Effect of full-contour Y-TZP zirconia surface roughness on wear of glass-based ceramics

Indiana University-Purdue University Indianapolis (IUPUI)The use of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), normally employed as a framework for all-ceramic restorations, has now started to be used without any veneering ceramics in patients with parafunctional activities. The aims of this study were to evaluate the influence of Y-TZP surface roughness on the wear behavior (volume/height loss) against glass-based ceramics (i.e., IPS Empress CAD and IPS e.max CAD, Ivoclar-Vivadent). Thirty-two Y-TZP full-contour zirconia (Ardent®) sliders (ϕ=2 mm, 1.5 mm in height) were milled in a CAD/CAM unit and sintered according to the manufacturer instructions. Sliders were embedded in brass holders using acrylic resin and then randomly allocated into 2 groups according to the surface treatment (n=16): G1-as-machined and G2-glazed (Diazir®). Empress and e.max antagonists were cut into tabs (13×13×2 mm) wet-finished and also embedded in brass holders. Two-body pin-on-disc wear testing was performed at 1.2 Hz for 25,000 cycles under a 3-kg load. Non-contact profilometry was used to measure antagonist height (μm) and volume loss (mm3). Qualitative data of the testing surfaces and wear tracks were obtained using SEM. Statistics were performed using one- and two-way ANOVAs (α=0.05). The results indicated that G1 yielded significantly higher mean roughness values (Ra=0.83 μm, Rq=1.09 μm) than G2 (Ra=0.53 μm, Rq=0.78 μm). Regarding antagonist loss, G1 caused significantly less antagonist mean height and volume loss (68.4 μm, 7.6 mm3) for Empress than G2 (84.9 μm, 9.9 mm3) while no significant differences were found for e.max. Moreover, Empress significantly showed lower mean height and volume loss than e.max (p<0.0001). SEM data revealed morphological differences on wear characteristics between the two ceramics against Y-TZP. Within the limitations of this study, e.max wear was not affected by Y-TZP surface roughness. However, Empress wear was greater when opposing glazed Y-TZP. Overall, based on our findings, surface glazing on full-contour Y-TZP did not minimize glass-ceramic antagonist wear when compared with as-machined group

Extension of market exclusivity and its impact on the accessibility to essential medicines, and drug expense in Thailand: Analysis of the effect of TRIPs-Plus proposal

Background In Thailand and the US negotiating FTA, the 'TRIPs-Plus' is one of the US proposal which would result in an extension of market exclusivity of innovative drugs. In addition, it would foreseeably lead to high and unaffordable medicine prices and inaccessibility to essential medicines.Objective To quantify the impact on medicine expense and medicine accessibility.Methods Based on 2000 to 2003 Thai Food and Drug Administration (FDA)'s and the Drug & Medical Supply Information Center (DMSIC), costs and accessibility were estimated upon the price and quantity costing between innovative drugs and their generics plus some parameters found from their competitive behaviour. Thereafter, we simulated the 10-year potential additional expense on the 2003 unit price of the patented and monopolized non-patented medicines.Results In 2003, the availability of generics helped to save 104.5% of actual expense and the accessibility would increase by 53.6%. By extension of market exclusivity, given that there were 60 new items approved annually, the cumulative potential expense was projected to be $US 6.2 million for the first year to$US 5215.8 million in tenth year.Conclusion The TRIPs-Plus proposal would result in a significant increase in the medicine expense; and a delay in the increase in drug accessibility via generics. Several options as well as other related mechanisms to help reduce the negative impact are proposed.TRIPs-Plus Market exclusivity Generic drugs Cost saving Policy Patents as topic Intellectual property