Inferior Alveolar Nerve Block: Anatomical and Geometric Morphometric Assessment of Injection Pathways

Authors

Victoria L. Lo, University of the Pacific Dugoni School of DentistryFollow
Supriya Kazi, University of the Pacific Dugoni School of DentistryFollow
Gary D. Richards, University of the Pacific Dugoni School of DentistryFollow

Lead Author Affiliation

Doctor of Dental Surgery Program

Lead Author Program & Year

DDS Year 2

Presentation Category

Research

Introduction/Context/Diagnosis

Mandibular dental procedures generally require an inferior alveolar (IA) nerve block. Success rates for this block vary (13-98%). Earlier work (Lambert et al., 2017) demonstrated the value of a new landmark set. Here we employ a digitally-based landmark assessment of needle positioning to better demonstrate the effectiveness of this new technique.

Methods/Treatment Plan

We CT scanned a sample of skulls (N=24), four of which are late stage juveniles (unerupted/erupting M³/₃) while the rest are adults. The mandibular model was positioned on the articular eminences. The incisal opening is ~40-45 mm. Orthoslices were employed to mimic the injection (LP_3-4 - maxillopterygoid junction) path and the occlusal, coronoid notch, and buccinators planes. We use Morphologika 2.5 to examine landmarks in 3D shape space via principle components analysis both with and without Procrustes transformations.

Results/Outcome

Employing the lower occlusal plane results in low and posterior injections; only 16.6% in acceptable position. Splitting the occlusal plane distance results in unacceptable needle positioning in 12.5% of cases. Also needle position is the most variable, ranging from the foramen to the condyle. The coronoid notch provides 100% acceptable positioning. Use of the new landmark resulted in 100% acceptable positioning of the needle. However, in two cases the needle tip is medial to the ramus by ≤5 mm, but still acceptable.

Significance/Conclusions

Assessment shows the maxillopterygoid junction as a suitable landmark for needle alignment. Clarifying relationships between landmarks employed in block procedures should lead to more standardized, patient-centered techniques and improved success rates.

Format

Event