Histology puts the development aspect in perspective. This chapter deals with the ontological aspects that encompass the changes from “Meckel’s cartilage” to tooth formation. Periodontal ligament structure, its unique joint with the jaw bone, vitality of teeth and how the jaw growth and dentition development are inter-dependant are elaborated upon in a succinct manner. Genetic diseases behind dental disorders are presented in a tabular form. The jaws and teeth have a single “aim”- occlusion. What leads to normal occlusion and what are the factors that prevent the development of occlusion are discussed in this chapter. How occlusion is achieved is the basis of gnathology.