Hello, I'm Dr. Junghoon Choi, director of Seoul Crown Dental Clinic.
In restoration consultations, I often hear things like:
"My crown broke again — just a few years after getting it done." "My jaw feels stiff and heavy every morning when I wake up."
These two complaints often come from the same person. Today I want to explain how clenching or grinding your teeth during sleep affects dental restorations, and why — as a prosthodontist — I always look at the occlusion (the way your upper and lower teeth come together) before designing any new restoration.
Short answer: When a restoration keeps breaking, I look at the forces first, not the restoration itself. Grinding and clenching during sleep put far more force on the teeth than chewing does, so I confirm the habit, design the material, thickness, chewing surface, and margin to match, and recommend a night guard to intercept that force.
When you chew during the day, your brain regulates how hard you bite. If you hit something firm, you instinctively ease up, and each chewing stroke is brief.
During sleep, that regulation is absent. The forces generated by grinding or clenching are far greater than those of normal chewing, they act directly tooth-to-tooth with no food to cushion them, and they are sustained for long periods. Natural teeth wear down under these forces — but restorations are less able to flex and redirect force the way a natural tooth root can, so they absorb the full impact.
In many people whose restorations fracture or come loose repeatedly, the nightly habit turns out to be the driving cause rather than anything wrong with the restoration itself.
If your jaw muscles feel sore or the area around your temples feels heavy when you wake up, that may be a sign your muscles were working through the night.
When the natural ridges of the back teeth have worn flat, or the edges of the front teeth look ground level, this is often the result of a long-standing habit.
A white line running along the inner cheek mucosa following the tooth line, or scalloped impressions along the sides of the tongue, suggest habitual clenching.
If the same restoration has broken more than once, or multiple teeth feel sensitive without a clear reason, I look at excessive force first. As I discussed in what to do when a crowned tooth feels sensitive, excessive force is one of the causes of that sensitivity.
Once this habit is identified, I shift the design priority from "aesthetically ideal" to "structurally resilient." Four things change specifically.
First, material selection. For positions that bear heavy force, I choose a higher-strength material — while also considering whether it will cause excessive wear on the opposing natural tooth. The relationship with the opposing tooth, which I covered in the article on older gold crowns, becomes even more important here.
Second, thickness. Every material has a minimum thickness it needs to function reliably, and I do not compromise that to make the restoration thinner. The balance between how much tooth structure needs to be prepared and what the material requires is something we work out together during consultation.
Third, the shape of the chewing surface. I design the occlusal contacts so that force is distributed rather than concentrated at a single point, and I adjust the contours to reduce lateral (sideways) forces.
Fourth, the margin — the edge where the restoration meets the tooth. Repeated heavy forces can cause the margin to open up over time, so I take a more conservative approach to where the margin sits and how closely it fits.
Eliminating the habit itself is not straightforward. What a night guard (also called a splint) does is prevent the teeth and restorations from making direct contact with each other during sleep, so the force is absorbed and distributed by the appliance instead.
When a habit is confirmed in someone who is getting a new restoration, I generally recommend making a night guard at the same time. Among all the variables that influence how long a restoration lasts, this is one of the few that can be reliably controlled. The appliance is custom-made to fit the individual's tooth arrangement, and its condition — wear, fit, any distortion — is checked at follow-up visits so it can be adjusted or remade as needed.
Grinding is commonly thought of as a nighttime problem, but many people unknowingly hold their teeth together and apply force while concentrating or under stress during the day — at the computer, while driving, or when lifting something heavy.
Daytime clenching is hard to block with an appliance, so awareness is the key. The resting position of a relaxed jaw is: lips closed, upper and lower teeth slightly apart. I recommend checking in with yourself a few times a day — "Am I holding my teeth together right now?" From the restoration's perspective, the less force applied, day or night, the better.
At routine check-ups I look at changes in wear patterns, the condition of restoration margins, and how much the night guard itself has worn. Because habits change gradually, check-ups roughly every six months is a realistic interval for tracking trends.
Q. I am not sure whether I grind my teeth. How can I tell?
Most people are unaware they do it. The signs listed above — morning jaw fatigue, worn flat surfaces, marks on the cheeks — combined with examining the wear pattern in the clinic allow a reasonable assessment. If someone who sleeps with you has noticed sounds, that is also an important clue.
Q. Is stress the cause? Will reducing stress help?
Stress is understood to be a contributing factor, but it is not the only cause, and individual variation is significant. Managing stress may help, but from the perspective of protecting a restoration, using an appliance to intercept the force is more practical than waiting for the underlying cause to resolve.
Q. If I wear a night guard, will my restoration definitely stop breaking?
It can substantially reduce the likelihood of fracture, but it does not eliminate the possibility entirely. The outcome depends on whether the appliance is worn consistently, how intense the habit is, and where the restoration is located. That said, there is a clear difference between absorbing force directly and having a guard in place — and tracking wear and margin condition at regular check-ups means problems can be caught early.
Q. Do I need to wear the guard every night?
If the habit is present, yes — nightly wear is recommended. Missing a few nights will not immediately cause a problem, but heavy forces can damage a restoration in a single night, so building the habit of not forgetting is what determines how effective the guard will be.
When treatment keeps repeating, the redo has to be designed right. If you have questions, feel free to ask.
WhatsApp: Message us on WhatsApp · Email: [email protected] · Phone: +82-2-3444-2888
Replies within 24 hours (KST, business days). Treatment plans and schedules are discussed individually after an examination.