Corrected entry: Throughout the first battle at "Hacksaw Ridge" some of the men are seen pulling the pins of grenades with their teeth. In actuality, the pins on the grenades (both modern and old ones) take at least 7 pounds of force to release the pin. If someone did that, they'd either cause severe damage to their teeth or maybe lose a couple.
Matdan97
8th Mar 2017
Correction: As a dentist, I can assure viewers that normal, healthy teeth can easily withstand the 7 pounds of lateral force needed to maintain a grip on a grenade pin loop while it is pulled. A more likely hazard is that an excited soldier might crack a tooth while biting down on the split ring loop attached to the pin.