Dental anesthetic nerve damage – What is the cause?
Dental anesthetic nerve damage after administering dental anesthetic is a known risk factor, although it is very uncommon. The exact cause may never be known because multiple things are happening at once, physical and chemical trauma.
Dental anesthetic nerve damage recovery rates
Temporary paresthesia occurs in around 1 in 6000 IANBs and is much more common than anything permanent, which occurs in about 1 in 30,000 IANBs. However, since the vast majority of cases go away on their own the reported rate of dental anesthetic nerve damage is likely much higher than reported. More than 80% with temporary damage will recover within 3 months, usually in the first 2 weeks. Another stat I have seen states 85% recovery in 8 weeks or less. After that time period about 1/3 do not recover. Some say their is no benefit to microsurgery, but that is debatable.
What is the cause of the nerve damage?
There exists three major theories on the cause of this nerve injury. Lingual nerve damages occurs about twice as often as IAN damage. Unfortunately around 1/3 of patients will experience dysesthesia instead of paresthesia. We do not give routine consent for IAN blocks due to the extreme rarity and this holds up in court.
- Direct trauma to the nerve from the needle itself.
- Intra-neural hematoma formation.
- Local anesthetic toxicity.
Why does the lingual nerve get more damage?
First and foremost it is in the way of the removal of the tooth more often. Secondly, it has a lot of variation that nearly assures certain people are going to have issues when they have a wisdom tooth removal procedure. Since there is no way for doctors to trace the nerve, it is an unknown risk.
What is the treatment for nerve damage?
There is no known treatment for nerve damage resulting from dental anesthetic. Steroids and anti-inflammatory are often used for treatment, but there is no evidence they are beneficial.
How do we test the nerve damage?
We have an entire post on nerve damage testing in dentistry but one of the most basic tests is mapping the issue.
Which anesthetics are more likely to cause damage?
It appears that the higher percentage anesthetics can cause local anesthetic toxicity that results in nerve damage. The approximate rate at which it happens overall is around 1:785,000. Such a low rate makes it difficult to study directly.
A lot of studies do say that articaine and prilocaine have a higher likelihood to cause paresthesia.
Pogrel JADA 1995 found no correlation between using lidocaine, prilocaine, and mepivacaine. There is a correlation between nerve damage and the number of times we inject a patient. Although this could result from more chances for physical injury and/or higher doses. There is also a correlation between the patient reporting a feeling of an electric shock, which is a sign the needle is injuring the nerve. Finally, a correlation was found for those that had dental work requiring local anesthetic in that area recently.
Pogrel 2000 found prilocaine more likely to have caused dental anesthetic nerve damage.
Again in 2007 Pogrel found prilocaine to be far more likely to cause nerve damage than articaine or lidocaine.
Garisto 2010 found dental anesthetics with higher concentration were more likely to cause dental anesthetic nerve damage. The main two anesthetics in the study are articaine and prilocaine. Prilocaine was 7x more likely to cause damage and articaine was 3.5x more likely. Others have found similar results, such as Haas 1995 and Gaffen 2009.
Unusual nerve damage from dental work or dental anesthetic
There are reports of taste changes after dental work that can occur from damage to the chorda tympani. These should all get better as most nerve damage from either needle or anesthetic heals and the body compensates for taste loss.
Unusual side effects of dental anesthetics
Facial blanching from dental anesthetics
Facial blanching occurs when anesthetic gets into a blood vessel and temporarily stops blood flow.
Twitching after numbness wears off.
Likely result of minor nerve damage either directly or from dental anesthetic itself. Twitching nerves respond well to tonic water because of the quinine.
Ophthalmologic complications from dental anesthetics
Double vision and droopy eyes will happen to many dentists in their career. In a survey of dentists on UIC dental facebook group we run 66% of respondents said they have had a patient have had this happen. That was 10% of all dentists who saw the survey. Since it it likely that those that have had a patient with ophthalmologic complications are likely more prone to participate, the true number of dentists that have seen this is likely lower than 66% but higher than 10%. Diplopia after inferior alveolar nerve block was a topic on facebook group. This is another post on the same topic.
A literature review on the topic by Alamanos 2016 shows 89 cases in the literature and 8% of those resulting in permanent damage. Since it is far more likely to be worthy of writing an article about if the damage is more severe the true number is certainly much smaller percentage of the cases. This case report has many nice references.