Dental injuries are FIVE times higher for basketball players than football players. The article addresses:
1 Is the mouthguard effective for preventing or reducing traumatic incidents during sporting events? Which type of mouthguard is most effective?
2 How can we fabricate properly fitted mouthguards? (custom molds)
3 Are mouthguards effective for concussions? (NO)
4 Are there any side effects of mouthguards? (comfort/communication/breathing)
5 How can we promote mouthguard usage among athletes?
The science is questioned. What do we know? It's complicated. "Custom-fitted mouthguards do not significantly affect rates of concussions or oral soft tissue injuries, but can significantly reduce the morbidity and expense resulting from dental injuries in men's Division I college basketball."
Custom-fitted mouthguards reduce complaints about difficulty breathing and communicating.
Ethylene vinyl acetate (EVA) is the material of choice for custom mouthguards with a minimum thickness of 4 mm.
Concussions. "Although most of previous studies did not indicate the effectiveness of mouthguards in reducing the incidence or severity of concussion, it is still better to advise players, particularly in collision sports, to wear a mouthguard as a safety measure in preventing dental injuries."
Exercise capacity. Studies showed that properly fitted mouthguards did not reduce ventilation (breathing) or maximal oxygen consumption, the best measure of aerobic fitness.
Promotion of mouthguards falls on coaches, coaching organizations, and regulators.
I wouldn't be able to choose based on this video.