This section is from the book "Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics", by Ferdinand J. S. Gorgas. Also available from Amazon: Dental Medicine.
Chronic or asthenic inflammation is a process in which all the cardinal symptoms of inflammation may be present, but in less degree than in the acute form, by which it is generally preceded. In chronic inflammation there is present a permanent local hyperaemia, attended with an exudation into the interstices of the inflamed part, or from its surface. The pain in this form is usually light, or may be intermittent, or even absent, or be no more than an itching sensation ; heat is present, but is not a prominent symptom; the redness is of a light hue, sometimes livid, from passive hyperaemia and the stretching of the vessels by the over-distention to which they had before been subjected, and the diminished force of the circulation ; the swelling is in the form of induration, owing to the exudation having become organized into tissue. This latter accounts for the hardness around an indolent ulcer, and an old sinus. Inflammatory induration is a process of hardening the tissues due to coagulation of the fibrinous elements of the exudates or the fixed tissue cells, and new formations in the connective tissues. In mucous membranes induration is indicative of chronic inflammation, and is caused by exudative infiltration into the substance of the submucous connective tissue, and a considerable change of structure in these membranes often occurs. Although the symptoms of chronic inflammation are present in a limited degree, yet they are more persistent, on account of the object for which the increased nutritive effort was made proving unsuccessful. Causes. - The causes of chronic inflammation are long-continued irritation, functional activity, and 9 constitutional dyscrasia, or diathesis; and its terminations are induration, hypertrophy, tumefaction, suppuration, ulceration, fatty degeneration, the formation of cold abscesses, and caseation. The local symptoms differ from those of the acuter form only in the degree of severity.