Aging Horse Teeth Flashcards
What to look for when aging horses?
**Mostly looking at incisors, especially lower
-eruption of teeth
-growth
-continuous wear
-profile changes of teeth over time
Eruption time criteria usage in aging horse
-can be accurate and used up to ~5yrs of age
Wear pattern based criteria in horses
-less reliable
-depends on diet, feeding habits, environment, genetics, disease
-due to less wear, teeth of stabled horses tend to appear younger than they are, and horses grazing in sandy areas appear older
First and most important step of aging horses
-determine if incisors are all deciduous, all permanent, or a combination of both
How to determine whether deciduous vs. permanent
-Deciduous: fairly distinct neck, less cement, pale colour, fine grooves
-Permanent: gradual transition to gum line, more cement, darker colour, coarse grooves
Infundibulum
-a funnel-shaped enamel infolding, lined by and filled at proximal end (bottom) with cement
Cup
-cavity in center of infundibulum
- looks black due to accumulated debris
In wear
-dentin starts to be seen
-begins when tooth reaches height of neighbours
Level
-start to see a complete circle of dentin/enamel around cup
Cup gone
-cavity within infundibulum has disappeared
Enamel spot
-a mark
- at the bottom of the infundibulum
-made of a ring of enamel and enclosed cement core
-resistant structure, standing proud above surrounding
Dental star
-section thru former pulp cavity
-now filled with repair/dark dentin
-surface smooth as surrounding, only darker colour
-changes shape over time from linear to round
-more rostral/labial to enamel spot
Round
-tooth profile becomes roundish
Triangular/rectangular
-tooth profile becomes triangular/rectangular
Order of events for Incisors, 1, 2, 3 (deciduous)
-deciduous incisors erupt at ~6days, 6weeks, and 6 months
-incisors in wear at ~1yr, 1yr, and 2 yrs
Order of events for incisors 1,2,3 (permanent)
-erupt at ~2.5, 3.5, 4.5 yrs
-in wear at ~3, 4, 5 yrs (approx. 6 months after eruption)
Occlusal surface changes due to wear
-permanent incisors wear ~2mm/year
-cup gets smaller and finally disappears
-lower cup: ~6mm deep,
so cup gone ~3yrs after
in wear
-upper cup: ~12mm
deep, so cup gone
~6yrs after in wear
-dental star appears and changes from a line to a round spot
When do cups disappear in horses?
-Lower incisor: cup gone at ~6,7,8 years
- Upper incisors: cup gone at ~9,10, 11 years
When does enamel spot disappear in lower incisors?
~12-18years
When do lower incisors become triangular?
~16-17 years old
When do lower incisors become rectangular?
-more than 18yrs
Galvayne’s Groove on upper incisors
-may appear on upper corner incisors (I3)
-not reliable, but can sometimes be useful
-a form of coarse groove
When does Galvayne’s groove appear?
10 yrs
Galvayne’s groove growth
-halfway down tooth at 15yrs
-reaches occlusal surface of tooth at 20 yrs
-only lower half at 25yrs
-gone at 30yrs (eventually tooth is worn down and groove will disappear)
Labial profile of upper incisor 3
-view from labial surface
-looks wider than it is tall at ~5-9yrs old
-looks almost square at ~10yrs
-looks taller than it is wide (more than 10yrs old)
When does upper incisor 3 appear?
4.5 yrs old
Hook on I^3
-known as 7yr or 11 yr hook
-very unreliable, may or may not appear from 5-15yr
Angle of upper and lower jaw
-can be used as a general guideline
-younger horses have more perpendicular jaws
-older horses have a sharper angle
Purpose of age estimation of ox
-used in border crossing/slaughterhouse inspections
-less studied
- also based on eruption times and tooth wear (mostly on lower incisors and canine usually included as I4)
Teeth of Ox
-only lower incisors
-dental pad
-Lower canine is considered a incisor
Eruption times of Ox teeth
-eruption time variations can be more than 1 year
-First permanent incisor: 1.5-2years
-Second permanent incisor: 2-2.5 years
-third permanent incisor: 3-3.5years
Wear of ox teeth
-start to wear from central to lateral
