No real alternatives at this point.  Chlorhexidine as a mouthrinse is unique
in that its antimicrobial action lasts after you are done swishing with it.
This is called "substantivity".  Other rinses, like Listerine, do not
possess this.  When using chlorhexidine, one must weigh the risks vs
benefits.  In the case of post-periodontal surgery, the benefits far
outweigh the staining and calculus issues.  I must say, I have not witnessed
the increased calculus formation myself, although I've seen the increased
staining.

    I'm not sure that chlorhexidene gluconate increases calculus formation,
but it certainly does stain, and will make any calculus much more
obvious because of this.  But good oral hygiene re-instituted as soon
postop as the surgeon allows, will minimize this.
    In any case, in the scheme of things, getting a cleaning after ChG
rinses are discontinued doesn't sound like a big deal.

    I'm not aware of any other antimicrobials being used that are nearly as
effective as ChG.  It not only protects against a wide bacterial
spectrum, but also has good substantivity in the mouth as it bonds to
proteins.  This is the same reason chlorhexidene gluconate scrub is
probably the most commonly used surgical scrub ( in 3 or 4% concentration).

Steve