Incomplete Implant Seating: Why Would This Happen?

Last Updated: May 17, 2010

Dr. B asks:
During placement of implants today, 18 and 19 positions, Nobel tapered Groovy implants, I ran into a perplexing situation.
Osteotomies prepared for a 5.0 x 13 fixture.
# 19 went to place with approx 40ncm torque, implant fixture is level with crestal bone.
# 18 went to approx 3mm of desired position ( 2mm was above tissue) and then the amount of torque required to turn implant decreased to approx 25 ncm ( it was at 35 previously) and implant would not seat any further.

I then removed the 5.0x 13 fixture and replaced with a 5.0 x 10mm fixture and placed it below the crestal bone by approx 1mm.

I have not had this happen to me in the 4 years I have been placing implants. Any thoughts on what happened? I am thinking that I bottomed out the implant in the osteotomy ( ie osteotomy was not deep enough). Any thoughts on what happened and how I treated the situation?

10 Comments on Incomplete Implant Seating: Why Would This Happen?

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Dr.Serge

05/18/2010

Your osteotomy wasn't deep enough. so your implant couldn't do a self drilling and lost part of its torque. i would have deepen the osteotomy and placed back my implant.

sb oral surgeon

05/18/2010

All you had to do was back out the implant, re-drill, tap if possible, and replace. There was no need to place a shorter fixture. Consider a parallel walled fixture, especially in dense mandibular bone. You won't have this problem.

David Anson

05/18/2010

If it is self-tapping, sometimes you just need to back it out one half to one turn to clear the bone, then torque it back to place.

dr howard marshall

05/18/2010

Most likely the osteotomy was not deep enough. This has happened to all of us one time or another.

RSB

05/19/2010

Two reasons, one there were some debris in the osteotomy site. the site should be flushed before placing the implant. Secondly the last drill u used could have been of shorter length & was kept in 13mm slot in the kit by mistake. This has happened to me in the begining. But as u said u r already 4 yrs. old into implantology, chances of doing such a mistake are less. Lastly i agree with previous comments on not changing the implant size but redoing the osteotomy & placing a 13mm.

Joshua Shieh

05/19/2010

*The comments given by the gentlemen above hold true about the insufficient osteotomy preparation. *This most often occurs in flapless procedures. *When one does not clinically appreciate the thickness of the overlying soft tissue, the initial pilot osteotomy preparation my be over looked. This problem can be avoided by: a)Raising a flap during the surgery b)Familiarizing the depth markings in the implant drills c)Confirming the osteotomy length after pilot drill preparation with x ray d)Sufficient use of the screw tap drills to the desired length *I guess all clinicians go through this situation during the implant surgery. *All we have to do is not worry and with a cool head,ASSESS THE SITUATION, RETROSPECTIVELY ANALYZE, AND PROCEED. *If in doubt, CALL FOR AN OPINION FROM A SENIOR IMPLANTOLOGIST.

osurg

05/20/2010

You were most likely short in your prep.Remember that with tapered implants the apex is of smaller diam. re-drill to proper depth using one drill short of the final drill. This will increase your hold of the bone. If you are using tapered drills the use your final drill to proper depth.

Paul

05/20/2010

FWIW, unless you're planning on immediate loading, 10mm is plenty of length. Once integrated, the vast majority of bite force is distributed within the first 10mm, most of it in the 1st 5mm actually. Placing a fixture longer than 10mm is rarely indicated unless you plan on immediate loading.

Robert J. Miller

05/21/2010

More than likely, you just simply hit the cortical bone of the submandibular fossa. You cannot judge the position of the fossa with a PA or Panorex. Some move more laterally than others and can be angulated. I have encountered this many times in second molar positions; your choice of a wide but shorter implant is the correct decision. Your drill may slide off the side of the bone during drilling, giving the "appearance" of depth. Or, occasionally, you may actually perforate the floor. But it is very difficult, especially with an implant with non-agressive threads, to drive the apex of the implant through that cortical plate. Hence the loss of torque as you strip the bone during final placement. Simple solution - take a CBCT scan prior to surgery and plan your implant length/diameter pre-surgically. RJM

Dr. Rushik Dhaduk

06/03/2010

There are two possible reason i look forward in this case. 1)You might not have drilled up to the desired depth. It is less likely to happen but it may be due to thickness of overlying gingiva. 2) You might not have removed the debris from the socket which might have prevented implant seating in the bony well. In this case, you should not compromise the implant fixture selection. First, you should remove the implant and flush the socket thoroughly and then verify the depth using the final drill. Just insert the final drill manually and verify. If not going upto the desire depth, you can drill it again.

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