Prediction accuracy of incisal points in determining occlusal plane of digital complete dentures.

PURPOSE

This study aimed to predict the positional coordinates of incisor points from the scan data of conventional complete dentures and verify their accuracy.

MATERIALS AND METHODS

The standard triangulated language (STL) data of the scanned 100 pairs of complete upper and lower dentures were imported into the computer-aided design software from which the position coordinates of the points corresponding to each landmark of the jaw were obtained. The x, y, and z coordinates of the incisor point (X, Y, and Z) were obtained from the maxillary and mandibular landmark coordinates using regression or calculation formulas, and the accuracy was verified to determine the deviation between the measured and predicted coordinate values. Y was obtained in two ways using the hamular-incisive-papilla plane (HIP) and facial measurements. Multiple regression analysis was used to predict Z. The root mean squared error (RMSE) values were used to verify the accuracy of the X and Y. The RMSE value was obtained after cross-validation using the remaining 30 cases of denture STL data to verify the accuracy of Z.

RESULTS

The RMSE was 2.22 for predicting X. When predicting Y, the RMSE of the method using the HIP plane and facial measurements was 3.18 and 0.73, respectively. Cross-validation revealed the RMSE to be 1.53.

CONCLUSION

Y and Z could be predicted from anatomical landmarks of the maxillary and mandibular edentulous jaw, suggesting that Y could be predicted with better accuracy with the addition of the position of the lower border of the upper lip.