Week 3- Ageing the human skeleton Flashcards
Estimation of age is based on:
- growth and development
- degeneration changes in adult skeletons
- Only estimate age range not a specific age
What are factors in age changes?
- environmental variables= diet, physical activity, trauma and disease
Several ageing methods
- Dental occlusal wear- Wearing down dental enamel, closely tied with diet (hard and abrasive diet wears faster)
- Pubic symphysis metamorphosis- changes on articular surface. Easy and straight forward. pubic bones tend to degrade in burial situations
- cranial suture closure
- auricular surface metamorphosis (ilium)- similar to pubic symphysis
- Rib eternal metamorphosis
- changes in trabecular bone density- humeral and femoral proximal ends
Dental occlusal wear cause
attrition from inner tooth contact
Abrasion from hard particulates (food that you are eating)
Cumulative
* we know how much time the teeth have been in occlusion and age progressive
When does M1 come into occlusion- start of permanent teeth eruption
6 years
M2 into occlusion
12 years
M3 into occlusion
18-20 years
The permanent teeth complete eruption
13 years
the exception of the 3rd molar ‘wisdom’ teeth, which usually erupt by the age of
21 years
Why might the wear be different and why was it different in the past?
- if you lose a maxillary or mandibular molar than it wont have anything to wear against
- past people used their teeth more usually affecting the anterior teeth
Age of individual years based on the condition of the M1
- polished enamel= 6
- dentine= 30
- secondary dentine= 42
Functional age of M2- condition of tooth
- polished enamel= 6
- dentine= 26
- secondary dentine= 45
Functional age of M3- condition of tooth
- polished enamel= 7
- dentine= 21-28
- secondary dentine= 49
What is the highest category age you can research
When you are old, you probably have no dentine left, so you reach a category where you cannot estimate age (Over 65)
Age changes in the pubic symphysis
- young adults= symphysial surface consists of horizontal grooves and ridges
- increase age= grooves are infilled and the margins are thickened to develop a rim around the joint surface
- old age= surface is pitted and porous with an irregular margin
There is a rippling effect over the surface
The rippling of the bones begins to wear away
- body responds by laying down bone
- late stages= small holes which can coalesce and become larger, edges build up to provide more support to articular surfaces
Suchy and brooks 1990 method
- 6 sequential stages of development from early to late
-separate age standard for male and female due to differences in rate of metamorphosis
early= good rippling, no edging
late= pitting and wear down of rim
Anterior surface of ilium
- Stages catergorized by changes in transverse organization
- becomes pitted and extra bone is laid on top of articular surface
- successive non overlapping 5 or 10 year age intervals
Cranial suture closure
- recorded at defined locations on the superior and lateral anterior cranial vault
- sutures present as you age
- closure observed over a stretch of 1cm of suture and scored from 0 (open)to 3 (closed)= scores are summed and evaluated
- most sutures fuse between 30-50
Changes in sternal ribs 4 to 6
- young adult= joint is smooth, straight walled and slightly indented
- articular surface changes with age
- increase age= increase in depth and width
Changes in head of humerus and femur
Thinning and cavitation of the trabeculae
increased height of the apex of
thinning of cortex of the diaphysis
Microscopic age estimation
- Root denting transparency- microscopic tubules in dentine are progressively infilled, starting at the root
- Cementum growth- accumulates in thin layers on the surface of the tooth roots.
- Osteon accumulation- bone areas in compact bones, long bones- continue to grow in adult life
Layers of the tooth
Enamel Dentine Secondary dentine cementum layers pulp cavity cement on tooth root
Growth standards based on
- increase with age in linear bone dimensions
- appearance and fusion of centres of ossification
- calcification, eruption and loss of deciduous teeth `
How to recognise immature bones?
- texture and density- Epiphyses are no fused on the shaft, smooth
- size and proportions- using shafts of long bones
- younger children are easier to age
Age estimation based on epiphyseal fusion
- fusion of growth centres and epiphyses occur at defined stage of growth
- fusion takes during adolescence
- end of long bone was initially separated from shaft-cartilage ossifies so they can fuse
The timings of proximal and distal end of the long bone, and the clavicle and sacral bodies
clavicle- completed early adult life
long bones-fuse at different times, timing may vary and the order is consistent
Foetal or young children indicators
vertebrae are as good as age indicators
- body and 2 neural arches
The 2 neural arches
- first neural arches will fuse together and then the body
fuse at different rates
Deciduous teeth- general characteristics
- smaller size, prominent bulge to crown above the cervical margin
- cemento-enamel junction is less sinuous
- roots of anterior teeth narrow
- roosts posterior teeth flared to accommodate premolar crowns
- pulp chambers are large with thinner primary dentine
- enamel wears quickly and prone to decay
- roots reabsorbed prior to exfoliation of crowns
- mandibular first molar does not look distinguishable, second more obvious
How do you evaluate age based on dental development?
pictorial charts of dental developmet- not sufficiently accurate
- can look at how much of the crown is formed and how much of the root is formed
- permanent first molar at the stage of 5.1 years
- canine crown estimated 4 years
Which is more reliable- dental eruption or calcification?
Calcification is much more reliable
crowns and roots estimate age
Growth standards are available for the following stages of dental development:
- calcification and emerge of the deciduous teeth
- root reabsorption and exfoliation of deciduous teeth
- calcification and emerge of permanent teeth
Pubic symphysis stages
1- billowing surface composed of ridges and furrows, well marked
2- retain some billowing, extremities show early stages of delamination with possible ossific nodules
3- smooth , retains some evidence of ridges, nodules, extremities show
4- fine grained, oval outline with distinctive rim, pubic tubercle not part of symphyseal surface. bony outgrowths may occur
5- depression of face of completed rim, outgrowths of ventral border
6- depression in rim erodes. Bony outgrowths. face pitted or porous
