In vitro precision of fit of computer-aided design and computer-aided manufacturing titanium and zirconium dioxide bars

OBJECTIVES Optical scanners combined with computer-aided design and computer-aided manufacturing (CAD/CAM) technology provide high accuracy in the fabrication of titanium (TIT) and zirconium dioxide (ZrO) bars. The aim of this study was to compare the precision of fit of CAD/CAM TIT bars produced with a photogrammetric and a laser scanner. METHODS Twenty rigid CAD/CAM bars were fabricated on one single edentulous master cast with 6 implants in the positions of the second premolars, canines and central incisors. A photogrammetric scanner (P) provided digitized data for TIT-P (n=5) while a laser scanner (L) was used for TIT-L (n=5). The control groups consisted of soldered gold bars (gold, n=5) and ZrO-P with similar bar design. Median vertical distance between implant and bar platforms from non-tightened implants (one-screw test) was calculated from mesial, buccal and distal scanning electron microscope measurements. RESULTS Vertical microgaps were not significantly different between TIT-P (median 16μm; 95% CI 10-27μm) and TIT-L (25μm; 13-32μm). Gold (49μm; 12-69μm) had higher values than TIT-P (p=0.001) and TIT-L (p=0.008), while ZrO-P (35μm; 17-55μm) exhibited higher values than TIT-P (p=0.023). Misfit values increased in all groups from implant position 23 (3 units) to 15 (10 units), while in gold and TIT-P values decreased from implant 11 toward the most distal implant 15. SIGNIFICANCE CAD/CAM titanium bars showed high precision of fit using photogrammetric and laser scanners. In comparison, the misfit of ZrO bars (CAM/CAM, photogrammetric scanner) and soldered gold bars was statistically higher but values were clinically acceptable.

The Road to Bali: ERIA Perspectives on the WTO Ministerial and Asian Integration

The World Trade Organization’s (WTO) forthcoming Ninth Ministerial Conference in Bali comes at a critical juncture for the multilateral trade body, long mired in the Doha Round stalemate. Beyond offering a critical first test at consensus-building and institutional renewal, the Bali Ministerial affords a unique opportunity to gauge contrasting perceptions across ASEAN and East Asian countries of the continued relevance of the WTO to trade and economic governance within the region and beyond. Resulting from the collaborative efforts of the Economic Research Institute for ASEAN and East Asia (ERIA), the Universitas Pelita Harapan (UPH) and the World Trade Institute at the University of Bern (WTI), this policy research initiative offers comparative scholarship on some of the key questions arising from the forthcoming WTO Ministerial gathering from an East Asian perspective. Specifically, it explores what scholars in the region expect the Bali Ministerial to produce by way of tangible outcomes and whether the Ministerial will restore the momentum needed to bring the Doha Round to a successful conclusion. Contributors also investigate how relevant the WTO remains to the multiple processes of deepening economic integration in ASEAN and East Asia (e.g. AEC, TPP, RCEP) and, importantly, what lessons in rule-design and market opening WTO Members could usefully draw from the ongoing march towards the establishment of an ASEAN Economic Community.