Compósitos híbridos: desenvolvimento de configuração e efeitos de umidificação

The advantage in using vegetable fibres in place of synthetic fibres such as glass fibre, for reinforcements in composites are: biodegradability, low cost, low density, good tenacity, good thermal properties, low energy content and reduced use of instruments for its treatment or processing. Even though, problems related to low mechanical performance of some of the natural fibres, has caused difficulty in their direct application in structural elements. The use of alternative materials like hybrid composites has been encouraged, thus trying to better the structural performance of the composites with natural fibres. This work presents a comparative study of the strength and stiffness of hybrid composites with orthopthalic polyester matrix reinforced with E-fibre glass, jute and curauá. The experimental part includes uniaxial tension and three point bending tests to determine the mechanical properties of the final product. The hybrid composite was manufactured in a local industry and was in the form of laminates. All the samples were projected to withstand the possible structural applications as reservoirs and pipes. CH (laminated hybrid composite with glass and curauá fibres). The results obtained show clearly the influence of the hybridization in all the types tested and indicate a good mechanical performance of the composite with glass/curauá fibres in relation to the composite with glass fibres. Aspects in relation to the interfaces glass/curauá composites besides the fracture characteristics for all loading types were also analysed

Avaliação clínica longitudinal do periodonto de dentes pilares e não pilares de próteses parciais removíveis

The literature has shown a relation between periodontics and the removable partial denture (RPD), with progressive destruction observed in the support structures. The aim of this study was to clinically assess periodontal condition in users of removal partial denture (RPD), and compare right abutments teeth, indirect abutments and controls before installation and after 1 year, in addition to comparing tooth-supported and tooth mucosa-supported abutments. A total of 50 patients, 32 women and 18 men, mean age of 45 years, took part in the study. The patients were examined by a single examiner at prosthesis installation and after 3, 6, 9 and 12 months. The following were verified at each examination: Probe Depth (PD), Plaque Index (PI), Gingival Index (GI), the amount of Keratinized Mucosa (KM), Gingival Recession (GR) and Dental Mobility (DM); in addition patients received oral hygiene orientation, accompanied by prophylaxis, periodontal scaling and root planing (PSRP), when necessary. Analysis of Variance (ANOVA) with Tukey-Kramer post test was used to assess the dependent variables (PD, PI, KM, GR) of the three groups over time while Friedman s test was used for GI. To assess the outcomes of prosthesis type in the right abutment group, a confidence interval-based analysis was performed. The results showed that the control group was the least compromised in all the variables studied. With respect to development of the groups over time, it was verified that the measures for GR, PD, GI and KM increased from initial examination to 1 year of use in all the groups, but only PI showed a significant increase. There was a non-discriminatory low prevalence of dental mobility. The tooth mucosa-supported prosthesis had significantly higher values for GR, GI and PI and significantly lower ones for KM when compared to tooth-supported. Over time, both types of prostheses showed no significant differences from initial to final examination for the variables GR, PD, KM and GI, with PI significant only for tooth-supported. The results showed that the teeth most involved in RPD design had greater potential of periodontal damage, probably because of greater dental biofilm accumulation. Abutments elements adjacent to the free extremities had less favorable periodontal condition than those adjacent to interpolated spaces, but the use of RPD did not worsen the initial condition