Morphology of the cementoenamel junction of primary teeth.

PURPOSE: The purpose of this study was to investigate anatomically the cementoenamel junctions (CEJs) of primary teeth by observation of the morphological relationship among enamel, cementum, and dentin. METHODS: One hundred five human extracted primary teeth were analyzed by scanning electron microscopy. The teeth were divided into 7 groups, each with 15 primary teeth, as follows: maxillary central incisors (group 1); maxillary lateral incisors (group 2); maxillary canines (group 3); maxillary molars (group 4); mandibular incisors (group 5); mandibular canines (group 6); and mandibular molars (group 7). The entire cervical region was analyzed, especially concerning regularity of the CEJ, for establishment of the type of enamel-cementum relationship (cementum over enamel, the edge-to-edge relationship between cementum and enamel, and presence of gaps with exposure of dentinal tubuli). RESULTS: All circumferences represented by CEJs exhibit an interchange and combination of 3 types of relationships: (1) cementum over enamel; (2) enamel and cementum in the edge-to-edge relationship; and (3) the presence of a gap between the enamel and cementum with dentin exposure. There was no predominance as to the dental groups. CONCLUSIONS: All primary teeth exhibited the 3 morphological tissue interrelation types along the circumference of the cementoenamel junction. The irregularity and fragility of cementoenamel junction structures indicate that this region is weak and should be handled with care and protected during application of chemicals and utilization of clamps, dental instruments, and restorative materials.