Answer:
periodontal ligament injury causes vascular response activation.
Step-by-step explanation:
Ligaments are shock-absorbent which prevents the teeth from injury upon biting something tough and all sorts of pressure exerted on teeth. With extreme pressure, teeth could be damaged and inflamed. The inflammation of ligaments in response to injury activates vascular responses. The resident leukocytes produce cytokines and neutrophils migrate to the area of inflammation. Later, lymphocytes and mast cells are also activated promoting inflammation. The initial innate immune response is then progressed into an acquired immune response and collagenolytic activity occurs. Hence, collagen production is increased so that injured tissue can be replaced with new one.