ABSTRACT
OBJECTIVE: This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. MATERIAL AND METHODS: Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20): Gc, no treatment (control); Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s). Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC) (TC). The specimens were submitted to the shear bond strength (SBS) test using a universal testing machine (1 mm/min). Failure mode was assessed using optical and scanning electron microscopy (SEM), together with the surface roughness (Ra) of the resin cement in the bracket using interference microscopy (IM). 2-way ANOVA and the Tukey test were used to compare the data (p>0.05). RESULTS: The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0), but thermocycling did not (p=0.6974). Considering the SBS results (MPa), Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9) and Gt-TC showed the lowest (8.45±6.7). For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157) but the surface treatments did not (p=0.458). For the thermocycled and non-thermocycled groups, Ra (µm) was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. CONCLUSION: Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are ...
Subject(s)
Humans , Ceramics/chemistry , Dental Bonding/methods , Orthodontic Brackets , Silanes/chemistry , Silicon Dioxide/chemistry , Analysis of Variance , Aluminum Oxide/chemistry , Hot Temperature , Materials Testing , Microscopy, Electron, Scanning , Resin Cements/chemistry , Shear Strength , Surface Properties , Time FactorsABSTRACT
El uso de dientes naturales en el proceso de enseñanza-aprendizaje de Odontología es fundamental, además los nuevos planes curriculares vigentes en la mayoría de instituciones de enseñanza brasileras de nivel superior dan privilegio a la investigación. Es de fundamental relevancia conocer tanto la procedencia y formas de uso de los dientes humanos extraídos, como los procedimientos de descontaminación y almacenamiento empleados para este fin. El presente trabajo tiene como objetivo analizar la forma de uso de dientes humanos en la enseñanza odontológica en la Facultad de Odontología de la Universidad Federal de Juiz de Fora a partir de la aplicación de 200 cuestionarios a los alumnos de primero a séptimo periodo de formación. Los resultados demuestran que todavía existe una despreocupación en lo que se refiere a los aspectos ético-legales y de bioseguridad en la obtención y manipulación de dientes humanos por parte de los alumnos. Los datos demuestran la relevancia de la funcionalidad del Banco de Dientes Humanos encargada de abastecer de dientes a los académicos, profesores e investigadores, de forma ética y legal dentro de los estándares de bioseguridad, favoreciendo al menor riesgo de contaminación cruzada.
The use of natural teeth in the dental education and research is essential, moreover, the new curriculum model currently in the majority of Brazilian institutions of higher education focuses on research practice. Besides the importance of knowing the origin and ways of using extracted human teeth, another relevant question is whether the procedures for decontamination and storage are being employed. This study aimed to investigate the use of human teeth in dental education in College of Dentistry of Federal University of Juiz de Fora by application of 200 questionnaires to students between 10 and 70 periods. Given the above study, it appears that there is still a lack of concern with the ethical-legal and bio-security in obtaining and handling human teeth by students. Data show the relevance of the functionality of the Human Teeth Bank, with the role of providing teeth to academics, teachers and researchers in an ethical, legal and standards of biosecurity, providing less risk of cross contamination.
Subject(s)
Learning/ethics , Tooth/anatomy & histology , /analysis , Teaching MaterialsABSTRACT
Avaliou-se a resistência de união porcelana metal utilizando 3 ligas nacionais de Ni-Cr (Resistal P, Nickron G, Kromalit) e uma experimental e o opaco Paint-On 88 empregado com agente de união - Uniseal. Outro aspecto também avaliado foi a vitrificação da primeira camada de opaco na resistência de união (Técnica de McLean). Os resultados mostraram que a resistência de união metal/porcelana foi maior para a liga experimental, seguida das ligas Nickron G, Kromalit e Resistal P, com diferenças estatisticamente significantes entre as ligas e que, a vitrificação do opaco na liga Experimental não apresentou resultados positivos