OCT-based beneath-the-surface investigations in ceramics sintering: modeling for the most relevant characteristic parameter

We present a investigations of dental ceramics using in-house developed swept source (SS) optical coherence tomography (OCT) systems. The issue is related to the loss of calibration of ovens utilized for the fabrication of dental crowns. In the first study http://dx.doi.org/10.3390/app7060552, metal-ceramics crowns were manufactured, in five study groups, with five maximum sintering temperatures: a normal one, two lower levels and two upper levels (up to +50ºC with regard to normal). OCT B- and C-scans were obtained, and qualitative rules-of-thumb were extracted to assess the oven temperature level by observing ceramic grains bellow the level of the tooth-shaped crowns. The second study https://doi.org/10.3390/ma12060947 moved to a quantitative assessment of the calibration loss of the ovens. A second type of material (for all-ceramic crowns) was considered, and three levels of its specific temperature were tested. For both ceramics reflectivity curves were obtained from OCT C-scans. These analyses demonstrated that there is (only) one parameter consistent with the shift of the maximum temperature in the oven: the ratio of the maximum and minimum (filtered) reflectivity.