Screw Retained Crowns - UCLA vs Ti Base
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- čas přidán 16. 07. 2024
- 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. - Věda a technologie
Your videos are amazingly helpful...thank you
great content,learned a lot for sure!
Glad it was helpful!
you have the best dental lab videos on youtube
Thank you so much!
Very helpful video. Thank you!
Glad it was helpful!
good work, great content, thank you.
Thank you!
0:18 Castable abutment (UCLA)
0:43 Titanium base (Ti base)
1:01 Comparison
Great sir,more information is needed on full arch implant prosthodontics
Thank you, we'll look in to making some of those!
Thanks a lot for the info
You're welcome!
Great video Alex, many thanks. Can you do a video on custom abutments, in terms of their materials and method of fabrication ? 👍🏽
Great suggestion!
Hey Alex! Awesome content! Question though: any major considerations or differences between these two as far as impression techniques?
Other than some very specific situations, the impression technique wouldn't typically be a determining factor when choosing the type of abutment.
Great breakdown! IMO, Atlantis Custom Abutments are the best option in most cases.
Atlantis makes quality abutments for sure, and we agree that a custom abutments is almost always superior to stock.
Superb
Thank you so much!
Great video. I had a query regrading a case planned for hybrid denture. I have a patient who is planned for a hybrid denture on Nobel implants. Five implants have been placed. For a hybrid denture, can I use the gold adapt non-engaging abutments or do I have to go for multi-unit abutments only?
Yes, you can use gold adapt non-engaging abutments for a hybrid but these days many labs would prefer to do a CAD titanium substructure instead of a cast metal substructure for hybrid dentures.
Excellent
Thank you so much 😀
Terrific video. Thank you. When using Tibase (variobase from Straumann), I always ask the lab to return the crown uncemented so I can check the fit. The crown always returns with slight rocking or twisting. Any solution you can think of please?
There are a few things that can contribute to that, with the main one being the design of the variobase. It's just a short cylinder with four small antirotation nodes. Those nodes do not extend the entire vertical length of the abutment so they have undercuts to them. Those undercuts have to be blocked out, either by software or with wax by hand. Depending on how well the block out is done; the pressed, milled, or cast restoration may not immediately fit. The technician must then adjust the inside of the crown so that it will seat on the abutment. This can make it so that the crown have some movement. There are also some parameters within dental design software that can affect how loose or tight the fit is. You will typically get a much more intimate fit when using a well designed custom abutment as opposed to a variobase.
@@OBrienDentalLab thank you very much for the prompt response
Can you have a custom abutment for screw-retained crown? Sounds like we only use Ti-base abutment (which is a stock abutment) nowadays and custom abutments are not used for screw-retained crown.. please clarify
Yes, it is possible to use either a custom abutment or a titanium base when making screw retained crowns. We generally prefer to use custom abutments for our screw retained crowns as they give us more control over sub-gingival contours, abutment height, and material thickness.
Alex, why can't you use zirconia or emax with the UCLA abutment? thanks!
For a UCLA abutment to be used to make a traditional screw retained crown, metal must be cast directly to the UCLA abutment. It is not possible to cast zirconia or lithium disilicate (emax). You may find this video helpful: czcams.com/video/GN26lncu2ZY/video.html
Hello Sir.
Does Tibase gives us a better emergence profile and do they come in different gingival height?
The Ti bases have a fixed emergence profile, so there's just less control. In some situations you may find that the diameter of the Ti base is too large, especially when the implant is significantly subcrestal. As far as the gingival height, it depends on the company. Some systems only come with one height and others come with multiple heights.
I wish to understand the difference between regular abutments vs ti- base
In your experience, how well do titanium abutments hold up to full cast gold crowns. My dental treatments are done at the Palo Alto VA hospital dental office.
Thank you
We find that they work great!
@@OBrienDentalLab
I was called and asked to change my zirconia implant premolar # 29 from zirconia to full cast noble gold because it to and risk of fracture # 30 will remain full cast gold as I requested. What questions can I ask my Dentist about screw retained implants that may help prevent fractures.
Grrrr
Ti base has to be upside down
😂😂😂😂
Dr.waldemarson DMD PhD