Geminated Odontome—Connation of the Incisors in the Dog-Its Etiology and Ontogeny

The appearance of two teeth united by enamel and dentin is commonly described as gemination, whether this occurs as apparent union of two members of the normal series or of a tooth of the normal dentition and a supernumerary tooth. The word "gemination," derived from the Latin "geminus" (a twin), is a most confusing term in this context and seems to have been introduced in 1746 as a result of Fauchard's1 description of the condition as "un double dent ou deux jumelles," a double tooth or two twins. The much earlier use of the metaphor of twinning in relation to the normal human dentition, made by King Solomon2 when he wrote "Thy teeth are as a flock of sheep which go up from the washing, whereof everyone beareth twins and there is not one barren amongst them," appears to have been ignored by that eighteenth-century leader of dental thought. In modern times, Thoma3 has attempted to discriminate between "gemination" and "fusion." The former, he said, occurs when one enamel organ produces two teeth still united, whereas the latter term describes the union of formerly separate tooth germs. This difference, however, is purely hypothetical and the ontogeny was not described. The term "fused teeth" is hardly satisfactory unless used to describe what is often known as pathologic gemination: the union or fusion of two teeth by cementum after tooth formation is complete. Teeth do not become fused by any other means, but it is admitted that tooth germs may unite prior to calcification, although it is difficult to conceive how this can occur when epithelial continuity has been broken and tooth germs are already separated by developing follicles. Tomes4 used two terms together: "connate and geminated." Because of fauchardian influence, the latter term has been widely used; whereas, "connate" (developed or born together) is almost unknown today. Whether the appearance is of the union of two members of the normal series or of the union of a tooth of the normal series with a supernumerary tooth, connation (the condition of being developed together) exactly describes the anomaly. This term is therefore used in this report, and a plea is made for revival of its general usage.