We keep a small box behind the counter of mouthguards people have brought back. Almost none of them are faulty. They are loose, thin at the front, chewed at the edges, or moulded so badly that the player has been holding them in place with their teeth for a whole season. Every one of them was fitted at home in about ninety seconds, in water that was too hot, by somebody who did not read the packet.
Fitting a boil-and-bite properly takes about ten minutes including the cooling. Here is the order it needs to happen in.
Step one: the day before, not ten minutes before kick-off
Do the fitting on a quiet evening at home, not in a clubhouse car park. A rushed mould is the single biggest cause of a bad fit, and if it goes wrong you want time to work out whether the guard allows a second attempt.
Check three things first. Is the guard the right size band for the age — junior guards are shorter and thinner, and an adult guard trimmed down is not the same thing. Does the packet say how many times it can be re-moulded, because most allow one or two and no more. And does the player have a fixed brace, because a standard boil-and-bite should not be moulded over fixed orthodontics without asking the orthodontist first. Brace-specific guards exist for exactly this reason.
Step two: the water (this is where it goes wrong)
Boil a kettle, pour into a deep mug or bowl, and then leave it for the time the packet specifies before the guard goes in. Some brands want water off the boil, some want it rested for a minute. That instruction is not generic filler — the softening temperature differs between materials, and water that is too hot turns the guard floppy and thin at the front where it matters most.
Have a bowl of cold water and a mirror ready before you start. Once the guard comes out of the hot water you have very little working time and you do not want to be looking for things.
Step three: in and out, and a quick cold dip
Submerge the guard fully for the time on the packet — usually somewhere in the region of twenty to sixty seconds, brand depending. Lift it out with a spoon or a fork rather than fingers, let the water drain, then dip it in the cold water for a second or two. That one-second dip takes the surface heat off so it does not burn the roof of the mouth, without hardening the guard.
Step four: the bite and the seal
This is the part people rush. In order:
- Line the guard up centrally on the upper teeth — the middle of the guard against the gap between the front two teeth — and push it up and back onto the teeth, not just down onto them.
- Bite firmly but do not chew or grind. One steady bite.
- Suck hard, as if drinking through a straw. This is what pulls the material tight against the teeth and creates the actual retention.
- Push the front of the guard against the teeth with both thumbs, and press the inside edge up against the roof of the mouth with the tongue. Hold all of this for around thirty seconds.
Then take it out carefully without twisting it and put it straight into the cold water for at least thirty seconds to set hard.
Step five: the fit test
Put it back in with no biting and no clenching, then run these checks.
- Tilt the head forward and open the mouth wide. The guard should stay put. If it drops, the seal failed.
- Look at the front teeth in the mirror. The guard should cover the biting edges and extend a little onto the gum. If you can see tooth showing through a thin patch, it was moulded in water that was too hot.
- Talk. Speech will be a little muffled — that is normal. Genuine difficulty breathing or a gag reflex at the back means it is too long and needs trimming to the packet's guidance.
- Ask whether it feels like it needs holding. It should not. A guard a player has to keep biting on is a guard they will spit out at the first scrum.
Step six: caring for it, and knowing when it is finished
Rinse in cold water after every use and let it dry before it goes back in a vented case. Hot water, dishwashers, radiators and the parcel shelf of a car in July will all distort it, and a distorted guard cannot be re-set by boiling it again. Store the case in the kit bag, not loose in the bag.
Replace it when the edges are chewed through, when it no longer stays up on the tilt test, or when the player has grown. That last one catches everybody out with juniors — a guard moulded at eleven will not fit properly at thirteen, because the adult molars have come through since. Treat a mouthguard as a per-season item for any child still growing, and check the fit at the start of every season rather than the first match.
It is worth saying that the laws of the game do not make mouthguards compulsory, but virtually every school and club in the country does, and there is no sensible argument for playing contact rugby without one. If a boil-and-bite will not sit properly after two attempts, a custom guard made from a dental impression is the next step up and worth the money for anyone playing regularly.
Guards, cases and the rest of the small stuff live in our accessories section, alongside the wider rugby range. If you want a second pair of hands for a first fitting, ask us in store — we would rather do it with you than sell you a replacement in October.