The Dirty Secret of 98.5mm Discs
One of the dirty little secrets of 98.5mm zirconia discs is that they really don't offer 98.5mm of working space. The outer indented ring part of the disc is 2.5mm thick, leaving only 93.5mm to work with. However, our Digital Dental discs are true 100mm discs PLUS an outer plastic ring, which not only saves on zirconia costs but improves stability in the mill. And while we sell our 100mm discs for the same price as 98.5mm discs, they typically yield 20% more restorations.
Most 98.5mm zirconia discs actually start out as 100mm discs, and they are then turned on a lathe and reduced to 98.5mm discs with stepped-down 93.5mm working areas. This results in extra processing time and extra work, and the zirconia that is cut away by the lathe is simply discarded, which is why we can offer a 100mm disc for the same price as a smaller 93.5mm disc area.
20% More Restorations per Disc
Using the formula for the area of a circle (A = π r2), a 100mm disc yields 7,854 sq. mm of area compared to 6,866 sq. mm for the 93.5mm working area of a 98.5mm disc. Our trusty area formula proves there is a 14.4% increase in zirconia material in each of our 100mm discs.
But in practice, the results are even better. Due to (1) the average size of a dental restoration, (2) the shrink factor, and (3) the round shape of a disc, our customers are seeing an average of 20% more restorations per disc. This 20% number is based upon aggregated production data from customers who own and compare milling machines that use both 98.5mm and 100mm discs.
Let's look at a sample nesting below. These discs were nested with a conservative nesting approach in groups of 2-3 restorations per group. This is our recommended nesting strategy, and we believe it allows for maximum yield per disc with minimal risk of breakage. Some companies nest tighter, in groups of 4-5 or even more, and some don't do any groupings, but the majority of labs nest conservatively like this.
|100mm Digital Dental Disc||98.5mm Disc|
Using a conservative nesting strategy, the 100mm disc on the left produced four more crowns than the 98.5mm disc, which is a 26.7% improvement. This is just one example, but it illustrates how our customers typically generate 20% more yield out of our discs.
To help better understand how this is possible, let's talk about pizza. If you think of discs as pizzas, and you are laying down pepperoni, you can imagine that depending on the size of the average pepperoni slice, a slightly larger pizza might be able to get a lot more pepperoni on the pizza.
To the right is a nesting image of the 100mm layout on top of a 98.5mm disc. You can see that the small difference in diameter can make a big difference. Now if teeth were about half the size (or maybe all anteriors), and if we didn't have a 25% shrink rate with zirconia, the improvement might be closer to 15% rather than 20% in practice (or even 30% as per the example above).
So, are you ready to try out our 100mm "no waste" discs to see what your improvement will be? Call us at 480.948.0466, and we'll see if we can start increasing your yield today.