ABSTRACT
Statement of the Problem: Marginal fitness is the most important criteria for evaluation of the clinical acceptability of a cast restoration. Marginal gap which is due to cement solubility and plaque retention is potentially detrimental to both tooth and periodontal tissues
Purpose: This in vitro study aimed to evaluate the marginal and internal fit of cobaltchromium [Co-Cr] copings fabricated by two different CAD/CAM systems: [CAD/milling and CAD/ Ceramill Sintron]
Materials and Method: We prepared one machined standard stainless steel master model with following dimensions: 7 mm height, 5mm diameter, 90[degree] shoulder marginal finish line with 1 mm width, 10[degree] convergence angle and anti-rotational surface on the buccal aspect of the die. There were 10 copings produced from hard presintered Co-Cr blocks according to CAD/ Milling technique and ten copings from soft non- presintered Co-Cr blocks according to CAD/ Ceramill Sintron technique. Marginal and internal accuracies of copings were documented by the replica technique. Replicas were examined at ten reference points under a digital microscope [230X]. The Student's ttest was used for statistical analysis. p< 0.001 was considered significant
Results: Statistically significant differences existed between the groups [p< 0.001]. The CAD/milling group [hard copings] had a mean marginal discrepancy [MD] of 104 micro m, axial discrepancy [AD] of 23 micro m and occlusal discrepancy of 130 micro m. For CAD/Ceramill Sintron group, these values were 195 micro m [MD], 46 micro m [AD], and 232 micro m [OD]. Internal total discrepancy [ITD] for the CAD/milling group was 77 micro m, whereas for the CAD/Ceramill Sintron group was 143 micro m
Conclusion: Hard presintered Co-Cr copings had significantly higher marginal and internal accuracies compared to the soft non-presintered copings
ABSTRACT
Statement of the Problem: Cardiovascular disease and osteoporosis are major health dilemmas. Osteoporotic patients frequently display vascular calcification that consequently increases the cardiovascular morbidity and mortality
Purpose: This study aimed to investigate the relation of osteoporosis, vascular calcification [atheroma, intima-media thickness [IMT]] and elongated styloid process [ESP] in a sample of osteoporotic and normal female individuals
Materials and Method: This study recruited 78 women who were assessed for bone mass density [BMD]. Sample included individuals with normal BMD [n=13, 17%], osteopenia [n=36, 46%], and osteoporosis [n=29, 37%]. The presence of atheroma and IMT was examined using color Doppler ultrasonography [CD-US]. In addition, digital panoramic radiographs [PRs] were obtained to assess ESP
Results: In this study, 55 subjects [70%] with low BMD exhibited at least one side ESP. Femoral BMD decreased significantly in subjects with ESP [p= 0.03]. Bilateral ESP was correlated with the presence of atheroma [p= 0.029]. The CIMT was greater in patients with ESP, although the relation was not significant
Conclusion: The obtained data suggest referring the aged individuals with ESP for BMD assessment and individuals with low bone mass and ESP for more cardiovascular risk assessment
ABSTRACT
Statement of the Problem: By introducing the coloring liquids, it is claimed that it is possible to make the color of frameworks fabricated from zirconium oxide extremely close to the natural tooth color.
Purpose: The purpose of this research was to evaluate the effect of two staining techniques on value changing in zirconia crowns.
Materials and Method: Three groups A, B, and C, each containing ten zirconia crowns, were used. The zirconium cores samples were fabricated by a CAD/CAM device. Group A was left uncolored, Groups B was submerged for two minutes in A2 coloring liquid and Group C was stained with brush. Then all cores were sintered and the porcelain was applied by using the layering technique. Ultimately, the crowns color was determined using a spectrophotometer. Their color changing [Delta E] and value changing [Delta L] in relation to A2 color were also assessed. The data were analyzed with one-sample t-test, post-hoc Tukey, and one-way ANOVA tests with significant level set at 0.05
Results: The mean value in all groups was higher than the value obtained from A2 color samples [p= 0.001]. The highest mean value was 78.31 +/- 1.22 belonging to group C [staining with brush] and the lowest mean value was 76.99 +/- 0.65 belonging to group B [submerging]. The results of post-hoc Tukey regarding both Delta E and Delta L variables showed a significant difference between groups A [uncolored] and C [staining with brush] with P Delta E=0.006 and P Delta L=0.039, respectively. A significant difference between group B [submerging technique] and C [staining with brush] were shown when these two variables were compared [P Delta E=0.001, P Delta L=0.015]
Conclusion: Due to the higher value increase in surface staining [brush], it is recommended to use the submerging technique for staining zirconia cores