Morphology of the Cementoenamel Junction in Permanent Teeth of Dogs: A Scanning Electron Microscopic Study

In human teeth, the cementoenamel junction (CEJ) can have different morphologies, known as Choquet cases or types: in type 1, the cementum overlaps the enamel; in type 2, the enamel overlaps the cementum; in type 3, the relationship between the cementum and enamel is edge-to-edge; and in type 4, there is a gap between the enamel and the cementum, with exposed dentin. Since little is known on the morphology of the CEJ in animals, the aim of this study was to characterize the structure of the CEJ of dog teeth by SEM. We studied 82 permanent teeth extracted from 4 dogs of similar size, aged from 7 months to 2 years. Teeth were grouped according to their size, sectioned and prepared for SEM. The teeth evaluated showed the 4 CEJ types. Type 3 was the most prevalent, being present, either alone or in combination, in 90.79% of the samples, followed by type 4 (present in 31.58% of the samples). Of the samples, 65.13% showed only one type, while 34.87% presented a combination of them. Types 3 and 4 were the only ones present alone (in 55.92% and 9.21% of the samples respectively), whereas the combinations between types 3 and 4 (20.40%) and types 1 and 3 (9.87%) were the most frequent. In all combinations, type 3 was predominant. The CEJ of the dogs evaluated showed a high degree of variability in the different types of teeth, within a same tooth, within the dentition of a single individual, and among individuals.