Effect of post-polymerization heat treatment on a denture base acrylic resin: histopathological analysis in rats

This work examined the histological effects, on the rat palatal mucosa, of a denture base acrylic resin, submitted or not to a post-polymerization heat-treatment. Methods: Fifteen adult female Wistar rats, with sixty days old, weighting 150 g – 250 g were divided in G1: animals being maintained under the same conditions as the experimental groups following described, but without the use acrylic palatal plates (control group); G2: use of heat-polymerized acrylic resin palatal plates made of Lucitone 550; G3: use of palatal plates identical to G2, but subjected to a post-polymerization treatment in a water bath at 55°C for 60 min. The plates covered all the palate and were fixed in the molar region with light-cured resin, thus being kept there for 14 days. After the sacrifice, the palate was removed, fixed in formaldehyde 10% and decalcified with EDTA. Sections were stained using haematoxylin and eosin. Images in duplicate were made from the central region of the cuts, to measure the thickness (μm) of the keratin layers (TKC), epithelium total (TET) and connective tissue (TCC). Statistical analyses were carried out by one-way ANOVA and Tukey post-tests (α=0.05). Results: According to the results there was significant difference in the thickness of keratin between G2 and G3, with G1 having the intermediate value and similar to the other groups. There was a significant difference in the connective tissue with G3 effective, from the viewpoint of biocompatibility, for the acrylic resin denture base investigated.

Effect of thermal and mechanical cycles on the hardness and roughness of artificial teeth

In this study the effects of thermal and mechanical cycles on the hardness and roughness of artificial teeth were evaluated. Materials and Methods:Specimens were prepared and stored in distilled water at 37ºC for 48 hours (n=10).The hardness and roughness readings were made in the following time intervals, according to each group:G1: after specimen storage in distilled water at 37°C for 48 hours; G2: after 600.000 constant mechanical cycles; G3: after 1.200.000 constant mechanical cycles; G4: after 2.500 thermalcycling baths, alternated between hot water (55°C) and cold water (5°C) and G5: after 5.000 thermalcycling baths, alternated between hot water (55°C) and cold water (5°C). After cycling and storage procedures, the specimens of each group were submittedto surface roughness and hardness readouts. Statistical evaluation was performed by three-way analysis of variance, complemented by the Tukey multiple comparisons of means test. The level of significance adopted was 5%. There was no significant difference between G1, G4 and G5 as regards mean roughness of different brands of artificial teeth. Groups G2 and G3 showed higher mean roughness values, and generally equivalent values in all time intervals, except for Trilux (G3> G2). Significant differences in hardness values were observed in different brands of artificial teeth, and differences in values after thermal and mechanical cycling. In conclusion, our findings suggest that thermal cyclingdid not change the roughness of the artificial teeth tested, but after the mechanical cycling the roughness values increased. Thermal and mechanical cycling influenced the hardness of the artificial teeth tested.

Preventive effect of a high fluoride toothpaste and arginine-carbonate toothpaste on dentinal tubules exposure followed by acid challenge: a dentine permeability evaluation

Coordenação de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Effect of method of caries induction on aged resin-dentin bond of primary teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the addition of antimicrobial agents on shore a hardness and roughness of soft lining materials

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Improvement of water transport and carotenoid retention during drying of papaya by applying ultrasonic osmotic pretreatment

The effect of ultrasound and osmotic dehydration pretreatments on papaya drying kinetics was investigated. The ultrasound pretreatment was carried out in an ultrasonic bath at 30 A degrees C. The osmotic pretreatment in sucrose solution was carried out in an incubator at 34 A degrees C and agitation of 80 rpm for 210 min. The drying process was conducted in a fixed bed dryer at 70 A degrees C. Experimental data were fitted successfully using the Page model for dried fresh and pretreated fruits, with coefficient of determination greater than 0.9992 and average relative error lower that 14.4 %. The diffusional model was used to describe the moisture transfer, and the effective water diffusivity was identified in the order of 10(-9) m(2) s(-1). It was found that drying rates of osmosed fruits were the lowest due to the presence of infused solutes, while the ultrasound pretreatment contributed to faster drying rates. Evaluation of the dried fruit was performed by means of total carotenoids retention. Ultrasound treatments in distilled water prior to air-drying gave rise to dried papayas with retention of carotenoids in the range 30.4-39.8 % and the ultrasonic-assisted osmotic dehydration of papayas showed carotenoids retention values up to 64.9 %, whereas the dried fruit without pretreatment showed carotenoids retention lower than 24 %.

Effect of melatonin intake on oxidative stress biomarkers in male reproductive organs of rats under experimental diabetes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of ceramic etching protocols on resin bond strength to a feldspar ceramic

This study sought to evaluate the resin micro-tensile bond strength (MTBS) stability of a leucite-reinforced ceramic after different ceramic etching protocols. The microtensile test had 40 ceramic blocks (5x5x6 mm) assigned to five groups (n=8), in accordance with the following surface etching protocols: NE nonetched (control); 9HF: hydrofluoric (HF) acid etching (9% HF)+wash/dry; 4HF: 4%HF+wash/dry; 5HF: 5%HF+wash/dry; and 5HF+N: 5%HF+neutralizer+wash/dry+ultrasonic-cleaning. Etched ceramic surfaces were treated with a silane agent. Next, resin cement blocks were built on the prepared ceramic surface and stored for 24 hours in distilled water at 37 degrees C. The specimens were then sectioned to obtain microtensile beams (32/block), which were randomly assigned to the following conditions, nonaged (immediate test) and aged (water storage for 150 days plus 12,000 thermal cycles), before the microtensile test. Bond strength data were submitted to one-way analysis of variance and Tukey test (alpha=0.05). Additional ceramic samples were subjected to the different ceramic etching protocols and evaluated using a scanning electron microscope (n=2) and atomic force microscopy (n=2). Aging led to a statistically significant decrease in the MTBS for all groups, except the untreated one (NE). Among the groups submitted to the same aging conditions, the untreated (NE) revealed inferior MTBS values compared to the 9HF and 4HF groups. The 5HF and 5HF+N groups had intermediate mean values, being statistically similar to the higher values presented by the 9HF and 4HF groups and to the lower value associated with the NE group. The neutralization procedure did not enhance the ceramic/resin cement bond strength. HF acid etching is a crucial step in resin/ceramic bonding.

Effect of cleansing methods on saliva-contaminated zirconia: an evaluation of resin bond durability

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effects of Water-Based and Callisthenic Exercise on Freezing of Gait, Postural Control, and Functional Independence in Patients With Mild to Moderate Parkinson Disease

Objective: This study aimed to analyze and compare the role of a water-based exercise program versus a combination of water and callisthenic exercises on postural control, functional independence, and freezing of gait (FOG) in patients with mild to moderate Parkinson disease.Methods: Twenty-five community-dwelling participants with idiopathic Parkinson disease were recruited. Of these, 9 participants took part in a water-based program of physical exercises and the other 16 participants took part in a combined program that consisted of callisthenic exercises plus an aquatic exercise session. Both programs were 16 weeks in duration. The clinical evaluation assessed the festination by means of the FOG score test; postural control was verified by means of the balance test of the short physical performance battery, and the Spanish validated version of the Unified Parkinson's Disease Rating Scale part 2 was used to assess functional independence. Participants were evaluated before and after 16 weeks of both proposed programs.Results: The results showed improvement in FOG for both groups, although a significant main effect was observed only in the patients who performed the callisthenic exercise plus an aquatic exercise program. Postural control did not show significant improvements after both proposed physical exercise programs as soon as functional autonomy. Our preliminary results suggest that training sessions with the combination of water plus callisthenic exercises may be a useful physical rehabilitation strategy for individuals with mild to moderate Parkinson disease who have FOG.

Effect of the competition of Cu(II) and Ni(II) on the kinetic and thermodynamic stabilities of Cr(III)-organic ligand complexes using competitive ligand exchange (EDTA)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sperm production of Steidachneridion parahybae (Steindachner 1877) and the effect of hormonal induction throughout one reproductive cycle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of cryoprotectants on the reconstitution of silica nanoparticles produced by sol-gel technology

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effect of simvastatin treatment on bone repair of femoral fracture in animal model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of low-temperature aging on the mechanical behavior of ground Y-TZP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)