RESUMO
Polymer shrinkage during photopolymerization of dimethacrylate monomers, used for many years to produce materials for dental restoration, can induce either the formation of tooth-restoration gaps or the production of residual stress depending on the quality of adhesion between tooth and dental composites. In this work, the effect of the power density, used to photopolymerize three commercial dental composites (Fill Magic, Supra Fill, and Z100), on the kinetics of the reaction was investigated to determine processing conditions in which the generation of residual stress would be reduced by allowing polymer chains and macromers to flow before freezing during gelation of the polymer network. The kinetics of photopolymerization of the dental composites was monitored by real-time infrared (FTIR) spectroscopy. Polymer shrinkage and mechanical properties were also investigated by using, respectively, density and microhardness measurements. Results showed that the final conversion (after 200 s), volumetric shrinkage, and microhardness values were not affected by different power densities, mainly because the amount of energy used during photopolymerization was set constant by using different irradiation times. Lower power densities were able to reduce the maximum polymerization rate and delay the formation of a rigid network. Conversion before the formation of the rigid network was also enhanced by using a lower power density. Considering that too premature gelation can lead to residual stress during shrinkage, the results of this work indicated that the use of a lower power density can be effective in terms of delaying the onset of the formation of a rigid network, providing then conditions for macromolecules to flow and relieve stress during shrinkage.
Assuntos
Resinas Compostas/síntese química , Teste de Materiais , Ácidos Polimetacrílicos/síntese química , Resinas Compostas/normas , Materiais Dentários , Cinética , Fotoquímica/métodos , Ácidos Polimetacrílicos/química , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
OBJECTIVE: To describe the ethical aspects involved in the dental care provided to patients who are HIV-positive or who have AIDS. METHODS: Literature review (textbooks and MEDLINE and LILACS databases), with an emphasis on the work developed at the School of Dentistry, Federal University of Minas Gerais, Brazil. We examined the social representation of AIDS, the risk of HIV infection during office visits, the refusal to provide care, referral to other professionals without justification, special charges and office visit hours for HIV-positive patients, and the confidentiality of the serological status of the patient. RESULTS: There is still prejudice and ignorance about the risk of HIV and AIDS infection, on the part of dental surgeons and of patients. CONCLUSIONS: An educational project should be undertaken at dental offices and at universities that train new professionals. In addition, the role of national and regional professional associations in providing information concerning ethical aspects involved in the care of HIV/AIDS patients should be reinforced.
Assuntos
Assistência Odontológica para Doentes Crônicos/normas , Ética Odontológica , Medo , Infecções por HIV , Preconceito , Adulto , Brasil , Criança , Honorários Odontológicos , HumanosRESUMO
The professionals and patients involved in dental examinations are at risk for infection by various disease-causing bacteria, viruses, and fungi, such as those responsible for hepatitis, tuberculosis, herpes, and AIDS. It is known that aerosols and spatter containing pathogenic microorganisms can spread during an examination. Nevertheless, some dental clinics are designed to have multiple examination areas in the same room, with no physical barriers between them. The objective of this study was to verify the reach of spatter resulting from the use of a triple syringe and high-rotation turbine during five simulated exams in a collective clinic, bearing in mind that spatter can contain the patient's saliva and blood. To facilitate tracking of the spatter, aniline dye (pink, blue, yellow, green, and brown) was added to the water in the appropriate receptacle in each of the five units. The room, the equipment, and the patient's and operator's clothing were covered with white paper. A high concentration of spatter was observed on the chair, the operator, and the floor of each unit, and it also appeared on the chairs and trays of the surrounding units. The maximum distance reached by spatter was 1.82 m from a point on the chair corresponding to the position of the patient's mouth. During real simultaneous examinations, the surrounding chairs and their patients and operators, as well as the trays containing sterilized instruments, are within spatter range. Therefore, there is a real possibility of cross-infection, and physical barriers should be placed between the units. This study also confirmed the need for protection of the operator's face, body, hair, and arms, since these regions were heavily affected by spatter.