Cementum
Definition
A thin, bone-like mineralised tissue that covers the external surface of the tooth root. Deposited incrementally throughout life in alternating translucent and opaque annual layers called cementum annuli. These layers can be counted in thin ground sections to estimate age at death.
- Composition
- Mineralised tissue chemically similar to bone but more resistant to degradation
- Forensic application
- Age estimation via incremental rings; DNA extraction substrate when pulp unavailable
- Lifespan change
- Continuous apposition and growth throughout life
Common questions
What is cementum and where is it on a tooth?+
Cementum is a thin mineralised layer that covers the root surface of the tooth. It anchors the periodontal ligament fibres (the connective tissue that holds the tooth in place). Think of it as the tooth's root covering that keeps everything together.
How can cementum help with age estimation?+
Cementum grows throughout a person's lifetime through a process called apposition, adding new layers incrementally. These growth rings can be examined and counted, similar to tree rings, to estimate the age of a deceased individual. This makes cementum a valuable tool in forensic age analysis.
Why is cementum useful for DNA extraction in forensic cases?+
Cementum is resistant to degradation and can retain adsorbed DNA from extracellular sources, even when the pulp is absent. This makes it a reliable extraction substrate for identification when other sources are unavailable.
Related terms
- Dentine
- The mineralised tissue forming the bulk of the tooth, surrounding the pulp chamber and root canal. Contains a network of dentinal tubules,...
- Enamel
- The outermost layer of the tooth crown, formed by ameloblasts before tooth eruption. Composed of approximately 96% hydroxyapatite mineral by weight. Acellular...
- Cementum Annuli
- Incremental growth layers in cementum, deposited at a rate of approximately one pair of translucent and opaque bands per year throughout adult...
- Crown
- The visible portion of a tooth above the gum line, covered by enamel. In forensic charting, crown morphology, restorations, and wear patterns...
- Cryogenic Grinding
- The technique of freezing a tooth sample to cryogenic temperatures (liquid nitrogen, approximately -196°C) before mechanical pulverisation. Freezing prevents frictional heat generation...
- Deciduous Dentition
- The first set of 20 teeth, also called primary or milk teeth, that erupt from approximately six months and are progressively replaced...
- Dentinal Tubules
- Microscopic channels running radially through dentine from the pulp cavity to the outer surface. They house odontoblast cell processes that can carry...
- Mitochondrial DNA (mtDNA)
- DNA located in mitochondria rather than the cell nucleus. Present in hundreds to thousands of copies per cell, making it recoverable from...
- Occlusion
- The way upper and lower teeth meet when the jaw closes. Occlusal wear patterns, class I/II/III relationships, and individual facets on specific...
- Odontoblast
- A specialised cell of neural crest origin that forms dentine. The cell body sits at the pulp-dentine junction while a long cellular...
- Pulp Extraction
- Accessing the soft tissue of the root canal (pulp) directly by cutting the tooth at the cementoenamel junction and removing the contents...
- Short Tandem Repeat (STR) Profiling
- The amplification and typing of microsatellite loci where short DNA sequences are repeated a variable number of times. When applied to canine...
Explained in these topics
- Dental Anatomy: Morphology, Tissues and the ArchesThe thin mineralised layer covering the root surface, anchoring the periodontal ligament fibres to the tooth. Cementum apposition continues throughout life and...
- Dental DNA, Tooth Sampling and Molecular IdentificationThe mineralised tissue covering the outer root surface, chemically similar to bone but more resistant to degradation. Although acellular in most of its layers,...
- Dental Tissue and Its Forensic ApplicationsA thin, bone-like mineralised tissue that covers the external surface of the tooth root. Deposited incrementally throughout life in alternating translucent and...