Dentists of the world, rejoice! The perfect album for your waiting rooms has just arrived. The latest Chicago record, 21 — perhaps their most exquisitely bland to date — is ideal to lull even your jumpiest patients into a state of total numbness. Call it novocaine for the ears. But wait: The album’s appeal doesn’t stop there. It’s also great for romantic obsessives. Nearly every track is a florid adult-pop ballad (with regular horn blasts to remind you of the group’s ”jazz-rock” roots) chronicling the life of some poor schnook who’s left wondering where it all went wrong. ”If It Were You” finds our hero getting shown the door, but the guy insists on clinging to his memories. In ”Only Time Can Heal the Wounded” he’s sunk but still opines ”(I) can’t let her go!” And in ”Explain It to My Heart,” he knows he’s been told to drop dead but demands to hear it ”one more time.” No wonder the guy keeps getting dumped. Who wants to hang around with such an utter masochist? Then again, at least these masochists are socially conscious. The one number where the group doesn’t end up red-eyed is ”God Save the Queen.” It’s not a cover of the Sex Pistols’ ode to anarchy, but rather a true original about acid rain and nuclear winter, containing the line ”Greenhouse condition, gettin’ steamier.” Did I mention that poets might like this album too?