Novel strategy to predict high risk of inferior alveolar nerve injury during extraction of lower third molar based on assessment of computed tomography images of multiple anatomical features

BACKGROUND A serious complication of surgical removal of impacted lower third molars is inferior alveolar nerve (IAN) injury. Evaluation of radiographic factors to predict IAN injury using CT and panoramic radiography includes root morphology assessment, follicular sac size, mandibular bone density, inferior alveolar nerve and vessels, condition of the overlying tissues, relation of the impacted tooth with the body and ramus of the mandible and the adjacent teeth. This study was done to evaluate the radiological features of the impacted lower mandibular teeth and their relationship with IAN through panoramic radiography and CT and to assess the most predictable radiological criteria for inferior alveolar nerve injury in impacted third molar surgery. METHODS All the patients indicated for lower third molar extraction were included in the study and pre-operative conventional panoramic radiographs (Planmeca Proline PM 2002 CC, Helsinki, Finland) and CBCT (Kodak CBCT) were taken. Any post-operative nerve injuries detected were followed up after 15 days or 1 month. Fisher’s exact test was done to find the association between the outcome variable and explanatory variables. RESULTS Only 11.4 % (N = 4) of all participants had IAN injury following surgical disimpaction. All the participants with IAN injury showed narrowing of the canal on their preoperative panoramic radiographs and presence of nerve approximation with the tooth in cone beam computed tomography (CBCT) reports (P < 0.05). CONCLUSIONS A statistically significant association exists between IAN injury and nerve exposure, radiographic signs of nerve involvement for panoramic radiograph, level of third molar impaction, and nerve approximation in CBCT. KEY WORDS Inferior Alveolar Nerve Injury, Lower Third Molar Impaction, Panoramic Radiography, CBCT

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Coronectomy vs. Total Removal for Third Molar Extraction

Journal of Dental Research ◽

10.1177/0022034512449346 ◽

2012 ◽

Vol 91 (7) ◽

pp. 659-665 ◽

Cited By ~ 66

Author(s):

H. Long ◽

Y. Zhou ◽

L. Liao ◽

U. Pyakurel ◽

Y. Wang ◽

...

Keyword(s):

High Risk ◽

Nerve Injury ◽

Inferior Alveolar Nerve ◽

Third Molar ◽

High Rate ◽

Total Removal ◽

Randomized Controlled ◽

Third Molar Extraction ◽

Root Exposure ◽

Inferior Alveolar Nerve Injury

The objective of this systematic review was to compare the outcomes between coronectomy and total removal for third molar extractions with high risk of nerve injury and to help practitioners make prudent decisions on whether and how third molars should be removed. PubMed, Embase, Web of Science, CENTRAL, and SIGLE were searched from January 1990 to October 2011 for randomized or non-randomized controlled trials. Four studies met our inclusion criteria. The pooled risk ratio (coronectomy vs. total removal) was 0.11 (95% CI = 0.03-0.36), 1.03 (95% CI = 0.54-1.98), 0.55 (95% CI = 0.28-1.05), and 1.14 (95% CI = 0.57-2.30) for inferior alveolar nerve injury, post-operative infection, dry socket, and pain at 1 wk after surgery, respectively. A relatively high rate of failed coronectomy in one study (38.3%, compared with 2.3%-9.4% in others) may be attributed to a higher proportion of narrowing roots and vertical impactions. Although root migration rate was high (13.2%-85.29%), the migration distances were short (3.06 ± 1.67 mm), and the directions were away from the nerves. Moreover, the rates of re-operation and root exposure were low. Therefore, coronectomy appears superior to total removal for reducing inferior alveolar nerve damage and could be used in clinical practice for third molar extractions with high risk of nerve injury.

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