapêutica para o sistema único de saúde. Porém algumas dificuldades são encontradas, entre elas a falta de informações científicas que subsidie o conhecimento tradicional de determinadas espécies. A espécie Licania macrophylla Benth pertence a família Chrysobalanaceae e é conhecida popularmente por anauera ou anuera . As cascas do caule dessa espécie é usada no estado do Amapá como antidiarréica e amebicida. A espécie Pradosiahuberi Ducke, pertence à família Sapotaceae, e é designada popularmente de casca doce ou pau doce , suas cascas do caule são usadas pelos povos amazônicos como auxiliar no tratamento de problemas gástricos e má digestão. No entanto o uso das cascas do caule dessas espécies na preparação de fitoterápico ou mesmo em preparações caseiras é uma prática predatória, pois a recuperação do dano causado pela retirada das cascas leva anos para sua reconstituição, quando não elimina o espécime. O objetivo deste trabalho foi realizar o estudo fitoquímico e biológico das espécies Licania macrophylla Benth e Pradosia huberi (Ducke) Ducke e comparar a composição química entre folhas e cascas do caule das duas espécies, de forma a sugerir se é possível substituir o uso das cascas do caule pelas folhas, e assim contribuir com a conservação das espécies em discussão. As espécies estudadas foram coletadas no município de Porto Grande Amapá Brasil e exsicatas estão depositadas no Herbário Amapaense HAMAB do IEPA. O estudo fitoquímico das cascas do caule da espécie L. macrophyla Benth (Chrysobalanaceae) levou ao isolamento de (-)- 4 -O-metil-epigalocatequina-3 -O-α-L-raminosídeo (Lm-1), (-)-4 -metil-epigalocatequina (Lm-2), enquanto das folhas foram isoladas feofitina A (Lm-3), 132-hidroxi-(132-S)- feofitinaA (Lm-4), feofitina B (Lm-5), β-sitosterol (Lm-6a), estigmasterol (Lm-6b), β-Oglicosídeo- sitosterol (Lm-7), álcool betulínco (Lm-8) e ácido oleanólico (Lm-9), sendo o primeiro não relatado na literatura. Da espécie Pradosiahuberi foi isolado 2,3- dihidromiricetina-3-α-L-O-raminosídeo (Ph-1) e das folhas éster graxo do eritrodiol (Ph- 2), éster graxo do ácido oleanólico (Ph-3), éster graxo do ácido betulínco (Ph-4) e espinasterol (Ph-5), todas identificadas através de técnicas de RMN de 1H e 13C uni e bidimensionais e comparações com a literatura. A avaliação da atividade antidiarréica do extrato metanólico das cascas do caule (EMC) de L. macrophylla mostrou que esse não interfere nos parâmetros intestinais: modulação da defecação normal; diarréia induzida por agente catártico e trânsito intestinal estimulado. Porém EMC apresentou-se ativo frente à Staphylococcus aureus ATCC 25928, Pseudomonas aeruginosa ATCC 25853 e Escherichia coli ATCC 10536, resultado semelhante ao obtido com Lm-1. O extrato metanólico das folhas (EMF) de L. macrophylla mostrou-se ativo frente as doze cepas bactérianas testadas, resultado semelhante ao observado com Lm-4 e Lm-9. No que se refere aos constituintes químicos isolados das cascas do caule e folhas nas duas espécies pode-se afirmar que não são semelhantes. Já em relação a atividade antimicrobiana do EMC e EMF esses apresentaram-se semelhantes, sugerindo que se a atividade antidiarréica fica comprovada que se deve apenas a ação antimicrobiana pode-se haver substituição do uso das cascas do caule pela folhas
Alves, Janainne Nunes - One of the best experts on this subject based on the ideXlab platform.
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Caracterização química dos extratos em diclorometano de Origanum majorana L. na inibição de Panicum maximum
Universidade Federal de Uberlândia, 2009Co-Authors: Alves, Janainne NunesAbstract:Foram estudados o potencial alelopático dos extratos da raiz, do caule e das folhas de Origanum majorana L.(catinga de mulata), quanto a inibição da germinação de sementes de Panicum maximum (capim-colonião), o ensaio foi realizado em caixas gerbox, com fotoperíodo de 10 horas e 7 dias, com soluções dos extratos diclorometânicos da raiz, caule e folha de O. majorana nas concentrações: 50,100 e 200 ppm, assim como foi feito o ensaio negativo (branco) com Panicum maximum para análise dos resultados. A inibição aumentou substancialmente com o aumento da concentração dos extratos, sendo que os extratos da raiz, caule e folha de O. majorana apresentaram inibição de 100% da germinação na concentração de 200 ppm. O extrato da raiz apresentou inibição de 80% da germinação na concentração de 100 ppm e o extrato das folhas de O. majorana apresentou eficiência de 83% na inibição da raiz e parte aérea, mesmo na concentração mais baixa (50 ppm). O extrato do caule também se mostrou eficiente inibindo 80% da raiz e parte aérea na concentração de 100 ppm. Posteriormente foram classificados os metabólitos secundários presentes na raiz, caule e folhas, da espécie em estudo por cromatografia de camada delgada (CCD), na raiz foram encontrados: flavonóides, agliconas antraquinônicas, triterpenos, esteróides e polifenóis. Nas folhas e caules foram encontrados: flavonóides, alcalóides, agliconas antraquinônicas, triterpenos, esteróides, taninos e polifenóis. Os extratos ativos foram analisados através da técnica de Cromatografia gasosa acoplada à espectrometria de massas, identificando: beta-farneseno, delta-decalactona e a lactona do ácido 5- hidróxi- 2-decenóico.It were studied the allelopathy potential of the extracts of the root, of the stem and of the leaves of Origanum majorana L., as the inhibition of the germination of seeds of Panicum maximum (grass-colonião), the rehearsal was accomplished in boxes gerbox, with light period of 10 hours and 7 days, with solutions of the extracts diclorometânicos of the root, stem and leaf of O. majorana in the concentrations: 50,100 and 200 ppm, as well as it was made the negative rehearsal (white) with Panicum maximum for analysis of the results. The inhibition increased substantially with the increase of the concentration of the extracts, and the extracts of the root, stem and leaf of O. majorana presented inhibition of 100% of the germination in the concentration of 200 ppm. The extract of the root presented inhibition of 80% of the germination in the concentration of 100 ppm and the extract of the leaves of O. majorana presented efficiency of 83% in the inhibition of the root and aerial part, even in the lowest concentration (50 ppm). The extract of the stem was also shown efficient inhibiting 80% of the root and aerial part in the concentration of 100 ppm. Later they were classified the present secondary metabólitos in the root, stem and leaves, of the species in study for thin layer chromatography (TLC), in the root were identifying: flavonoids, triterpenes, steroids and polyphenols. In leaves and stems were identifying: flavonoids, anthraquinone anglicones, triterpenes, steroids, tanines and polyphenols. The active extracts were analyzing through gas chromatography coupled mass spectrum, identifying: beta-farnesene, delta-decalactone and lactone of acid 5-hidroxy- 2-decenoic
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Caracterização química dos extratos em diclorometano de Origanum majorana L. na inibição de Panicum maximum
'EDUFU - Editora da Universidade Federal de Uberlandia', 2009Co-Authors: Alves, Janainne NunesAbstract:It were studied the allelopathy potential of the extracts of the root, of the stem and of the leaves of Origanum majorana L., as the inhibition of the germination of seeds of Panicum maximum (grass-colonião), the rehearsal was accomplished in boxes gerbox, with light period of 10 hours and 7 days, with solutions of the extracts diclorometânicos of the root, stem and leaf of O. majorana in the concentrations: 50,100 and 200 ppm, as well as it was made the negative rehearsal (white) with Panicum maximum for analysis of the results. The inhibition increased substantially with the increase of the concentration of the extracts, and the extracts of the root, stem and leaf of O. majorana presented inhibition of 100% of the germination in the concentration of 200 ppm. The extract of the root presented inhibition of 80% of the germination in the concentration of 100 ppm and the extract of the leaves of O. majorana presented efficiency of 83% in the inhibition of the root and aerial part, even in the lowest concentration (50 ppm). The extract of the stem was also shown efficient inhibiting 80% of the root and aerial part in the concentration of 100 ppm. Later they were classified the present secondary metabólitos in the root, stem and leaves, of the species in study for thin layer chromatography (TLC), in the root were identifying: flavonoids, triterpenes, steroids and polyphenols. In leaves and stems were identifying: flavonoids, anthraquinone anglicones, triterpenes, steroids, tanines and polyphenols. The active extracts were analyzing through gas chromatography coupled mass spectrum, identifying: beta-farnesene, delta-decalactone and lactone of acid 5-hidroxy- 2-decenoic.Mestre em QuímicaForam estudados o potencial alelopático dos extratos da raiz, do caule e das folhas de Origanum majorana L.(catinga de mulata), quanto a inibição da germinação de sementes de Panicum maximum (capim-colonião), o ensaio foi realizado em caixas gerbox, com fotoperíodo de 10 horas e 7 dias, com soluções dos extratos diclorometânicos da raiz, caule e folha de O. majorana nas concentrações: 50,100 e 200 ppm, assim como foi feito o ensaio negativo (branco) com Panicum maximum para análise dos resultados. A inibição aumentou substancialmente com o aumento da concentração dos extratos, sendo que os extratos da raiz, caule e folha de O. majorana apresentaram inibição de 100% da germinação na concentração de 200 ppm. O extrato da raiz apresentou inibição de 80% da germinação na concentração de 100 ppm e o extrato das folhas de O. majorana apresentou eficiência de 83% na inibição da raiz e parte aérea, mesmo na concentração mais baixa (50 ppm). O extrato do caule também se mostrou eficiente inibindo 80% da raiz e parte aérea na concentração de 100 ppm. Posteriormente foram classificados os metabólitos secundários presentes na raiz, caule e folhas, da espécie em estudo por cromatografia de camada delgada (CCD), na raiz foram encontrados: flavonóides, agliconas antraquinônicas, triterpenos, esteróides e polifenóis. Nas folhas e caules foram encontrados: flavonóides, alcalóides, agliconas antraquinônicas, triterpenos, esteróides, taninos e polifenóis. Os extratos ativos foram analisados através da técnica de Cromatografia gasosa acoplada à espectrometria de massas, identificando: beta-farneseno, delta-decalactona e a lactona do ácido 5- hidróxi- 2-decenóico
Jeong-won Park - One of the best experts on this subject based on the ideXlab platform.
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Considerations during crown reattachment procedure over the pulpal exposure: case report
Korean Academy of Conservative Dentistry, 2012Co-Authors: Bona Kim, Su-jung Shin, Min-ju Song, Yoon Lee, Jeong-won ParkAbstract:Crown reattachment is the most conservative treatment which can be used to restore fractured tooth, presumably with sufficient strength, while maintaining original contour, incisal translucency, and reducing chair time and cost. However, in case of crown fracture with pin-point pulp exposure, we should cautiously minimize the irritation to the pulp and consider pre-treatment pulpal status, choice of pulp capping materials, choice of bonding system and treatment sequence during crown reattachment procedures. This case reports the considerations while crown reattachment with direct pulp capping using calcium hydroxide (Dycal, Dentsply Caulk)
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The evaluation of surface roughness and polishing time between polishing systems
Korean Academy of Conservative Dentistry, 2011Co-Authors: Ye-mi Kim, Su-jung Shin, Min-ju Song, Jeong-won ParkAbstract:Objectives The purpose of this experiment was to evaluate four different polishing systems of their polishability and polishing time. Materials and Methods 4 mm diameter and 2 mm thickness Teflon mold was made. Z-250 (3M ESPE) hybrid composite resin was slightly overfilled and pressed with slide glass and cured with Optilux 501 for 40 sec each side. Then the surface roughness (glass pressed: control group) was measured with profilometer. One surface of the specimen was roughened by #320 grit sand paper and polished with one of the following polishing systems; Sof-Lex (3M ESPE), Jiffy (Ultradent), Enhance (Dentsply/Caulk), or Pogo (Dentsply/Caulk). The surface roughness and the total polishing time were measured. The results were analyzed with one-way ANOVA and Duncan's multiple range test. Results The surface roughness was lowest in Pogo, and highest in Sof-Lex. Polishing times were shortest with Pogo, and followed by the Sof-Lex, Enhance and Jiffy. Conclusions One-step polishing system (Pogo) is very effective to get the smooth surface in a short time, therefore it can be recommended for final polishing system of the restoration
Osorio R. - One of the best experts on this subject based on the ideXlab platform.
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Influence of surface treatments and resin cement selection on bonding to densely-sintered zirconium-oxide ceramic
'Elsevier BV', 2009Co-Authors: De Oyagüe R. C., Monticelli F., Toledano M., Osorio E., Ferrari M., Osorio R.Abstract:OBJECTIVES: To evaluate the effect of surface conditioning on the microtensile bond strength of zirconium-oxide ceramic to dual-cured resin cements. METHODS: Eighteen cylinder-shaped zirconium-oxide ceramic blocks (Cercon Zirconia, Dentsply) were treated as follows: (1) Sandblasting with 125 microm aluminum-oxide (Al(2)O(3)) particles; (2) tribochemical silica coating using 50 microm Al(2)O(3) particles modified by silica; (3) no treatment. Each ceramic cylinder was duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent) using a silicon mold. Composite cylinders were bonded to conditioned ceramics using: (1) Calibra (Densply Caulk); (2) Clearfil Esthetic Cement (Kuraray); (3) Rely x Unicem (3M ESPE). After 24h bonded specimens were cut into microtensile sticks that were loaded in tension until failure. Data were analyzed using two-way ANOVA and Student-Newman-Keuls test for multiple comparisons (p
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Effect of water aging on microtensile bond strength of dual-cured resin cements to pre-treated sintered zirconium-oxide ceramics.
'Elsevier BV', 2009Co-Authors: Rc Oyagüe, Ferrari Marco, Monticelli F., Toledano M., Osorio E., Osorio R.Abstract:OBJECTIVES: To evaluate the hydrolytic stability of different dual-cure resin cements when luted to zirconia ceramic. METHODS: Eighteen cylinder-shaped zirconia blocks (Cercon Zirconia, Dentsply) were conditioned with: Group 1, no treatment; Group 2, sandblasting (125microm alumina-Al(2)O(3)-particles); Group 3, tribochemical silica coating (50microm silica-modified Al(2)O(3) particles). Ceramic blocks were duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent). Composite disks were luted to pre-treated ceramic surfaces using: (1) Clearfil Esthetic Cement (CEC; Kuraray); (2) Rely X Unicem (RXU; 3M ESPE); (3) Calibra (CAL; Dentsply Caulk). After 24h, bonded samples were cut into microtensile sticks (1mm(2)). Half of the sticks were loaded in tension until failure (cross-head speed of 0.5mm/min). The remaining half was tested after 6 months of water storage at 37 degrees C. Data was analyzed with three-way ANOVA and Tukey's test (P
James D. Okun - One of the best experts on this subject based on the ideXlab platform.
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PCBS IN BUILDING Caulk: HEALTH HAZARD OR
2016Co-Authors: James D. OkunAbstract:Growing public concern about the past use of polychlorinated biphenyl (PCB) containing building Caulk in schools has prompted expensive Caulk removal projects at a time of limited public resources. Building Caulk, used during construction to fill narrow gaps around windows and door frames, was often formulated with PCBs to increase its plasticity and durability. This PCB use was banned in 1978, but even three or more decades later, schools with PCB containing Caulk may still have detectable levels of PCBs in indoor air. The USEPA (2010a) has expressed concern that the inhalation of these airborne PCBs may be a significant exposure pathway for children. Despite their presence in buildings for more than 30 years, there have been no reported adverse health effects attributable to PCBs in building Caulk or other building materials. Health concerns about PCBs in schools are based on results of risk assessment models that rely on toxicity factors derived from animal studies. The USEPA has opted to use animal studies for estimating PCB risk to peopl
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HOW OVERLY CAUTIOUS RISK ASSESSMENT METHODS OVERSTATE RISK FROM PCBS IN INDOOR AIR
2016Co-Authors: James D. Okun, Andy Rezendes, James OcchialiniAbstract:The past use of building materials that contained polychlorinated biphenyls (PCBs) is prompting public concern and expensive PCB removal projects. Building materials that may contain PCBs include paint, Caulk, floor finishes and many other interior and exterior construction components manufactured before 1972. While initial concern about PCBs in buildings has focused on schools, it is likely that PCB-containing materials will also be found in many residential, commercial, and industrial structures. In buildings, the primary route of human exposure is the inhalation of PCBs that volatilize out of building materials. The USEPA has indicated that inhalation of airborne PCBs may pose a significant human exposure pathway in schools. EPA’s approach to PCBs in schools is evolving quickly. Initial estimates of health risk from indoor PCBs were calculated using risk assessment methods an