Three Dimensional evaluation of forces on impacted maxillary canine

Methods: A dentiform model was modified to simulate a palatally impacted canine. Load cells installed in the dentiform simultaneously measure the three forces (Fx, Fy, Fz) and three moments (Mx, My, Mz) of the canine recovery force systems tested: Kilroy spring, elastic-chain and steel ligature wire. The activation range and force system attenuation, as the canine moves, were measured. The results were analyzed statistically.

Results: Force in the occluso-gingival direction(Fz) was the primary component of the total force involved in the eruption of the impacted canine. Fz decreased for all the three groups as the canine moved towards the occlusal plane, however the decrease was more significant for Ligature wire (0.00±0.00) and EChain (1.71±0.08) when compared with Kilroy spring (p<0.001). Kilroy spring has an activation range of 13mm (Fz), elastic-chain has an activation range of 12mm (Fz) and ligature wire has an activation range of 1mm (Fz). The full range of the elastic-chain cannot be utilized due to its limited elastic behavior.

Conclusion: The three dimensional force system can be quantified using the developed technology. Quantification of the force system provides critical information for selection of the appliance.