patient had implant supported crown placed may/12, after 4 months healing, implant is 5mm NBiocare platform shift, crown is screw retained. xray taken today (crown in place for 15 months now) shows some bone loss on first few threads. patient also notices some odor coming from around implant. no visible signs of inflamation. good oral hygiene. i checked bite and adjusted. hopefully this will solve the problem if it is occlusally related. can't see any other cause. what would you do?
by Terry Grover at Thu, Aug 22, 2013 10:59 PM
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Terry Grover Replied at Tue, Sep 3, 2013 6:13 PM
thanks albert and mark; the implant was 5 mm replace tri lobe platform shift, so a 4.3 abutment (all authentic NB parts) was placed, and the crown is screw retained. i agree, the two main suspects in this case are occlusion and possible screw loosening. if i were to do this case again, i would use conical connection, as i have been using connical connections for a while now with good success. i can see why they phased out the trilobe. i will follow up and possible tighten screw if required. thanks again.
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Mark Kwon Replied at Fri, Aug 30, 2013 6:03 PM
Hi Terry, I think i can answer this one. After healing and loaing for a while, bone will stablize at the level which will coincide with adaptive window zone in Frost diagram. Ie. where bone turn over is sustained. This usually in conventional thread shaped implant is at the level of first 'true' thread (not at micro thread). Thus such predictable bone loss was often evident with conventional Internal plug-fit type of implants. The attempt was made to prevent this by "platform shifting" the crest module to create first thread to be at the top where shifting was occurring. However, it seems that bone still finds its way to its first "real thread" and thats exactly what i see here. I dont have perfect answer but this may be part of the answer. Conical connection provides better fit and less odor incident than trilobe fit. Clinical bone loss often related to: 1. Submarginal cement 2. Lack of platform shift 3. Lack of real thread at the top of implants 4. And many other reasons... - mark