O uso de gengiva artificial para melhorar a estética de dentes naturais e implantes / The use of artificial gum to improve aesthetic of natural teeth and implants

Apesar dos grandes esforços feitos para alcançar o resultado estético das restaurações implantossuportadas, complicações podem ocorrer. Para o tratamento destas complicações, correções podem ser necessárias, sendo elas cirúrgicas (reconstrução óssea e do tecido mole) ou protéticas. Quando muito extensas e diante da recusa dos pacientes pelos procedimentos cirúrgicos, a alternativa para estas situações clínicas é a prótese gengival. Esta pode ser fixa ou removível e feita a partir de acrílico, resinas e materiais à base de porcelana. Pode ser utilizada para reconstruir proteticamente regiões onde houve perda de estrutura óssea e/ou de tecido mole, para minimizar defeitos estéticos de exposição da cinta metálica em componentes angulados, e em casos de doença periodontal com migração apical da margem gengival, provocando sensibilidade, dificuldades fonéticas por escape do ar e espaços negros na região de dentes anteriores. Compreender os métodos usados para incorporar próteses gengivais em tratamento protético é vital para assegurar que aos pacientes sejam oferecidas todas as possíveis opções no início do planejamento do tratamento. É procedimento de baixo custo e confecção, ao alcance de qualquer laboratório e facilmente aceito pelos pacientes pela facilidade de manutenção (AU)

Despite the great efforts to achieve good aesthetic results of dental implants restorations, complications can occur. For the treatment of these complications, corrections may be necessary. This corrections can be surgical (bone and soft tissue reconstruction) or prosthetic. When major reconstructions are required and the patient refuses to submit to surgical procedures, the prosthetic gingival reconstruction is an alternative. This prosthesis can be fixed or removable and made of acrylic, resin materials and porcelain. It can be used to reconstruct prosthetic regions with bone and/or soft tissue loss, to minimize metal exposure of angulated abutments in aesthetic regions, and in cases of periodontal disease and apical migration of gingival margin, causing sensitivity, phonetic problems due to air escape, and black spaces in the region of anterior teeth. Understanding the methods used to incorporate gingival prostheses in prosthetic treatments is vital to ensure that patients all possible options are presented to the patient at the beginning of treatment planning. It is a low cost procedure that can be manufactured by any laboratory and easily accepted by patients due to its simple maintenance (AU)

Avaliação do selamento cervical pela mudança de pH na presença de materiais clareadores / Effect of cervical barrier by pH change in the presence of intracoronal bleaching

O objetivo desse estudo foi avaliar as mudanças de pH extrarradicular pós tratamento clareador utilizando três diferentes barreiras cervicais. Caninos superiores extraídos foram instrumentados e obturados, tiveram 2mm de material obturador removidos, sendo divididos em três grupos experimentais. Defeitos artificiais ao longo da junção cemento-esmalte foram realizados e as barreiras cervicais confeccionadas com os cimentos fosfato de zinco, óxido de zinco sem eugenol e ionômero de vidro. Os dados obtidos foram submetidos à análise estatística, sendo que os resultados indicaram diferença significativa entre os grupos (p <0,05), sendo que valores de pH mais constantes e menores foram obtidos com o cimento óxido de zinco sem eugenol, enquanto os outros dois cimentos permitiram elevação significativa do pH.

Comparison of silorane and methacrylate-based composite resins on the curing light transmission.

The aim of this study was to investigate the influence of different composite resins - Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) - on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25%) was significantly higher than that of Heliomolar (12%). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.

Comparison of silorane and methacrylate-based composite resins on the curing light transmission

The aim of this study was to investigate the influence of different composite resins - Filtek P90 (silorane-based composite) and Heliomolar (methacrylate-based composite) - on light transmission and decrease in Knoop hardness between the bottom and top of cured specimens. The irradiance of a light-curing unit (LCU) was measured with a power meter (Ophir Optronics; 900 mw/cm2) and spectral distributions were obtained using a spectrometer (USB 2000). Twenty standardized cylindrical specimens (2 mm thick x 7 mm diameter) of each composite resin were obtained by curing using the LCU for 40 s. Light energy transmission through the composite was calculated (n=10). The Knoop hardness number for each surface was recorded as the mean of 3 indentations. The difference in Knoop hardness between the top and bottom (DKH) of the same specimen was calculated (n=10). The irradiance of light that passed through Filtek P90 (272 mW/cm2) was not significantly greater than that the passed through Heliomolar (271 mW/cm2). The DKH of Filtek P90 (25 percent) was significantly higher than that of Heliomolar (12 percent). There was a greater degree of subsurface polymerization of the methacrylate-based composite compared to the silorane-based composite.

O objetivo deste estudo foi avaliar a influência da diferença entre a dureza do topo e da base em compósitos restauradores. Foram utilizados os compósitos restauradores Filtek P90 (compósito à base de silorano) e Heliomolar (compósito à base de metacrilato). A irradiância da unidade foto-ativadodora (UF) foi mensurada com um potenciômetro Ophir Optronics (900 mw/cm2) e o espectro de luz foi obtido usando um espectrofotômetro (USB 2000). Vinte espécimes cilíndricos padronizados (2 mm de espessura por 7 mm de diâmetro) foram obtidos pela fotoativação utilizando UF (40 s) para cada compósito. A irradiância que passou através do compósito foi mensurada (n=10). O número de dureza Knoop para cada superfície foi calculado pela média de 3 penetrações. A diferença da dureza Knoop entre o topo e base (DDK) de um mesmo espécime foi calculada (n=10). A irradiância que passou através da Filtek P90 (272 mW/cm2) não foi estatisticamente superior a Heliomolar (271 mW/cm2). A DDK da Filtek P90 (25 por cento) foi estatisticamente superior a Heliomolar (12 por cento). O compósito a base de metacrilato apresentou melhor grau de polimerização na base quando comparado ao compósito à base de silorano.

Effect of different light curing units on Knoop hardness and temperature of resin composite.

AIM: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. MATERIALS AND METHODS: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). RESULTS: For both composites, there were no significant differences (P > 0.05) in the top surface hardness; however, PAC promoted statistically lower (P < 0.05) Knoop hardness number values in the bottom. The mean temperature increase showed no significant statistical differences (P > 0.05). CONCLUSION: The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins.

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74 degrees C for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (alpha= 0.05%). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

Light energy transmission through composite influenced by material shades.

This study investigated the influence of different composite resin shades on light energy transmission through the composite, hardness and cross-link density (CLD). The composite Filtek Z250 was used in shades A1, A2, A3, A3.5 and A4. A quartz tungsten halogen light curing unit was used at an irradiance of 900 mW/cm(2). Thirty specimens were made for each shade. Light energy transmission that passed through the composite was calculated (n=10). Differences in Knoop hardness between the top and bottom (DKH) of the same specimen were calculated (n=10). The Knoop hardness value for each surface was recorded as the average of three indentations (KHN(1)). Thereafter, the specimens were soaked in absolute ethanol for 24hr at room temperature, and hardness was again determined (KHN(2)). The CLD was estimated by the softening effect produced by ethanol, i.e., by decrease in hardness. The percentage of decrease in KHN(2) compared with KHN(1) (PD) in the same specimen was then calculated for both surfaces (n=10). The data were submitted to an ANOVA in different tests (Light energy transmission, Knoop hardness and CLD). The irradiance of light that passed through composite shade A1 (408 mW/cm(2)) was statistically greater than that through shade A2 (376 mW/cm(2)), and was greater through A2 than A3 (359 mW/cm(2)) and through A3 than A3.5 (327 mW/cm(2)); A3.5 showed no statistical difference when compared to A4 (324 mW/cm(2)). The DKH of A4 (20.56%) was not statistically higher than that of A3.5 (20.14%), which was greater than that of A3 (14.08%), A2 (11.65%) and A1 (9.06%). There was no statistical difference in CLD. Darker shades had a significant influence on light energy transmission through dental resin composite and its hardness. However, CLD was not affected by darker dental composite shades.

Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (α= 0.05 percent). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

Este estudo verificou o efeito de repetidas desinfecções por microondas sobre a dureza, impacto e resistência à flexão das resinas acrílicas Clássico, Onda-Cryl e QC-20. Matrizes de alumínio foram incluídas em muflas metálica ou plástica com gesso pedra tipo III, de acordo com a técnica de inclusão tradicional. A proporção polímero/monômero usada foi de acordo com as recomendações dos fabricantes. Depois da polimerização em água à temperatura de 74ºC por 9 h, água em ebulição por 20 min ou por energia de microondas a 900 W por 3 min, os corpos-de-prova foram demuflados após esfriamento da mufla em temperatura ambiente e submetidos ao polimento convencional. Testes de dureza, impacto e resistência à flexão foram feitos nos corpos-de-prova controle e experimentais. Cada corpo-de-prova foi submetido individualmente a 5 desinfecções por microondas em forno doméstico com 900 W de energia por 3 min, imersos em 150 mL de água destilada. O teste de dureza Knoop foi realizado com carga de 25 g por 10 s, de resistência ao impacto pelo sistema Charpy com 40 kpcm e de resistência à flexão por três pontos com velocidade de 0,5 mm/min até fratura. Os dados obtidos foram submetidos à análise de variância e ao teste de Tukey (α=0,05 por cento). Repetidas desinfecções por microondas diminuíram a dureza das resinas Clássico e Onda-Cryl, não promoveram nenhum efeito sobre a resistência ao impacto da resina QC-20. A resistência à flexão foi similar para todas as resinas.

Effect of microwave disinfection on physical and mechanical properties of acrylic resins.

This study evaluated the effect of microwave energy on the hardness, impact strength and flexural strength of the Clássico, Onda-Cryl and QC-20 acrylic resins. Aluminum die were embedded in metallic or plastic flasks with type III dental stone, in accordance with the traditional packing technique. A mixing powder/liquid ratio was used according to the manufacturer's instructions. After polymerization in water batch at 74 degrees C for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling at room temperature, and submitted to finishing. Specimens non-disinfected and disinfected by microwave irradiation were submitted to hardness, impact and flexural strength tests. Each specimen was immersed in distilled water and disinfected in a microwave oven calibrated to 650 W for 3 min. Knoop hardness test was performed with 25 g load for 10 s, impact test was carried out using the Charpy system with 40 kpcm, and 3-point bending test with a crosshead speed of 0.5 mm/min until fracture. Data were submitted to statistical analysis by ANOVA and Tukey's test (alpha=0.05). Disinfection by microwave energy decreased the hardness of Clássico and Onda-Cryl acrylic resins, but no effect was observed on the impact and flexural strength of all tested resins.

Effect of microwave disinfection on physical and mechanical properties of acrylic resins

This study evaluated the effect of microwave energy on the hardness, impact strength and flexural strength of the Clássico, Onda-Cryl and QC-20 acrylic resins. Aluminum die were embedded in metallic or plastic flasks with type III dental stone, in accordance with the traditional packing technique. A mixing powder/liquid ratio was used according to the manufacturer's instructions. After polymerization in water batch at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling at room temperature, and submitted to finishing. Specimens non-disinfected and disinfected by microwave irradiation were submitted to hardness, impact and flexural strength tests. Each specimen was immersed in distilled water and disinfected in a microwave oven calibrated to 650 W for 3 min. Knoop hardness test was performed with 25 g load for 10 s, impact test was carried out using the Charpy system with 40 kpcm, and 3-point bending test with a crosshead speed of 0.5 mm/min until fracture. Data were submitted to statistical analysis by ANOVA and Tukey's test (?=0.05). Disinfection by microwave energy decreased the hardness of Clássico and Onda-Cryl acrylic resins, but no effect was observed on the impact and flexural strength of all tested resins.

Este estudo verificou o efeito da desinfecção por microondas sobre a dureza, impacto e resistência à flexão das resinas acrílicas Clássico, Onda-Cryl e QC-20. Matrizes de alumínio foram incluídas em muflas metálica ou de plástico com gesso pedra tipo III, de acordo com a técnica de inclusão tradicional. A proporção polímero/monômero foi de acordo com as recomendações dos fabricantes. Depois da polimerização em água à temperatura de 74ºC por 9 h, água em ebulição por 20 min ou por energia de microondas a 900 W por 3 min, os corpos-de-prova foram demuflados após esfriamento da mufla em temperatura ambiente e submetidos ao polimento convencional. Testes de dureza, impacto e resistência à flexão foram feitos nos corpos-de-prova submetidos ou não à desinfecção por microondas. Cada corpo-de-prova foi submetido individualmente à desinfecção por microondas em forno doméstico com 900 W de potência por 3 min, imersos em 150 mL de água destilada. O teste de dureza Knoop foi realizado com carga de 25 g por 10 s, a de impacto pelo sistema Charpy com 40 kpcm e o de flexão por três pontos com velocidade de 0,5 mm/min até fratura. Os dados foram submetidos à análise de variância e ao teste de Tukey (?=0,05). A desinfecção simulada por microondas diminuiu a dureza Knoop das resinas Clássico e Onda-Cryl e não promoveu nenhum efeito nas resistências ao impacto e à flexão das resinas estudadas.

Dimensional changes occurred in cast for complete dentures evaluated by tri-dimensional measurements / Alterações dimensionais ocorridas em modelo para prótese total avaliadas por medições tridimensionais

This study verified the dimensional changes occurred in stone casts by tri-dimensional design obtained from mathematicalcalculation. Dental stone casts were made in molds of addition silicone, alginate or impression compound relayedby alginate obtained from an aluminum pattern die. Screws were used to establish reference points of the distances,creating segments for area and volume calculation of the generated figures. Tri-dimensional measurement equipmentfitted out with Renishaw PH9 measurement head and TP 200 searcher with 1mm diameter was used for this distancemeasurement. Computer Aided Design system was used to determine the X, Y, Z coordinates, which permitted to getthe geometry dimensions. Results were submitted to statistical calculation and study of the differences (5%). Siliconeimpression produced casts with smaller dimensional changes and larger repetition capacity. The casts presented smallvariation of the variables values among the copies, when compared to alginate or impression compound relayed withalginate molds. Alginate produced casts with better copy fidelity, with absolute values of the variables close of the absolutevalues of the variables of the metallic die. Alginate presented good capacity to copy the metallic die among theimpression materials, although in dimensional conditions no similar.

O estudo verificou as alterações dimensionais ocorridas em modelo de gesso por meio de desenho tridimensional obtidocom cálculos matemáticos. Modelos de gesso de uma matriz metálica representando uma maxila desdentada foram obtidos em moldes de silicone por adição, godiva ou godiva reembasada com alginato. Parafusos foram colocados em pontos referenciais para estabelecer as distâncias, criando segmentos para cálculo da área e volume das figuras geradas.Um equipamento para medições tridimensionais com sonda para medição Renishaw PH9 e escaneador TP 200, componta ativa de 1mm de diâmetro foi usado para medir as distâncias. Um sistema de desenho auxiliado por computador foi usado para determinar as coordenadas X, Y e Z, as quais permitiam a captura das dimensões geométricas. Os resultadosforam submetidos à análise estatística e ao estudo das comparações (5%). O molde de silicone produziu modelos com alteração dimensional pequena e grande capacidade de repetição. Os modelos apresentaram valores com pequenavariação entre os modelos quando comparados com os modelos feitos em moldes de alginato ou godiva reembasada comalginato. O alginato produziu moldelos com melhor fidelidade de cópia, com valores absolutos das variáveis próximosdos valores absolutos das variáveis do modelo padrão metálico. O alginato apresentou boa capacidade para copiar o modelo metálico entre os materiais moldadores, embora em condição dimensional não similar.

A cor e o mistério das palavras / The color and the mystery of words

Existem métodos científicos para evitar freqüentes equívocos na avaliação e comunicação de cor. Falta de conhecimento e informações mal transmitidas são os maiores entraves para o sucesso do trabalho estético