Figure 1.

Animal models of periodontitis: characteristics and contributions. Animal models are contrasted with in vitro models and human studies in terms of their advantages and disadvantages, followed by a summary of key animal model-based contributions to understanding periodontal disease pathogenesis. It should be noted, however, that animal model-based research benefits from both in vitro models and human studies for obtaining mechanistic insights in finer molecular detail and for determining clinical relevance, respectively. The cycle connecting the 3 experimental systems is meant to demonstrate this interrelationship. For instance, the arrows emanating from “Animal models” and “Human studies” to “In vitro models” indicate the reliance of the former systems on the more tractable in vitro system for dissecting plausible molecular mechanisms. Conversely, the reverse arrows indicate that in vitro model-based mechanisms depend on animal and human systems for testing potential biological relevance. One of the greatest contributions of animal models is the testing of cause-and-effect relationships that cannot be typically addressed in human studies, most of which are correlative. Conversely, candidate drugs identified in animal models require the ultimate test in human clinical trials before they can be validated and enter the clinic.