Blood flow, collagen components of oral tissue and salivary kallikrein in young to senescent, germfree and conventional rats. A study on the etiologic factors of periodontal disease.

In oral tissues of rats, progress of age resulted in a gradual reduction of regional blood flow and in decreased levels of eluable (labile) hydroxyproline from the collagen component. These were paralleled by an increment of salivary kallikrein. The presence of the microbial flora in the oral cavity, portrayed by the comparison of conventional and germfree rats, caused an elevation of blood flow in all age groups, without exerting a marked effect on eluable hydroxyproline. In addition to aging and flora effects, the action of chronic hypoxia and of mechanical stress has been observed on the mentioned parameters. The presently used animal models and experimental design permit a critical study of etiologic agents and characteristic lesions of peridontal disease.