Tissues and the CEJ

Enamel, dentin, pulp, cementum — what you are looking at when a scan turns yellow.

Objectives

Order enamel, dentin, cementum, and pulp by hardness and by location.
Define the CEJ and why it matters for a margin.
Recognize that CAD enamel is a material assignment, not a tissue.

What the colors are

Enamel — hardest, acellular. Most of this crown mesh.
Teal band — CEJ zone. Facial CEJ curves toward the apex.
Dentin — crowns only, so the cervical cut is stained as dentin. No root to pin.

Read this

Four tissues

Enamel is the hardest, acellular, and does not regenerate. Dentin is vital, tubular, and yellow. Cementum covers the root. Pulp is the neurovascular core. On a prep scan, enamel and dentin do not look the same — dentin is warmer and more matte.

CEJ

The cementoenamel junction. Facial CEJ curves toward the apex; mesial CEJ curves toward the incisal more than distal. A margin that dives past the CEJ onto cementum is a periodontal problem wearing a crown.

Open the practice lab

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