Effects of various polishing techniques and thermal cycling on the surface roughness and color change of polymer-based CAD/CAM materials.

PURPOSE: To investigate and compare the effects of several polishing systems and thermal cycling on the surface roughness and color change of various polymer-based CAD/CAM materials. METHODS: Bar-shaped specimens (GC CeraSmart, CS; Lava Ultimate, LU and Vita Enamic, VE) were prepared. All specimens were polished with SiC papers. The specimens in Group A served as control and no additional surface polishing was applied. Final polishing was performed using diamond polishing paste (Diapolisher Paste) in Group B. In Group C, aluminum oxide abrasive discs (Sof-Lex XT Pop on) were used. Group D was polished with diamond impregnated spiral polishing system (EVE Diacomp Plus Twist). In Group E, polishing was done with rubber-based silicon abrasives (Polydentia). Thereafter, the specimens were submitted to thermal cycling. The surface roughness and color measurements were performed. Kruskal-Wallis and the Mann-Whitney U tests were applied for the evaluation of ΔE00 data. Ra data were evaluated using three-way ANOVA. Pearson's correlation between Ra and ΔE00 was further investigated. RESULTS: Neither the CAD/CAM materials nor thermal cycling affected the Ra data (P> 0.05). In contrast, significant difference was found among the polishing methods (P< 0.001). On the other hand, VE showed the highest color change whereas LU showed the lowest (P< 0.05). Additionally, the specimens in Group D exhibited significantly higher color change than other tested groups (P< 0.05). A moderate positive correlation was seen between Ra and ΔE00 data of LU (rho = 0.390, P= 0.01). CLINICAL SIGNIFICANCE: The diamond impregnated two-stage polishing procedure may not be an appropriate method for the tested CAD/CAM materials, as it resulted in the highest color change. On the other hand, all tested materials exhibited visually perceptible, but clinically acceptable color changes following the different polishing techniques. Additionally, diamond paste polishing could be a clinically acceptable procedure in terms of surface roughness.

A comparison of hair and serum trace elements in patients with Alzheimer disease and healthy participants.

BACKGROUND/AIM: To determine whether there was a difference between serum and hair trace elements' concentrations in patients with Alzheimer disease (AD) and healthy participants. MATERIALS AND METHODS: Hair and serum copper, selenium, zinc, magnesium, manganese, and iron levels were measured by inductively coupled plasma-mass spectrometry in patients with AD and healthy participants, and the obtained results were statistically compared. RESULTS: The mean hair selenium and zinc levels of patients with AD were significantly lower than the levels found for control participants (P < 0.05). Patients with AD had significantly higher mean hair copper and manganese levels than the controls. There were no significant differences between AD patients and controls with respect to the hair iron and magnesium levels (P > 0.05). Hair and serum trace element (copper, selenium, zinc, magnesium, manganese, and iron) levels in patients with AD showed no significant difference according to mini mental test scores or sex (P > 0.05). CONCLUSION: Some trace element levels may change in patients with AD. Due to the more permanent status, the analysis of these element levels in hair might be superior to blood analysis.

Potential genetic biomarkers in the early diagnosis of Alzheimer disease: APOE and BIN1.

BACKGROUND/AIM: Alzheimer disease (AD) is triggered by interactions of multiple genetic and environmental factors. The APOE gene E4 allele is the best-known risk factor for AD, yet it represents a small ratio of genetic factors. According to genome-wide association studies, the BIN1 gene is the second important risk factor for AD, following the APOE gene. We aimed to identify a novel biomarker indicating susceptibility to AD by investigating APOE alleles and BIN1 gene polymorphisms in a Turkish population. MATERIALS AND METHODS: Fifty-three AD patients and 56 controls were included to examine polymorphism and allele frequency of the APOE and BIN1 genes. Genomic DNAs were isolated from whole blood by SDS/proteinase K treatment, phenol-chloroform extraction, and ethanol precipitation. RFLP was done for identification of polymorphisms in the APOE gene and allele-specific PCR was used for the BIN1 gene. RESULTS: Frequency of the APOE E4 allele was higher in the AD patient group, while the frequency of the E2 allele was higher in controls. The E4/E4 genotype was detected in the AD patient group, while this genotype was not observed in the controls. The frequencies of BIN1 alleles were similar in both groups. CONCLUSION: There was a strong association between AD and the APOE E4 allele, while no such relation was observed with BIN1 gene polymorphism.

Possible effects of rosuvastatin on noise-induced oxidative stress in rat brain.

The problem of noise has recently gained more attention as it has become an integral part of our daily lives. However, its influence has yet to be fully elucidated. Other than being an unpleasant stimulus, noise may cause health disorders through annoyance and stress, including oxidative stress. Rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, may possess antioxidant properties. Based on rat models, our project investigates the effect of rosuvastatin on noise-induced oxidative stress in the brain tissue. Thirty-two male Wistar albino rats were used. The rats were divided into four groups: Noise exposure plus rosuvastatin usage, only noise exposure, only rosuvastatin usage, and control. After the data had been collected, oxidant and antioxidant parameters were analyzed in the cerebral cortex, brain stem, and cerebellum. Results indicated that superoxide dismutase values were significantly decreased in the cerebral cortex, while malondialdehyde values in the brainstem and cerebellum were significantly increased in the group with only noise exposure. Superoxide dismutase values in the brainstem were significantly increased, but nitric oxide values in the cerebellum and brainstem and malondialdehyde values in the cerebellum and cerebral cortex were significantly decreased in the group where only rosuvastatin was used. During noise exposure, the use of rosuvastatin caused significantly increased superoxide dismutase values in the cerebral cortex and brainstem, but significantly reduced malondialdehyde values in the brain stem. Consequently, our data show that brain tissue was affected by oxidative stress due to continued exposure to noise. This noise-induced stress decreases with rosuvastatin therapy.