Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Clinical Dentistry

Program

Orthodontics

Supervisor

Ali Tassi

Abstract

Objectives: To determine the association between anatomic and functional ankyloglossia (tongue-tie), and malocclusion development. Secondarily, to investigate the association between ankyloglossia and obstructive sleep apnea risk.

Material and Methods: This was a cross-sectional chart review of 235 subjects from a university orthodontic clinic. Anatomic and functional ankyloglossia, measured with Kotlow free tongue measurement and tongue range of motion ratio (TRMR) respectively, were assessed for association with cephalometric and dental cast variables, representative of maxillofacial skeletal and dental structures. OSA risks were estimated with age-appropriate questionnaires and assessed for association with the tongue measurements.

Results: TRMR measurements of free tongue mobility, and Kotlow measurements of free tongue length were found to be moderately and positively correlated. Both TRMR and Kotlow measures were associated with molar occlusion, with more severely tongue-tied groups presenting with lower proportions of Angle Class I relationships. However, no other cephalometric or dental cast variables were consistently associated with both TRMR and Kotlow tongue measurements, including those indicative of maxillary transverse deficiency. Although Kotlow classification showed some association with patient-reported mouth breathing, neither TRMR nor Kotlow measures were associated with increased risks of obstructive sleep apnea.

Conclusions: These findings suggest that restricted tongue mobility and lingual frenulum attachment level may affect the development of malocclusion. However, this was mostly evident in only the most severe cases of ankyloglossia, and the degree of impact may not be clinically significant.

Summary for Lay Audience

With the ongoing interest and controversies, the study was designed to assess the relationship between tongue-tie and the development of facial and dental structures. Over 200 patients from a university orthodontic clinic were assessed for varying degrees of tongue-tie. Radiographic and dental measurements were also made and assessed for possible association to the tongue-tie measurements in these patients. Secondarily, the risk of obstructive sleep apnea (OSA) was assessed with questionnaires and its relationship to the tongue-tie measurements was also determined.

Overall, tongue-tie was associated with some features of dental structures, most notably the length of the lower dental arch as well as the antero-posterior relationship of upper and lower molars. On the other hand, there was no significant finding regarding the relationship between tongue-tie and facial skeletons as well as OSA risks.

As a result, we postulate that the degree of tongue mobility and anatomic tongue-tie may affect the development of malocclusion, but the degree of its impact is most evident in the severe cases of tongue-tie and may be clinically insignificant.

Available for download on Friday, August 07, 2026

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