Tongue-tie assessment tools: appearance, function and validation

Tongue-tie assessment involves more than identifying a lingual frenulum or assigning a score to its appearance. The clinical question is whether the tongue’s structure and movement are restricted in a way that may affect feeding, and whether the findings are consistent with the difficulties experienced by the infant and feeding dyad.

Several tools are used by healthcare professionals to assess infant tongue-tie, also known as ankyloglossia. They differ in their assessment criteria, the functions they examine and the evidence supporting their use. Some concentrate on anatomical appearance, some assess tongue movement, and others incorporate a broader range of oral function or feeding-related observations.

Understanding these differences is important because a tool can help to structure an assessment without necessarily establishing the cause of feeding difficulties or predicting the outcome of frenulotomy. A score is one part of the clinical picture, not a substitute for clinical reasoning.

The systematic review by Necus et al. (2025) identified nine assessment tools used in infants from birth to 12 months and found variation in their content and supporting evidence. This highlights the continuing challenge of identifying a consistent, reliable approach to assessing tongue-tie in infants.

For further information, see What does a tongue-tie assessment consider? and How is tongue-tie assessed in babies safely?.

The distinction between appearance and function

The lingual frenulum is a normal anatomical structure. Its appearance varies between individuals, and visible differences do not automatically indicate a functional restriction. Conversely, the appearance of the frenulum alone may not fully describe how the tongue moves during feeding.

Ankyloglossia is generally understood as a congenital condition in which the lingual frenulum restricts tongue movement. However, there is no universally accepted definition or single assessment method that establishes the clinical significance of every presentation (Messner et al., 2020; Thomas et al., 2024).

A comprehensive assessment considers several related areas:

• Anatomy: the appearance of the lingual frenulum and its relationship to the tongue and floor of the mouth.

• Function: the tongue’s ability to elevate, extend, lateralise and move in ways relevant to feeding.

• Feeding impact: whether observed feeding difficulties are consistent with the functional findings, taking account of the wider feeding dyad.

These areas need to be considered together. A visible frenulum, a particular attachment point or a numerical score cannot independently establish that tongue-tie is responsible for feeding difficulties.

Hatami et al. (2022), in a systematic review of tongue-tie assessment tools, found limitations in the evidence supporting the use of assessment classifications to determine which infants would benefit from frenotomy. Identifying an anatomical variation, classifying its severity and deciding whether an intervention is clinically indicated are related but different tasks.

Hazelbaker Assessment Tool for Lingual Frenulum Function (HATLFF/ATLFF)

The Hazelbaker Assessment Tool for Lingual Frenulum Function, also referred to as the Assessment Tool for Lingual Frenulum Function (ATLFF), was developed by Alison Hazelbaker. It assesses both the appearance of the lingual frenulum and aspects of tongue function.

The tool includes anatomical features as well as functional items such as lateralisation, lift and extension of the tongue, alongside observations relating to sucking. Its broader structure is intended to provide more information than an assessment based on the frenulum’s appearance alone.

Amir, James and Donath (2006) examined the reliability of the Hazelbaker tool. They reported good agreement between assessors for several functional items, although agreement was weaker for some appearance items. Their findings illustrate why the reliability of individual assessment components matters when interpreting a total score.

The HATLFF/ATLFF has also been used as a comparison tool during the development of other assessment methods. However, its use as a reference does not establish that every tool correlated with it can independently predict feeding outcomes or the need for frenulotomy (Hatami et al., 2022).

Bristol Tongue Assessment Tool (BTAT)

The Bristol Tongue Assessment Tool was developed by Ingram et al. (2015) to provide a simpler, structured way of assessing tongue-tie in infants.

The BTAT assesses four features:

• The appearance of the tongue tip.

• The attachment of the lingual frenulum to the lower gum ridge.

• Tongue elevation.

• Tongue protrusion.

Each item contributes to the overall score, allowing the assessor to record findings consistently.

Importantly, Ingram et al. (2015) state that the BTAT was developed from clinical practice with reference to the Hazelbaker Assessment Tool for Lingual Frenulum Function. The authors compared the BTAT with the ATLFF in a group of infant assessments and reported a strong correlation between the tools, alongside acceptable internal reliability and good consistency between assessors using the BTAT.

These findings supported the BTAT as a practical, shorter assessment method. They do not demonstrate that a BTAT score alone can identify the cause of feeding difficulties or reliably predict which infants will benefit from frenulotomy.

The 2026 systematic review and meta-analysis by Dhar et al. reported high discriminative accuracy for the BTAT and TABBY when identifying ankyloglossia. However, the authors rated the overall certainty of evidence as very low. The distinction between identifying a restrictive lingual frenulum and establishing its functional impact therefore remains important.

Tongue-tie and Breastfed Babies Assessment Tool (TABBY)

The Tongue-tie and Breastfed Babies Assessment Tool, known as TABBY, was developed by Ingram et al. (2019) as a pictorial version of the BTAT.

TABBY uses illustrations to represent the same four assessment areas: tongue-tip appearance, frenulum attachment, elevation and protrusion. Its visual format is intended to make the assessment criteria easier to understand and apply consistently.

The score ranges from 0 to 8, with lower scores indicating greater restriction according to the tool’s scoring system. The illustrations can help assessors communicate the features being observed, but the score still needs to be interpreted alongside the infant’s function and feeding assessment.

Ingram et al. (2019) evaluated TABBY in clinical practice and reported high agreement between TABBY and BTAT scores. Agreement between two related tools is useful evidence of consistency, but it is not the same as demonstrating that either tool can predict feeding outcomes or the response to frenulotomy.

The 2026 review by Dhar et al. considered BTAT and TABBY together and reported promising diagnostic discrimination, while emphasising the very low certainty of the overall evidence. These findings support structured assessment rather than using a score in isolation to determine treatment.

Lingual Frenulum Protocol for Infants (LFPI)

The Lingual Frenulum Protocol for Infants, developed by Martinelli and colleagues, provides a more comprehensive assessment framework. It incorporates a range of anatomical and functional observations and includes information relating to sucking and feeding.

The original protocol was described by Martinelli, Marchesan and Berretin-Felix (2012). It has two parts: a clinical history, including questions about family history and breastfeeding, and a clinical examination incorporating anatomical and functional assessment alongside non-nutritive and nutritive sucking observations.

Martinelli et al. (2016) subsequently published validation work on the protocol. Its broader scope is relevant when considering the relationship between oral structure, tongue movement and feeding function.

Necus et al. (2025) identified the LFPI as the most comprehensive of the tools included in their review and reported that it had the greatest amount of reported reliability and validity evidence among the tools they examined. This should not be interpreted as proof that it is a definitive diagnostic standard. The review identified limitations in the evidence base across the available tools, and the comprehensiveness of a protocol does not automatically establish its ability to predict clinical outcomes.

The LFPI illustrates the difference between a brief screening or classification tool and a more extensive assessment protocol. The appropriate approach depends on the clinical question, the assessor’s competence and the wider assessment of the infant and feeding dyad.

Coryllos classification

The Coryllos classification describes the anatomical location and pattern of lingual frenulum attachment. It divides tongue-tie into four types, from attachment at the tip of the tongue to attachment further underneath the tongue or towards its base. It is an anatomical classification rather than a numerical score of tongue function.

The four types are commonly described as follows:

• Type I: the frenulum attaches at or very close to the tip of the tongue. The attachment may be associated with a heart-shaped appearance when the tongue is extended.

• Type II: the frenulum attaches approximately 2–4 mm behind the tongue tip, on or near the alveolar ridge.

• Type III: the frenulum attaches around the middle of the underside of the tongue and the middle of the floor of the mouth.

• Type IV: the frenulum attaches towards the base of the tongue and may be deep or submucosal, making it less readily visible on inspection.

Types I and II are generally described as anterior presentations, while types III and IV are often discussed in relation to posterior tongue-tie. The term posterior tongue-tie is itself subject to debate, and the presence of a less visible frenulum does not independently establish functional restriction (Messner et al., 2020; Thomas et al., 2024).

Unlike the BTAT or HATLFF/ATLFF, Coryllos classification does not assign points to several assessment items and produce a total score. The assessor assigns an anatomical type according to the attachment observed or palpated.

The classification can therefore help describe the anatomical finding, but it does not measure the degree of restriction during feeding or establish whether the infant’s difficulties are caused by the frenulum. A type should not be interpreted as a direct measure of clinical severity or as an indication for frenulotomy.

Kotlow classification

The original Kotlow classification grades tongue-tie according to the measured length of the free portion of the tongue. This is the distance from the tongue tip to the point where the lingual frenulum attaches to the underside of the tongue. Kotlow (1999) proposed four classes based on this measurement, with shorter free-tongue length assigned a higher grade.

The commonly reported original categories are:

| Kotlow classification | Free tongue length | Description | |---|---:|---| | Within the stated normal range | More than 16 mm | Normal free-tongue length according to this classification | | Class I | 12–16 mm | Mild ankyloglossia | | Class II | 8–11 mm | Moderate ankyloglossia | | Class III | 3–7 mm | Severe ankyloglossia | | Class IV | Less than 3 mm | Complete ankyloglossia |

These measurements describe the anatomical length of the free portion of the tongue. They do not directly measure the tongue’s ability to elevate, extend, lateralise or maintain the movements needed for effective feeding.

It is important not to confuse Kotlow’s original length-based classification with modified grading systems that classify the position of the frenulum’s attachment in relation to the tongue tip. Modified systems may use different class boundaries and measurement criteria; the version being used should therefore be identified rather than treating all Kotlow grading systems as interchangeable.

Obtaining a consistent measurement in an infant may also be challenging, particularly when tongue movement is restricted or the attachment point is difficult to identify. The classification should be understood as an anatomical description, not a comprehensive functional assessment.

Kotlow’s original paper, ‘Ankyloglossia (tongue-tie): a diagnostic and treatment quandary’ (1999), proposed diagnostic criteria and a classification method. The use of a measurement to grade anatomy does not, by itself, establish whether frenulotomy is indicated or predict the likely feeding outcome.

Comparing tongue-tie assessment tools

| Tool | Main focus | Important consideration | |---|---|---| | HATLFF/ATLFF | Appearance and several aspects of tongue function, including sucking-related observations | A broader tool, but reliability varies between individual items | | BTAT | Four structured anatomical and movement items | Developed with reference to the ATLFF; a score does not independently establish feeding impact | | TABBY | Pictorial assessment of the same four areas as BTAT | Visual format may support consistent scoring; it does not replace clinical assessment | | LFPI | Broader anatomical and functional assessment, including sucking and feeding-related information | More comprehensive, although limitations remain in the evidence base | | Coryllos | Four types based on the location and characteristics of frenulum attachment | Describes anatomical type rather than providing a comprehensive functional score | | Kotlow | Original classification uses four grades based on measured free-tongue length | A measurement-based anatomical grade does not directly assess feeding function |

The tools differ in purpose and scope, so they should not be treated as interchangeable. A tool designed primarily to classify anatomy answers a different question from a protocol that includes functional observations. Similarly, a tool’s reported reliability does not necessarily establish its validity for predicting feeding outcomes.

Feeding assessment alongside tongue-tie assessment

Tongue movement and feeding function need to be considered together. A structured tongue assessment can document anatomical features and movement, but it cannot replace an assessment of the feeding dyad.

For breastfeeding, relevant observations may include attachment, positioning, milk transfer, sucking patterns, swallowing, maternal comfort and the sustainability of feeding. For bottle feeding, the assessment may also consider the infant’s oral seal, sucking pattern, coordination, flow tolerance and signs of feeding difficulty. The particular observations required depend on the infant and the reported concerns.

The assessment also needs to consider other factors that may contribute to feeding difficulties. These can include positioning, feeding technique, milk flow, oral-motor function, infant state, discomfort and wider health or developmental considerations. The presence of a lingual frenulum does not establish that it is the cause of every feeding difficulty.

An assessment should therefore explore the reported difficulties, observe feeding where appropriate and relate those findings to the tongue’s functional movement. This helps distinguish the identification of an anatomical variation from the clinical judgement that the variation is contributing to a feeding problem.

Further reading includes What does an infant feeding specialist do?, What is an IBCLC? Feeding Support Explained and Lactation support: What does a Lactation Consultant do?.

Training, competence and diagnostic responsibility

Using an assessment tool consistently requires an understanding of its purpose, scoring criteria and limitations. Professionals also need to recognise when findings are unclear, when further assessment is needed and when feeding difficulties may have more than one contributing factor.

Training can support consistent use of an assessment tool, but familiarity with a scoring system does not automatically establish competence in every aspect of tongue-tie assessment or frenulotomy. Practitioners need to work within their professional scope, training and governance arrangements, and should be familiar with the evidence and guidance relevant to their clinical role.

The terms and conditions associated with individual tools may also differ. Professionals should check the relevant publication, permissions and training requirements rather than assuming that every tool has the same conditions for reproduction or teaching.

Where frenulotomy is being considered, the practitioner responsible for the procedure must reach an appropriate clinical decision based on their assessment, the infant’s presentation and the feeding concerns. A score should not be used as the sole justification for a procedure.

For further information, see What 'Tongue-tie School' teaches healthcare professionals and Tongue-tie training for evidence-based care.

Integrating assessment findings into clinical decisions

The Academy of Breastfeeding Medicine (2021) describes ankyloglossia as a functional diagnosis and states that the presence of a sublingual frenulum alone is not an indication for frenotomy. The clinical decision needs to consider whether there is a functional restriction associated with breastfeeding difficulties and whether appropriate support has addressed potentially modifiable factors.

The American Academy of Pediatrics clinical report by Thomas et al. (2024) similarly emphasises the importance of a comprehensive assessment of feeding difficulties and consideration of other causes before intervention. These recommendations reinforce the distinction between anatomical identification and a decision about treatment.

Assessment tools can help professionals record findings, communicate with colleagues and monitor changes over time. Their value depends on using them for the purpose for which they were developed and interpreting their findings in context.

A clinical decision should bring together the infant’s oral anatomy, tongue movement, observed feeding, the concerns described by the feeding dyad and the response to appropriate feeding support. Where the findings do not align, further assessment may be needed rather than allowing a numerical score to determine the outcome.

For related information, see Does my baby need a tongue-tie release?, When feeding doesn't feel right: Looking beyond tongue-tie and Tongue-tie: understanding assessment, feeding, treatment and aftercare.

References

Academy of Breastfeeding Medicine (2021) ‘Academy of Breastfeeding Medicine position statement on ankyloglossia in breastfeeding dyads’, Breastfeeding Medicine, 16(4), pp. 278–281. doi: 10.1089/bfm.2021.29179.ylf.

Amir, L.H., James, J.P. and Donath, S.M. (2006) ‘Reliability of the Hazelbaker Assessment Tool for Lingual Frenulum Function’, International Breastfeeding Journal, 1, article 3. doi: 10.1186/1746-4358-1-3.

Dhar, V. et al. (2026) ‘Diagnostic Assessment of Ankyloglossia and Association With Infant Feeding Challenges: A Systematic Review and Meta-Analysis—Part 1’, Pediatric Dentistry, 48(2), pp. 68E–82E.

Hatami, A., Dreyer, C.W., Meade, M.J. and Kaur, S. (2022) ‘Effectiveness of tongue-tie assessment tools in diagnosing and fulfilling lingual frenectomy criteria: a systematic review’, Australian Dental Journal, 67(3), pp. 212–219. doi: 10.1111/adj.12921.

Ingram, J., Johnson, D., Copeland, M., Churchill, C., Taylor, H. and Emond, A. (2015) ‘The development of a tongue assessment tool to assist with tongue-tie identification’, Archives of Disease in Childhood: Fetal and Neonatal Edition, 100(4), pp. F344–F349. doi: 10.1136/archdischild-2014-307503.

Ingram, J., Johnson, D., Copeland, M., Churchill, C., Taylor, H. and Emond, A. (2019) ‘The development and evaluation of a picture tongue assessment tool for tongue-tie in breastfed babies (TABBY)’, International Breastfeeding Journal, 14, article 31. doi: 10.1186/s13006-019-0224-y.

Kotlow, L.A. (1999) ‘Ankyloglossia (tongue-tie): a diagnostic and treatment quandary’, Quintessence International, 30(4), pp. 259–262.

Martinelli, R.L.C., Marchesan, I.Q. and Berretin-Felix, G. (2012) ‘Lingual frenulum protocol with scores for infants’, International Journal of Orofacial Myology, 38(1), pp. 104–112. doi: 10.52010/ijom.2012.38.1.8.

Martinelli, R.L.C., Marchesan, I.Q., Gusmão, R.J., Honório, H.M. and Berretin-Felix, G. (2016) ‘Validation of the Lingual Frenulum Protocol for Infants’, International Journal of Orofacial Myology, 42(1), pp. 5–13. doi: 10.52010/ijom.2016.42.1.1.

Messner, A.H. et al. (2020) ‘Clinical consensus statement: Ankyloglossia in children’, Otolaryngology–Head and Neck Surgery, 162(5), pp. 597–611. doi: 10.1177/0194599820915457.

Necus, E., Claessen, M., Hennessey, N. and Smart, S. (2025) ‘Assessment of tongue structure and function in infants for the diagnosis of ankyloglossia: A systematic review’, International Journal of Pediatric Otorhinolaryngology, 196, article 112485. doi: 10.1016/j.ijporl.2025.112485.

Thomas, J. et al. (2024) ‘Identification and management of ankyloglossia and its effect on breastfeeding in infants: Clinical report’, Pediatrics, 154(2), article e2024067605. doi: 10.1542/peds.2024-067605.