Polymer-Infiltrated Ceramic Network for CAD-On to Zirconia Copings and Implants

Objectives: Porcelains and glass-ceramics have been used to produce CAD-milled veneers and crowns for zirconia copings, abutments, and implants—the CAD-On technique. We propose to use CAD-milled resin-based materials onto zirconia. Thus, the bond-strength of a polymer-infiltrated ceramic network (PICN), Vita Enamic, has been tested for CAD-On to zirconia, using two adhesive strategies. Also, two reference CAD-On materials (IPS e.max and Vitablocs Mark II) were tested.
Methods: Traditional 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals) was used to prepare long-beams (3×6×40 mm³). For the three CAD-On materials, short-beams (3×6×15 mm³) were prepared. Adhesive bonding systems were: (1) Panavia 21+Clearfil Ceramic Primer (an MDP-containing cement), or (2) Multilink Automix+Monobond Plus primer. Zirconia and each CAD-On material were bonded in a cross-beam arrangement and subjected to a modified tensile bond-strength test. Half of the samples (n = 10) were tested 5 days after bonding (baseline) and the remaining (n=10) underwent aging (50,000 thermo-cycles at 5°C and 55°C for 30s each), prior to bond-strength testing.
Results: The effects of material, cement, and time on the tensile bond-strength were tested using a three-way-ANOVA. Means and standard deviations are displayed in Table 1. There were no significant differences in the bond strength of the PICN with both cements. E.max+Multilink are the current pair of choice for CAD-On restorations and their bond strength was similar to that of PICN and Mark II. Finally, the long-term retention of the PICN was not statistically different than the two reference materials or baseline values.
Conclusions: Due to the comparable bond strength between all materials, PICN is the favorable choice for CAD-On to zirconia copings and implant-abutments because of its superior resistance to fatigue fracture relative to dental porcelain. Additionally, this material resembles natural dentition, providing occlusal comfort to patients and preventing wear of the antagonist.