THE SECRET LIVES OF DENTISTS [1/2]

Accomplished but smug do mestic drama. Running time: 105 minutes. Rated R (sexuality and lan guage). At the 72nd Street East, the Lincoln Square, the Chelsea, the Angelika.

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IT’S tough being a den tist – people fear and loathe you and, as Campbell Scott’s char acter laments in the voiceover that kicks off “The Secret Lives of Dentists,” “Your best work never sees the light of day.”

Soon, Scott’s Dr. David has even more to complain about: He suspects his wife, Dana (Hope Davis), also a dentist, of having an affair and is goaded by his fevered imagination to the brink of madness.

Idiosyncratic indie director Alan Rudolph (“The Moderns,” “Mrs. Parker and the Vicious Circle”) does a fine job of illustrating the way a kernel of suspicion can swell to proportions that block out the sun.

But the flimsy screenplay, adapted by Craig Lucas, betrays its diminutive origins – a novella by Jane Smiley called “The Age of Grief.”

Lacking a solid narrative beyond the worsening marital crisis, this humor-flecked domestic drama ends up relying heavily on directorial tricks such as splashes of magic realism, giving it a self-satisfied air that quickly becomes grating.

For no apparent reason, David is visited in his fear-fueled hallucinations by a belligerent, trumpet-playing patient (Denis Leary, wearing the similarly ethereal Brad Pitt character’s sleazeball wardrobe from “Fight Club”).

This apparition – who functions as the anti-marriage devil on David’s shoulder, doling out bitter advice on how to deal with his wife and three rambunctious young daughters – is an initially funny contrivance that turns tiresome.

“Dentists” is essentially a montage of variously tender and funny set pieces – including a drawn-out sequence in which a bad bout of intestinal flu sweeps through the entire family – with the whole adding up to less than the sum of its parts.

Still, there’s pleasure to be had just in watching the hugely talented Scott and Davis being put through their paces by a director who holds actors in high regard.