The cementoenamel junction (CEJ) is the anatomical landmark where the enamel covering the crown of the tooth meets the cementum covering the root. At this junction, there is a variation in how these two tissues relate to each other, which is important for both clinical and anatomical understanding.

There are three primary patterns observed at the CEJ:

1. Cementum overlaps enamel – This is the most common pattern, occurring in approximately 60% of teeth. Here, the cementum extends slightly over the enamel.
2. Cementum and enamel meet edge-to-edge – This occurs in about 30% of teeth, where the two tissues meet exactly without overlap or gap.
3. Gap between cementum and enamel – In about 10% of teeth, there is a small gap between the enamel and cementum, which can expose the underlying dentin and potentially lead to sensitivity.

Understanding that 60% of teeth exhibit cementum overlapping enamel at the CEJ is critical, especially for dental procedures involving root surface instrumentation and for diagnosing hypersensitivity related to exposed dentin.

Key Point: The most frequent anatomical relationship at the CEJ is cementum overlapping enamel in approximately 60% of teeth.

Reference: Ten Cate's Oral Histology, 9th Edition, Chapter 5 - The Cementoenamel Junction / Page 124