The use of magnetic resonance imaging to assess swelling after the removal of third molar teeth

Objective—To assess the suitability and accuracy of magnetic resonance imaging (MRI) in measuring the swelling of the face and lingual tissues after removal of third molar teeth. Design—Prospective open study. Setting—Teaching hospital, Scotland. Subjects—5 patients 19–22 years old with bilateral mesioangular impacted wisdom teeth. Interventions-Magnetic resonance imaging scans taken before, and 1 and 7 days after, removal of bilateral lower wisdom teeth under general anaesthesia. Main outcome measures—Amount of swelling measured postoperatively compared with preoperatively. Coefficient of analytical variation calculated for the main observer, and between him and a second observer to assess accuracy and reproducibility for each examiner and between examiners. Results—Buccal swelling on the first postoperative day was significantly greater than preoperative (P < 0.01). There was no significant difference in lingual swelling. The mean coefficient of variation for the first examiner was 1.92 and there was no significant difference between the two examiners. Conclusions—Measurements on MRI scans are both recordable and reproducible for buccal swelling, but lingual swelling is more difficult to measure because of problems in defining the lateral border of the tongue. MRI scans provide an objective measurement of swelling after extraction of wisdom teeth and could be used to evaluate the efficacy of drug regimens.