Photogrammetric measurement of initial tooth displacement under tensile force.

The purpose of this study was to quantitatively measure tooth displacement under low horizontal tensile force (≤18 N) and to test the reproducibility of measurements. Anterior tooth mobility was measured using a photogrammetric measurement technique in 23 periodontally healthy subjects. While slowly increasing the tension on each tooth, an automated software program recorded three-dimensional tooth displacement at 3 N intervals, up to 18 N. Measurements were repeated three-times for each tooth. The vector of absolute tooth mobility in the buccal direction was calculated. Intra-class correlations of the three repeated measurements of each tooth were calculated and ranged between "good" and "optimal". The agreement of measurements was significant (p≤0.05). The analysis of differences between the deviation vectors of contralateral teeth revealed that most differences emerged to be statistically non-significant. The combination of a mechanical loading approach with the optoelectronic system allowed the measurement of three-dimensional tooth mobility in vivo.