The periodontal ligament, commonly abbreviated as the PDL, are a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which they sit.

All these fibers help the tooth withstand the naturally substantial compressive forces that occur during chewing and remain embedded in the bone.

Transseptal fibers (H) extend interproximally over the alveolar bone crest and are embedded in the cementum of adjacent teeth; they form an interdental ligament.

[4] The PDL substance has been estimated to be 70% water, which is thought to have a significant effect on the tooth's ability to withstand stress loads.

The PDL is a part of the periodontium that provides for the attachment of the teeth to the surrounding alveolar bone by way of the cementum.

When mechanical stimuli are introduced to the cells, osteocytes in the PDL will differentiate into osteoclasts which will then reform and remodel the bone structure in the affected area.

For example, orthodontic treatment involves application of a mechanical force on to the teeth to align them and this is done through this complex combination of physical and cellular processes.

[8] The PDL is a part of the periodontium that provides for the attachment of the teeth to the surrounding alveolar bone by way of the cementum.

[11] There are progenitor cells in the periodontal ligament that can differentiate into osteoblasts for the physiological maintenance of alveolar bone and, most likely, for its repair as well.

[15] Nicotine, the major pharmacologically active ingredient in tobacco smoke, lessens a host's ability to defend against bacterial invasion induced by plaque.

[16] Tobacco smoking impairs phagocytic and chemotactic activities of leukocytes[17] and impedes wound healing,[18] specifically by affecting gingival blood flow.

[citation needed] At the cellular level, nicotine reduces the proliferation of red blood cells, macrophages, and fibroblasts and increases platelet adhesiveness.

[citation needed] Macroscopically, this affects healing and tissue perfusion due to micro clot formation in the blood vessels.

[23][24] Nicotine also has a sympathomimetic action, stimulating epinephrine and norepinephrine release, which causes vasoconstriction and limits tissue perfusion.

[citation needed] Nutritional status of an individual can be a crucial factor in the progression and healing of periodontal tissues.