Instead of premedication, why not use a rinse of hydrogen peroxide. Use equal volumes of hydrogen peroxide to either water, mouthwash, or some other oral astringent.
In response to your recommendation regarding premedication for plates, pins or screws in the body:
The American Heart Association guidelines published in April 2007 specifically state that premedication is not required for pins, plates or screws. It is also not required for heart murmurs, Mitral Valve Prolapse with or without regurgitation, Rheumatic Heart disease,etc. You can find out more information by googling for the guidelines. Hope that helps.
Definately...premedication of some sort of antibiotic is necessary with any kind of joint replacement and/or artificial parts. This is because infection caused by stirring up bacteria in your mouth during dental cleanings and other dental treatment that is likely to cause bleeding enters the blood stream and is most likely to harbor around artificial parts. It is only a precaution and most dentists/hygienists won't do anything that may cause bleeding if you haven't premedicated one hour before your appointment. I would check with the surgeon who placed your pins and plates. They would usually make the determination as to what antibiotic you may need.