Efficacy and safety of a novel bioabsorbable polymer-coated, everolimus-eluting coronary stent: the EVOLVE II Randomized Trial.

BACKGROUND Drug eluting stents with durable polymers may be associated with hypersensitivity, delayed healing, and incomplete endothelialization, which may contribute to late/very late stent thrombosis and the need for prolonged dual antiplatelet therapy. Bioabsorbable polymers may facilitate stent healing, thus enhancing clinical safety. The SYNERGY stent is a thin-strut, platinum chromium metal alloy platform with an ultrathin bioabsorbable Poly(D,L-lactide-co-glycolide) abluminal everolimus-eluting polymer. We performed a multicenter, randomized controlled trial for regulatory approval to determine noninferiority of the SYNERGY stent to the durable polymer PROMUS Element Plus everolimus-eluting stent. METHODS AND RESULTS Patients (n=1684) scheduled to undergo percutaneous coronary intervention for non-ST-segment-elevation acute coronary syndrome or stable coronary artery disease were randomized to receive either the SYNERGY stent or the PROMUS Element Plus stent. The primary end point of 12-month target lesion failure was observed in 6.7% of SYNERGY and 6.5% PROMUS Element Plus treated subjects by intention-to-treat (P=0.83 for difference; P=0.0005 for noninferiority), and 6.4% in both the groups by per-protocol analysis (P=0.0003 for noninferiority). Clinically indicated revascularization of the target lesion or definite/probable stent thrombosis were observed in 2.6% versus 1.7% (P=0.21) and 0.4% versus 0.6% (P=0.50) of SYNERGY versus PROMUS Element Plus-treated subjects, respectively. CONCLUSIONS In this randomized trial, the SYNERGY bioabsorbable polymer everolimus-eluting stent was noninferior to the PROMUS Element Plus everolimus-eluting stent with respect to 1-year target lesion failure. These data support the relative safety and efficacy of SYNERGY in a broad range of patients undergoing percutaneous coronary intervention. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01665053.

In vitro fracture strength and thermal shock resistance of metal-ceramic crowns with cast and machined AuTi frameworks

STATEMENT OF PROBLEM: AuTi alloys with 1.6% to 1.7% (wt%) Ti provide sufficient bond strength to veneering ceramics, but the strength of entire metal-ceramic restorations fabricated from these alloys is not known. However, this information is important to assess the clinical performance of such materials. PURPOSE: This in vitro study evaluated the fracture strength and thermal shock resistance of metal-ceramic crowns with AuTi frameworks produced by milling or casting. MATERIAL AND METHODS: Frameworks of the alloy Au-1.7Ti-0.1Ir (wt%) (Esteticor Vision) were produced by milling or casting (test groups). A high-gold alloy (Esteticor Special) was used as the control. The frameworks were veneered with ceramic (VMK 95). Specimens (n=7) were loaded until fracture. Loads at failure (N) were recorded and the mean values statistically evaluated using 1-way analysis of variance and a post hoc Dunnett test (alpha=.05). To assess the crazing resistance of the veneering ceramic, 6 additional crowns of each group were subjected to a thermal shock test. Fractured surfaces were documented by scanning electron microscopy. Coefficients of thermal expansion of the materials used were measured (n=2) to assess the thermal compatibility between alloys and ceramic. RESULTS: The mean fracture strength of the crowns with machined AuTi frameworks (1294 +/- 236 N) was significantly lower (P=.012) than that of the cast AuTi frameworks (1680 +/- 150 N), but statistically not different than the high-gold alloy (1449 +/- 159 N). Bonding failure to the AuTi alloy predominantly occurred at the alloy-oxide interface. For the high-gold alloy, more ceramic residues were observed. In the thermal shock test, crowns with milled AuTi frameworks showed significantly higher thermal shock resistance compared to the other groups. The coefficients of thermal expansion (Esteticor Vision cast: 14.5 microm/m.K; Esteticor Vision milled: 14.3 microm/m.K; Esteticor Special cast: 13.7 microm/m.K) did not correlate with the results of the thermal shock test. CONCLUSION: The in vitro fracture strength of crowns with milled AuTi frameworks is lower than that obtained with cast AuTi frameworks, but comparable to those crowns produced with a high-gold alloy.

Ceramic bonding to a machined Au-Ti alloy

Objective: To assess in vitro the bond strength of a machined surface of a Au-Ti alloy to a veneering ceramic. Method and Materials: Metal strips of the alloy Au 1.7-Ti 0.1-Ir were milled from a semiproduct fabricated by continuous casting and cold forming. For comparison, the same alloy as well as a traditional Au-Pt-Pd-In alloy were used in the as-cast state. Six samples of each group were fabricated for the crack initiation test, according to ISO 9693:1999, by preparing appropriate metal strips that were veneered with ceramic using a standard firing procedure. The crack initiation test was performed in a universal testing machine. Load at fracture was recorded. Means of bond strength were calculated for each group and the results compared by use of a 1-sided Student t test (P < .05). Fracture sites were documented by means of SEM. Results: Bond strength in the 3 groups was in the same order of magnitude. Failure mode was different for both alloys. Failure of the bonding to the Au-Ti alloy predominantly occurred at the alloy-oxide interface, no matter which fabrication process was used. On the Au-Pt-Pd-In alloy, more ceramic residues were observed. Conclusion: The machined alloy Au 1.7-Ti 0.1-Ir provides sufficient bond strength to veneering ceramics, but this has to be proven by a clinical study. (Quintessence Int 2007;38:867-872).