>> Immunological Reactions :
Immunological reactions also occur due to presence of different antigens (Ag) in the dental plaque that induce many immune responses .The Ag present in dental plaque are : plaque Ag , plaque mitogen , & Ag of bacteria found in the plaque and their products .The immunological responses include both : Antibody response (Ab) and cell mediated immune responses (CMI) . These immune responses try to kill the organisms but the resulting immunological reaction will increase the tissue destruction around the teeth .
Complenet will be activated by both classical & alternative pathways .The released anaphylatoxin ( C3a & C5a ) will cause degranulation of mast cell and release of many vasoactive amines some of them lead to more vasodilatation in the area with more oedema fluids and chemotactic factors with more inflammatory cells and prostaglandin with more bone destruction .
Lymphokines are produced as a result of cell-mediated immune response , one of these lymphokines is osteoclast activating factor that produce bone destruction while other lymphokines will attract other cells and produce more oedema , more vasodilatation and more inflammation .
The end result of these inflammatory and immunological reactions is inflammation in the tissues near the dental plaque , accumulation of inflammatory and oedema fluid in dental crevices (periodental pocket) . The tooth become loose due to destruction of periodontal ligaments and also due to bone destruction . By time , the inflammatory process will spread by the effect of hyaluronidase enzyme ( spreading factor ) produced by the organisms .
