Comparative tests of arbitrary and kinematic transverse horizontal axis recordings of mandibular movements

The reliability of recording maxillomandibular relationships for articulator programming with a transverse horizontal axis determined arbitrarily with an arbitrary face-bow has not been verified against a kinematically determined and recorded transverse horizontal axis in an in vivo study.

The goal of this study was to determine the measuring accuracy of the Cadiax Compact system in a clinical series of tests and to determine whether there is a clinically significant difference between the 3-dimensional measurements recorded from kinematically and arbitrarily determined transverse horizontal axes.

Thirty subjects (11 women, 19 men; ages 21 to 26) participated in this study. Mandibular movement, the sagittal condylar inclination (SCI) angle, and the transversal condylar inclination (TCI) angle were recorded in each subject with the Cadiax Compact system, by use of first an arbitrarily and second a kinematically determined transverse horizontal axis. A subset of 10 subjects was examined with another computerized axiograph, the Gamma Cadiax system. Measurements were made and recorded twice, on different days under similar circumstances. To compare the systems and measurement methods, the SCI measurements taken at 3- and 5-mm sagittal protrusion and the TCI taken at 3- and 5-mm mediotrusion were used. The lengths and characteristic curvatures of protrusion, opening, and mediotrusion tracings were determined for the evaluation as follows: tracing lengths (<8 mm, 8 to 12 mm, and >12 mm); degree of overlap of the excursive and incursive tracing; and tracing curvature. The intraclass correlation was used to compare angle values at the 95% confidence interval. To assess the track progression, kappa values were calculated.

Repetition of the mandibular track inclination angles and the condylar movement pattern was highly reliable (intraclass correlation of >0.8) with the Cadiax Compact system. When the mandibular track inclinations determined kinematically and arbitrarily by the Gamma Cadiax and Cadiax Compact systems were compared, both systems demonstrated high reliability (ICC>0.8). The congruence results of the protrusion tracings from kinematic and arbitrary measurements with the Cadiax Compact system were as follows: strong congruence in quantity, characteristics, and horizontal tracing; only the quality diminished slightly (Kappa 0.46 in the first measurement, which still represented a clear congruence). The opening and mediotrusion tracings demonstrated fair to almost complete congruence in all parameters.

Within the limitations of this study, the kinematic and arbitrary measurements of the Cadiax Compact system could be reliably used for articulator programming. The results suggest that arbitrarily determined posterior reference points may be comparable to a kinematically determined transverse horizontal axis.