Different ways to look at a tongue tie:

Kotlow (anatomic) classification — defines anterior attachment and measured free tongue length

  • Class I (Mild): Free tongue length 12–16 mm; minimal restriction.

  • Class II (Mild–Moderate): Free tongue length 8–11 mm; some functional limitation.

  • Class III (Moderate): Free tongue length 3–7 mm; clear functional restriction (lifting, protrusion).

  • Class IV (Severe): Free tongue length <3 mm; severe restriction, often posterior frenulum/fibrous tissue with marked functional impairment.

Coryllos classification — anatomic types by frenulum insertion (used mainly in surgical planning)

  • Type I (Anterior): Frenulum attaches at tip of tongue (visible, anterior); usually most apparent and often considered less complex to release.

  • Type II (Near anterior): Frenulum attaches just behind tip; still anterior but slightly more posterior.

  • Type III (Posterior / Submucosal): Frenulum attaches to mid-tongue or under mucosa; less visible externally and often causes more functional restriction.

  • Type IV (Posterior / Sublingual): Very posterior, submucosal, or under-surface fibrous bands; often the most functionally significant and hardest to visualize.

Hazelbaker Assessment Tool for Lingual Frenulum Function (HATLFF) — combines Appearance (0–10) and Function (0–14) scores; lower total/function scores indicate greater impairment

  • Appearance items (each 0–2): length of lingual frenulum when lifted, attachment to tongue, attachment to inferior alveolar ridge, elasticity, etc. Lower appearance subtotal = more abnormal appearance.

  • Function items (each 0–2): lateralization, lift, extension, spread, cupping, peristalsis, snapback; lower function subtotal = worse function.

  • Interpretation (commonly used cutoffs):

    • Recommendation for frenotomy likely: Appearance score ≤8 OR Function score ≤11 (i.e., low scores indicate more severe restriction).

    • Milder/no treatment suggested: Higher appearance and function scores (closer to maximums) indicate normal or near-normal appearance/function.

Notes:

  • Kotlow and Coryllos are primarily anatomical; Kotlow uses measured free-tongue length, Coryllos uses position/type.

  • HATLFF focuses on function and appearance with numeric scoring where lower scores reflect greater severity — which can cause confusion when “Grade 1” or low numbers mean worse function.