export_chapter 7 aging Flashcards
(26 cards)
What was old theory of force for tooth eruption in horses?
What is thought now?
- root lengthening
- PDL remodeling
At what age to equine incisor teeth stop growing?
When do they stop erupting?
Between what ages is the size of horse incisors constant?
- age 17
- never
- between 6 and 17
What is rate of occlusal wear of equine incisors?
- 2.5 mm /year
Where is the dental star found?
- between labial edge of incisor and the cup
What is the “mark” on equine incisors?
How does it change with time?
- when the bottom of the infundibulum which is filled with cementum comes into occlusion making a cementum core surrounded by enamel
- young horses oval, become smaller, rounder and move caudally, turns into enamel spot, then disappears
How do incisor teeth change shape with time?
- oval mesiodistal, trapezoid, triangular, oval labiolingual
What are three categories of incisor shapes and corresponding age?
5-9, wider than tall
9-10 square
>10 taller than wide
What is Galvayne’s groove and is it accurate?
- Groove in labrial surface that appears around age 10 and supposed to be gone by 30
- No, more than 50% of horses do not have groove between 10 and 30
What are most accurate ways to age horses by teeth?
- eruption and dental stars
What color are dental stars and what does the color vary with?
- yellow to brown
- diet (brown on grass/fodder, yellow on other foods)
Why does dental star have a white dot?
Few tubules (tertiary dentin)
What forms dentin tubules?
- retreating odontoblast (leaving only cytoplasmic process behind)
Where are primary, secondary and tertiary dentin located?
Primary right next to enamel
Secondary central
tertitary - only between tip of pulp chamber and occlusal surface
What is difference structurally between primary and secondary dentin?
- peritubular (intratubular) dentin
What is structure of dentin in dental stars?
Where is the peritubular dentin?
- central core of tertiary dentin (very few tubules)
- broad ring of secondary dentin
- neither
Why is secondary dentin of the dental star pale on inside with dark ring on outside?
- periphery tubules end perpendicular to occlusal (vs inside tubules are parallel) surface so more penetration by food pigments and whole tubule doesn’t wear away as quickly (paralell tubules wear in 1 day)
How does accuracy of dental aging by teeth change with age?
- gets worse as horse ages
What factors affect teeth vs age?
- breed
- diet
What breeds is the eruption schedule described in this book accurate?
- standardbred, Belgian draft, arab, shetland mini pony
What is the schedule for eruption of deciduous central incisors?
Middle?
Third?
- 4-6 weeks
- 4 months
- 12-18 months
When do the permanent incisors erupt?
- 2.5-3 yr
- 3.5-4
- 4.5-5
When do canines erupt in males?
- 4.5-5
When do dental stars appear?
When does white spot appear?
- 4.5 to 7-8,5.5 to 9-11, 6.5 to ?
- 6-7, 8. 9-15
When do cups on central incisors disappear?
middle?
corner?
- all breeds 6-7
- 7-11
- 9-15
