Exploring the Risk Factors for Injury To Nerves During Wisdom Teeth Removal

An interesting article titled “Risk Factors for Permanent Injury of Inferior Alveolar and Lingual Nerves During Third Molar Surgery,” appears in The Journal of Oral and Maxillofacial Surgery, vol. 72, issue 12, and written by Edward Nguyen and et al. The article assesses the incidence of and risk factors for permanent neurologic injuries to the inferior alveolar nerve (IAN) or lingual nerve (LN) after wisdom teeth removal.

The article states

“It has been well documented in the literature that the risk factors for IAN and LN injuries include increasing age, unerupted teeth, deep impaction, distoangular impaction, irregular root morphology, lack of clinician experience, lingual flap and retraction, and radiographic signs of proximity of the third molar to the IAN canal. The main forms of altered sensation that can occur include paraesthesia, anesthesia, or dysesthesia, which may be temporary or permanent. The literature reports an incidence of temporary IAN and LN injury ranging from 0.26 to 8.4% and from 0.1 to 22%, respectively, whereas permanent damage ranges from 0.3 to 0.9% for these 2 nerves.”

The researchers accessed a database at the Royal Dental Hospital of Melbourne from January 2006 through December 2009, which was part of a Clinical Incident Review process. During this time period, 11,599 mandibular third molars were removed in 6,803 patients.  Eighty-one patients who sustained 84 neurologic injuries were included in the study. The overall incidence of someone suffering a nerve injury after the removal of lower wisdom teeth was 0.72%. When factoring in surgical removal, the incidence of an IAN injury was 0.68%, and the incidence of an LN injury was 0.15%. The incidence of permanent injury to the IAN and LN was found to be 0.24% and 0.079%, respectively.

The researchers found that important risk factors for permanent IAN injury were increasing age (25 or older), surgery performed by staff dentists, surgery under general anesthesia, and mesioangular impactions. No factors were found to statistically increase the risk of LN injury, although most injuries were seen in patients with a distoangular impaction. The researchers found that the mean age of the patients with nerve damage was 34 years and most permanent IAN injuries occurred in patients older than 45 years old.

The researchers also state ”

“In previous studies, it was reported that in the first 4 to 8 weeks after surgery, 96% of IAN and 87% of LN injuries spontaneously resolve and these can be attributed to neuropraxia.”

In their study it was found that most most neurologic disturbances resolved completely within the 4- to 8-week follow-up period.

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