The mandibular lingula (spine of Spix) in contemporary research
A comprehensive critical review of global morphological variability of the mandibular lingula, showing that shape frequencies, morphometric expectations, and surgical landmark value are strongly influenced by study method, population, and the difference between dry-bone and CBCT approaches.
The lingula is clinically important, but its morphology is too variable for simplistic rules.
The review integrates major studies from 2000–2025 and argues that morphology, bilateral symmetry, and landmark reliability depend on how and where the lingula is studied. Clinical planning should therefore be evidence-based, population-aware, and patient-specific.
Why the lingula matters
The lingula is a key landmark for inferior alveolar nerve block, sagittal split ramus osteotomy, and other mandibular ramus procedures. Its reliability therefore matters directly for oral and maxillofacial practice.
Years reviewed
Major studies spanning 2000–2025 were synthesised.
Shapes discussed
Triangular, truncated, nodular, assimilated, and bridge/M-shaped morphologies.
Subjects
Meta-analytic morphometric data represented 4694 individuals.
Populations
Evidence spanned at least nineteen populations on six continents.
The lingula is morphologically diverse
The review consolidates the main morphotypes discussed in contemporary literature and adds the recently described bridge/M-shaped state to the classical four-shape framework.
Dry-bone and CBCT studies do not tell the same story
A central contribution of the review is methodological: the most frequent lingula shape changes when the literature is split by study type. Pooling these data without caution can therefore distort interpretation.
Four clinically useful conclusions
The review translates descriptive anatomy into guidance for mandibular procedures and landmark selection.
The internal oblique/mylohyoid ridge is a strong auxiliary landmark
It was highly visible in the reviewed evidence and yielded superior reported success rates when used to guide inferior alveolar nerve block.
The antilingula should not be trusted alone
The review critically re-evaluates the antilingula and concludes that it has limited value as a sole landmark, although it may still supplement a broader strategy when posterior safety margins are respected.
Bilateral symmetry cannot be assumed
Right–left similarity is not consistent enough for procedural planning. Patient-specific assessment is more defensible than symmetrical assumptions.
Protocols should be population-aware
The review explicitly argues for evidence-based, population-specific surgical and anaesthetic protocols rather than universal rules.
From descriptive variation to safer use
This scheme condenses the review’s logic from morphology and method bias to procedural consequence.
Selected values highlighted in the review
These values support the argument that auxiliary landmarks may outperform standard assumptions in practice.
Ridge visibility
The internal oblique/mylohyoid ridge emerges as a strong alternative landmark.
Reported success
Superior IANB success has been reported when that ridge guides injection.
Traditional method
Conventional IANB success rates are lower in the comparison cited by the review.