3D EVALUATION OF MICROGAPS AT THE IMPLANT-ABUTMENT CONNECTION BEFORE AND AFTER THERMODYNAMIC CYCLING.

PURPOSE: To analyze the microgap changes between hybrid-abutment crowns made of two materials and three internal taper connec9on implants with different connection designs before and after thermodynamic loading. MATERIALS AND METHODS: A total of 30 implants-10 each of Straumann Bone Level Implant-RC (STR); GC AADVA Implant (AAD); and Astra-Tech OsseoSpeed EV (AST)-were included in this laboratory study. Each implant had an internal taper connection, but their designs were slightly different. Five hybrid-abutment crowns were fabricated using a lithium disilicate ceramic (LD), and five were fabricated using polymethylmethacrylate (PMMA) with CAD/CAM technologies for each implant system, providing six sample groups STR-LD, AAD-LD, AST-LD, STR-PMMA, AAD-PMMA, and ASTPMMA. The microgap volume was measured using micro-CT images obtained before and after thermodynamic loading equivalent to 4 months of clinical use. Student t test, one-way ANOVA, and Tukey test were used for comparisons. RESULTS: The greatest microgap volume increase was recorded (3.405% ± 1.567%) in the AST-LD group, and the lowest increase (0.45% ± 0.373%) was in the STR-PMMA group. A statistically significant difference in microgap increase was not detected among PMMA and LD groups: for STR-LD/STR-PMMA (t test: P = .273); for AAD-LD/AAD-PMMA (t test: P = .374); and for AST-LD/AST-PMMA (t test: P = .268). However, the difference in the microgap increase between the different implant systems was statistically significant. CONCLUSIONS: The microgap between hybrid-abutment crowns and implants increased after short-term thermodynamic cycling. Hybrid-abutment crowns with different elastic modulus showed similar microgap increase. The geometric shape of the connection influenced the microgap increase.

Possible Effect of Chelation Treatment on Metabolomic and Lipidomic Analysis in Lead Exposure.

OBJECTIVE: This study aimed to examine patients with lead poisoning in terms of metabolomic profiles and bioactive lipids (oxysterols and sphingosine 1-phosphate [S1P]) before and after chelation therapy. METHODS: Consent was obtained from 42 individuals diagnosed with lead poisoning and blood and urine samples were collected before and after chelation therapy. The levels of 7-ketocholesterol (7-KC), cholestan-3b,5a,6b-triol (Ctriol), and S1P were measured via LC-MS/MS. Metabolomic analysis was performed via GC-MS. RESULTS: 7-KC and C-triol levels were detected higher before chelation therapy compared with after therapy (P < 0.001 for both). S1P levels were measured higher before the therapy. The results also showed that sphingolipid metabolism-related pathways were affected by lead toxicity as well as other related pathways. CONCLUSION: This preliminary study showed that lipid metabolism is affected in lead exposure and chelation therapy is effective in reversing possible damage.

Evaluation of oxysterol levels of patients with silicosis by LC-MS/MS method.

Silicosis is one of the prolonged and irreversible occupational diseases. Crystalline silica dust, which has been linked with silicosis, occurs in different industrial areas such as constructions, ceramic, quarry, and pottery. There are significant numbers of newly diagnosed cases every year in Turkey. Patients with silicosis suffer from inflammatory respiratory disorders and silicosis-related complications such as rheumatoid arthritis, systemic sclerosis, and vasculitis. Oxysterols are defined as 27-carbon intermediates or end products of cholesterol. They are also implicated in the etiology of disease states such as atherosclerosis, neurodegenerative, and inflammatory diseases. The aim of the study is to evaluate cholesterol oxidation products in the patients with silicosis and determination of sphingosine-1-phosphate (S1P) levels which is a sphingolipid metabolite. In addition to these parameters, it is aimed to determine the possible lipid peroxidation by different parameters. For this purpose, blood samples and urine were collected from 47 patients and 30 healthy individual with their consents. In order to evaluate oxysterols, 7-ketocholesterol and cholestan 3ß,5α,6ß-triol levels were measured by LC-MS/MS method. The measured levels of 7-KC were 0.101 ± 0.005 µmol/l in patient and 0.050 ± 0.003 µmol/l in control plasma samples. Triol levels were measured as 0.038 ± 0.005 µmol/l in patient group and 0.033 ± 0.004 µmol/l in control group (p < 0.001). In addition, lipid peroxidation products were measured by human-8-isoprostane, human-4-hydroxynonenal (4-HNE), and human malondialdehyde (MDA) ELISA kits. The measured levels of HNE in the patient and control groups were 735.14 ± 288.80 pg/ml and 595.72 ± 108.62 pg/ml in plasma and 606.02 + 118.23 pg/ml and 531.84 + 107.18 pg/ml in urine, respectively (p < 0.05). F2-iP results of patients and controls were 450.0 + 101.40 pg/dl and 386.9 + 112.7 pg/ml for urine and 432.7 ± 188,8 pg/dl and 321.9 ± 69.4 pg/dl for plasma, respectively (p < 0.05). MDA levels of plasma were measured as 44.1 ± 14.6 nmol/ml in the patient and 31.9 ± 10.5 nmol/ml in the control (p < 0.05). Levels of MDA for urine samples were 30.15 + 5.06 nmol/ml and 25.15 + 6.07 nmol/ml in patients and controls, respectively (p < 0.05). S1P levels were decreased in patients compared to control group (49.05 ± 10.87 and 67.57 ± 16.25, p < 0.001). The results not only indicate a correlation between cholesterol oxidation, lipid peroxidation, and silicosis, but also provide better understanding of the role of the lipids in the mechanism of this inflammatory disease.