Keeping teeth shiny and clean turns frowns into smiles and smiles into makeshift headlamps for spelunking excursions. Shine on with today's Groupon: for $39, you get a take-home professional teeth-whitening kit from Dr. Benson and Associates in Wyandotte (a $300 value).

Dr. Benson and Associates upgrades smiles with whitening kits that can be used at home to lighten teeth over the course of about two weeks. After filling out a brief medical history, patients sink their teeth into a pair of impression trays, which the dentist will use to fabricate a pair of plastic whitening trays. Patients will return for a second 15-minute visit to adjust the fit of their trays and pick up their take-home kit, which includes the custom-fit trays and whitening gel. Depending on the shade desired, stains fade over the course of approximately two weeks, banishing evidence of years of coffee drinking and wine-cork chewing. To preserve the gel’s effectiveness, leftovers can be stored in a cold, dark environment such as a refrigerator or a chocolate-banana split, where they can be called upon to freshen smiles as needed. Dr. Benson also offers refill kits ($50) that can last up to two years.