Identification of the Incisive branch of the inferior alveolar nerve in edentulous mandibles using cone beam computed tomography (CBCT)

Objective

Risk of iatrogenic paresthesia and postoperative complications increases in patients with edentulism. This study measures agreement of a standard, cone beam computed tomography (CBCT)-derived incisive branch (IB) measurement across independent observers and secondarily compares average IB characteristics in relation to patient demographics.

Study Design

A retrospective study of edentulous mandibles was performed using CBCT to assess IB anatomical variation. Three independent observers (2 dental students, 1 licensed oral and maxillofacial radiologist [OMR] independently measured IB length. Eighty-five bilateral measurements were pooled for agreement analysis using coefficients of interrater reliability (IRR). A paired, one-way analysis of variance tested for significant differences between observers. Additionally, the OMR recorded 236 observations for demographic analyses. These were subject to a one-way analysis of variance testing whether IB length varied by sex or port exit. A Pearson's correlation tested for a significant correlation with age. All statistics were performed using R (version 4.1.2) packages IRR, survival, and PerformanceAnalysis.

Results

IRR results show strong, significant agreement across all observers (intraclass correlation coefficient = 0.944, 95% confidence interval 0.921-0.962, P < .0001), indicating no systematic differences was detected. This was corroborated by high correlations between observers (R² = 0.95, P < .0001) and non-significant analysis of variance results (P = .74, F = 0.303). Trained student observers were within 2 mm of OMR values 90% to 93% of the time. Descriptive results showed a mean IB length of 9.93 ± 4.11 (9.72 ± 4.05 for left, 10.17 ± 4.18 for right). A lingual port of exit was observed in 13.56% of cases. There was a significant effect of port on IB length (F = 10.21, P = .002), with lingual ports being shorter (7.82 ± 3.06 mm vs 10.27 ± 4.16 mm). A significant effect was reported for sex (F = 3.916, P = .05), with women having shorter IB lengths (8.98 ± 3.3 mm vs 10.38 ± 3.67 mm). There was no significant correlation with age (R² = −0.094).

Conclusion

The IB measurements had high agreement across observers with varying experience. Edentulous mandibles have a varied anatomic landscape and establishing a predictive IB dimension will aid practitioners in surgical planning.