Do “Night Guards” Really Work? The Latest Evidence on Oral Splints for TMD and Bruxism

Reference
Riley, P., Glenny, A. M., Worthington, H. V., Jacobsen, E., Robertson, C., Durham, J., … & Boyers, D. (2020). Oral splints for temporomandibular disorder or bruxism: a systematic review. British dental journal, 228(3), 191-197.

  1. Introduction: The “mystery” behind a familiar treatment
    “Jaw heaviness in the morning,” “clicking sounds when eating,” “family says my grinding is loud.” For TMD (temporomandibular disorders) and bruxism complaints, dentists often first propose a mouthpiece (oral splint). It’s the go‑to in clinical practice. But does simply inserting a plastic plate in the mouth truly have solid scientific backing? A recent systematic review in the British Dental Journal (BDJ), synthesizing 37 rigorous randomized controlled trials, offers a reality check.
  2. Takeaway 1: A conclusion that challenges the “default” treatment
    The headline finding is sobering for clinicians and patients alike: there is no robust evidence supporting oral splints for either TMD or bruxism. A meta‑analysis of 13 trials (1,076 participants) found a standardized mean difference (SMD) for pain reduction of only −0.18—classified as a “very small effect” and statistically non‑significant. In other words, the splint group and the no‑treatment group showed clinically negligible differences.
    “There is no evidence to support the use of oral splints for either condition based on the results found.”
  3. Takeaway 2: Not just pain—other expected benefits also lack support
    Beyond pain relief, many hope splints will reduce joint noises, improve mouth opening, and enhance quality of life (QoL). The review found no adequate evidence of meaningful improvement in:
  • TMJ clicking sounds
  • Limitation in mouth opening
  • Quality of life
    The common belief that a splint will comprehensively resolve jaw problems is not currently corroborated by science.
  1. Takeaway 3: On “protecting teeth,” the evidence gap is stark
    One of the main reasons splints are prescribed is to prevent tooth wear from grinding. Yet the review identified no clinical trials that properly tested whether splints actually prevent occlusal wear. While some studies (e.g., Gomes, 2015) reported pain reduction in bruxism patients, overall certainty of evidence remains “very low.”
  2. Takeaway 4: Why we cannot claim “proven effectiveness” — study design limits
    This does not prove splints never work; rather, high‑quality evidence sufficient to claim effectiveness is lacking. Dentistry faces unique blinding challenges: unlike drug trials with indistinguishable placebos, patients can tell whether a splint is in their mouth, making placebo effects hard to exclude.
    Safety: The review found no strong evidence of serious adverse events from splints (reassuring), but adverse event reporting itself was limited. Future trials should adopt international outcome frameworks (e.g., IMMPACT for pain, COMET for core outcome sets) to define “clinically meaningful improvement” more rigorously.

Conclusion: How should patients respond?
Long‑held “common sense” does not always align with the latest evidence. This does not mean you must discard your splint today. It means engaging your dentist as a partner and asking evidence‑informed questions—for example: “Based on IMMPACT thresholds, what percent pain reduction (e.g., 20–50%) can I reasonably expect?” Evidence evolves; wise health decisions weigh current science, transparency about uncertainty, and personal values.
A final question: How much time and money will you invest in a therapy that lacks sufficient high‑quality evidence?

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