Abstract
ObjectivesTo assess the lingual nerve (LN) visualization using a 3D double-echo steady-state MRI sequence (3D-DESS).Materials and methodsThree readers prospectively evaluated the LN for its continuous visibility in 3D-DESS MRI in 19 patients with an indication for removal of mandibular impacted third molars, using a 5-point scale (4 = excellent to 0 = none). Six LN anatomical intermediate points (IP) were selected and checked for their detectability by a 4-point scale (4 = yes to1 = no). Inter- and intra-rater agreement was evaluated using intraclass correlation coefficient and percentage of agreement.ResultsThe average nerve continuity score was 3.3 ± 0.46. In 35% of the cases, the entire course was continuously visible. In 10%, the proximal and 60%, the distal part of the nerve was not continuously visible. Inter- and intra-reader agreement was good (ICC = 0.76, ICC = 0.75). The average detectability score of all IP was 3.7 ± 0.41. From IP1 to IP5, the detectability was excellent; meanwhile, IP6 had lower visibility. The inter- and intra-reader percentage of agreement was 77% and 87%.ConclusionsThe 3D-DESS sequence allowed accurate and continuous visualization of the LN with high reproducibility in more than one-third of the patients. This could improve the preoperative clarification of the LN position and thereby reduce complications during dentoalveolar surgical interventions.Clinical relevance3D-DESS MRI might be beneficial in clinical scenarios where the second molar is elongated or presents a difficult rotational position while simultaneously having a close positional relationship to the third molar. Thereby, osteotomy performed more lingually, indicating extended lingual flap detachment may increase the risk of LN damage.
Highlights
Knowing the exact anatomical course of the lingual nerve (LN) is important in various dental and oral surgical interventions
We focused on the anatomical relationship of the third molar teeth, the anatomic proximity to the alveolar ridge of the lingual cortical plate, and the diameter of the LN using the 3D double-echo steady-state Magnetic resonance imaging (MRI) sequence (3D-DESS) sequence
The study population included patients with an indication for removal of partially retained, fully retained, or impacted third molar in the third or fourth mandibular quadrant with the additional indication for three-dimensional imaging according to the guidelines of the Swiss association of dentomaxillofacial radiology admitted to the Clinic of Cranio-Maxillofacial and Oral Surgery of the Center of Dental Medicine (University of Zurich) either by a private practitioner or by themselves
Summary
Knowing the exact anatomical course of the lingual nerve (LN) is important in various dental and oral surgical interventions. The nerve demonstrates large individual anatomical variability regarding position and proximity to important structures, especially in the third molar region. Iatrogenic injuries of the LN can occur in various surgical procedures such as osteotomy of mandibular ramus, orthognathic surgery, endodontic treatments, tumor excision, or local anesthetic application prior to extraction of the mandibular third molar and due to the extraction itself. The insertion of dental implants or even general periodontal procedures can damage the trigeminal nerve’s extracranial branch [1]. Injuring the LN, a rare complication during the removal of mandibular third molars [2, 3], is associated with sensory disturbances in the ipsilateral anterior two-thirds of the tongue [4].
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