"The less tooth structure you remove, the longer the tooth will last, " says Dr. Spitz, who is occasionally paid to speak for Biolase.

WSJ: To Cut Tooth Decay: A Laser vs. a Drill

Lasers vary in type, but one major brand, Waterlase, works by heating water molecules in the tooth, which then expand and dislodge decayed tooth structure, according to manufacturer Biolase Inc.

WSJ: To Cut Tooth Decay: A Laser vs. a Drill