What does this mean?
The local anaesthetic used in dental treatment temporarily stops a nerve from carrying signals. Depending on the drug, the dose and the area, this effect mostly wears off within two to eight hours; in the lip and the tongue, normal feeling is the last to come back. Numbness that has not gone by the end of the same day can no longer be put down to the normal duration of the drug.
What sets this apart from other kinds of numbness is that its starting point is known. You know which procedure it began after, and the area it covers matches the territory of the nerve running close to that procedure. It is seen most often in the lower lip, the point of the chin and the lower gum. Different mechanisms can produce the same picture: contact with the tip of the needle, bleeding around it, or pressure during surgery. If the numbness is only on one side of the tongue, a different nerve is involved.
The area of altered feeling can change over time. A numb patch that shrinks, tingling that starts up and touch that begins to come back are the signs that get followed; what changes over the first few weeks often gives an idea of which way things are going. How long it takes and how far it goes differs from person to person, so it cannot be said at the outset. That is why regular check-ups and a written record are asked for.
The numbness usually comes from a nerve running through the area where the procedure was done; which nerve and which mechanism is involved comes out of the borders of the numb area and the type of procedure that was carried out.
Likely causes
What helps at home?
- Take care not to bite the numb area; the lip and the inside of the cheek can be chewed and injured without you noticing, and you will not feel a burn from a hot drink either.
- Once a week, draw the border of the numb area on paper and date it; it is hard to remember later where feeling came back, and a drawing makes that visible.
- Tell the dentist who carried out the procedure when the numbness started and which area it covers; an early record is the starting point for follow-up and, if needed, for further assessment.
- Do not treat the numb area yourself with massage, heat or supplements you decide on alone; none of these has been shown to help, and they delay assessment.
- If 24 hours have passed since the procedure and the numbness has not eased at all
- If there is burning, an electric feeling or pain on touch in the numb area
- If the numbness comes with loss of strength in that area, a drooping corner of the mouth or an eyelid that will not close
- If the numb area is growing rather than shrinking over time
- If the numbness comes with a fever, increasing swelling or a limited ability to open your mouth
Frequently asked questions
- How long does an anaesthetic normally last?
- It varies with the drug used, the dose and the area it is given in; anaesthetics that also contain a vessel-narrowing agent last longer. As a rule, numbness in the lip and tongue wears off within a few hours and is expected to be gone completely the same day. Numbness that is still there the next day is not what is expected and should be reported to the dentist who carried out the procedure.
- Will the feeling come back?
- In most people feeling comes back over time, but how long that takes and how far it returns cannot be said at the outset. What decides it is how badly the nerve was affected, and that only becomes clear by following the change over time. This is why regular check-ups and a written record are asked for in the first weeks, and why, when it drags on, the assessment carries on in oral and maxillofacial surgery.
- Can you tell whether the numbness came from the injection or from the procedure?
- The two cannot always be told apart with certainty. The border of the numb area, the type of procedure and the moment the numbness began are weighed up together. Where the injection is involved, the numbness runs without a break from the moment the needle went in; where surgery is involved, the picture can change as the swelling settles. This distinction usually shapes the follow-up rather than the treatment.
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.