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Junction of Abutment and Implant Fixture: Potential Source of Infection?

posted in Restoration of Dental Implants, Abutments, Dental Implant Systems, en

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Dr. B. asks:
The literature seems to support the view that the junction of the abutment and implant fixture is a potential source of infection and inflammation that produces die-back of 1.5-2.0mm. When the abutment undergoes micro-movement under occlusal loading, bacteria enter the microgap with the implant. If this can be prevented, bone loss should be minimized. Which implant systems have the smallest microgaps between the abutment and implant? Which implant systems allow the least micro-movement of the abutment? Or does this even matter in the long run? How can this problem be overcome, if it truly is a problem?

16 Responses to “ Junction of Abutment and Implant Fixture: Potential Source of Infection? ”

• Wleed Haq April 7th, 2009

  
  

  The microgap or absence of it is critical for long term maintenance of crestal bone levels. Ankylos, Astra and Bicon all have good implant/abutment connections with good long term follow up results.

• Peter Fairbairn April 7th, 2009

  
  

  The main issue here is level of placement if subcrestal then microgap could be an issue thus these systems need a good seal but on crestal or supra-crestal not an issue and micromovement can ” Break ” stress thus leading to less bone loss as a result of possibly the most important area occlusal force. Tom Driskell invented the morse taper to address this issue as he designed his implants to be placed sub crestally.

• Dr.Amit Narang April 7th, 2009

  
  

  Sub crestal or supra crestal if there is substantial microgap then it will add to space for colonisation of bacteria, hence bicon, astra, ankylos have a great advantage, also if one piece is best in this regard because of absence of a connection.

• dr.A.Romano med: med. dent: italy April 7th, 2009

  
  

  I never understood why the three or two pieces implants are used commonly while we can use the one piece implants that are more economic, much easier to use withougt pain for the patient, quasi ready to load and finally and totally free of microgap infection.

• ghasab Ngan April 7th, 2009

  
  

  The only way to avoid this is to have no micro movement. The only implant with 22 yrs+ clinical data and use is Ankylos by Dentsply. If you are not using this Implant system, you are experiencing bone loss. It is a given!
  Why do they have no bone loss? No micro gap = 100% bacteria proof!

  In my many years, I have never seen results like this for tissue and bone response. AWESOME!

• Dr Dwayne Karateew April 7th, 2009

  
  

  In the spirit of full disclosure, i receive and honorarium from TDS and am therefore one of their advocates. however, i am responding as one professional to another. the issue of microgap and micromovement is becoming more understood with respect to its proposed roll in the ‘dieback’ which is traditionally seen on many implant systems. there are in fact a series of “Industrial Micro CT” movies made by Weigel at the University of Frankfurt which clearly show a gap opening between the abutment and implant shoulder under forces approximating occlusal load in many different systems. implant connections which employ a true Morse taper (Ankylos) do not demonstrate this micromovement and microgap formation and thus cannot be colonized by bacteria. this means that the implant can be placed subcrestally, maintain bone above the shoulder of the implant (with no dieback) and this inturn can support the gingival soft tissue and promote papillae which leads to optimal esthetics with a minimal of clinical manipulation. the gingival and peri-implant tissue are maintained in a much healthier state with this system. this is supported with published lit and clinical cases.

• Dr Sengupta April 7th, 2009

  
  

  I have a sightly different understanding of this
  First modern machining techniques minimise the microgap to almost nothing.
  i do not beleive that in a modern approved implant that the microgap is an issue to the extent being discussed above

  Die back of the bone to tpically the first thread has been a phenomenon observed in EVERY system including the one piece implants in the first year .Whether one system has a greater resistance to another has never been conclusively shown in any documented study I have ever seen.
  Further if this bone loss is due to bacteria from microgap…the bugs dont disappear after one year when it stabilises and reduces to 0.1mm each succesive year??
  Remember that the microgap with a cover screw presents a similar situation
  Like many of you I have had bone grow right over the cover screw during healing using traditional placement for 2 stage techniques.
  That blows the microgap-causing- bone-loss- theory away…. to my mind

  1-1.5mm bone loss to the first thread over a certain period of time has had the following postulations
  1) Raising a full thickness flap thus stripping blood supply from crucial crestal ridge area..yet we see bone loss around implants which have had cookie-cut tissue punch placements
  2)Engineering principles absolutely dictate that there are stress concentrations around the neck of the implant ..under load.this could very conceivably)cause this bone loss
  However the periodondists argue that bone loss must have a bacterial component
  3) lack of proper biological seal around the transmucosal component of implant
  An implant prosthesis has 10% of collagen fibres within the transmucosal seal
  4) modulus of elasticity of bone to implant is greater than bone to tooth creating a greater stress contour
  otherwise known as composit beam analysis
  this contour is xactly in line with where the bone loss occours …but why then does it stop?

  As in most things I believe that the answer lies in a little of everything
  We need to be cognizant of the multiple factors and not be too caught up with marketing hype of any one system

• Dr.Amit Narang April 8th, 2009

  
  

  with due respect to comments from previous surgeon, i would like to add that micro-movement of cover screw cannot be compared with that of an abutment because cover screw is never ever subjected to any vertical/lateral biting forces, which are the actual cause of micro-movement in the abutment

• NJHamp April 8th, 2009

  
  

  Dr. Sengupta:

  I do understand your argument however you are forgetting a key variable…each and every individual has the ability to fight infections differently…toxicity load is what we have come to call it. After the prosthesis is put into place and is loaded then over time bone loss can and WILL occur if you don’t have a 100% seal at the IAJ…even Ankylos has this problem over time. Ankylos just does a better job in minimizing the micromovement…so does Astra, PerioSeal…the fact is it depends on the patient. The small amount of bone loss in the beginning is mainly to a full flap (this is something I 100% agree with)…also it can be from over drilling. We can go on and on about this, but the fact remains is the dental community is still split on deciding what is the truth. For us to ignore the obviously truth of bacterial reponses around implants is the same as stating bacteria is no longer a problem around teeth.

  Bacteria has no preference on where they like to colonize…titaium, on teeth, or on instruments! Why do we sterilze our tools? Turning the other check is what the true problem of today is…no one wants to work together anymore because they think they will lose business if they help another doctor out….

  Now with that said…the local response is not the real problem…systemic response is the TRUE problem! There is a connection and the question is it a true X factor…NO…but it still assists in lowering the body’s defenses.

  this is very contreversial subject and does need more attention to gain more research!

• Erik Lennartsson April 9th, 2009

  
  

  This is another “hot topic”. This week I have had three patients on checkup and all of them have had their implants/prostheses in place for OVER 20 years. The patients had 6 machined Branemark implants in their lower jaw. None of the patients had lost ANY bone during this period! Amazing?

  There are many studies comparing the machined Branemark and for example Atra fixtures. Two years after the bridge connection the two brands has exactly the same bone hight around the implants. I´m not saying that platform shift isn´t the the answere but biology takes time and we won´t have any real answeres for many, many years.

  Let´s not jump to conclusions to fast!

  Very Best / Erik, Stockholm

• Dr Sengupta April 15th, 2009

  
  

  I think it is fair to say that we have seen excellent bone levels where we may not expect and poor bone levels where we do not expect
  To my mind this clearly points to a multi-factorial cause for this bone loss
  The factors being
  a)Overload with poor biomechanics
  b) Microgap presence (apparently better with a mesial or platform shift)
  c)Aggresive flap surgery
  d) Composit beam theory
  e) Immediate placement
  f) Immediate load

  No individual or company can tell me their system stops this phenomenon
  When you have been in this feild for a while you have seen problems and successes with the most unexpected situations.
  It is incumbent on us to be aware of these different cases and studies without jumping to conclusions and worst of all giving in to marketing hype.

• Peter Fairbairn April 15th, 2009

  
  

  Well said Dr Sengupta , and then there are all the patient factors , such as smoking etc and even patient physiology varies, thus unless a study is a RCT the variables can be to many to allow a positive conclusion.

• Dr. K. F. Chow April 15th, 2009

  
  

  All things being equal, i.e. no major systemic problem and local conditions are healthy…a morse taper connection ensures that there is no microgap between the fixture and the abutment and therefore no toxic pump as a result of colonisation of the gap together with function. Fact is the 2 pieces behave like one piece….basic engineering principle. Thus in makes like Astra, Bicon, Ankylos and others like some Korean Implants, the Morse taper connections cum platform shifting(if its Morse taper, it automatically translates into a platform shift), there is little or no bone resorption in the majority of cases. In fact often it can be seen that the bone grows right onto the “gap”!

  There are 2 critical margins:- one is the abutment-fixture margin and the other is the abutment-crown margin which is also a major problem in that excess cement from this margin often remains in the gum-implant interface and can cause resorption of the bone as well as inflammation of the gums.

  The abutment-fixture connection problem,I feel has been largely addressed successfully by the Morse taper solution. The crown-abutment margin with its excess cement or microgap if screw-retained is still quite an enigmatic problem that is yet to be addressed as successfully. I call it the “critical margin” in oral implantology.

  Cheers!

• Dr. Dr. April 20th, 2009

  
  

  Strauman Bone Level has 0,6u +-0,3u

• anon April 24th, 2009

  
  

  ankylos: morse taperconnection..subcrestal placement…platform shift… …no movement …no microgap…no infection..no bone loss…

• Dentist Richmond Hill October 29th, 2009

  
  

  The microgap causing bacterial entry and subsequent bone loss is just a theory that has yet to be proven. More likely, the 1-1.5mm bone loss is due to raising a full thickness flap thus stripping blood supply from crestal ridge.

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