Adin Implants: Morse Taper Cold Weld?

No, you won't have the hex advantage, because you are using non-hexed abutments for a screw retained bridge.

Not sure what the deal is on bacterial ingrowth with an abutment since it won't decay and bacteria are always present in the mouth everywhere. The two materials are not exact so I don't think they will expand to form a weld the same way. Perhaps you should see what the manufacturer says. I do however think you should use screw retention to avoid the cement issue, that way the prosthesis is retrievable. Is there a compatible hex in the Zirconium?

There are many differing taper values over and above the "Morse" Taper, but a combination of taper and force and intimate surface contact of compatible metais required for the "cold weld" seal. Usually a 1-2 degree taper is required for rigid fixation on such a short device as a dental implant to bring about a true bacterial seal and significant mechanical resistance to rotational torque. As such, I'd not rely on those properties for an 8 degree taper. That said, it's certain that a porcelain will not "cold weld" to a metal, so you need to find a hex abutment compatible with your implant. A ceramic, properly designed to match your implant, may work fine, but would not include the "cold weld" function. John

[comment on the bacterial growth post from CRS] Yes, bacteria are always present in the mouth, but just like an endodontic problem, if those bacteria can grow where macrophages cannot reach (about 2mm), and be nourished by fluids from the mouth/body, then they will persist in producing toxins that can destroy bone and tissue. Ideally, we should create a hermetic (air-water-tight) seal at the abutment/implant platform interface. A morse taper not only helps to create this seal, but can mechanically stabilize the abutment/implant connection against micro-movement.

A morse taper "cold weld" is only between like materials. It is essentially a cohesive bone between the metals. CRS, the metals do not expand to form the locking mechanism it's a friction fit of precisely machined same material components (an actual engineering concept converted to dentistry). Also, CRS, bacteria percolating at the abutment implant interface (commonly known as the microgap) can lead to bone loss. Yes, there's bacteria in the mouth but we would prefer not to have it pumping in and out of our microgap. A morse taper does not create a microgap and minimizes micromovement between the abutment and implant to decrease fluid movement and stabilize the abutment. So by all means use an implant with a morse taper but know that it doesn't truly work with Zirconium.

When you say Morse you mean taper connection. These taper connection were invented for an easy and cheap way for replacing machining cutting tools, such as twist drill bits. For every material (metal) there is a specific taper. For example for Titanium the taper is 1.5 degree for steel it is approximately 1.2 degree. A very important condition for a proper function of the tapered connection is to have both cones, inner and outer made of the same material. It can be metal, ceramics or resin. If your abutment is made of any thing else but titanium most probably you are loosing the molecular effect of the tapered connection. Having said that you may consider go with cement retained C&B. Of course you don't want to have issue with the cement in the peri-implant area. The solution is to Use G-Cuff for cementation.

As far as Morse taper is concerned there are interesting studies out of berne that show abutments rocking under load with a series of "morse tapered2 connections. Its the tolerance of the milling and preciscion of fit between the two components - also all testing is done at room temperature not body temp and it does affect the quality fo fit. Astra make a big deal abouth their connection but its reported to have 7 micron level freedom of fit (or slackness) according to a german study. Bacteria around the implant abutment interface combined with rocking will cause crestal bone loss even in platform switched set ups.

A couple of misunderstandings in the previous blogs: First, all of the internal tapered abutment connections are classified as "cone-fit". However, the Morse taper is specific to engineering in that it represents an 8 degree taper. If it is less than 8 degrees, it is not Morse. So, all Morse tapered connections are cone- fit, but not all cone-fit connections are Morse taper. Second, the only real advantage of cone-fit is the resistance to screw loosening. The torque value needed to unscrew a cone-fit abutment is greater than the seating torque. This indicates that a cold-weld has occurred. Third, if one compares the difference of microleakage values between cone-fit systems, there is a significant difference between abutments that are malleted into place and those that are screwed into place. The malleted abutments wedge into postion, but the screw-in abutments signifcantly score the inside of the implant interface, actually creating a mismatch between the components. If you look at an SEM of a removed screw type cone-fit abutment, you would readily identify this problem. The net result is that there is a larger reservoir for bacterial colonization in these abutments than normal internal attachments. This was proven in an NYU study from a few years ago showing that Ankylos had a 500% worse microleakage than the 3 other implants in the study. In fact, one of the authors subsequently asked that the Ankylos statistics be removed from the study and it was published without them. Last, percolation of fluids requires abutment movement. The worst offenders (assuming all are internal connections) are the flat-to flat abutments (i.e. Nobel Replace Select). This type of abutment has the greatest liftoff from the implant interface in shear loading. The opening and closing of this type of connection has a HUGE plunging effect and tansfer of bioburden. This is why we see the greatest amount of bone loss in this type of architecture. Cone-fit attachments show far less plunging (hence, far less bone less). But the best type of implant abutment for reduction of microleakage (as per the literature) is a Ferrule attachment. This a combination of cone-fit and outside shoulder connection. This "inside/outside" attachment is demonstrably more stable and exhibits the least amount of microleakage (translating into the least amount of crestal bone loss after loading). RJM

Could you name the systems offering combination type connection.

Morse Taper is ~ 1.5 degrees . There are three companies that I'm aware of that have a Morse taper connection. Those are Bicon, Quantum and Kat. Any other company stating they have a Morse Taper Connection are actually only a conical connection. It's easy to distinguish: Morse Tapers are self engaging and don't need any form of engagement, only friction. Conical Connections need threads to retain the abutment on the implant. Taper Name Large Taper/ Taper/ Angle Small Length End Foot Inch From End Center ----------------------------------------------------------------------- #0 Morse 0.3561 .6246 .0521 1.4908 0.2520 2.00 #1 Morse 0.4750 .5986 .0499 1.4287 0.3690 2.13 #2 Morse 0.7000 .5994 .0500 1.4307 0.5720 2.56 #3 Morse 0.9380 .6024 .0502 1.4377 0.7780 3.19 #4 Morse 1.2310 .6233 .0519 1.4876 1.0200 4.06 #4-1/2 Morse 1.5000 .6240 .0520 1.4894 1.2660 4.50 #5 Morse 1.7480 .6315 .0526 1.5073 1.4750 5.19 #6 Morse 2.4940 .6257 .0521 1.4933 2.1160 7.25 #7 Morse 3.2700 .6240 .0520 1.4894 2.7500 10.00 ----------------------------------------------------------------------- #1 Brown & Sharpe 0.2392 .5020 .0418 1.1983 0.2000 0.94 #2 Brown & Sharpe 0.2997 .5020 .0418 1.1983 0.2500 1.19 #3 Brown & Sharpe 0.3753 .5020 .0418 1.1983 0.3125 1.50 #4 Brown & Sharpe 0.4207 .5024 .0419 1.1992 0.3500 1.69 #5 Brown & Sharpe 0.5388 .5016 .0418 1.1973 0.4500 2.13 #6 Brown & Sharpe 0.5996 .5033 .0419 1.2013 0.5000 2.38 #7 Brown & Sharpe 0.7201 .5015 .0418 1.1970 0.6000 2.88 #8 Brown & Sharpe 0.8987 .5010 .0418 1.1959 0.7500 3.56 #9 Brown & Sharpe 1.0775 .5009 .0417 1.1955 0.9001 4.25 #10 Brown & Sharpe 1.2597 .5161 .0430 1.2320 1.0447 5.00 #11 Brown & Sharpe 1.4978 .5010 .0418 1.1959 1.2500 5.94 #12 Brown & Sharpe 1.7968 .4997 .0416 1.1928 1.5001 7.13 #13 Brown & Sharpe 2.0731 .5002 .0417 1.1940 1.7501 7.75 #14 Brown & Sharpe 2.3438 .5000 .0417 1.1935 2.0000 8.25 #15 Brown & Sharpe 2.6146 .5000 .0417 1.1935 2.2500 8.75 #16 Brown & Sharpe 2.8854 .5000 .0417 1.1935 2.5000 9.25 #17 Brown & Sharpe 3.1563 .5000 .0417 1.1935 2.7500 9.75 #18 Brown & Sharpe 3.4271 .5000 .0417 1.1935 3.0000 10.25 ----------------------------------------------------------------------- #2 Jarno 0.2500 .6000 .0500 1.4321 0.2000 1.00 #3 Jarno 0.3750 .6000 .0500 1.4321 0.3000 1.50 #4 Jarno 0.5000 .6000 .0500 1.4321 0.4000 2.00 #5 Jarno 0.6250 .6000 .0500 1.4321 0.5000 2.50 #6 Jarno 0.7500 .6000 .0500 1.4321 0.6000 3.00 #7 Jarno 0.8750 .6000 .0500 1.4321 0.7000 3.50 #8 Jarno 1.0000 .6000 .0500 1.4321 0.8000 4.00 #9 Jarno 1.1250 .6000 .0500 1.4321 0.9000 4.50 #10 Jarno 1.2500 .6000 .0500 1.4321 1.0000 5.00 #11 Jarno 1.3750 .6000 .0500 1.4321 1.1000 5.50 #12 Jarno 1.5000 .6000 .0500 1.4321 1.2000 6.00 #13 Jarno 1.6250 .6000 .0500 1.4321 1.3000 6.50 #14 Jarno 1.7500 .6000 .0500 1.4321 1.4000 7.00 #15 Jarno 1.8750 .6000 .0500 1.4321 1.5000 7.50 #16 Jarno 2.0000 .6000 .0500 1.4321 1.6000 8.00 #17 Jarno 2.1250 .6000 .0500 1.4321 1.7000 8.50 #18 Jarno 2.2500 .6000 .0500 1.4321 1.8000 9.00 #19 Jarno 2.3750 .6000 .0500 1.4321 1.9000 9.50 #20 Jarno 2.5000 .6000 .0500 1.4321 2.0000 10.00 ----------------------------------------------------------------------- #0 Jacobs 0.2500 .5915 .0493 1.4117 0.2284 0.44 #1 Jacobs 0.3840 .9251 .0771 2.2074 0.3334 0.66 #2 Jacobs 0.5590 .9786 .0816 2.3350 0.4876 0.88 #2 Short Jacobs 0.5488 .9786 .0816 2.3350 0.4876 0.75 #3 Jacobs 0.8110 .6390 .0532 1.5251 0.7461 1.22 #4 Jacobs 1.1240 .6289 .0524 1.5009 1.0372 1.66 #5 Jacobs 1.4130 .6201 .0517 1.4801 1.3161 1.88 #6 Jacobs 0.6760 .6229 .0519 1.4868 0.6241 1.00 #33 Jacobs 0.6240 .7619 .0635 1.8184 0.5605 1.00

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