2003 Volume 7 Issue 2 Pages 134-142
PURPOSE： The purpose of this study was to clarify the effects of the vertical dimension of occlusion (VDO) on the swallowing function of edentulous individuals．
SUBJECTS and METHODS： Nine healthy edentulous individuals (6 males and 3 females，mean age 57.4) who wear complete dentures were tested．A 5cc bolus of liquid was repetitively given to the subjects to swallow with three different occlusal dimensions using experimental apparatus．The apparatus contacts the maxillary and mandibular ridges， but the vertical relationship can be varied．The setting dimensions include normal VDO (Normal)，a reduced VDO (Reduced)，and a condition without the apparatus (None)．Movements of the tongue surface were quantified by measuring grooving depth on coronal sections during swallowing by ultrasonography (SSA-320A，Toshiba Medical)．Differences among the respective dimensions were analyzed by ANOVA and Fisher's PLSD test (p＜0.05)．
RESULTS and DISCUSSIONS： Results of the present study showed a significant increase in the grooving depth during swallowing with no apparatus compared to that of the Normal VDO (p＜0.05)，and there was no significant difference between the Normal and Reduced groups．In the group without the apparatus，the tongue seemed to require greater movement for swallowing，suggesting that restoring some VDO，perhaps even with an upper single denture，can improve the swallowing function．
CONCLUSION： lt was suggested that providing prosthetic apparatus with at least some VDO significantly improved the tongue movements during swallowing．
