Dr. K. asks:
I have a recently experienced two posterior Astra implant fractures using 5mm dental implants. One occurred 6 months after final restoration while the other came back after 17 months. My Astra rep told me that he had not seen this happen before. I was told by a colleague that Astra implants are made up of commercially pure titanium, while most other implant systems use an alloy. Could this difference be responsible for the fracture? Would this be a problem for current cases and should I consider for future cases an implant system which uses alloys for their implant composition? I’m interested in better understanding the benefits and risks of pure titanium vs. alloy.
Implant Systems: Commercially Pure Titanium vs. Alloy?
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Iwould stay with pure titanium implants, most alloys contain aluminium and or vanadium (not as biocompatible) and actually have had only 1 fracture in 4500 implants through 15 years…, there are other type of implants that are more strong than the astra, I would say that in 5mm , Endopores are the best choice if you have little height, and for longer 5mm , I would use Alpha Bio if you like internal connection.
best of luck
I have to tell you of my experiences with CP Titanium. They fracture. The Nobel 3.5 is notorious for fracture or at least distortion. Granted, the cam design is also a problem. I have changed to Grade 23 titaninum that is offered by Implant Direct or Grade 5 Titanium by Camlog. I do not see a difference in intergration as was dictated by Branenmark. There are many times that I need to torque the implant down just a little more and I do this with security with an Alloy. Implant Direct makes a Astra clone that is Alloy. Heck its cheaper and they don’t fracture. When they fracture they are hard to remove and you better be able to place a wider implant. Good Luck.
Fixture fracture is a rare occurance and Astra is an extraordinarily reputable company. (I don’t use them, but I wouldn’t doubt anyone who does). You might want to evaluate the occlusion, as I am sure that this is contributing to the fracture. If the patient is not a bruxer and the scheme is great, by a lottery ticket as you have stats on your side
Astra is not commercially pure…and I’m unaware of any manufacturer other than some minis using anything resembling commercially pure. Strength testing on Astra and Straumann have revealed them to be remarkably strong…if you want a reference I have them. In short, your colleague stating Astra is commercially pure titanium is grossly misinformed.
In addition, implant direct makes nothing that is an Astra clone. I don’t know who got the idea they did but I’ve seen there line and they don’t make one. The closest thing to a clone I’ve seen is Osstem’s. Implant direct doesn’t have anything similar-they have an implant with some threads thrown at the top with nothing similar to the implant-abutment interface and a platform shift on an implant with variable amounts away from the bone based on diameter and available components. I think whoever indicated that is misinformed. Please clarify what you think is the same so I can better able you to understand.
I’ve had one 4.5 Astra fixture fracture…and given what transpired in that case I don’t think any system would have held up to the challenge. There are currently studies going out to 10 years on Astra with bone levels noted that do not have any issue with fracture. I don’t think anyone would questions Wennstrom’s study at 5 years…Rasmussen has 10, etc. However if you want a study on fracture resistance..this is what you can find:
J Prosthet Dent. 2000 May;83(5):567-71. Links
In vitro evaluation of the strength of the conical implant-to-abutment joint in two commercially available implant systems.Norton MR.
Bedford Hospital, Bedford, England. nortonimplants@compuserve.com
STATEMENT OF PROBLEM: The cone-screw abutment has been shown to diminish micromovement, reducing the burden of component loosening and fracture. However, it is unclear whether the conical taper and joint design influence strength of the interface, with respect to unfavorable bending moments. PURPOSE: This comparative study evaluated the resistance to bending for the ITI Straumann and Astra Tech ST implant systems using an 8- and 11-degree internal cone, respectively. MATERIAL AND METHODS: Assembled units from each system were mounted in a 3-point bending apparatus. High load tests were performed, 4 mm from the joint, and bending moments necessary to induce first point of plastic deformation and ultimate failure were measured. All units were inspected to determine the critical zone of failure. RESULTS: Bending moments necessary to induce first point of plastic deformation were considered well above that expected in clinical function for both systems. However, the critical zones of failure differed in that the solid Astra abutment deformed before the cone joint with its 11-degree taper and smooth transition into the neck of the screw, preventing screw fracture. By contrast, all ITI screws fractured at the head of the screw where it met the base of the 8-degree cone. It is unclear which aspects of the joint design were responsible for the difference observed in mode of failure or if it was a direct result of the experimental design. CONCLUSION: For clinically relevant levels of bending moment, no problems were anticipated with respect to component failure for either system.
There are more but many are lab studies…bottom line is that there are 3 systems on the market that have 10 years of data with bone level noted and Astra is one of them…if there was a fracture problem I think it would already have shown up. It showed up much sooner than that with the Paragon 3.5 fixtures.
First law of Mechanics: Any solid can deform an ultimately break.
That’s just function of the solid’s design, material and the force applied to it.
So, the material, (CP or Ti Alloy) is only ONE of the parameters of the equation.
Consequently, you need to look at the other parameter also…..
Unfortunately, you look at your problem with a too simplistic approach.
Hope that will help….
In answer to A Bergs comments, it is not the actual Titanium, Aluminum or Vanadium which is biocompatable with bone. Almost all metals will oxidize when exposed to air/water. We are all familiar with a metal nail that rusts (AKA oxidizes). Both C.P.Titanium and 6/4 alloy (6% Aluminum, 4% Vanadium, 90% Titanium) when cut, instantly form a titanium oxide surface. If a Titanium alloy has more than 85% Titanium content, it will form a Titanium Oxide surface layer or veneer that encloses the other metals preventing them from contacting the bone. It is the Titanium Oxide that is biocompatable with bone, not the actual metal.
Both Astra and Nobel Replace Select (w/Tiunite) are CP. Material choice probably driven by surface treatment technique. Trade-off is with internal connections, a weaker material(CP) will have a higher rate of fractures due to thinner walls. Smaller diameters will have greater risk – makes sense to hear of colleauges having issues with these systmes.
Astra implants are Grade IV CP titanium.
It has been very difficult to get an answer regarding the composition of the Nobel implants. I have heard they are CP (no grade specified) titanium and others have said that the TiUnite implants are titanium alloy. The TiUnite I am told, requires titanium alloy for the TiUnite surface to form.
DOES ANYBODY HAVE HARD FACTS AND A REFERENCE ON THE NOBEL COMPOSITION?
“DOES ANYBODY HAVE HARD FACTS AND A REFERENCE ON THE NOBEL COMPOSITION?”
Just go on Nobel’s web site. It clearly states they use CP titanium.
http://www1.nobelbiocare.com/en/implant-solutions/products/nobelactive/technical-facts.aspx
I was just looking at some Straumann and Lifecore Stage-1 implant drawings and the material specified was grade 4 titanium.
Last time…commercially pure when you consider early implants are not the same as grade III or grade IV titanium….there were early implants made of commercially pure titanium that were not the grades they are currently-they fractured. My understanding is that Astra is grade IV and Nobel is grade III. Straumann tissue levels are grade IV. All the “theory” espoused about grade IV titanium is interesting except for the fact that there is already 10 year data documenting that fracture is not an issue on multiple systems using grade IV.
Most implants manufactured in Europe are, in fact, commercially pure titanium. The reason for this phenomena is that the early Branemark research indicated that there was a leaching of ions into biological fluid from alloys and therefore considered a contaminant. The earliest grades (I and II) were too soft and often fractured soon after loading. They were later replaced by work hardened CP (III and IV). Work hardening changes the grain size and orientation to withstand loading forces. The later grades showed significantly greater working strength and virtually all CP implants are of these work hardened grades. The problem occurs with smaller diameter implants. CP, regardless of the grade, still has high ductility. This constant bending moment will weaken thin walled implants, thus leading to the reports listed above. American manufacturers realized early on that titanium alloys would have a higher strength and utilized them from the beginning. The only problem with grade 5 (the earliest alloy) is that it is so stiff that, when there is a small microfracture along a stress line, it cleaves like a crystal. Most implant manufacturers now use an alloy called grade 23 ELI (extra low interstitial) which has a working strength closer to grade 5 and some of the ductility of the original CP implants. This alloy is strong enough in smaller diameters AND the ductility so that there are no self-propogating fracture lines after long term cyclical loading. However, this does not mitigate the fact that, if you under-engineer a case, you may still experience fracture of small diameter implants.
Thank you bseavey for the Nobel link.
Nobel uses Grade IV CP titanium for all its TiUnite implants and Ti6Al4V for standard abutments and screws
Titanium Alloys with aluminum and vanadium are two to tree times stronger than pure titanium. And it does not interfere with ossointegration. I’ve seen some fracture implants, different companies, but never an alloy implant. I even have a similar case than you.
Literature have not enough evidence to tell about local or systemic complications with alloys.
I believe the patients occlusion is probably the cause of the fixture failure.There are failures in immediate placement and a lot of clinicians recognize the bite being a major factor. In the period following an immediate implant placement does one see a fixture failure ?In my cases I always relieve the lateral posterior excursions,and leave light contact in CO.Bite forces are twice the anterior forces and I make sure there is smooth ant guidance.I would be curious to see what the masticatory mm’s EMG, in sleep studies, look like in patients with these fractures.
Bill Pace
Implants in narrow diameters are the weakest and fractures while infrequent do occasionally happen. In the case of Nobel Replace implant in the 3.5 diameter the packaging comes with a insertion torque warning which should not be exceeded due to the weak wall and weak titanium material which can fracture at insertion. In order to create the TiUnite surface, alloy cannot be used as it is too hard. Nobel does however make their HA coated implants out of alloy. So if you are concerned about grade 4 titanium fracturing you can order the HA version and it is somewhat stronger.
HA is coated on the outside of implant, how does that make it stronger ?
I’m speaking purely about the structural strength of the implant body with respect to the HA coating.
If you were considering ordering an HA coated implant that was somehow structually stronger (I fail to see how a coating can make a fixture stronger if the fundamental design is the same), I would consider the downsides. First, there is a week point between the HA coating and the implant surface. There were a lot of coating fractures in the 80′s and early 90′s. Also HA coated implants showed lower BIC after a reasonable integration period. So your “stronger” HA coated implant is less prone to fracture, but more prone to failure. Again, I would check the occusion, deliver a guard and replace the fixtures
CP4 and you’re cool
I spent part of the weekend with a gentleman that has forgotten more about titanium than any of those posting remembers…you’ll have to trust me on this. I used commercially pure incorrectly as I only viewed it as the earlier types that fractured quite easily. Whoever posted that Nobel is type IV is correct…but you have to bear in mind there are also different type IV subtypes. A narrow implant with a type IV alloy is NOT necessarily prone to fracture…but the connection type may predispose it as appears to be the case with one of the most popular systems on the market. I am aware that Straumann did something different with their 3.3 fixture to make it stronger…but there has been no need based on fractures of the 3.5 Astra fixture (screw fractures did occur when it had a 1.4mm screw or if the same lab was used in the lab as was in the mouth), and NeOss which has a pseudo 3.5 fixture has never had a fracture in 7 years and is CPIV. Fixtures smaller than 3.5 generally come with a disclaimer to use them only for lateral incisors and lower anteriors…examples are the 3.0 Xive (3.25 restorative platform), 3.25 external hex (3i micro-mini for example), 3.0 Astra, etc.
Barring extreme circumstances a 3.5 fixture is perfectly safe for most applications with the possible exception of an implant noted to sometimes fracture on insertion…what makes that implant popular is beyond my understanding. However, as noted before opinions notwithstanding 5 and 10 year data speaks more than anything written or voiced.
For narrow diameter implants check out the Thommen SPI system which has a time tested connection on a 3.5 straight and 3.5 tapered implant. 3mm deep internal hex with and external stabilization ring.
I think that should be concerned about the occlussion and the desing of the case instead of the alloy of the implant. I agree with coleagues that mentioned the use of bite guards. Good luck.
Case like this one should be photocopied to get the right answer about the cause of fracture (X-ray, treatment plan). I agree that overloading (wrong occlusion) was the main problem.
To JawGuy:
Just to explain a bit further. I think you missed in my post that the body was alloyed.
Because TiUnite surface cannot be created on alloy, only on softer metal, Nobel alternatively makes alloy implants and uses HA to create a bioactive microtexture. As you know HA is a highly successful and proven surface.
From a manufacturing standpoint, CP and Ti alloy have identical strength requirements to meet ISO specifications. Therefore, one cannot ALWAYS be considered stronger than the other, although alloy does tend to be stronger when considered in quantity.
All implant systems fail… and all had fractures!!! The reason for this don´t depends of the titanium grade IV (most of the actual systems use this material) but other factors as :
1- type of connection implant – abutment
2 – occlusal forces
3 – quality and height of the bone
4- Protocol that doctor use
5- Planninng and prosthetics solution.
Most of manufacturers inform that the failures are between 1,3% and 3,8%.
If one company sale 10 millions implants and other only 1 million probabily the first one has more fractures cases than the other !!!
In this case we are talking in one of the 5 biggest in world which are :
Nobelbiocare
Straunmann (ITI )
3 i BIOMET
DENTSPLY FRIADENT
and
ASTRA
Good luck
I believe that the initial extra torque creates the average higher
stress around which the future variable tension induced from lateral
bending will have to …adapt,
LIKE with COMET PRESSURISATION,
so,
ONLY A controlled process ,
BUT MY QUESTION IS different,
Have a 21,22,23 temporary plastics and ,
12 broke,
Going for symmetry,
SOLUTION 21FIXED,22 FREE,23FIXED ,ALL EXISTANT,
6 MONTHS OF PLEASURE,
monday,repeating, 11 root canal fix, 13 same, 12(broken)…extraction,
finally ,one peace, SYMMETRY,
21,23,11,13 SUPPORTS
22.12 FREE
HOW CAN AT AGE 62 PLUS can make a case for IMPLANT????
Thanks,with gratitude,for an opinion,
Sergiu
Dear EO,
Just wanted to update you. The 5 largest companies worldwide are Nobel Biocare, Straumenn, 3i, zimmer, Osstem. Astra and dentsply are no where top sellers worldwide.
I had 3 Astra implants fractures.
All these implants had 3.5 diameter
Statistically that’s a data lower than 1% of all fixtures inserted.
These implants were abutments of 3 units fixed ceramic bridges. No parafuctions, no overloading.
The problem linked to Astra implant of 3.5 diameter is that implant thickness, at connection abutment-implant, is narrow and, indipendently by titanium’s features, this is a weak point of the system.
In the past Astra had bigger problems about implant 3,5 diam fractures, Then they changed 3.5 structure, doing it thicker, (small threads in the coronal aprt of the implnat) and problems become smaller.
However, especially when you have bridge with cantilever or with tilted implant, the risk of Astra 3.5 implant fracture is higher, so that is better using 4.5 diam.
KAT (Key Assisted Transfer) 3.5mm implant is a two-piece implant that has the strength of a one-piece implant. It is made from Ti6Al4V ELI and was tested by an independent lab to withstand 425 N of force over 5 million cycles (FDA approved protocol). NobelActive 4.3 can withstand 355 N, NobelActive 3.5 – 222 N. Design of Astra 3.5mm implant is very similar, so the strength should also be in the low 200 N range. KAT 3.5mm implants are recommended for replacement of all posterior teeth. Sales in US start in January of 2010.