From Medgadget:

DentaSafe™ is a disposable foam strip designed to prevent anesthesiologists, EMTs and ER personnel from eviscerating patients’ teeth. Your correspondent, an anesthesiologist himself, humbly recalls a recent fishing expedition to extract two fallen teeth from around a patient’s uvula.

From the product page:

This medical-grade, elastic, hypoallergenic, and latex free foam strip is designed to stretch and conform while providing the flexibility to maneuver intubations with ease, even for the most difficult intubations.
It prevents costly damage to the upper incisors, which are the most frequently affected teeth during intubation.

Single use, disposable foam strip attaches to the flange of the laryngoscope blade and prevents direct contact between the metallic blade and the patient’s upper teeth…

Simply peel the self-adhering DentaSafe™ strip using the grip tab and apply it to the flange of the laryngoscope blade. Press the strip against the blade.