Sensor to Induce and Quantify Interproximal Forces during Tooth Movement

Objectives: Preliminary research conducted at UCSF utilized a modified “Waldo Method” to induce experimental tooth movement (ETM) using an elastic spacer placed interproximally between mice molars. In this proof-of-concept study, the first objective was to replace the spacer with a capacitive sensor to induce and quantify the real-time force on the tooth-crown. The second objective was to relate the force on the crown to changes in the PDL-space. Experiments were performed on a rabbit model in situ for correlation of measured forces on the crown with displacement of the tooth-root within the dentoalveolar complex.
Methods: The effect of change in sensor capacitance on change in PDL-space width was investigated by using sensors of thicknesses 60%, 20%, and 0% greater than PDL-space. Sensors were placed interproximally between mandibular molars of freshly harvested rabbits. Shifts in capacitance values were recorded by the sensor, and spatial associations of teeth relative to their respective bony sockets were mapped using X-ray micro-computed tomography (micro-XCT) scans.
Results: For a 68% overall increase in capacitance, 24% widening and 65% narrowing of the PDL-space in the experimental group were observed. Altered PDL-spaces also were observed for a 36% increase in sensor capacitance, with 20% widening and 9% narrowing. However, it is likely that the time-dependent component of the PDL could dominate and the intended long-term effect of the 36% capacitance increase could be minimal toward tooth movement.
Conclusions: This proof-of-concept data illustrated that the initial effect of 36% increase in capacitance on tooth movement could be masked by the viscoelastic effects of the PDL. However, a 68% capacitance increase could prompt significant tooth translation. Tuning capacitance and thereby force on the tooth-crown and correlating these adjustments with changes in PDL-space could provide insights into mechanistic processes within the periodontal complex.