Nilgün Akgül

The effects of amalgam restorations on plasma mercury levels and total antioxidant activity

OBJECTIVE This study evaluated the effects of amalgam restorations on plasma mercury levels and total antioxidant activities (TAA). DESIGN The study was comprised of 48 subjects ranging in age from 20 to 32 years. Of these, 33 had dental amalgam restorations and 15 had no dental amalgam restorations. In those patients with amalgams, the total number of amalgam restorations and surfaces were counted, and the total and occlusal areas (mm(2)) of restorations were measured using a Counting Measurement Machine. Blood samples were collected from all participants. Plasma mercury levels were measured using an Atomic Absorption Spectrometer and Hydride System, and plasma TAA levels were measured using an Antioxidant Assay Kit. Statistical analysis was performed using the SPSS 10.01 software program. Data was evaluated by t test and correlation analysis. RESULTS Plasma mercury (P-Hg) levels were found to be significantly higher in subjects with amalgam restorations when compared to subjects without amalgams (p<0.01); the differences in P-TAA levels between subjects with and without amalgams were not found to be statistically significant (p>0.05). No significant correlations were found between P-Hg concentrations and P-TAA levels (p>0.05). Significant positive correlations were found between P-Hg concentrations and the number of amalgam restorations (p<0.01), number of amalgam surfaces (p<0.05), total amalgam surface area (p<0.05) and amalgam occlusal surface area (p<0.01). However, no significant correlations were found between these parameters and P-TAA (p>0.05). CONCLUSIONS The results of our study showed that dental amalgams are a major source of plasma mercury; however, amalgam restorations were not found to have a significant effect on plasma-total antioxidant activities.

The Effect of Surface Treatments on the Bond Strength Between CAD/CAM Blocks and Composite Resin.

PURPOSE The aim of this study was to evaluate the microtensile bond strength of three computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three surface treatment techniques. METHODS AND MATERIALS Three different CAD/CAM blocks were used in this study: (1) Lithium disilicate, (2) feldspar ceramic, and (3) resin nano ceramic. All groups were further divided into four subgroups according to surface treatment: control, roughened with bur (B); roughened with bur and 5% Hydrofluoric acid (HF); roughened with bur and sandblasting (HF); and roughened with bur and CoJet (C). After surface treatments on each group, a silane and bonding agent were applied, and ceramics were repaired with a nano-hybrid composite. Then, the repaired ceramics were cut with a low-speed diamond saw for microtensile bond testing. Microtensile bond tests for 40 specimens per subgroup were carried out with a universal testing machine. The data were analyzed with ANOVA, Tukeys, and LSD at the 95% significance level. RESULTS Mean bond strengths (MPa) of subgroups B, HF, S, and C were: 0, 29.8, 0, 23.3 for lithium disilicate ceramic; 26.4, 22.3, 22.4, 22 for feldspar ceramic; 54.8, 25.3, 42.1, 25.7 for resin nano ceramic. For subgroups B and S of lithium disilicate ceramics, bonding failed during specimen preparation. No significant differences were observed among all CoJet groups. In subgroups B and S, resin nano ceramics showed the highest bond strength. In feldspar groups, subgroup B showed higher bond strength than the other subgroups. CONCLUSION This study demonstrates that lithium disilicate porcelain blocks required etching for repairing with composite material. Surface treatments did not increase the bond strength in feldspar ceramic groups and reduced the bond strength in resin nano ceramic groups.

Inhalation of mercury vapor can cause the toxic effects on rat kidney

Dental amalgam has been used in dentistry as a filling material. The filler comprises mercury (Hg). It is considered one of the most important and widespread environmental pollutants, which poses a serious potential threat for the humans and animals. However, mercury deposition affects the nervous, cardiovascular, pulmonary, gastrointestinal, and especially renal systems. In most animals’ species and humans, the kidney is one of the main sites of deposition of mercury and target organ for its toxicity. In this study, the effects of mercury intake on kidney in rats were searched. For the this purpose; we used 24 adult female Wistar albino rats (200 g in weight) obtained from Experimental Research and Application Center of Atatürk University with ethical approval. Besides, they were placed into a specially designed glass cage. Along this experiment for 45 days, subjects were exposed to (1 mg/m3/day) mercury vapor. However, no application was used for the control subjects. At the end of the experiment, kidney samples were obtained from all subjects and processed for routine light microscopic level and stereological aspect were assessed. Finally, according to our results, mercury affects the histological features of the kidney. That means, the severe effects of mercury has been shown using stereological approach, which is one of the ideal quantitative methods in the current literature. In this study, it was detected that chronic exposure to mercury vapor may lead to renal damage and diseases in an experimental rat model.

Evaluation of enamel pearls by cone-beam computed tomography (CBCT).

Objective: The aim of this study was to evaluate the frequency of enamel pearls according to population, sex and tooth groups on Cone-Beam Computed Tomography (CBCT) or Dental Volumetric Tomography (DVT) scans of patients, retrospectively. Study Design: In this study, 15185 teeth belonging to 768 patients, 430 female and 338 male, was performed cross-sectional examination by CBCT. The volumetric Computed Tomography used in the study is Newton FP based on flat-panel. The data were analyzed with Pearson chi-squared test. Results: Enamel pearls were detected in 36 subjects (4.69%). Of these enamel pearls, 19 were detected in male and 17 were in male. There was no statistically a significant association between prevalence of enamel pearls and sex. All of enamel pearls were detected in molar teeth, for prevalence 0.83%. Conclusion: All of enamel pearls are found upper and lower molar teeth, especially the most commonly in maxillary second and third molars. Key words: Enamel pearls, ectopic mineralization, radiography, CBCT, DVT.

Effect of mercury vapor inhalation on rat ovary: Stereology and histopathology.

Mercury, an environmental contaminant, is a risk factor for health in whole living organisms. In this study, we investigated whether mercury vapor (HgO) inhalation has an effect on rat ovary.

A stereological and histopathological study of the effects of exposure of male rat testes to mercury vapor

Mercury is ubiquitous in the environment; it is an occupational pollutant and a potential toxicant. We investigated the effects of exposure of rat testes to mercury vapor (Hg0). Twelve male rats were divided into two groups of six: the rats of the Hg0 group were exposed to mercury (1 mg/m3/day) in a chamber for six weeks; the control group rats were housed under the same conditions without exposure to Hg0. After the experimental period, the testes were removed, sections of testis were evaluated histopathologically after hematoxylin and eosin staining, and stereologically using the Cavalieri principle and optical fractionator methods. We found significant decreases in the total volume of testis, diameters of seminiferous tubules and total volume of seminiferous tubules. Significant decreases were detected in the numbers of Sertoli cells, spermatogonia, spermatocytes and spermatids of the Hg0 group compared to the control group. In the Hg0 exposed group, spermatogenic cells were degenerated and seminiferous tubules were atrophied.

HPLC ANALYSIS OF ELUTED MONOMERS FROM DENTAL COMPOSITE USING DIFFERENT IMMERSION MEDIA

Numerous factors may play a role in the monomer release of dental materials. The aim of this study is to measure the release of monomers from commercially available hybrid composite resin Tetric Ceram (Ivoclar Vivadent AG, Schaan, Liechtenstein) in the following time schedule, 1 hr, 24 hr, 7 d, and 30 d after the polymerization and observation of the effects of different immersion media on released monomers. Twelve specimen discs were prepared using hybrid composite resin for each analyte in three media [ethanol/water solution (75:25, v/v), distilled water, artificial saliva]. The High Performance Liquid Chromatography (HPLC) method was used for the analysis of released monomers from the hybrid composite resin. All monomers were released in ethanol/water solution with higher efficiency than the other two media, and the highest amount of release was obtained from BisGMA (p < 0.001). Ethanol/water solution which is suggested to simulate the environment of the mouth is the most effective media for monomer release from composite resins.

The association between the DMFS index and levels of salivary Streptococcus mutans and lactobacilli of subjects living in Erzurum, Turkey

Background/purpose The objective of this study was to examine the association between the DMFS (the mean of decayed, missing, and filled permanent surfaces) index and levels of salivary Streptococcus mutans and lactobacilli of subjects living in Erzurum, Turkey. Materials and methods The study was carried out on 133 subjects (62 females and 71 males) aged 20–50 years. To determine the DMFS values of subjects, oral examinations were done and S. mutans and lactobacilli levels were determined using a CRT bacteria kit (Ivoclar Vivadent AG, Schaan, Liechtenstein). Results The prevalence of females with a level of S. mutans of 3 10 5 colony-forming units (CFU)/mL was 69%, while that of males was 65%. However, the prevalence of females with a level of lactobacilli of ≥ 10 5 CFU/mL was 95%, while that in males was 90%. It was determined that the levels of S. mutans and lactobacilli were not dependent on sex (P > 0.05). The average DMFS values of subjects whose S. mutans and lactobacillus levels were ≥ 10 5 CFU/mL were 19.58 ± 18.21 and 19.68 ± 17.30, respectively. Also, the average DMFS values of subjects whose S. mutans and lacto-bacillus levels were 5 CFU/mL were 18.02 ± 14.18 and 11.50 ± 9.30, respectively. No statistically significant differences between the DMFS mean values and S. mutans or lactobacillus levels were found (P > 0.05). Conclusion The present study showed that high S. mutans and lactobacillus levels in the saliva did not by themselves influence the DMFS index.

A histopathological and stereological study of liver damage in female rats caused by mercury vapor

Abstract We examined the possible effects of elemental mercury vapor on the liver of the female rats. We divided the animals into an untreated control group and an experimental group that was exposed to mercury vapor for 45 days. Liver samples were obtained for histological and stereological analysis. The total liver, parenchyma and sinusoid volumes were increased significantly in the mercury vapor treated group compared to controls. Also, the mean density, total number and mean nuclear diameter of hepatocytes, except for binucleated hepatocytes, was decreased in the experimental group compared to controls. Light and electron microscopy revealed alterations of liver structure of the experimental animals compared to controls.

Comparison of the translucency of two multishaded composite resins polymerized with direct or indirect method

Abstract The aim of this study was to measure the translucency of one indirect and direct resin composite after polymerization and to examine the effect of color parameters on this property. Tescera and Filtek Ultimate, each containing three shade groups (Enamel, Dentin and Body for Filtek Ultimate; and Incisal, Opaceous Dentin and Body for Tescera), were investigated. The translucency parameter (TP) was measured as the color difference between a specimen over a white and black background. Significant differences were observed in TP values between shade groups. Tukey’s multiple comparison test revealed TP values among the groups of Filtek Ultimate-Enamel > Tescera-Incisal > Filtek Ultimate-Body > Tescera-Body = Filtek Ultimate-Dentin > Tescera-Opaceous Dentin. In conclusion, it is concluded that the translucency of resin composite was affected by polymerization and color parameters.