Coronal Cementum and Reduced Enamel Epithelium on Occlusal Surface of Impacted Wisdom Tooth in a Human

There is only limited research on the coronal cementum of a tooth, and the mechanisms of its forming process are not well-defined. This report presents a coronal cementum on the occlusal surfaces of enamel in an impacted wisdom tooth in a human, which is not nearly the cervical portion. The tooth (Tooth #1) was derived from a 46-year-old female. Histological analysis, including hematoxylin and eosin (HE) and toluidine blue (TB) staining, and Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometer (SEM-EDS) analysis of the extracted tooth were conducted. Radiographic examination showed that Tooth #1 was horizontally impacted in the maxilla and had the apex of a single root placed between the buccal and palatal roots of Tooth #2. Coronal cementum was distributed widely on the enamel, and reduced enamel epithelium was also found with enamel matrix proteins histologically. The formation of acellular cementum was observed to be more predominant than that of the cellular cementum in Tooth #1. SEM showed that the occlusal cementum connected directly with enamel. Calcium mapping revealed an almost similar occlusal cementum and enamel. In addition, the spectrum of elements in coronal cementum resembled the primary cementum according to SEM-EDS. Thus, coronal cementogenesis in impacted human teeth might be related to the existence of reduced enamel epithelium.