[2] Active recession of the gingiva reveals the cementoenamel junction in the mouth and is usually a sign of an unhealthy condition.

[3] In the tooth bud, regions where enamel formation is completed, the enamel organ gives rise to Hertwig's epithelial root sheath, composed of two epithelial layers derived from the external and internal epithelia.

The sheath is irregularly fragmented in time and space as it promotes cementum deposition on the newly formed dentin.

Consequently, the relationship between cementum and enamel at the CEJ presents an irregular contour, as observed during scanning electron microscope (SEM) analysis of the primary teeth.

Fragmentation of Hertwig's epithelial root sheath and exposure of dentin covered by a thin layer of intermediate cementum are fundamental for the onset of cementogenesis.

Posterior teeth have flatter CEJ curvatures on the inter-proximal surfaces in comparison to the anteriors.