Relationship between anterior occlusion, arch dimension, and mandibular movement during speech articulation: A three-dimensional analysis

Statement of problem: Studies correlating occlusal morphology from 3-dimensional intraoral scans with both soft and hard tissue dynamic landmark tracking within the same participant population are lacking. Purpose: The purpose of this clinical study was to use 3-dimensional intraoral scanning, computer-aided design, electrognathography, and artificial intelligence to investigate the relationships between anterior occlusion and arch parameters with hard and soft tissue displacements during speech production. Material and methods: An artificial intelligence (AI) driven software program and electrognathography was used to record the phonetic activities in 62 participants for soft tissue (ST) and hard tissue (HT) displacement. Soft tissue displacement was quantified by the mean difference between subnasale and soft tissue pogonion peaks during phonetic expressions, and hard tissue displacement was directly measured with an electrognathograph. Intercanine and intermolar distances, arch perimeters, and horizontal and vertical overlap were measured from the intraoral scan data. Results: ST and HT displacements were successfully estimated for fricative (ST=7.16 ±4.51 mm, HT=11.86 ±4.02 mm), sibilant (ST=5.11 ±3.49 mm, HT=8.24 ±3.31 mm), linguodental (ST=5.72 ±4.46 mm, HT=10.01 ±3.16 mm), and bilabial (ST=5.56 ±4.64 mm, HT=11.69 ±4.28 mm) phonetics. Vertical overlap correlated positively with hard tissue movement during all speech expressions except bilabial phonetics (ρ=.30 to.41, P<.05). Maxillary and mandibular arch perimeters showed negative correlations with soft tissue displacement during linguodental and bilabial speech (ρ=−.25 to −.41, P<.05) but were significantly correlated with hard tissue movement during all speech assessments (ρ=−.28 to −.44, P<.05). Maxillary intermolar distances negatively correlated with hard tissue phonetic expressions (ρ=−.24 to −.30, P<.05). Participant age positively correlated with soft tissue displacement during all speech patterns (ρ=.28 to.33, P<.05) and with weight increase (ρ=.27, P=.033), and hard tissue displacement (ρ=.25, P=.048) during maximum mouth opening significantly correlated with linguodental phonetics. Conclusions: Within the study population, vertical overlap, maxillary intermolar distance, and dental arch perimeters correlated significantly with mandibular displacement during phonetic expression.