Tongue Volume Reduction Effects on Craniofacial Growth:A Longitudinal Study

Objective: The interaction between tongue size/volume and craniofacial skeletal growth is essential to understand mechanisms of specific types of malocclusion and evaluate outcomes of various surgical and/or orthodontic treatments. This study was designed to address this important issue.

Methods: Five 12-week-old sibling pairs of Yucatan minipig were used. Of each pair, one recieved uniform glossectomy to reduce tongue volume by 15-17%(reduction), and the other had the same incision without tongue tissue removal(sham). Before surgery, five stainless screws were implanted into various craniofacial skeletal locations. Lateral and axial cephalography were taken one week before, two and four weeks after surgery. These longitudinal cephalograms were traced using superiposition and digitized for linear and angular measurements. Upon sacrifice, osteometric measurements were made on harvested skulls. Five en-bloc bone pieces were cut for bone mineral examination by DEXA.

Results: 1)Tongue volume reduction had a negative effect on craniofacial skeleton linear expansion, even though daily food comsumption and weekly body weight were not significantly affected. 2)Premaxillary and mandibular symphysis lengths, and anterior dental arch width were significantly less in reduction animals, two and/or four weeks post-operatively, as compared to sham animals in cephalometric measures. 3)Anterior mandibular length, ramus height, anterior dental arch width midface widths were significantly smaller in reduction than sham animals in osteometric measures. 4)Premaxillary/maxillary and mandibular bone mineral density and content were lower in reduction animals than sham animals. This difference was most pronounced in the anterior mandible.

Conclusions: Tongue body volume reduction in young animals slows craniofacial skeletal growth and anterior dental arch expansion. In particular, symphysis portion of the mandible and the anterior dental arch width are most affected. These effects may attribute to changes in local loading environment during function, occurring in the anterior mouth following the volume reduction.

Funded by NIH grants R01DE15659.