Repair of Orthodontically-induced Tooth Root Resorption by Ultrasound

Tooth-root resorption, also known as shortening or erosion,(TRR) is one of the adverse outcomes of dental trauma, orthodontic tooth movement and dental replantation/transplantation. Orthodontically induced inflammatory root resorption (OIIRR) is somewhat different from other types of TRR. The treatment protocol of teeth diagnosed with severe OIIRR or other forms of TRR always involves root canal treatment or extraction of these teeth in severe cases and prosthetic replacement. Sometimes teeth with minor TRR may stay for an extended period of time with compromised bite functions. Although several trials have been proposed to minimize or prevent TRR or OIIRR, none is capable of being used in clinical situation to treat TRR or OIIRR in humans except for Low Intensity Pulsed Ultrasound (LIPUS). However, research examining the use of LIPUS to treat OIIRR has been limited to simple orthodontic tooth tipping. In reality, tooth movement is a combination of different types of tooth movements, namely tipping, bodily, rotational, torque, intrusion and extrusion tooth movements. However, the literature have pointed out that torque tooth movement, especially when the root apices are torques against cortical plates of bone produces the most dramatic type of tooth root resorption with poor prognosis. Our long-term goal is to develop a standard protocol for treating severe tooth root resorption with poor prognosis in humans, regardless of origin. Our preliminary data demonstrates that LIPUS can produce healing of OIIRR in humans after simple tipping movement, this was confirmed by an in-vitro study on isolated cementoblasts. The objective of the present proposal is to evaluate the effect of different treatment protocols of LIPUS on the healing process of orthodontically induced tooth-root resorption due to torque (Complex)type of tooth movement in humans. The study Hypotheses are (I) LIPUS treatment for 20 minutes per day for 4 weeks will be effective in repairing OIIRR due to tor