They may be unusually large or small, increased or decreased in number, or even entirely absent. In congenital syphilis the upper central incisors of the permanent set are frequently malformed, being deeply notched at the edge.

Inflammation may involve the surrounding alveolar periosteum or the pulp of the tooth. It may go on to pus formation with loosening and death of the teeth. Caries is generally the result of malnutrition or lack of care of the teeth. The enamel of the tooth is destroyed by lactic acid, which is formed by many varieties of bacteria. The organisms are then able to enter the canals in the dentin with subsequent disintegration. The tumors of the teeth have been described in Part I.