What is the outcome when optimum orthodontic force is equal to capillary pressure?

The optimum force levels for orthodontic tooth movement should be just high enough to stimulate cellular activity without completely occluding blood vessels in the PDL. Both the amount of force delivered to a tooth and the area of the PDL over which that force is distributed are important in determining the biologic effect. The PDL response is determined not by force alone, but by force per unit area, or pressure. Because the distribution of force within the PDL, and therefore the pressure, differs with different types of tooth movement, it is necessary to specify the type of tooth movement as well as the amount of force in discussing optimum force levels for orthodontic purposes.