Influence of lost lateral teeth on speech sound production

Aims: The present investigation explores the possibility to characterize causal connections between speech sound articulation and dental irregularities in the form of the loss of lateral teeth. Material and methods: Edentulous patients with full dentures were used as subjects. Precise duplicates of their dentures were modified in a way to create seven varieties of arrangements of the lateral teeth, ranging from a "full set of teeth" to large unilateral or bilateral edentulous areas. A phonetically balanced text was read aloud and recorded digitally. Standard acoustic and auditory analyses were performed, as well as perception tests with groups of listeners with different degrees of professional auditory skills. Thus, it was possible to discern both acoustic and auditory deviations of consonants from their phonetic norms. Results and conclusions: The results show that immediately after insertion of the different varieties of test prostheses, only a small number of acoustic and perceptual deviations occurred. It is concluded that the disturbances caused by the artefacts were not severe enough to impede the course of the normal automatic sequence of articulatory movementsdrastically. This may be regarded as a fine example of what phoneticians call the ability of the vocal apparatus for 'articulatory compensation'. Keywords: Disturbance of phonation, loss of lateral teeth, shortened dental arch, articulatory compensation, analysis of speech