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Screw Retained Crowns - UCLA vs Ti Base

00:00 Introduction Screw retained crowns can either be made with UCLA castable abutments or with titanium bases and in this video I'm going to go over the difference between the two and why we would choose to use one over the other. 00:18 UCLA Abutments Castable UCLA abutments have been used since the 1980s and for years they were the standard method for creating screw retained crowns and bridges. They're made of a gold alloy and work by waxing up the crown directly to the abutment which is then cast in to a compatible metal. This method can be used to make full cast crowns or porcelain to metal crowns. For porcelain to metal crowns, once the substructure has been cast, the porcelain is applied and fired directly to the surface. 00:43 Titanium Base Abutments A titanium base is a stock abutment that can also be used to make screw retained crowns. Unlike UCLA abutments however, it's not possible to cast metal directly to a titanium base. So in order to use one to make a screw retained restoration, the crown must be fabricated separately and then later cemented to the base. 01:01 UCLA Limitation A major limitation to UCLA abutments is the fact that they can only be used for full cast and porcelain to metal crowns whereas titanium bases can be used for all crown types. This means that if you want an e.max or zirconia crown, a titanium base is your only option. 01:16 UCLA Cost Using UCLA abutments tends to be much more expensive than titanium bases as well. The abutment itself is typically more expensive than a titanium base and you'll also be charged for the alloy that the abutment is cast in to. Depending on the current cost of gold and palladium, this can be a fairly substantial fee. 01:33 UCLA is not a precision interface UCLA abutments are more technique sensitive than ti bases and even with our best efforts the interface can be damaged by metal flashing during the casting process and it's also subjected to errant glass microbeads in the porcelain oven. This can result in an increase in micro-motion between the abutment and implant due to a less precise connection. 01:52 Titanium Base Limitations Titanium bases aren't without their limitations as well. Most bases are about 4mm tall which works for many situations, but in cases with limited vertical space these abutments can be too tall to use. With a UCLA abutment our only height limitation is the top of the screw, but with titanium bases, we have to be concerned with the amount of retention between the crown and the base. If the base is less than 3 to 4 mm tall there's a much higher chance that delamination will occur. This makes UCLA abutments the best and sometimes only option for cases with extremely limited space. Another current limitation to titanium bases is that non-engaging variants aren't available for many implant systems. Non-engaging abutments are necessary for making splinted restorations so there are situations where UCLA non-engaging abutments are the only option. This information is true for abutments of virtually every implant system including Nobel Biocare, Straumann, ZimVie, Dentsply Astra, BioHorizons, Blue Sky Bio, Implant Direct, and most others.