Cementum Annulation
Definition
The annual ring pairs visible in ground sections of the tooth root cementum, laid down one per year in normal conditions. Counting rings from the point of eruption gives an age estimate typically accurate within two to three years.
- Structure
- Annual ring pairs in tooth root cementum
- Deposition rate
- Approximately one ring pair per year
- Counting reference point
- Point of tooth eruption
- Accuracy
- Typically within two to three years
- Viewing method
- Ground thin section under transmitted light
Common questions
Why must ring counting start from the point of eruption rather than the tooth root apex?+
Cementum continues to be deposited only after a tooth has erupted into function, so rings laid down before eruption are not part of the countable annual sequence and would bias the age estimate if included.
What can distort a cementum annulation age estimate?+
Illness, malnutrition, pregnancy and irregular occlusal loading can all disturb the normal annual deposition rate, producing extra, missing or unclear rings that widen the margin of error in the final estimate.
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