What does this mean?
The lower jaw is a single arch of bone, joined to the skull by a joint at each end. The way your teeth sit against one another is set by the geometry of that arch and those two joints, so even a shift of less than a millimetre is noticed straight away in the mouth. If the way your teeth meet has changed after a blow, what has changed is usually not the teeth but the position of the structure carrying them.
What tells these apart is not how severe the pain is but the bite itself. A bruised muscle hurts when touched and makes it harder to open your mouth, yet the teeth still meet as they did before. If only the back teeth on one side touch, a gap is left between the front teeth, or the lower jaw closes as though it has shifted to one side, that picture is not explained by muscle pain.
A second detail is numbness in the lower lip and at the point of the chin. The nerve that runs inside the lower jawbone can be injured along a fracture line, so numbness tells you something about whether the bone is intact. Timing matters too: once bone has started to heal in the wrong position, correcting it calls for a more extensive procedure, which is why the assessment is not put off.
Several separate structures can lie behind a bite change after a blow: the tooth itself, the ligament that holds the tooth in place, the jaw joint, or the integrity of the bone. Which one is involved is separated out by examination and imaging.
Likely causes
What helps at home?
- Keep your jaw still; do not force your mouth open, do not chew hard food, and stay on soft food and liquids for a few days
- Do not clench your teeth or push your jaw with your hand to settle the bite back into place; these movements can shift a fractured or dislocated area
- Apply something cold to the outside of your face and keep your head raised when lying down; swelling increasing over the first few days is an expected course
- If a tooth or a piece of a tooth has come out or broken off, do not throw it away; keep it in milk or saliva and take it with you when you go to be assessed
- If you have numbness or tingling in your lower lip or at the point of your chin
- If your teeth meet on one side only and you cannot close your mouth fully
- If blood or clear fluid is coming from your ear or your nose
- If you cannot open your mouth two fingers wide, or you have difficulty swallowing
- If there was loss of consciousness, vomiting or blurred vision after the blow
Frequently asked questions
- Will my bite go back to how it was once the swelling settles?
- A temporary change caused by muscle swelling settles within a few days. If the bite is still different after the first week, swelling becomes harder to blame; at that point imaging is used to assess whether the bone or the head of the joint has shifted.
- My pain isn't bad, do I still need an X-ray?
- How severe the pain is does not tell you whether there is a fracture. Fractures close to the head of the joint in particular can run with little pain, and a change in the bite may be their only sign. The decision is therefore made on the bite and the examination findings rather than on pain; a panoramic X-ray is usually the first step.
- What happens if the jaw heals on its own?
- If the bone heals in the wrong position, the way your teeth meet can stay changed for a long time, chewing becomes less efficient, and correcting it may need more extensive surgery. A bite change after trauma is for this reason one of those findings assessed without delay.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.