“Your baby has a tongue-tie” often raises more questions than it answers — how severe is it, how was that decided, and does the grade actually determine whether treatment is needed? Tongue-tie grading is the clinical process dentists and other providers use to describe and categorize a restriction, and understanding how it works can make the diagnosis feel a lot less like a guess.
This article is for general education and isn’t a substitute for an in-person evaluation.
What Is Tongue-Tie Grading?
Tongue-tie grading refers to the systems providers use to classify the severity of ankyloglossia — the medical term for tongue-tie — based on the anatomy of the lingual frenulum and, in more thorough assessments, how the tongue actually functions. Rather than a single universal test, several different classification systems have been developed over the years, and providers often use one or a combination of them depending on their training and the specifics of the case.
Dr. Monica Kim walks through exactly how this evaluation works in her patient video, “How Do Dentists Grade Tongue Ties?”, available on our Frenectomy Care page.
The Main Grading Systems Used Today
Kotlow’s Classification. One of the most widely referenced systems, developed by Dr. Lawrence Kotlow, measures “free tongue length” — the distance from where the frenulum attaches to the underside of the tongue to the tip of the tongue itself. Based on that measurement, ties are generally categorized into four classes: mild, moderate, severe, and complete, with shorter free-tongue measurements indicating more significant restriction.
Coryllos Classification. This system focuses on where the frenulum attaches relative to the tongue, using four types: Type 1 (attached at the very tip of the tongue), Type 2 (attached 2–4mm behind the tip), Type 3 (attached near the mid-tongue), and Type 4, which captures posterior tongue-tie — a restriction hidden under the mucosal tissue at the base of the tongue that can be easy to miss on a quick visual exam.
Hazelbaker Assessment Tool for Lingual Frenulum Function (HATLFF). Unlike the appearance-based systems above, HATLFF scores both anatomical appearance and actual tongue function — things like lateral movement, tongue lift, and the ability to extend the tongue past the lower lip. Because it incorporates function rather than just structure, it’s considered more comprehensive, though it also takes more time and training to administer consistently.
Why Grading Alone Doesn’t Tell the Whole Story
Here’s something worth understanding clearly: a tongue-tie’s grade describes its anatomy, but grade alone doesn’t necessarily predict whether treatment is the right call. A 2022 systematic review examining these classification tools found no statistically significant correlation between the severity score assigned by these systems and post-treatment outcomes in breastfeeding or speech — meaning a moderate-grade tie doesn’t automatically translate to a moderate functional problem, and a mild-grade tie doesn’t guarantee mild or no impact.
This is part of why a thorough evaluation looks beyond frenulum measurement alone. Posterior tongue-tie is a good example of why: because it’s hidden beneath mucosal tissue rather than clearly visible, a posterior tie can be missed entirely by an appearance-only exam, even though it can meaningfully restrict tongue function, particularly for feeding. This is one reason a functional evaluation — actually watching how the tongue moves and performs specific tasks — is such an important complement to anatomical grading, not a replacement step to skip.
There’s also meaningful inconsistency in how these systems are applied in practice. Different providers may lean on different classification tools, use different measurement techniques, or weigh function differently in their overall assessment. This is a normal part of a field where diagnostic criteria are still evolving, but it’s also why getting a second opinion or a more comprehensive evaluation can be reasonable if a diagnosis or recommendation doesn’t feel fully explained.
What This Means for Your Evaluation
When we assess a tongue-tie, grading is one part of a bigger picture, not the whole diagnosis. We look at anatomical classification alongside functional testing and, most importantly, whatever specific problem brought you in — a feeding struggle, a speech concern, or discomfort. The decision to move forward with a frenectomy is based on that full picture, not a grade number in isolation.
If you’d like the broader context on what a frenectomy actually treats and how the decision-making process works overall, our pillar guide covers it in full: What Is a Frenectomy? Tongue-Tie and Lip-Tie Explained.
What Happens After Diagnosis
If an evaluation confirms a tongue-tie that’s genuinely affecting feeding, speech, or comfort, the next step is typically discussing frenectomy treatment. We perform releases using laser technology for many of our patients — you can read more about that specific approach, and why we chose it, in Laser Frenectomy & BabyLase: Why We Use It.
Getting an Accurate Diagnosis
Because grading alone doesn’t reliably predict functional impact, the most useful evaluation combines anatomical assessment with a real look at how the tongue is actually functioning day to day. If you suspect a tongue-tie in your child — or in yourself — schedule a consultation with our team for a complete evaluation rather than relying on appearance alone.
References
- Effectiveness of tongue-tie assessment tools in diagnosing and fulfilling lingual frenectomy criteria: a systematic review. PubMed. https://pubmed.ncbi.nlm.nih.gov/35689515/
- Diagnosis, Classification and Management of Ankyloglossia Including Its Influence on Breastfeeding. PMC, National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC8522341/