Periodontitis is a highly prevalent, chronic immuno-inflammatory disease of the periodontium that results in progressive loss of gingival tissue, the periodontal ligament, and adjacent supporting alveolar bone 1. The deterioration of the tooth-supporting structures caused by the biofilm and the host reaction to it eventually results in the clinical indications of periodontitis, with the teeth eventually becoming loose in their sockets. Scaling and root-planing are used in conjunction with strict dental hygiene to stop the disease's progression. Regenerating periodontal tissue through non-surgical or surgical methods should be the ultimate goal of periodontal treatment. Although human cell cultures were found to be useful models for replicating some aspects of the periodontal disease process at the cellular level, information about the complex host response was not prominent 2. As a result, animal models have been used to evaluate the pathogenesis of periodontal diseases and various periodontal treatment modalities. Wessler in 1983 defined an animal model as “a living organism with an inherited, naturally acquired, or induced pathological process that in one or more respects closely resembles the same phenomenon in men.” The Institute of Laboratory Animal Resources (ILAR) of the National Academy of Sciences adopted and modified Wessler’s definition as follows: “An animal model is a living organism in which normative biology or behaviour can be studied, or in which a spontaneous or induced pathological process can be investigated, and in which the phenomenon in one or more respects resembles the same phenomenon in humans or other species of animal” 3. Animal models have undergone extensive research in order to understand specific biological phenomena, with the hope that findings from these studies would provide light on how other organisms function. Animal models have proved indispensable in the advancement of science, especially in the biomedical field, with various diseases, including periodontal disease being studied extensively. Periodontal disorders may be carried on experimentally, spontaneously, or both depending on the species. Large animal models have been chosen in the context of regenerative medicine employing biomaterials due to the reproducibility and surgical accessibility of experimental abnormalities. Dogs have been extensively utilised for modelling the regeneration of periodontal abnormalities with biomaterials, in addition to monkeys, which are the perfect model in pre-clinical trials. Rats, miniature pigs, sheep, rabbits, and cats have all been employed in several research. In order to guarantee reproducible models that enable statistical analysis, various techniques have been proposed 4.

Prior to conducting clinical trials on people, it is crucial to do experimental research to determine the cause and pathophysiology of the illness process in animal models. Therefore, before being utilised on humans, animal models are used to assess the success of innovative surgical procedures, the efficacy and impact of restorative materials on dental pulp, the etiopathogenesis, clinical characteristics, and histological and immunologic components of periodontal disease 4, 5.

For selection of suitable animal; specific anatomical, physiological, pathological, and/or psychological characteristics need to be considered based on current scientific literature as under 7.

The following are the benefits of the use of animal models in research: 8, 9, 10

Before initiating their research projects, all scientists using experimental animal models should abide the national or institutional ethical standards. Everyone should completely abide the recommendations of the animal ethics committee.

Many regulatory organisations are concerned about the welfare of the animals, which results in the development of policies governing the proper handling and use of animals in research. Five basic principles were developed by the regulatory authorities' advisory committee for the use and treatment of animals employed in research and testing.

It is important to know the animal profile prior to the use in research. 13 Table 1

Alternative models have been developed to address the drawbacks and unethical practice of utilising experimental animals as models. Alternative approaches have the benefits of speed, requiring less labour, and being economical. In biomedical research and testing, anything that completely or partially replaces the use of live animals is regarded as an alternative or substitute. A few examples of alternatives to animal testing include stem cells, microdosing, DNA chips, microfluidics chips, human tissue, novel imaging technologies, and post marketing drug surveillance 14. The majority of experimental animal models can be replaced with computer simulations, cell and tissue cultures, and different alternative creatures like invertebrates, lower vertebrates, and some microorganisms like prokaryotes, protists, and fungus. No doubt that these alternatives will minimize the usage of animal models, but they cannot completely eliminate their usage in pre-clinical studies.

The research carried out using animal models are indicated as biomedical research since the fundamentals of biology have now reached the molecular level and different phenomena of life are now reliant on genes. For instance, current animal models for human diseases are enhanced by the coordinated use of genetic, cellular engineering, and embryonic manipulation principles in accordance with the needs or study objectives.

Following are the objectives to follow during the usage of animal models. 15, 16

Periodontal disorders, and particularly the severe types of periodontitis, have long been and are a mystery to both individuals who experience them and those who work to understand and avoid them. Since more than a century ago, efforts have been made continually and with varied degrees of success to comprehend these disorders through clinical and experimental study. In addition to humans, a number of other mammals, especially those raised in captivity or in the home environment, acquire periodontitis on their own as they get older. In order to discover an answer to the subject that has perplexed us for a long time, a variety of mammals and animals' periodontal tissues as well as the safety and effectiveness of new biomaterials and treatments have been thoroughly researched.