Microwave Sintering of Ceramics for Dentistry: Part 2

Each tooth was then placed upon the reticulated zirconia in the thermal containment box and the technique of Microwave Hybrid Heating (MHH) was applied. The temperature measurements were taken every two minutes. We attempted to sinter the teeth in the microwave furnace with both fast and gradual heating rate (per minute) by manipulating the power rate. The power was increased gradually for few samples and for some samples, the power was increased rapidly (rapid bursts). The sintering temperature was 800°C with a hold of one minute. However, one tooth was fired to approximately 700°C with a hold of one minute. Two teeth samples (anterior) were sintered with rapid bursts of power. The cooling temperature profile was recorded every two minutes. Accordingly, the posterior tooth copings were enameled with the layers of the dental glass-ceramic. They were fired with the power-temperature profile that worked well with the anterior teeth copings. Two individual teeth were utilized in each run with the ideal power-profile. The remaining six tooth samples were placed one at a time on the reticulated zirconia in the thermal containment box and fired according to the gradual power-time profile to approximately 800°C with a thermal time histrory as depicted in Figure 1. Once the samples were sintered, they were removed from the furnace, bagged and numbered for further measurements.