Experimental Verification of the Mathematical Formulae for Mandibular Movement

Abstract

The mathematical formulae derived kinematically by the authors which descrive the motion of the mandible in relation to the maxilla were evaluated experimentally to establish if they were practical and sufficiently accurate for clinical use. By applying measured data of nonworking and working condylar paths together with rotational angle of the mandible around intercondylar axis to the mathematical formulae, the theoretical value for the incisal path was computed. Then, this value was compared statistically with the measured value for the incisal path of the same patient. Two sets of data measured by different researchers were used independently for increasing the reliability of the results.
The correlation coefficients between the theoretical and measured values were as high as 0.99. The regression lines were very close to and almost coincided with the lines of agreement (Y=X), and the root residual variances were not greater than 2.4 degrees.
In conclusion, the accuracy of the computation using the mathematical formulae for mandibular movement derived by the authors has proved to be sufficient for clinical application. The verified formulae can be applied to various studies of mandibular movement. Application of the formulae include future CAD/CAM for artificial teeth.