Two-body wear behavior of human enamel versus monolithic zirconia, lithium disilicate, ceramometal and composite resin

PURPOSE: To investigate and compare the surface roughness (SR), weight and height of monolithic zirconia (MZ), ceramometal (CM), lithium disilicate glass ceramic (LD), composite resin (CR), and their antagonistic human teeth enamel. MATERIALS AND METHODS: 32 disc shaped specimens for the four test materials (n=8) and 32 premolars were prepared and randomly divided. SR, weight and height of the materials and the antagonist enamel were recorded before and after subjecting the specimens to 240,000 wear-cycles (49 N/0.8 Hz/5℃/50℃). SR, height, weight, and digital microscopic qualitative evaluation were measured. RESULTS: CM (0.23 + 0.08 µm) and LD (0.68 + 0.16 µm) exhibited the least and highest mean difference in the SR, respectively. ANOVA revealed significance (P=.001) between the materials for the SR. Paired T-Test showed significance (P < .05) for the pre- and post-SR for all the materials. For the antagonistic enamel, no significance (P=.987) was found between the groups. However, the pre- and post-SR values of all the enamel groups were significant (P < .05). Wear cycles had significant effect on enamel weight loss against all the materials (P < .05). CR and MZ showed the lowest and highest height loss of 0.14 mm and 0.46 mm, respectively. CONCLUSION: MZ and CM are more resistant to SR against the enamel than LD and CR. Enamel worn against test materials showed similar SR. Significant variations in SR values for the tested materials (MZ, LD, CM, and CR) against the enamel were found. Wear simulation significantly affected the enamel weight loss against all the materials, and enamel antagonist against MZ and CM showed more height loss.

MRI enhancement as a predicator of uterine fibroid volume reduction after embolism

Aim of the Study: To evaluate the response of necrotic fibroids to UAE and to identify whether pre-UAE enhancement or other factors are predictors of fibroid shrinkage

Materials and methods: This is a retrospective review of all women who underwent UAE for symptomatic fibroids from January 2013 till July 2017, who experienced a follow-up MRI 5-6 months after UAE were included. There were 54 fibroids [37 non-enhancing and 17 enhancing] among 24 women with a mean age of 56 [range 40-59] years. All fibroids were assessed for size, position, enhancement on subtraction images, and Apparent Diffusion Constant [ADC]

Results: Enhancing fibroids had an average decrease in diameter by 23 +/- 6%, not significantly different compared to that non-enhancing fibroids which decreased by 19 +/- 3% [p=0.491]. Multiple linear regression with percent change in fibroid diameter as the dependent variable and patient age, fibroid position, and preUAE fibroid diameter, enhancement, and ADC as independent variables, showed that ADC [p<0.005] and pre-UAE diameter [p<0.005] were the only significant independent variables

Conclusion: Pre-UAE size and ADC, but not contrast enhancement, predicted fibroid diameter reduction. Enhancing and non-enhancing fibroids had similar size reduction after UAE. Non-enhancement should not be considered a contraindication to UAE