Hi, I am from India and in Indian Labs they follow the procedure outlined below. What is the correct way? This question is for a Prosthodontist. I have spoken to numerous labs and have been informed that when they make a crown they apply a spacer only upto the two third of the vertical surface and leave the rest one third of the area without spacer. This is also done when they do digital crowns such as MLS. When they do the designing they mark the spacer only upto the one third. Why is this so? The labs themselves dont know why, they say thats how they have been doing all these years. Why would you leave the area without spacer, where will the cement lie then? If the crown is touching the tooth at the margins without cement in between then the imperfect seal will lead to secondary caries way faster than any possible event with cement dissolution taking place. I thought that maybe it is to do with casting shrinkage and that this absence of spacer was done to compensate for it, though I dont really know for sure - this was just a thought that occurred to me. And if this is so then where is the need to follow this technique of applying spacer where we are doing digital 3D printed crowns and there is no casting being done? I am attaching two pictures - the one on the left shows what labs are doing currently, the one on the right shows how I think the spacer should be applied. Somebody please explain. Thanks.
Posted on: Sat, 29 Nov 2014 13:03:24 +0000