Dr Chow on connection problems between the implant and the crown

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 Chow on Allergy to grafts in oral implantology

Dr K. F. Chow May 14th, 2009

Theoretically, an individual can be allergic to anything because anything can be an allergen i.e. a substance that is considered by the immune system as a foreign body. Once the immune system identifies a foreign body, it responds basically 4 different possible ways…..4 types of hypersensitivity mediated either by B cells of T cells.

Your patient’s sounds like the 4th type….T cell mediated delayed hypersensitivity……allergic contact dermatitis likely due to your gloves..powder….ointment or something that touched your patient’s face.

Treatment is usually steroids systemic or topical or both. If things are getting better, that means things are getting better and no drastic treatment like removing the grafts etc. is necessary. Just make a note on your patient’s record and avoid the possible causes in the future.

Cheers!