Evaluation of intensity standards of tungsten-halogen and led curing units / Evaluación de estándares de intensidad de unidades de curado tugsteno-halógenas y leds

Current evidence indicates that the minimum light intensity of photo curing units required to polymerize in a reliable way a composite resin, in increments of 2mm, is 300mW/cm2. The recent introduction of new generations of composite resin materials for large volume increments, partially contrasts with ISO 4049 (2009), calling for the use of light intensity of 1,000mW/cm2. Therefore, it is considered relevant to carry out periodic measurements of the emission intensity of light-curing units of clinical use. The aim of this study was to test the intensity [mW/cm2] of a representative sample of tungsten-halogen and LED photopolymerization units used in private and public health service in different areas of the Valparaíso Region in Chile. This was achieved through the use of dental radiometers, without considering the variables of intensity modification over time (either spontaneously, by undesirable inherent characteristics of the device, or by programs of intensity modification in time), or the density of accumulated power needed. This in vitro diagnostic test, evaluated a sample of 507 units, 107 halogen and 400 LED, for a period of around one month, using two radiometers as measuring instruments. For LED units the Bluephase Meter® radiometer, from Ivoclar-VivadentTM was used, and for halogen units we used the Coltolux® from ColténeTM. As a result, 85% of the LED and halogen units achieved the minimum requirements of intensity needed for the polymerization of conventional dental biomaterials. However, only 25% from the tested units achieved a power density of 1,000mW/cm2.

Emerging technology and techniques.

A technique of fabricating feldspathic porcelain pressable ingots was proposed. A 5 ml disposable syringe was used to condense the powder slurry. The condensed porcelain was sintered at 900°C to produce porcelain ingots. The fabricated porcelain ingots were used in pressable ceramic machines. The technological advantages of pressable system improve the properties, and the fabricated ingot enhances the application of feldspathic porcelain.

Próteses obturadoras para pacientes maxilarectomizados: estado atual da tecnologia e necessidades de aprimoramentos / Obturator prostheses for maxillectomized patients: inventory of the existing technology and the need for improvements

Pacientes portadores de comunicação oronasal necessitam de dispositivo protético obturador, para o restabelecimento da sua função, estética e qualidade de vida perdida, devido à remoção ou ausência da maxila. Esta tecnologia reabilitadora vem se desenvolvendo há alguns séculos, com aprimoramentos das técnicas de confecção e materiais odontológicos que auxiliem na elaboração de obturadores cada vez mais eficientes, principalmente no que se refere a sua adaptação. Esta tecnologia é fortemente dependente tanto do domínio das técnicas laboratoriais, quanto de habilidades específicas na arte da reconstrução da face (manuais, sensitivas e tácitas), pois sua confecção é artesanal, personalizada e individualizada, determinando que a disponibilidade e distribuição dos recursos humanos qualificados para a sua elaboração constituam-se em obstáculo significativo para um acesso mais amplo e equânime. O trabalho em tela teve por objetivo examinar o estado da arte relativo às diferentes técnicas de moldagens e confecção das próteses obturadoras utilizadas no cuidado reabilitador de pacientes maxilarectomizados, buscando subsidiar proposições para o seu aprimoramento. Este estudo teórico-exploratório utilizou dois caminhos metodológicos complementares. O primeiro tomou por base uma revisão de literatura científica nacional e internacional e acadêmica, publicada sob a forma de artigos, teses e dissertações, utilizando as bases bibliográficas MEDLINE, BBO, LILACS, SCIELO, Biblioteca Virtual de Saúde e Colaboração Cochrane, e as bases de dissertações e teses da CAPES – Banco de Teses; Base Thesis e Biblioteca Digital de Teses e Dissertações (BDTD), do Instituto Brasileiro de Informação em Ciência e Tecnologia (IBICT)...

Patients with oral-nasal connection due to the absence or extirpation of themaxilla need a prosthetic obturator for esthetical reasons, to restore function, and to partially regain the lost quality of life. This technology has evolved in the course of many centuries in conjunction with the improvement in manufacturing techniques and odontological materials that play a role in the elaboration and design of more efficient obturators, especially regarding their adaptation. This technology is exceedinglydependent on the mastery of laboratorial methods as well as specific skills in the art of facial reconstruction because its confection is artisanal, personalized, and customized. The existence and distribution of suitable human resources are an evident obstacle to the evenly access to this technology. The aim of this work was toscrutinize the “state of the art” regarding different moulding and manufacturing techniques of prosthetic obturators employed in the rehabilitation process of maxillectomized patients, intending to make a contribution for its improvement. This theoretical-exploratory study used two complementary methodological instruments. One was a broad review of the national and international scientific literature published as articles, doctoral thesis and dissertations, utilizing different bibliographical databases: MEDLINE, BBO, LILACS, SCIELO, Biblioteca Virtual de Saúde (Virtual Health Library), and The Cochrane Collaboration, as well as the doctoral thesis and dissertations included in the CAPES database - Base Thesis andDigital Library of thesis and dissertations, from the Brazilian Institute of Information in Science and Technology...

Influence of light-curing units on the flexural strength and flexural modulus of different resin composites

Aim: This study aimed to evaluate the flexural strength and flexural modulus of different resin composites (MasterFill, Opallis, Z250, Supreme) after photoactivation with quartz-tungsten-halogen (QTH - XL2500) or light-emitting diode (LED - Radii and Ultrablue Is) light-curing units (LCUs). Methods: The irradiance and spectral emission of each unit were evaluated using a power meter and a spectrometer. Flexural strength (MPa) was determined in a three-point bending test in accordance with the ISO4049 standard specifications. Flexural modulus (GPa) was measured from the linear-elastic range on the stress-deformation profile. Data were submitted to two-way ANOVA and Tukey’s test (p<0.05). Results: Different values for irradiance (850, 780 and 590 mW/cm2) and peak of emission (484, 456, 467 nm) were detected for XL2500, Radii and Ultrablue Is, respectively. Flexural strength and modulus were dependent on both material and LCU. Among the resins, Z250 and Supreme showed significantly higher strength and modulus than MasterFill and Opallis. Comparing the LCUs, Ultrablue Is showed significantly lower flexural strength and modulus than the others. Conclusion: Flexural strength and modulus were dependent on the irradiance and the spectral emission of the curing units, as well on the resin composite tested.

Influence of different light curing units on the bond strength of indirect resin composite restorations

The aim of this study was to evaluate the influence of different light sources on the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement. The superficial dentin of human third molars was exposed and acid-etched and an adhesive system was applied (Single Bond 2). Four-mm-thick indirect resin composite restorations (Gradia) were fabricated and cemented using a dual-cure resin cement (Rely X). Four light sources were used to polymerize the cement: QTH - Optilux 401; LED1 - L.E.Demetron 1; LED2 - Optilight CL; and LED3 - Ultralume 5. The teeth were stored for 24 h and then sectioned, yielding stick-shaped specimens for each group with a bonded area of 1.0 mm². The specimens were then tested in a universal testing machine, at a crosshead speed of 1 mm/min. Data were analyzed using ANOVA. Bond strength mean values were: QTH: 22.5 (± 8.4); LED1: 22.7 (± 9.4); LED2: 21.4 (± 10.2); and LED3: 27.3 (± 13.8). No statistically significant difference was observed among the experimental groups. The bond strength values when the cement was polymerized using different LED lights were equivalent to the values when the QTH light was used. It can be concluded that the variety of light sources used in the present study did not influence the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement.

[Study of microbial contamination of laboratory dental pumice in the city of Shiraz, Iran]

Cross contamination via dental laboratories is an important problem. Among dental and laboratory procedures, two of the most important topics are disinfection of impressions and disinfection of prostheses. Because pumice slurry is widely used in final stages of polishing and finishing of prostheses, it should not be contaminated and if so, it could be a serious potential source of cross-infection. Therefore, this study was done to determine the incidence and also the type of pathogenic oral and non-oral microorganisms in polishing pumice of dental laboratories in the city of Shiraz. This study was a descriptive-analytical investigation. In the same controlled and sterilized condition, the used pumice samples were collected from 12 dental laboratories. Immediately, they were transported to microbiology section of standard institute and cultured in specific and non specific media. For isolation of different types of oral and non oral microorganisms, 16 different tests were applied. A wide range of microorganisms were isolated from all samples of dental pumices. Dominant bacteria in our study in order of frequency were: Acinetobacter lowffi, Bacillus cereus, Staphylococcus aureus, pseudomonas aeroginosa, diphtheroids, citrobacter frundi, enterobacter aerogenes, morganella morganii, clebsiella pneumonia, staphylococcus saprophyticus, streptococcus viridanse. 85.70% of the bacteria detected were non-oral microorganisms and 14.30% were oral microorganisms. This study showed that dental pumices are heavily contaminated with oral and especially with non-oral microorganisms and there was a high risk of cross-infection between clinician, patient and technician. Therefore infection control in all steps of prosthesis construction is recommended

Influence of composite restorative materials and light-curing units on diametrical tensile strength

O objetivo deste estudo foi avaliar a resistência à tracão diametral (DTS) de três compósitos fotoativados com dois aparelhos de fotoativacão (LCU). Os compósitos utilizados neste estudo foram: resina de micropartículas A110 (3M Espe); P60 (3M Espe), indicada para restauracões posteriores, e micro-híbrida Charisma (Heraeus-Kulzer). As fontes de luz foram: halógena (HAL) - Degulux (Degussa) e luz emitida por diodos (LED) - Ultrablue (DMC). As amostras foram confeccionadas através de dois incrementos inseridos em uma matriz de Teflon bipartida medindo 3 mm de profundidade e 6 mm de diâmetro interno e foram fotoativadas pelas LCUs (n = 10). As amostras foram armazenadas dentro de recipientes escuros contendo água destilada a 37ºC por 7 dias. O ensaio de DTS foi realizado com a Máquina de Ensaio Universal Instron com velocidade de 0,5 mm/min. Os dados obtidos foram submetidos à Análise de Variância e ao teste de Tukey. Os resultados foram (MPa): A110/HAL: 276,50 n 62,94a; A110/LED: 306,01 n 65,16a; P60/HAL: 568,29 n 60,77b e P60/LED: 543,01 n 83,65b; Charisma/HAL: 430,94 n 67,28c; Charisma/LED: 435,52 n 105,12c. Desta forma, os resultados indicaram que não houve diferenca significativa de DTS em relacão aos aparelhos para uma mesma resina. Entretanto, entre os materiais ocorreram diferencas significativas nos valores de DTS.

Microscópio odontológico para o clínico geral: a qualidade total chega aos consultórios odontológicos / The operating microscope for the general clinician: the excellence era arrives to the dental office

Desde o princípio do século, tanto a medicina como a odontologia, tem se beneficiado enormemente do uso da magnificaçäo, tendo consequentemente seus horizontes ampliados. A melhora da acuidade visual dos profissionais, conseguida principalmente através do uso intenso de magnificaçäo óptica, tem tornado parte integral dos consultórios odontológicos modernos. Através da grande tendência mundial da Micro-Odontologia, os autores usaram princípios de microcirurgia para melhorar a acuidade visual, bem como a precisäo das técnicas operatórias já existentes, para modificar e ampliar definitivamente o espectro da açäo da Odontologia moderna. Este artigo tem por objetivo fornecer um breve histórico da utilizaçäo da magnificaçäo (Microscópio Odontológico) na odontologia, uma suscinta descriçäo do Microscópio Odontológico, bem como o quanto os Cirurgiöes Dentistas podem se beneficiar desta nova tecnologia. Certamente estamos diante de uma nova era na Odontologia: a era da excelência clínica