Dr. Bayet, DDS
Over the counter sports guards are cheaper than the custom ones made by the dentist. The reason is that the material used for over the counter sports guards are not durable and very thick. Also they are ill fitting and uncomfortable. The custom ones are usually fitted to the upper jaw (maxillary) by the dentist taking an impression of your teeth that ensures the fit.
The quality if excellent and very durable since it is made by the lab. Hard thermoplastic material can be used on the outside for strength and soft material can be used on the inside for comfort.
Ask your dentist about your sportsguard needs and how it can be custom made for you.