Zirconia ceramics is a primary material for state-of-the-art dental industry. Its primary benefits are superior strength (x5 better than porcelain), durability, biocompatibility, natural color and translucency to match a natural teeth. However, as any other ceramics, ZrO2 discs are prone to invisible cracking which lead to dentures breakage during milling or initial wear. RUV technology is adapted to 100% accuracy of cracks inspection in ZrO2 dental discs before disc processing in a dental lab.
Through a resonance frequency curve selected from a broad range (20 - 250kHz) the Multi-angle Vibration (MAV) method enables screen out materials with hidden invisible cracks. A crack introduced into ceramics alters the MAV peak parameters: amplitude, bandwidth and peak position. The inspection approach is illustrated in Figure. Specifically, the crack in a dental ZrO2 disc measured at different angles in the rotation mode shows the following MAV feature: large individual peak variation between three scans (right plot) compared to high coincidence for a good sample (left plot). Therefore, the MAV approach is based on a fast measurement and analyses (below 5 seconds per scan) of a specific resonance peak and automatic part rejection if peak characteristics deviate from the normal non-cracked samples.