What Is The Best Zirconia?
Many disc manufacturers use or claim to use zirconia powder produced by Tosoh of Japan, forget it’s fake or true, let start with a disc manufacturer that uses the best raw products.
The production of the disc now begins with at the minimum, a three-step process:
Step one is a great press and dies. The dies should be perfectly manufactured and polished by the machine shop and the initial Axial Press where they are used should produce at least 30,000psi while creating the step one disc.
Step two in the minimum process is taking the stamped disc and partially sintering the zirconia (generally somewhere around 900-1000 degrees centigrade). This adds rigidity to the material and will aid in its ability to be milled without fracture or chipping.
Step three is packaging and shipping to the end-user.
For many low-cost manufacturers,’ this is the complete process, but you will notice that there is no Isostatic pressing in this production model.
Cold isostatic pressing is a process in which the powder/granulate is pressed uniformly in all directions. The equal compression ratios (hydrostatic) give a highly homogeneous density of the green (not sintered) product in both the axial and radial direction, making the disc the same uniform shrinkage and mechanical resistance throughout the product.
Remember that when we are speaking of shrinkage, we are discussing two separate disc shrinkage opportunities. First is the shrinkage at the time of the pre-sinter done by the manufacturer, and second is the shrinkage at the time of the final sinter after you have milled the part. You can see that an inconsistently dense material, when contained in the structure of a bridge span, may shrink at different rates along the span causing a misfit in your final structure.
A well-manufactured dental zirconia block, dental zirconia disc, dental zirconia blank, zirconia pucks will have a six-step process:
Step One: Start with the Best Zirconia powder
Step two: Great axial press and dies, minimum 30,000psi
Step Three: Cold Isostatic Press of the axial pressed disc
Step Four: Partial Sintering (900-1000C) for stability during milling
Step Five: Milled to exact dimensions for the end-user milling machine to accept
Step Six: Packaged and shipped to end-user
That's the Standard production process of the Vsmile factory, the last suggestion, please don’t be taken in by the pricing alone in your decision to purchase Dental Zirconia products. check out the company and ask the processing questions for a well manufactured Zirconia disc. if they do not know the answers, they may not be the ones to trust.