THE RELATIONSHIP OF TONGUE POSITION VIA THE MODIFIED MALLAMPATI TONGUE SCORE TO CRANIOFACIAL MORPHOLOGY AND HEAD POSTURE

Abstract

Introduction: The Modified Mallampati Tongue score is a quick and reliable method commonly used in anesthesiology to assess airway patency and predict the ease of intubation. Modified Mallampati Tongue scores range from I – IV with higher Mallampati scores being associated with more difficult intubations as well as increased sleep-disordered breathing, such as obstructive sleep apnea. The Mallampati Tongue score is determined by visibility of the oropharynx when the mouth is opened as wide as possible with the tongue maximally protruded and is directly affected by the position of the tongue. The tongue is an influential muscle to the craniofacial complex; it plays an essential role in the development of the dentoalveolar structures, and its position affects airway volume which influences natural head posture, which influences craniofacial growth. Objective: The primary aims of this study were to identify if any associations exist between Modified Mallampati Tongue scores (I-IV) and 1) craniofacial sagittal and vertical relationships of the jaws and 2) craniofacial head posture (including the postural relationships of the cervical vertebrae, hyoid bone, cranium, and tongue). A secondary aim was to identify if any associations exist between Modified Mallampati Tongue score and age, sex, or race/ethnicity. Methods: This retrospective study included 400 subjects from the Temple University Kornberg School of Dentistry Department of orthodontics who had pre-orthodontic treatment diagnostic records obtained from June 1st 2020 through September 1st 2021. Each patient’s Modified Mallampati Tongue score (I-IV) was recorded in an intraoral photograph of maximum mouth opening with tongue protrusion. All lateral cephalograms were traced in Dolphin Imaging and Amira Morphometrics Software by two examiners tracing 200 subjects each. The craniofacial morphological features were analyzed through the Steiner, Wits, and McNamara analyses for assessment of the sagittal relationships of the maxilla and mandible and by the Jarabak analysis for assessment of the vertical relationships and divergence. Craniofacial head posture was assessed through an analysis that represents the postural relationships of the cervical vertebrae, cranium, length/height of the tongue, and position of the hyoid bone. For statistical analysis, One-way ANOVA, Pearson’s correlation, and Chi-square tests were conducted. Probability values of <0.05 were considered significant. Results: Overall, this study included 400 subjects with ages ranging from 7-73 years old (mean age of 17.99 years), of which there were 288 females (72%) and 112 males (28%). Of the 400 subjects, 60% (241) were African American, 32% (127) Hispanic, 7% (26) Caucasian, and 2% (6) Asian. The most prevalent Modified Mallampati Tongue Score was III (142 subjects, 36%). Out of all of the craniofacial morphology and head posture variables compared against Modified Mallampati Tongue scores (I-IV), significant findings from the one-way ANOVA tests included vertical position of the hyoid bone to the neck, vertical position of the hyoid bone to the mandible, ANB, and Wits values. Higher Mallampati Tongue scores were associated with higher ANB and higher Wits values. Greater Mallampati scores were associated with increased vertical distance of the hyoid bone to the mandible and to the neck, meaning a lower position of the hyoid bone. In addition, correlations that were statistically significant given a 95% confidence interval, included significant positive correlations between Mallampati Tongue score and increased ANB, Wits, and distance of the hyoid to the mandible and to the neck. Pearson’s Correlation Index also showed a significant negative correlation between Mallampati Tongue scores and craniofacial morphology values for SNB and pogonion to nasion-perpendicular, showing that increased Modified Mallampati Tongue scores correlate with more retrognathic mandibles. When evaluating the results of the Chi-Square analyses, there were no significant differences between Modified Mallampati Tongue score and race/ethnicity or age, but there was a significant difference between genders showing that women were more likely to have lower Mallampati Tongue scores than men. Inter-examiner and intra-examiner reliability for the craniofacial head posture measurements, craniofacial morphology measurements, and Modified Mallampati Tongue scores were excellent (correlation coefficients: 0.84 – 0.99). Conclusions: This study reveals that a higher Modified Mallampati Tongue score correlates with higher ANB and Wits values, meaning that higher Modified Mallampati Tongue scores are associated with a Skeletal Class II relationship of the jaws, which could be due to retrognathic mandibular growth. In addition, a higher Modified Mallampati Tongue score is significantly associated with increased distance of the hyoid bone to the mandible and to the neck. This study also found women more likely to have lower Modified Mallampati Tongue scores than men. The results of this study allude to the potential for Mallampati Tongue scores to be used as predictors of Class II skeletal sagittal growth which would ultimately help with orthodontic treatment planning decisions and enhance overall treatment outcomes.