Nightguards, dentures, mouthguards: the plastics nobody talks about.
Retainers and aligners get the attention, but they have quieter siblings: the nightguard ground between clenched teeth for eight hours, the denture worn through every meal for decades, the sports mouthguard bitten through every match. All plastic. Almost none of it discussed.
The nightguard: wear by design
A nightguard exists to be worn down — it takes the grinding force so your enamel doesn't. Most are made from the same thermoplastic families as retainers (EVA, PET-G, acrylics), and the mechanism that protects your teeth — sacrificial abrasion — is precisely the mechanism that generates particles. If you grind hard enough to flatten a guard in a year, that material went somewhere, and much of it was swallowed. Research specific to nightguard particle release is thin, which is itself the point: a device designed to abrade in the mouth, nightly, for years, has barely been studied for what its abrasion produces.
Dentures: decades of contact
Denture bases are acrylic — PMMA — worn against soft tissue through every meal, every day, often for decades. The 2025 Journal of Hazardous Materials review of micro- and nanoplastics in dentistry specifically identified denture wear among the release routes, alongside composites and aligners, via degradation and mechanical wear. Older, roughened dentures shed more than new ones — another reason (beyond hygiene and fit) that replacement schedules matter.
Sports mouthguards
Boil-and-bite guards are EVA — softened in hot water, formed by biting, then chewed on through every session. Softer polymers abrade faster, and a guard's pocked, bitten surface after a season tells you where the material went. For an adult, occasional use is a modest exposure; for a child in a guard three times a week through a decade of sport, the honest answer is that nobody has measured it properly.
The pattern, and the fix
Across all three, the pattern is the same one we found in retainers: petroleum-derived thermoplastics, held in the mouth for extraordinary contact hours, with wear that visibly consumes material — and essentially no manufacturer publishing what that wear releases. The fix isn't fear; it's measurement. Ask what any oral device is made of. Ask whether its shedding has been tested. Replace worn devices on schedule rather than running them to destruction. And support the principle that what sits in your mouth should be tested in the open — the principle behind the bio. Standard, where every lot of every bio. device is published.
Related reading: How often should you replace your retainer? · Microplastics in the human body
Your retainer doesn't have to be part of the problem.
Same thermoplastic family, same nightly hours — but ours is different: a bio-derived material, independently tested lot by lot, replaced fresh every year on subscription so wear never runs to destruction.