Possible Clues:

• With 39-Across, teeth-cleaning aid
• Superficial impression made on a student of teeth
• Poor Dante at the opening of Limbo provides description of various teething problems perhaps
• Tooth-related insurance type
• Start to floss?
• Books included in agreement with canine association
• It may be offered alongside medical and vision
• Coverage category
• Employee benefit option
• Insurance that covers dams?