Not All Mouthguards Are Equal — But the Old Argument Was Wrong

Here's a conversation that goes badly in dental offices every week.

Parent: "He's got a mouthguard. We got it at the sporting goods store."

Dentist: "Those are worthless. You need a custom one."

Parent: (hears "you wasted your money and I want more of it")

You lost that one before you finished the sentence. Let's fix it, because the correction is also more accurate than what most of us were taught.

The four categories, honestly described

Stock guards are purchased ready-to-wear and require no alteration. There's no retention — they're held in place only by biting down. At impact they typically dislodge. Speech is difficult. This category genuinely should not be recommended by a health professional, and you can say so plainly.

Mouth-formed ("boil and bite") guards are the most prevalent guards in use today. The material is thermoplastic at low temperature so it can be adapted in the athlete's mouth. Because the athlete bites down during forming, occlusal thickness is reduced, and adaptation degrades further with repeated wear. Fit quality depends entirely on the user's technique.

Here's the correction. For years, publications — including ours — stated flatly that boil-and-bite guards should never be recommended by a health professional. Current ADA guidance is more permissive than that. The ADA position is that a dentist may recommend either a custom-fit mouthguard or a properly fitted over-the-counter guard carrying the ADA Seal of Acceptance, depending on the circumstances.

And in a randomized trial of orthodontic patients, mouth-formed guards substantially outperformed pre-fabricated instant-fit guards, and were the patients' second choice overall.

Custom vacuum-formed guards are laboratory-fabricated on a model of the patient's arch using a single sheet of material under low heat and one atmosphere of vacuum. Fit and retention beat anything over the counter. The limitation is thickness control — single-layer vacuum processing thins the material unevenly, including over the incisal edges of the upper anteriors, precisely where athletes are most often injured. Thickness is the major determinant of mechanical performance and shock absorption.

Heat/pressure laminated guards are built from multiple laminated layers of ethylene-vinyl acetate under high heat and high pressure. This is the construction method that lets thickness be placed deliberately where it's needed. Current literature consensus places optimal EVA thickness at approximately 4 mm; beyond that, additional thickness adds minimal impact resistance and starts causing discomfort from bulk. The EA4SD position statement specifies maintaining 1.5 to 2 mm over the incisal edges of the anteriors.

The other correction: hard inserts

Many of us — again, including this publication — promoted a hard polycarbonate insert layer for high-velocity impact sports.

Recent in vitro impact testing does not support that claim. A custom guard without a hardened insert outperformed a comparable custom guard incorporating a hardened EVA shell insert across the impact conditions tested. The authors concluded their results do not support a protective advantage for the hard insert.

The counter-literature isn't unanimous, and that was a typodont study with real limitations. But the claim can no longer be stated as settled. Describe what a rigid component is designed to do. Don't describe it as proven superior protection.

The script that actually works

Parent: "He's got one from the sporting goods store."

You: "Good — that's better than nothing, and I'm glad you thought about it. Let me show you what it can't do. That guard was formed by your son biting into softened plastic, which means the material thinned exactly where it needed to be thickest, and it's thinned further every time he's worn it. A laboratory-made guard lets me put four millimeters where the impact lands and taper it where it doesn't, and it stays in his mouth when he takes a hit. Can I show you the difference?"

You've validated the parent, taught them something true, and made the case on mechanism rather than on dismissal. That conversation converts. The other one doesn't.

American Dental Association. Athletic mouth protectors (mouthguards). ADA Oral Health Topics.

Kalra A, et al. Eur J Orthod. 2022;44(1):101–109. doi:10.1093/ejo/cjab062

Roberts HR. Dent Traumatol. 2023;39(2):101–108. doi:10.1111/edt.12809

Avgerinos S, et al. Dent Traumatol. 2025;41(3):246–251. doi:10.1111/edt.13019

Harrington C, et al. Eur J Orthod. 2022;44(1):95–100. doi:10.1093/ejo/cjab023

Sliwkanich L, Ouanounou A. Dent Traumatol. 2021;37(5):661–671.