RESUMO
The purpose of this study was to analyze the biomechanical properties of implants made of different materials to replace missing teeth by using three-dimensional finite element analysis and provide a theoretic basis for clinical application. CBCT data was imported into the Mimics and 3-Matic to construct the three-dimensional finite element model of a missing tooth restored by an implant. Then, the model was imported into the Marc Mentat. Based on the variations of the implant materials (titanium, titanium-zirconia, zirconia and poly (ether-ether-ketone) (PEEK)) and bone densities (high and low), a total of eight models were created. An axial load of 150 N was applied to the crown of the implant to simulate the actual occlusal situation. Both the maximum values of stresses in the cortical bone and implant were observed in the Zr-low model. The maximum displacements of the implants were also within the normal range except for the PEEK models. The cancellous bone strains were mainly distributed in the apical area of the implant, and the maximum value (3225 µstrain) was found in PEEK-low model. Under the premise of the same implant material, the relevant data from various indices in low-density bone models were larger than that in high-density bone models. From the biomechanical point of view, zirconia, titanium and titanium-zirconia were all acceptable implant materials for replacing missing teeth and possessed excellent mechanical properties, while the application of PEEK material needs to be further optimized and modified.
RESUMO
Hepatoblastoma (HB) is the most prevalent primary hepatic cancer in children aged 6 months to 3 years. LIN28A is recurrently mutated in various diseases, and critically involved in tumorigenesis. However, a limited number of studies have examined the involvement of LIN28A polymorphisms in HB risk. We used the TaqMan assay to genotype four LIN28A polymorphisms (rs3811464 G>A, rs3811463 T>C, rs34787247 G>A, and rs11247957 G>A) in 275 Chinese children with HB and 1018 cancer-free controls from five medical centers in China. Their association with HB risk was evaluated on the basis of odds ratio (OR) and corresponding 95% confidence interval (CI). Overall, no significant associations were found in single locus and combine analysis. Interestingly, in the stratified analysis, we found that subjects with 1-3 risk genotypes were more likely to develop HB in patients ≥17 months of age (adjusted OR=1.76, 95% CI=1.04-2.98, P=0.034). The rs3811464 GA/AA genotypes were associated with decrease HB risk in patients with clinical stage III+IV disease (adjusted OR=0.50, 95% CI=0.26-0.96, P=0.038). Our results suggest that the LIN28A polymorphisms have a weak association with HB susceptibility in the Chinese children. LIN28A rs3811464 G>A may decrease HB risk in stage III+IV patients which need further validations with larger samples and different ethnicities.
RESUMO
Hepatoblastoma is one of the malignant liver tumors in children. However, genetic mechanisms underpinning the initiation of hepatoblastoma remain largely unclear. The previous study showed that lin-28 homolog B (LIN28B) might play a role in the development of hepatoblastoma. To detect the association between LIN28B gene polymorphisms and hepatoblastoma risk in Chinese children, we conducted a five-center case-control study of 275 hepatoblastoma patients and 1018 cancer-free controls. Four potentially functional polymorphisms were genotyped using the Taqman method. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of the associations. We found that the rs314276 C>A polymorphism (AA vs. CC: adjusted OR=2.05, 95% CI=1.36-3.10, P=0.0006; AA vs. CA/CC: adjusted OR=2.11, 95% CI=1.43-3.12, P=0.0002) and rs9404590 T>G (GG vs. TT: adjusted OR=1.89, 95% CI=1.20-3.00, P=0.007; GG vs. TT/TG: adjusted OR=1.87, 95% CI=1.20-2.92, P=0.006) were associated with increased hepatoblastoma risk. Combination analysis of risk genotypes showed that patients with four risk genotypes had a higher chance of developing hepatoblastoma than carriers of 1 to 3 risk genotypes. Stratification analysis showed the significant association between the rs314276 AA genotype and hepatoblastoma risk in both age and sex groups, as well as clinical stages III+IV cases. The rs9404590 GG genotype was associated with hepatoblastoma risk in participants' ≥17 months, in females, and for those with clinical stages III+IV disease. Furthermore, four risk genotypes confer higher hepatoblastoma susceptibility in both age and sex groups, as well as groups with clinical stages III+IV disease. Genotype-based gene expression analysis confirmed that the rs9404590 T>G polymorphism was significantly associated with altered LIN28B gene expression. We further validated our findings using false-positive probability analysis. This finding suggested that LIN28B gene polymorphisms may be associated with an increased predisposition to hepatoblastoma.
