When I consulted a dentist last week, he asked me to start wearing mouthguards while swimming. I have the habit of clenching my teeth while swimming. It becomes worse when I concentrate on something or exerting myself. I grind my teeth so badly and the dentist told me that I need crowns. Since he told me this, I noticed that my jaw is actually tired from the clenching after swimming. So, I am planning to purchase custom mouthguards ( http://www.parkerhilldental.com/our-services/night-guards-and-sport-guards/ ) from Mississauga to protect my teeth. I know that it is tough to get used to, especially while swimming and exhaling under water. Anybody have any experience or advice with this? I want to desperately protect my teeth.