A dynamic analysis of the display of the dentition during speech

The aim of this prospective study was to quantify the display of the dentition through the soft tissue frame during speech using videography for different age groups. Two hundred and sixty-one subjects were initially screened and were divided into five groups: group 1 (G1) (15-19 years), G2 (20-29 years), G3 (30-39 years), G4 (40-49 years), and G5 (≥ 50 years). Groups were also made on the basis of gender and history of orthodontic treatment. Video equipment was used to capture video and each frame was analysed out of which two frames that best represented the maximal display of maxillary incisors (MDMI) during speech and the widest transverse display of dentition (WTDD) during speech were selected. The data obtained was analysed using one-way analyses of variance with Fisher's least significant difference post hoc test. MDMI and WTDD were found to be highly significant during speech across all age groups (P < 0.05). G1-G3 displayed approximately similar levels of maxillary incisor (P > 0.05) but was greater (P < 0.05) than G4 and G5. The buccal corridor showed significant differences as a function of age (P < 0.05). Orthodontic treatment had a significant impact on the display of the maxillary incisors (P < 0.05) but not on the buccal corridors (P > 0.05). Mandibular incisor display was relatively stable across G1-G3, increasing only for G4 and G5. It appears that the maximum display of maxillary incisors decreases with age and the decline is particularly rapid with increasing age. Females tend to display more teeth both in the transverse and vertical directions.