Orthodontic Tooth Movement

The different types of force characteristics such as heavy versus light forces and continuous versus intermittent force and the type of tooth movement influence the rate and force of orthodontic tooth movement. Heavy forces generally results in pain development, necrosis of cellular components within the PDL and undermining resorption of alveolar bone adjacent to the affected tooth (Proffit, Fields, & Saver, 2013). A study carried out by Alikhani et al., observed a linear relationship between the magnitude of force and the expression of inflammatory markers when orthodontic force was first applied. However, the inflammatory response plateaued with high magnitude of orthodontic force. This plateau occurred between the force level of 10 and
There are a few types of tooth movements to acknowledge such as tipping, rotation, and bodily movements also known as translation. For different types of orthodontic tooth movements, there are contrasting optimum forces. The ideal forces for the various tooth movements are: tipping at 35-60gm, bodily movement at 70-120gm, and rotation at 35-60gm. From experiments with animals and clinically obtained experience with humans, it is suggested that lighter forces are better for smaller teeth. Furthermore, if two forces are applied simultaneously to the crown of a tooth, the movement of the root apex and crown can be translated in the same direction and amount. It is evident that to produce the same pressure in the PDL and hence, the same biologic response, twice as much force is needed for translation than for tipping (Proffit, Fields, & Saver, 2013). When categorizing data according to type of tooth movement, duration and magnitude of force, care should be taken as optimal forces are often influenced by individual variability (Ren, Maltha, Kuijpers-Jagtman,
Research continues for the optimal force for orthodontic tooth movement not only for ideal tooth movements but to prevent unwanted side effects such as root resorption. Biological reactions to externally applied mechanical stimuli has manifested its way into the spotlight as one of the main methods to determine ideal force and rate of tooth movements. There is no one ideal force for tooth movements. The duration and magnitude of force depend on the type of tooth and tooth movement. There are currently many uncontrolled factors that deviate ideal rate and force results from optimal orthodontic tooth movement. Therefore, in the future, well-controlled and standardised experiments or clinical research should be carried out beyond the early phases of treatment and include data from the linear phase. Furthermore, with improved technology in the future, a computer simulation model may be able to reproduce local tissues’ stress and strain responses and to calculate tooth movement when orthodontic forces are applied (Ren, Maltha, & Kuijpers-Jagtman, 2003). Collectively, these alternatives may provide a better understanding of techniques to improve orthodontic