Viscoelasticity
Definition
Skin's combined elastic (spring-back) and viscous (flow) behavior under stress. Because skin is viscoelastic, it deforms under biting pressure in ways that do not faithfully preserve tooth geometry, and the degree of distortion varies with bite force, location on the body, and the victim's age and hydration.
- Components
- Elastic (recoverable) plus viscous (time-dependent) response
- Relevant tissue
- Human skin
- Effect on bite marks
- Distorts tooth-arch geometry recorded in the mark
- Variable factors
- Bite force, body site, age, hydration
Common questions
Why does this matter for matching a bite mark to a suspect's teeth?+
Because skin does not deform uniformly or predictably, a bite mark's width and arch shape can differ from the biter's actual dentition by a variable amount. This is a core reason bite mark pattern comparison has been criticised as lacking a validated error rate, and why courts increasingly treat it with caution.
Does distortion happen the same way on every part of the body?+
No. Skin overlying bone, such as the scalp, distorts less than skin over soft tissue such as the abdomen or breast, because the underlying support changes how the tissue stretches and recoils under bite pressure.
Related terms
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Contusion
- Bruising without a break in the skin surface. Many bite marks present as contusion patterns: paired arches of discolouration with no laceration....
- Dental Arch
- The curved row of teeth in the upper (maxillary) or lower (mandibular) jaw. The shape and width of each arch is partly...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Petechial Haemorrhage
- Tiny pinpoint bleeds within the skin, sometimes visible inside the bite circle as a result of suction. Their presence can help confirm...