Effects of Volumetric Alterations of the Tongue Base on Craniofacial Growth in the Adult Minipig

Craniofacial growth determines the proper functional coordination of skeletal and soft tissue structures. Alterations related to size, volume, and other parameters may impair expected growth and function. Thus, this study aimed to analyze the effects of volume-reduced and volume-enlarged tongue base on craniofacial skeletal growth. Three groups of Yucatan minipigs included control, 7-8-month-old (n = 8), half each sex; experimental volume-reduction group treated by coblation (n = 6), with concurrent left masseter volume-reduction as well for later myoregeneration analysis; and experimental volume-enlargement group (n = 6), via diet-induced obesity. Both experimental groups were 7-9-month-old same-sex sibling pairs, half each sex. After cardiac perfusion fixation, the tongue and masseter were dissected, followed by soft tissue removal from each skull. Over 90 anatomic landmarks yielded 51 linear distances, and weights/sizes/volumes of the tongues and masseters were measured. All measured variables in controls were normalized for age prior to statistical analysis. One-way ANOVA with Bonferroni post hoc and Pearson's correlations were used. The reduction group showed significantly smaller craniofacial skeletal and dental arch than controls. For instance, the midfacial width (p = 0.042), maxillary inter-canine width (p = 0.001), and mandibular ramus height (p = 0.035) were significantly reduced. The enlargement group also showed significantly decreased distances between sides compared to controls (i.e., inter-canine width p = 0.001, inter-premolar width p = 0.005, and inter-molar width p = 0.007). Strongest associations were found between the whole tongue and structures in the base of the skull of the reduction group, and between the tongue base volume and mandibular structures such as the mandibular ramus height (r = -0.804, p = 0.016). In conclusion, volumetric alterations of the tongue base either enlargement or reduction significantly increase and decrease craniofacial growth. These findings may help clinicians to understand the potential mechanisms of disease in respiration and swallowing disorders induced by changes in soft tissue affecting the craniofacial skeleton.