🦷 Bruxism (Teeth Grinding) Contribution Simulator

Normal Sleep — Relaxed Masticatory System

Healthy sleep keeps jaw muscles quiet and the joint unloaded.

• <10%: Resting Muscle Activity (baseline EMG tone)
• 0: Nightly Grind Episodes (healthy sleeper)
• Low: TMJ Compressive Load (passive joint position)
• Normal: Disc Position (centered over condyle)

A quiet masticatory system

Masseter and temporalis stay relaxed during restful sleep.

The TMJ at rest

The disc glides freely, cushioning condyle against skull.

Why baseline matters

A relaxed baseline is the reference point for comparison.

Bruxism Episode Begins — Involuntary Clenching

A grinding episode ignites sudden, involuntary muscle contraction.

• ~60%: Muscle Activity Spike (above resting EMG)
• Arousal: Episode Trigger (micro-arousal from sleep)
• 2-3×: Bite Force (normal chewing force)
• ~10 sec: Typical Episode Length (burst of clenching)

Micro-arousal trigger

Brief sleep-stage shifts trigger sudden jaw muscle firing.

Masseter and temporalis fire

Both muscles contract together, clamping teeth forcefully shut.

Rhythmic grinding motion

Jaw slides laterally, teeth grinding against opposing surfaces.

Sustained Muscle Overactivity Through the Night

Repeated episodes stack up, keeping muscles under near-constant strain.

• ~90%: Muscle Activity (sustained peak EMG)
• 6-10: Episodes per Night (moderate-severe bruxers)
• Rising: Muscle Fatigue (lactate buildup)
• Common: Morning Jaw Soreness (reported symptom)

Episodes compound overnight

Multiple grinding bursts recur across sleep cycles nightly.

Muscle fatigue accumulates

Repeated forceful contractions exhaust muscle energy reserves.

No recovery window

Muscles rarely fully relax between successive episodes.

Joint Loading — Force Transmitted to the TMJ

Excess muscle force presses directly onto the disc and condyle.

• Severe: TMJ Compressive Load (well above tolerance)
• Elevated: Disc Compression (thinning under load)
• High: Condyle Pressure (joint surface strain)
• Hours: Load Duration (per night, repeated)

Force reaches the joint

Muscle contraction transmits compressive force into the TMJ.

Disc under pressure

The fibrocartilage disc flattens under repeated compressive loading.

Condyle displacement risk

Sustained force can shift condyle position within the fossa.

Cumulative TMJ Stress — Long-Term Dysfunction

Weeks of untreated grinding compound into lasting joint dysfunction.

• Weeks: Cumulative Stress (accumulates with severity)
• Increases: Disc Displacement Risk (with chronic loading)
• Common: Joint Clicking/Pain (chronic bruxers)
• Early = Better: Reversibility (with treatment)

Stress accumulates weekly

Untreated nights compound joint wear week after week.

Disc dysfunction emerges

Chronic loading can displace or degrade the TMJ disc.

Managing bruxism helps

Night guards and stress reduction can lower joint strain.