Relation between the Changes in the Vertical Dimension of Occlusion and Patient’s Subjective Evaluation in Complete Denture Wearers

Abstract

The vertical dimension of occlusion（VDO）must be correctly estimated when fabricating complete dentures to achieve efficient mastication and swallowing. The comfortable zone（CZ）method for VDO estimation is based on trichotomous subjective response. However, the difference in comfort level within and out of the CZ still needs to be determined. Therefore, this study aimed to examine the differences in subjective comfort on a 100-mm visual analog scale（VAS）when raising or lowering the VDO and to assess the relationship among the responses to the CZ method. Eight edentulous patients（five men and three women, with a mean age of 78.5±7.6 years）were recruited. The VAS score was obtained two times at the most comfortable position（MCP）and when it was raised from +1 to +7 mm（7VDO）. The VAS score was also obtained when the MCP was lowered from -1 to -3 mm（3VDO）. One-way analysis of variance and Bonferroni’s multiple comparison test were performed to analyze the differences in VAS scores at 11 VDOs. The VAS score significantly decreased when the VDO was raised by +3 mm from the MCP（p = 0.009）and continued to decrease in +4（p = 0.001）, +5, +6, and +7 mm（p < 0.001, respectively）. In addition, it significantly decreased when the VDO was lowered by -2 mm from the MCP（p = 0.048）. The results suggest that VDO estimates may be appropriate between -1 and +2 mm from the MCP when fabricating new complete dentures.