Инженеры сократили время обжига керамических коронок с 100 часов до 30 минут

A Dental Crown Bottleneck That Once Took 100 Hours Now Takes Under 30 Minutes in the Lab The reason your permanent crown takes weeks is not that the dentist is slow. It is that somewhere in a laboratory, a printed ceramic cap sits in a furnace, with plastic burned out of it at a deliberately punishing crawl, and that step alone can run for 100 hours. Engineers at the University of Texas at Dallas have compressed it to under 30 minutes. Their method, described in the September 2025 print edition of Ceramics International and announced in October, targets the stage that has kept printed zirconia out of dental offices. The distinction is worth getting right. Same-day crowns already exist. Same-day crowns made of printed zirconia, the material dentistry treats as the standard for permanent work, do not. The Step That Kept Printed Zirconia Out of Dental Offices Printing a zirconia crown produces a composite object, not a ceramic one. Fine zirconia particles are held by a light-cured resin, and that resin must come out before the particles can be fused. That removal is called debinding, and it is a heat process. "Debinding has been the bottleneck in the process," said Majid Minary, professor of mechanical engineering at UT Dallas and corresponding author, in a university announcement. "It must be done very slowly. If you speed it up, the polymer being burned off turns into gas, and if that gas cannot escape, the crown may crack or fracture." Conventional debinding runs 20 to 100 hours. Minary was direct about what that means commercially: such a timeline is not practical for same-day dental service, and, consequently, printed permanent zirconia restorations are not yet on the market. Sintering, the second thermal step that fuses the particles into a solid, follows and requires additional time. Graphite Felt, a Vacuum Pump, and 2,550 Degrees The fix is a thermal protocol rather than a new material. Porous graphite felt, capable of reaching temperatures above 2,550 degrees Fahrenheit, covers the printed restoration and transfers heat directly into it. The felt's porosity is the point. Gas from the burning resin escapes through it rather than building pressure inside the piece, while a vacuum pulls it away. Faster heating plus an escape route removes the reason the process had to be slow. "The combination of all of these features is what makes it work," Minary said. He added that a practitioner could deliver a chairside printed zirconia crown within a few hours. Doctoral student Mahdi Mosadegh is the first author. Collaborators include Pan-AM Dental Laboratory, 3DCeram Sinto Inc., and prosthodontist Amirali Zandinejad. The project has drawn a $550,000 National Science Foundation award to pursue commercialization, with support from the U.S. Air Force Office of Scientific Research. Same-Day Crowns Already Exist, but Not in This Material Chairside milling systems carve a crown from a solid block, and they work. The trade-offs: milling wastes material, limits achievable geometry, and risks micro-cracking during milling or sintering. Same-day printed crowns exist too, but in resin-based ceramics weaker than zirconia. Printing zirconia offers finer feature reproduction and less waste. A small in vitro comparison of 20 crowns in Dentistry Journal found the two comparable on internal fit and marginal adaptation, with printed crowns more precise overall and truer on occlusal and axial surfaces. Milled crowns were truer on the fitting surface that seats against the tooth. Clinical data on printed zirconia is thin. A short-term pilot study followed 15 patients for 24 weeks and reported no deterioration of periodontal tissue, though one tooth was extracted due to a vertical root fracture. Fifteen patients over six months is a starting point, not an evidence base. Clinical Validation and Regulatory Approval Still Sit in the Way UT Dallas has been explicit that the method will require clinical validation and regulatory approval before it reaches the market. Nobody has published patient outcomes for crowns made this way. The debinding advance solves a manufacturing problem and says nothing about how these restorations perform against chewing forces over years. There is also the question of equipment. Chairside printing means a dental office buys a printer, a debinding furnace, and a sintering furnace and trains staff to run them, a different decision from sending a scan to a laboratory. The demand is not in question. Crowns cap damaged or decaying teeth and anchor bridges, and about 1 in 5 adults 75 and older have lost all their natural teeth, according to CDC survey figures. For now, anyone getting a crown should expect a temporary crown and a second appointment, and should discuss materials with their dentist rather than wait for technology that has not yet reached the clinic. Key Questions Answered What is debinding and why does it take so long? It is the heat step that burns out the resin binder in a printed ceramic. It has to be slow because escaping gas can crack the piece, which is why it conventionally runs 20 to 100 hours. How did the researchers speed it up? Porous graphite felt covers the restoration, transfers heat directly, and allows gas to escape, while a vacuum system removes that gas. This cut the step to under 30 minutes. Can my dentist print a zirconia crown today? No. Printed permanent zirconia restorations are not commercially available, and this method still requires clinical validation and regulatory approval. Are same-day crowns already possible? Yes, through chairside milling from a zirconia block or by printing resin-based ceramics. The gap this work targets is specifically in printed zirconia. Is printed zirconia better than milled zirconia? Not straightforwardly. A small in vitro study found comparable fit, with printing truer on some surfaces and milling truer on others. Long-term clinical comparisons are limited. What clinical evidence exists for printed zirconia crowns? Very little. One pilot study followed 15 patients for 24 weeks and reported no periodontal problems; one tooth was extracted due to a root fracture. Published by Medicaldaily.com