Purpose: Appropriate examination of the height of the residual ridge is critical in complete denture treatment. To clarify the possibility of establishing standards for improving the reproducibility of subjective evaluation, the relationship between conventional subjective evaluation by several dentists and objective evaluation by model measurement was evaluated.
Methods: Locations for evaluation were the sites corresponding to the central fossa of the right and left first molars in study models (100 sets) of edentulous maxillas and mandibles. Subjective evaluation with a three-grade scale was performed by some dentists and objective evaluation was performed with digital vernier calipers. The relationship between objective evaluation and subjective evaluation was studied separately in dentists with less than 3 years of clinical experience and those with more than 7 years. Discrimination values for objective evaluation were determined at changeover points of the rate of subjective evaluation. In addition, we studied the correction between subjective evaluation and objective evaluation with the discrimination values.
Results: Marked variations were noted in subjective evaluation depending on the individual and number of years of clinical experience. Discrimination values were obtained from subjective evaluation for dentists with more than 7 years of clinical experience: for the maxilla, "low" and "middle" were 6 mm and "middle" and "high" were 10 mm; for the mandible, "low" and "middle" were 0 mm and "middle" and "high" were 5 mm. The correlation between subjective evaluation and objective evaluation based on these discrimination values was extremely low regardless of the individual's clinical experience.
Conclusions: Reproducibility of subjective evaluation of the residual ridge height was low. To improve the universality and reproducibility of the examination, subjective evaluation must be performed by referring to the discrimination values.