Ceramic Base Crown Near-net-shape Using Gel-casting Technique

Objective: The aim of this research is to investigate the application of gel-casting technique for dental ceramic core to get near-net-shape forming and to obtain a precious base of dental ceramic crown with no shape changing after sintering. Materials and Methods: Applying the reformative gel-casting technique to build green body of core. The primal ceramic powder used in this experiment has an average particle size of 1µm commercial high-purity a-Al2O3 powder, an average particle size of 30 nanometer 3Y-TPZ powder. MgO and TiO2 were used as its sintering aids. For gel-casting, acrylamide (AM) was used as the monomer, N,N-methylenebisacrylamide (MBAM) as a coupling agent, N,N,N,N-tetramethylethylenediamine(TEMED) as a catalyst, ammonium persulphate as an initiator and SD-07 as a dispersant. Strong ammonia and strong hydrochloric acid were used for adjusting the slurry PH. Using this material a 60vol% slurry was formed. The slurry was then in vacuum ball-milled for 10 hours to promote dispersibility and homogeneity. After milling, the slurry was brushed on the teeth models to prepare the core. Results: The dental ceramic green body would have the high strength of 20-30MPa by applying the reformative gel-casting technology and can easily to be shaped and reconstruct. When the sintering temperature is below 1150°C, the ceramic shrinkage is low than 0.4%. It can nearly reach the near-net-shape forming. Conclusion: With high solid content, gel-casting technology can be applied for easily building green body in dental ceramic base crown. And it can also reach the near-net-shape forming after been sintered. Further research is required that if green body can reach the near-net shape forming when it is sintered completely by altering the materials ingredients proportion.