Cryogenic Grinding
Definition
The technique of freezing a tooth sample to cryogenic temperatures (liquid nitrogen, approximately -196°C) before mechanical pulverisation. Freezing prevents frictional heat generation during grinding, which would degrade DNA, and the resulting fine powder maximises extraction buffer contact.
- Temperature
- Approximately -196 degrees Celsius, using liquid nitrogen
- Reason for freezing
- Prevents frictional heat degrading DNA during grinding
- Output
- Fine powder with high extraction buffer contact
- Applies to
- Dental DNA sampling for identification
Common questions
Why does grinding at room temperature risk damaging the DNA sample?+
Mechanical grinding generates friction, and the heat produced can denature or fragment DNA before it is ever extracted, which is a particular problem with hard tissues like tooth material that require forceful pulverisation to break down.
Does a finer powder actually improve DNA yield, or is the freezing step the main benefit?+
Both matter together: freezing prevents heat damage, and the resulting fine, brittle powder exposes far more surface area to the extraction buffer than coarse fragments would, so the two effects combine to increase the amount of usable DNA recovered.
Related terms
- Cementum
- A thin, bone-like mineralised tissue that covers the external surface of the tooth root. Deposited incrementally throughout life in alternating translucent and...
- 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...
- 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...