Comparison of primary human gingival fibroblasts from an older and a young donor on the evaluation of cytotoxicity of denture adhesives

Abstract Denture adhesives (DA) improve the retention and stability of ill-fitting dentures, especially for older adults. These materials should be biocompatible, i.e., they cannot cause undesired biological responses and be non-cytotoxic to oral tissues. However, in vitro testing of DA biocompatibility employing primary cell culture may possibly be affected by other factors, such as the donor age. Objective To compare the cytotoxicity of three different denture adhesives when assessed in primary gingival fibroblasts from a young donor or from an older donor, as well as the release of the basic fibroblast growth factor (bFGF), and the inflammatory response marker interleukin-6 (IL-6). Material and Methods Gingival fibroblasts isolated from a 30- and a 62-year-old donor were assayed for proliferation (1-7 days) and sensitivity to latex (positive control). Fibroblasts were indirectly exposed to Corega Ultra (cream), Corega powder and Fixodent Original for a 24 h period and assayed by XTT and Crystal Violet tests. The release of IL-6 and bFGF by exposed cells was determined by ELISA. Results While cells from the young donor presented higher cell growth after 7 days, the sensitivity to increasing concentrations of latex extracts was very similar between young and older cells. Both XTT and CVDE detected no difference between the DA and the control group. All materials induced higher levels of IL-6 and bFGF compared to control. Cells from the older donor exposed to Corega Ultra released lower levels of cytokine and growth factor. Conclusions All materials were considered non-cytotoxic, but affected cytokine and growth factor release. The biological differences found between fibroblasts from both donors could be due to individual or age-related factors. The authors suggest the use of cells from older donors on studies of dental products aimed at older patients, to better simulate their physiological response.

Noncontact three-dimensional evaluation of surface alterations and wear in NiTi endodontic instruments

Abstract The aim of this study was to undertake a qualitative and quantitative assessment of nanoscale alterations and wear on the surfaces of nickel-titanium (NiTi) endodontic instruments, before and after use, through a high-resolution, noncontact, three-dimensional optical profiler, and to verify the accuracy of the evaluation method. Cutting blade surfaces of two different brands of NiTi endodontic instruments, Reciproc R25 (n = 5) and WaveOne Primary (n = 5), were examined and compared before and after two uses in simulated root canals made in clear resin blocks. The analyses were performed on three-dimensional images which were obtained from surface areas measuring 211 × 211 µm, located 3 mm from their tips. The quantitative evaluation of the samples was conducted before and after the first and second usage, by the recordings of three amplitude parameters. The data were subjected to statistical analysis at a 5% level of significance. The results revealed statistically significant increases in the surface wear of both instruments groups after the second use. The presence of irregularities was found on the surface topography of all the instruments, before and after use. Regardless of the evaluation stage, most of the defects were observed in the WaveOne instruments. The three-dimensional technique was suitable and effective for the accurate investigation of the same surfaces of the instruments in different periods of time.

BiodentineTM is cytocompatible with human primary osteoblasts

Abstract Calcium silicate-based materials have been widely studied due to their resemblance to, and similar applicability of, mineral trioxide aggregate (MTA). Among these, Biodentine™ (BD) was specifically designed as a "dentin replacement" material for applications such as root perforations, apexification, treatment of resorptive lesions, and as a retrograde filling material. The present study aimed to assess the in vitro response of human primary osteoblasts to BD using MTA AngelusTM as a reference material, by simultaneously analyzing three different cell viability parameters, namely mitochondrial activity, membrane integrity, and cell density. BD and MTA extracts were prepared by incubation on culture media for 24 h or 42 days after mixing. Primary human osteoblasts were exposed to extracts for 24 h, at 37oC with 5% CO2, and cell viability was evaluated by the XTT, NRU, and CVDE assays. Both materials induced cell viability levels higher than 70% when extracted for 24 h. However, when cells were exposed to extracts with increased conditioning times, MTA presented significant cytotoxic effects (p < 0.05) in comparison to the control and MTA at 24 h. After 42 days, the XTT assay identified a significant reduction in cell viability by BD when compared to the control (p<0.05), despite the fact that levels above the 70% viability cutoff were attained for biocompatible materials. It can be concluded that BD is cytocompatible with human primary osteoblasts, indicating its adequacy in direct contact with bone tissues.

Cytotoxicity Evaluation of Two Bis-Acryl Composite Resins Using Human Gingival Fibroblasts

Abstract Bis-acryl resins are used for temporary dental restorations and have shown advantages over other materials. The aim of this work was to evaluate the in vitro cytotoxicity of two bis-acryl composite resins (Protemp 4 and Luxatemp Star), obtained at 1, 7 and 40 days after mixing the resin components, using a standardized assay employing human primary cells closely related to oral tissues. Human gingival fibroblast cell cultures were exposed for 24 h to either bis-acryl composite resins, polystyrene beads (negative control) and latex (positive control) extracts obtained after incubation by the different periods, at 37 °C under 5% CO2. Cell viability was evaluated using a multiparametric procedure involving sequential assessment (using the same cells) of mitochondrial activity (XTT assay), membrane integrity (neutral red test) and total cell density (crystal violet dye exclusion test). The cells exposed to the resin extracts showed cell viability indexes exceeding 75% after 24 h. Even when cells were exposed to extracts prepared with longer conditioning times, the bis-acryl composite resins showed no significant cytotoxic effects (p>0.05), compared to the control group or in relation to the first 24 h of contact with the products. There were no differences among the results obtained for the bis-acryl composite resins evaluated 24 h, 7 days and 40 days after mixing. It may be concluded that the bis-acryl resins Protemp 4 and Luxatemp Star were cytocompatible with human gingival fibroblasts, suggesting that both materials are suitable for use in contact with human tissues.

Resumo Resinas bisacrílicas são usadas em restaurações dentárias provisórias e têm mostrado vantagens em relação a outros materiais. O objetivo deste trabalho foi avaliar a citotoxicidade in vitro de duas resinas compostas bisacrílicas (Protemp 4 e Luxatemp Star), obtidas após 1, 7 e 40 dias da mistura com os componentes da resina, usando um ensaio padronizado empregando células primárias humanas fortemente relacionadas aos tecidos orais. Culturas de células de fibroblastos gengivais humanos foram expostas por 24 h aos extratos das resinas bisacrílicas, esferas de poliestireno (controle negativo) e látex (controle positivo), obtidos após diferentes períodos de incubação, a 37 °C e com 5% CO2. A viabilidade celular foi avaliada usando procedimentos multiparamétricos que envolvem a avaliação sequencial (usando as mesmas células) da atividade mitocondrial (ensaio XTT), a integridade de membrana (teste do vermelho neutro) e a densidade celular total (teste de exclusão do corante cristal violeta). As células expostas aos extratos mostraram viabilidade celular acima de 75% depois de 24 h. Mesmo quando as células foram expostas aos extratos com aumento do tempo de condicionamento, as resinas bisacrílicas não apresentaram efeitos citotóxicos significativos (p<0,05), comparadas ao grupo controle ou em relação às primeiras 24 h de contato com os produtos. Não houve diferença entre os resultados obtidos para as resinas bisacrílicas avaliadas entre as 24 h, 7 e 40 dias depois da mistura. Concluímos que as resinas bisacrílicas Protemp 4 e Luxatemp Star foram citocompatíveis com os fibroblastos gengivais humanos, sugerindo que ambos materiais são adequados para uso em contato com tecidos humanos.

A comparison of two reciprocating instruments using bending stress and cyclic fatigue tests

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 mm in length, were tested. The bending resistance was evaluated through the results of a cantilever-bending test conducted using a universal testing machine. Static and dynamic cyclic fatigue testing was conducted using a custom-made device. For the static and dynamic tests, a cast Ni-Cr-Mo-Ti alloy metal block with an artificial canal measuring 1.77 mm in diameter and 20.00 mm in total length was used. A scanning electron microscope was used to determine the type of fracture. Statistical analyses were performed on the results. The WaveOne instrument was less flexible than the Reciproc (p < 0.05). The Reciproc instrument showed better resistance in the static and dynamic cyclic fatigue tests (p < 0.05). The transverse cross-section and geometry of the instruments were important factors in their resistance to bending and cyclic fracture. Both of the instruments showed ductile-type fracture characteristics. It can be concluded that the Reciproc 25-08 instrument was more resistant to static and dynamic cyclic fatigue than the WaveOne 25-08 instrument, while the WaveOne 25-08 instrument was less flexible. Bending and resistance to cyclic fracture were influenced by the instruments’ geometries and transverse cross-sections. Both of the instruments showed ductile-type fracture characteristics.

Riscos ocupacionais no exerc¡cio da Odontologia – revisÆo sistem tica / Occupational hazards in Dentistry – systematic review

O presente trabalho teve como objetivo levantar evidˆncias relacionadas …s doen‡as profissionais e/ou ocupacionais que os cirurgiães-dentistas estÆo vulner veis. Elaborou-se mediante a aplica‡Æo de m‚todos expl¡citos e sistematizados de busca, aprecia‡Æo cr¡tica e s¡ntese da informa‡Æo selecionada, uma revisÆo da literatura sobre o tema. Os trabalhos foram selecionados das bases de dados eletr“nicas (PubMed, Bireme, Nature, Scielo e Cochrane), sendo consultados no per¡odo de 1990 a 2013 sobre as seguintes tem ticas: “doen‡as ocupacionais na Odontologia”, “risco ocupacional odontol¢gico”, “Odontologia do trabalho”, “occupational disease Dentistry”, “occupational hazards”, “dentist”, “cirurgiÆo-dentista”, nos idiomas portuguˆs e inglˆs. Selecionaram-se 21 artigos de um total de 40 potencialmente relevantes, identificados nas pesquisas de base de dados, que reportaram sobre as diversas doen‡as ocupacionais. Concluiu-se que os cirurgiães-dentistas devem conscientizar-se dos riscos ocupacionais e que trabalhos educativos no sentido de preven‡Æo das doen‡as profissionais sÆo necess rios.

The present study aimed to collect evidence related to occupational diseases to which dental surgeons are exposed. A literature review on the subject was elaborated through the application of explicit and systematic search methods, critical appraisal, and synthesis of selected information. The studies were chosen from electronic databases (Pubmed, Bireme, Nature, SciELO and Cochrane), consulted in the period from 1990 to 2013 on the following topics: “occupational diseases in Dentistry”, “occupational hazards in Dentistry”, “dental work”, “occupational disease Dentistry”, “occupational hazards”, “dentist”, “dental surgeon”, in Portuguese and English. Twenty-one articles were selected from a total of 40 potentially relevant studies identified in the databases concerning various occupational diseases. It was concluded that dentists should become aware of occupational hazards and that further educational programs towards the prevention of occupational diseases are still necessary.

Effect of time of extraction on the biocompatibility of endodontic sealers with primary human fibroblasts

The aim of this work was to evaluate the effects of different times of extraction on the cytotoxicity of six representatives of different root canal sealer groups-Real Seal SE, AH Plus, GuttaFlow, Sealapex, Roth 801, and ThermaSeal Plus-with human gingival fibroblasts. The materials were prepared according to manufacturers' specifications, and were incubated in culture medium (DMEM) at 37ºC for 1, 7, 14, 21, and 28 days, with daily washing, to simulate periodontal ligament clearance. Human fibroblasts were exposed to the final extracts at 24 hours, and cell viability was determined by MTT assay, with exposure to unconditioned DMEM as a negative control. Statistical analysis comparing cytotoxicities at each exposure time was performed by ANOVA with Scheffé adjustment for multiple comparisons at a 95% confidence level. Results indicated that GuttaFlow was significantly less cytotoxic than all other sealers (p < 0.05) at 1 day of extraction. After 7 days of extraction, cell viability for GuttaFlow was significantly increased as compared with that of all groups except sealer AH Plus. At day 14, cytotoxicity of Sealapex was significantly higher than that of all other sealers (p < 0.05). At days 21 and 28, there were no significant differences in cytotoxicity among sealer groups. All materials presented some level of cytotoxicity to fibroblasts, while GuttaFlow was the least cytotoxic sealer tested. However, the cytotoxicity of all materials seemed to decrease similarly in a time-dependent manner.

Ação do ácido cítrico e o bardac 2250 na remoção de Ca++ e smear layer no canal radicular / Intracanal removal of Ca++ and smear layer by citric acid and bardac 2250

O presente trabalho compara in vitro a desobstrução dos túbulos dentinários e a quelação de Ca++, utilizando trinta dentes instrumentados, aleatoriamente distribuídos em três grupos de dez elementos que receberam a irrigação final com 10ml de Bardac 2250 a 0,5 por cento; 10ml de ácido cítrico a 10 por cento; e 10ml de hipoclorito de sódio a 5 por cento (grupo controle). Dois métodos foram utilizados para verificar a eficácia das soluções: o estudo pelo espectofotômetro de absorção atômica e a leitura ao microscópio eletrônico de varredura. Conclui-se que o ácido cítrico a 10 por cento apresenta-se melhor na captura de Ca++ e na remoção de smear layer (p<0,05), e que eles não apresentam diferenças estatisticamente significativas quanto à remoção de smear layer (p>0,05)