Colyer's Variations and Diseases of the Teeth of Animals

Introduction

Enamel hypoplasia is the term used for conditions where the formation of enamel is defective, usually in quantity, although there is a condition, usually called enamel hypocalcification, in which the enamel is of normal thickness but is not fully mineralized; therefore it does not have the characteristic translucency of enamel but is white and opaque and may be grossly softer than normal. Enamel hypocalcification is little referred to in species other than man.

There are varieties of enamel hypoplasia which are of genetic origin; these would naturally tend to affect enamel formation over the whole tooth surface and may affect both deciduous and permanent dentitions. Enamel may be virtually totally absent but, more commonly, the crown has a thin partial covering of enamel which has an irregular and uneven surface. Proof of genetic origin is heritability and this is impossible to establish in museum specimens and where the condition is only observed at death.

Statistics on the prevalence of enamel hypoplasia in various species and under various conditions, for instance captive compared with wild state, are scarce.

Systemic causes

Many systemic environmental conditions can affect enamel formation, for instance, malnutrition of nonspecific or specific character and systemic infections. Disorders of the local environment of the tooth, such as local infection and trauma, can also produce lesions of the enamel.

Many systemic conditions exist only for limited periods and therefore they produce zones of defective formation in the incremental pattern of enamel formation, that is produce ring-like zones around the crown of the tooth.