Effect of lingual plates on generating intra-oral pressure during swallowing: an experimental study in healthy subjects

BACKGROUND: Although palatal augmentation prostheses (PAPs) can improve dysphagia, their application is compromised in the absence of maxillary abutment teeth. Experimental lingual plates (ELPs) used for raising the tongue may be employed as alternative to PAPs. METHODS: Influence of different ELP designs, plateau (P–type) and drop-shaped (D–type), on the intra–oral pressure during swallowing were tested. Eleven healthy dentate volunteers, with a mean age of 35.5±10.5 years, participated in this study. Tongue pressure on the hard palate was measured using an ultra-thin sensor sheet with five measuring points, whilst performing dry, 5–ml and 15–ml water swallows, with and without the ELPs in situ. Additional pressure sensors were installed in the lingual aspects of the ELPs, and on the vestibular aspect of the lower molars for measuring sublingual and oral vestibule pressures, respectively. Each measurement was recorded thrice. A repeated measures ANOVA was employed to verify differences in duration, maximal magnitude and integrated value for the different experimental situations. Tukey’s post hoc test was performed for comparison testing. Statistical significance was set at p<0.05. RESULTS: The sequence of tongue–palate contact on the median line of the hard palate without ELPs was maintained, except for the 15 ml P–type swallow. Tongue pressure started earlier with the D–type but reached its peak nearly at the same time as without ELPs. The peak magnitude and cumulative tongue pressure against the hard palate decreased by wearing ELPs (p<0.05), but was inconsistent between the two types of ELPs and for the different swallowing volumes. Both, maximum and cumulative vestibular pressures were mostly similar or larger with P–type than that with D–type. CONCLUSION: D-type and P-type ELPs seem to have the inverse effect of PAPs on the palatal tongue pressure during swallowing. These first counterintuitive findings do not yet justify rejecting the basic rationale of using ELPs for the treatment of dysphagia; hence a rather biologically designed piezographic lingual plate may be more appropriate.