The anesthesia technique for the inferior alveolar nerve (IAN) is commonly used for mandibular dental and surgical procedures. However, it has a high failure rate between 38 % to 77 %, often attributed to operator-related issues and anatomical variations. This study aims to quantify the average needle penetration depth during the IAN block procedure and their relationship with facial index and sex in adult patients. A cross-sectional study was conducted in 182 adult patients aged 18–45 years who required mandibular tooth extraction. Participants were classified according to their facial index (euryprosopic, mesoprosopic, or leptoprosopic) and sex. The average needle penetration depth for females was 24.24 mm (±3.66 mm) and 25.03 mm (±3.84 mm) for males. Regarding facial index, the euryprosopic group had the deepest average penetration (26.06 mm ± 3.27 mm), followed by the mesoprosopic group (25.28 mm ± 3.64 mm). Statistically significant differences in needle penetration length were observed between facial index groups (p < 0.05). The study found that euryprosopic individuals requiring deeper needle insertion for the IAN block. These findings suggest that facial index may serve as an additional factor to consider when determining needle depth, potentially enhancing the precision and success of the IAN block technique.
KEY WORDS: Inferior alveolar nerve block; Needle penetration; Facial index; Leptoprosopic; Sex; Dental anesthesia.
ARAVENA, P. C. & CARTES-VELÁSQUEZ, R. Relationship between facial index and needle penetration depth in inferior alveolar nerve block: A cross-sectional study. Int. J. Morphol., 43(5):1619-1623, 2025.
