The Secret Lives of Dentists is a mysterious and apt title for a striking, subtle adult drama about the care of teeth as a metaphor for the maintenance of marriage. The dentists we come to know so intimately out of the pages of Craig Lucas' eloquent script (based on Jane Smiley's great 1977 novella, ''The Age of Grief'') are Dave Hurst (Campbell Scott) and his wife, Dana (Hope Davis) -- partners at work, parents of three young daughters, and possessors of all the health and prosperity a husband and wife could wish for.
It's the secrets that cause decay, though, and in his experimental layering of flashback, fantasy, and documentation of everyday domesticity, director Alan Rudolph (''Afterglow'') probes the bruisable tissue of conjugal connection. Methodical Dave comes to believe that Dana is having an affair, but won't confront her because, as he rationalizes, ''If she tells me she loves him, then we have to do something about it.'' Dana -- whose more vibrant personality complements her husband's emotional containment -- watches in bafflement and growing frustration as Dave withdraws. She can't possibly know that, in his private torment, Dave has been carrying on imaginary conversations with Slater (Denis Leary), an obnoxious patient whose cynical commentary about relationships -- his own wife threw him out -- Dave now hears in his head even when Slater isn't around, pushing the dentist toward revenge.
As for Scott and Davis, the two don't so much act as effortlessly embody: They inhabit Dave and Dana with the kind of confident modesty that defines their best work. Don't let unpleasant personal dental associations stand in the way of seeing a luminous specimen of independent filmmaking.