Anatomy and Development Flashcards
1
Q
In Schrock’s 2013 study “Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes,” equine incisors reach their maximum length how many years post eruption, and after what tooth age does the tooth length start to decrease rapidly?
Staszyk BMC Veterinary Research 2013
A
Maximum length 2-4 years
decrease rapidly after 13-15 years
2
Q
In Schrock’s 2013 study “Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes,” identations are present in the enamel of what surfaces of the teeth, and enamel reaches further apically on the labial or palatal sides of the teeth?
Staszyk BMC Veterinary Research 2013
A
Indentations: mesial and distal
Enamel reaches further on labial surface
3
Q
In Schrock’s 2013 study “Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes,” what incisors are stat sig longer than the others in the upper and lower quadrants respectively?
Staszyk BMC Veterinary Research 2013
A
Upper: middle
Lower: corner
4
Q
In Sahara’s 2014 paper “Development of Coronal Cementum in Hypsodont Horse Cheek Teeth,” this image of a mandibular fourth premolar occlusal surface is most consistent with what age horse?
The Anatomical Record 2014
A
3.5 years
5
Q
In Sahara’s 2014 paper “Development of Coronal Cementum in Hypsodont Horse Cheek Teeth,” how was the resorption of enamel evaluated with histochemistry?
A
tartrate-resistant acid phosphatase (TRAP) activity as a marker for odontoclasts and their precursors using the azo-dye method
Study showed for the first time that prior to coronal cementogenesis TRAP-positive odontoclasts resorbed the enamel surface of the reserve crown in horse cheek teeth
6
Q
In Sahara’s 2014 paper “Development of Coronal Cementum in Hypsodont Horse Cheek Teeth,” what are the structural composition differences between infolding and peripheral cementum?
A
Infolding cementum: free from extrinsic collagen fibers (Sharpey’s fibers), cellular with abundant blood vessels, maintains occlusal surface
Peripheral cementum: contains Sharpey’s fibers and provides anchorage for PDL, tertiary cementum thickest in subgingival region
Secondary and tertiary cementum provides sites for insertion of the PDL
7
Q
In Omura’s 2015 paper “Measurement of Incisor Overjet and Physiological Diastemata Parameters in Quarter Horse Foals,” maximum growth of the maxillary and mandibular diastemata occured in what age group?
JVD 2015
A
4-5 months old
8
Q
In Omura’s 2015 paper “Measurement of Incisor Overjet and Physiological Diastemata Parameters in Quarter Horse Foals,” overjets were most common in what sex of Quarter horses of what lineage?
JVD 2015
A
female Quarter horses of show lineage
9
Q
In Iacopetti’s 2015 article on the mandibular nerve, in 95% (38 horses) of the subjects examined, the nerve changes direction between which roots of which teeth?
Anat Histol Embryology 2015
A
mesial root of M1 and the distal root of PM4
In the remaining 5% of the subjects examined (2 horses), a variation was found in the course of the nerve at this site → the IAN runs lingually and coronally as described above, but passes between the distal and the mesial roots of PM4 instead
10
Q
In Suske et al’s paper “Infundibula of equine maxillary cheek teeth. Part 1: Development, blood supply and infundibular cementogenesis”, which cheek tooth infundibula has blood supply for longer in development?
The Vet Journal 2016
A
Distal infundibulum
Equine infundibula are assumed to represent extreme deep and large pits in between enamel cusps
According to this concept, the enamel organ invaginates from an occlusal direction and produces the infundibular enamel
Consequently, the dental follicle tissues (including blood vessels) have to follow the occlusal route to initiate the onset of infundibular cementogenesis.
After tooth eruption the afferent blood vessels are assumed to have been destroyed and therefore cementogenesis immediately stops
11
Q
According to White and Dixon 2010 what is the range of distance between between the occlusal surface and pulp tissue (depth of subocclusal secondary dentin) in a 4 year old vs 16 year old horse?
A
4 yro: 5-33mm
16 yro: 2-24mm
12
Q
In Listmann’s 2017 paper “Occlusal Angles of Equine Incisors,” what significant differences in the left and right sides were observed for teeth in same triaden position and the jaws themselves respectively?
JVD 2017, Issue 4, Staszyk
A
No stat sig differences in angles for same triaden teeth positions right to left
Marked differences between left and right sides of upper and lower jaws
13
Q
In Listmann’s 2017 paper “Occlusal Angles of Equine Incisors,” were the upper or lower bars most suitable to determine incisor angulations?
JVD 2017, Issue 4, Staszyk
A
Lower bars due to relatively straight profile vs curve of maxillary bars and facial crest
The TMJ and eyeball were not useful reference points
14
Q
In Hole’s 2016 study “Dimensions of 65 Extracted Equine First Premolar Teeth,” what were the correlations between crown height and root length and total length?
JVD 2016
A
Crown height and crown width were either not correlated or poorly correlated with root length
Crown height was poorly correlated with total length
15
Q
In Hole’s 2016 study “Dimensions of 65 Extracted Equine First Premolar Teeth,” what measurements were statistically significantly correlated?
JVD 2016
A
Total tooth length was correlated with root length
16
Q
In Hole’s 2016 study “Dimensions of 65 Extracted Equine First Premolar Teeth,” what was the median total length and median root length?
JVD 2016
A
Median total length: 21mm
Median root length: 13mm
17
Q
In Englisch’s 2018 paper “Anatomy of equine incisors: Pulp horns and subocclusal dentine thickness”, what was the subocclusal dentine thickness range for upper and lower incisors
EVJ 2018
A
1.5 and 11.7 mm in upper
0.7 and 6.7 mm in lower incisors.
18
Q
In Englisch’s 2018 paper “Anatomy of equine incisors: Pulp horns and subocclusal dentine thickness”, what variations of pulp horns were present anatomically in the incisors?
EVJ 2018
A
1-2 pulp horns, labiomesial and labiodistal
Majority of upper incisors (≥65%) featured both a labiomesial and a labiodistal pulp horn.
Lower central (301/401) and middle incisors (302/402) showed the same prevalence (≥65%) of the two pulp horns.
All lower corner incisors (303/403) only the labiomesial pulp horn was present.
Almost all incisors (97%) featuring only one single pulp horn possessed the labiomesial pulp horn
19
Q
In Poschke’s 2018 study “Molecular Characteristics of the Equine Periodontal Ligament,” what tendon molecular components were significantly higher in mature PDL tissue vs mature tendon tissue?
Staszyk, Frontiers 2018
A
COL1, COL3
20
Q
In Poschke’s 2018 study “Molecular Characteristics of the Equine Periodontal Ligament,” what was the ratio between mean relative COL1 and COL3 gene expression for mature equine PDL?
Staszyk, Frontiers 2018
A
3.3:1
21
Q
In Horbal’s 2019 paper “A Computed Tomographic (CT) and Pathological Study of Equine Cheek Teeth Infundibulae Extracted From Asymptomatic Horses. Part 1: Prevalence, Type and Location of Infundibular Lesions on CT Imaging” which max cheek tooth infundibulum was more frequently affected by occlusal caries? Which triadan position?
Frontiers 2019
A
Rostral infundibulum
09s
The rostral infundibulae were significantly more frequently affected by higher grades of caries than the caudal infundibulae
22
Q
In Horbal’s 2019 paper “A Computed Tomographic (CT) and Pathological Study of Equine Cheek Teeth Infundibulae Extracted From Asymptomatic Horses. Part 1: Prevalence, Type and Location of Infundibular Lesions on CT Imaging” of 200 infundibulae examined by standard CT, how many had some form of subocclusal cemental lesion?
Frontiers 2019
A
182 (91%)
23
Q
In Horbal’s 2019 paper “A Computed Tomographic (CT) and Pathological Study of Equine Cheek Teeth Infundibulae Extracted From Asymptomatic Horses. Part 1: Prevalence, Type and Location of Infundibular Lesions on CT Imaging” what percent of infundibulae without occlusal caries had subocclusal developmental infundibular lesions?
Frontiers 2019
A
72% of infundibulae without occlusal caries
24
Q
In Tanner’s 2019 study “A Retrospective Study of the Prevalence of First Premolars in 306 Thoroughbred Yearlings,” what overall percent of horses had erupted maxillary first premolars at the time of examination and what was the average age?
JVD 2019
A
73% erupted maxillary first premolars
Average age at time of examination 15 months
25
In Tanner's 2019 study "A Retrospective Study of the Prevalence of First Premolars in 306 Thoroughbred Yearlings," horses less than or equal to 13 months old and greater than or equal to 18 months old had what prevalence of erupted maxillary first premolars?
< 13 months old 50% prevalence
> 18 months old 90%
## Footnote
20-23 months old 100%
26
In Tanner's 2019 study "A Retrospective Study of the Prevalence of First Premolars in 306 Thoroughbred Yearlings," what percent of males vs females had erupted first premolars?
## Footnote
JVD 2019
Males 67%
Females 77%
## Footnote
stat sig fewer males than females
27
In Tanner's 2019 study "A Retrospective Study of the Prevalence of First Premolars in 306 Thoroughbred Yearlings," what age was the eruption age of maxillary first premolars in TBs suggested to be lengthened to?
18 months (present in 90%)
28
What developmental disorder is depicted?
## Footnote
EVE 2020 Dixon
Dental dysplasia
abnormal buccal protrusion composed mainly of dentine and peripheral enamel
29
What developmental disorder is depicted here?
## Footnote
EVE 2020 Dixon
Dental dysplasia
No infundibulum, abnormal distribution of pulp horns
## Footnote
More prone to central wear with no INF
30
What is the most common supernumerary tooth in the horse? Least common?
## Footnote
EVE 2020 Dixon
Incisors are most common
Least common is a mand CT as Maxillary cheek teeth > mandibular cheek teeth
Of the cheek teeth, tend to be 11s
31
What is the least common dental disorder in the horse?
## Footnote
EVE 2020 Dixon
Hypodontia or anodontia is the rarest equine dental developmental disorder with a prevalence of 0.25% in one study of 400 horses (Dixon et al. 1999).
32
In Domanska-Kruppa's 2019 study "Cephalometric Study of the Overjet Development in Warmblood Foals," what percent of foals evaluated had a overjet, what percent of those foals had spontaneous regression of incisor misalignment, and what percent of control foals developed an overjet?
## Footnote
Frontiers 2019
2% (13/650) foals had an overjet
69% (9/13) spontaneous regression
31% (4/13) control foals developed overjet
33
In Domanska-Kruppa's 2019 study "Cephalometric Study of the Overjet Development in Warmblood Foals," what two ratios were useful to determine whether a foal born with physiological incisor alignment would develop overjet?
## Footnote
Frontiers 2019
PiMx/PiMn, Mna/ML
34
In Domanska-Kruppa's 2019 study "Cephalometric Study of the Overjet Development in Warmblood Foals," did short or long lines have improved accuracy and what were the most accurate measurements?
## Footnote
Frontiers 2019
Long lines improved accuracy
most accurate measurements: FL-facial, EtL-ethmoidal cephalometric lines
35
In Kau’s 2020 paper “Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns,” which of the following is most correct?
A) Regardless of tooth position, tooth generation, or age, the majority of examined horses showed an acute interincisal angle.
B) A non-linear age-related angle decline most distinctive in first incisor length was shown
C) Period of greatest decrease in clinical crown IIA < 13-15 years had constant tooth length ratios
D) Age estimate based on the interincisal angle of clinical crowns was recommended by the authors
## Footnote
Frontiers 2020
C) Period of greatest decrease in clinical crown IIA < 13-15 years had constant tooth length ratios
## Footnote
A) obtuse interincisal angle
B) third incisor length was shown
D) age estimates NOT recommended
36
In Kau’s 2020 paper “Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns,” what two trends were noted overall in regards to the angle?
## Footnote
Frontiers 2020
IIA (the interincisal angle) tends to approach an end value in older horses
Third incisor teeth show a significantly higher overall angle decrease compared to first and second incisors
37
In Kau’s 2020 paper “Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns,” can the interincisal angle determine age?
## Footnote
Frontiers 2020
No - authors do not recommend, not accurate
38
Define hetertopic polydontia and dentigerous cyst
## Footnote
Platt JVD 2021 issue 1
Heterotopic polyodontia: Extra tooth outside the dental arcade. Includes dentigerous cysts in the temporal region of the horse
Dentigerous cysts Aka temporal teratoma, ear tooth, ectopic tooth or heterotopic polyodontia
Congenital abnormality that form due to premature closure of the first branchial cleft during embryologic development → ectopic dental tissue
39
In Pimentel's 2021 study "The Frequency of Communication Between the Synovial Compartments of the Equine Temporomandibular Joint: A Contrast-Enhanced Computed Tomographic Assessment" what do each arrow indicate for location of the contrast media?
## Footnote
Frontiers 2021
presence of the radiopaque contrast material in the discotemporal joint (yellow)
discomandibular joint (blue)
varying amounts outside the joints (white)
40
In Pimentel's 2021 study "The Frequency of Communication Between the Synovial Compartments of the Equine Temporomandibular Joint: A Contrast-Enhanced Computed Tomographic Assessment" what was the conclusion of the communication between compartments?
## Footnote
Frontiers 2021
No communication in non-diseased TMJs
41
What characteristic was described as possibly unique to paranasal sinus cysts in Ostrowska's 2020 EVJ paper "Computed tomography characteristics of equine paranasal sinus cysts"?
## Footnote
EVJ 2020
A discrete hyperattenuating wall-like structure was detected in the periphery of the sinus lesion in precontrast acquisition in 7/8 horses with paranasal sinus cysts.
42
In Guerrero Cota's study "Regional and disease-related differences in properties of the equine temporomandibular joint disc" what region of the disk showed the highest stiffness/strength?
## Footnote
Journal of Biomechanics 2019
Rostral region
## Footnote
The disc also exhibits increasing GAG content and compressive stiffness with increasing age
43
What is the definition of syndesmosis?
## Footnote
Verwilghen Vet Sciences 2022
A non-synovial joint
Think of the sutures between facial bones
## Footnote
During the fetal period, the bones of the calvaria (top of the skull) and face are formed from intramembranous ossification sites within the mesenchyme covering the brain.
44
When do the facial bone sutures close?
## Footnote
Verwilghen Vet Sciences 2022
Only the frontomaxillary suture expresses complete bony fusion in horses older than 20 years.
The lacrimomaxillary and zygomaticomaxillary sutures remained at least partly filled with connective tissue even in some individuals of up to 30 years of age.
45
In equine hypsodont dentition, three types of peripheral cementum are defined according to their order of appearance. What are the 3?
## Footnote
James EOTRH Review JVD 2022 Issue 4
(1) A thin primary layer is deposited directly on the peripheral enamel
(2) The second layer is the functional, thicker layer responsible for anchorage to the periodontal ligament (PDL). This layer is able to constantly remodel when triggered by the normal process of continuous tooth eruption
(3) The third layer consists of tertiary cementum that is deposited subgingivally, forming part of the clinical crown once the tooth erupts
46
Enamel is comprised of what percentage of inorganic materials vs organic components and water?
## Footnote
Arnbjerg, 2014
96-98% inorganic, 2-4% organic materials and water
47
Dentin is comprised of what percentage of inorganic materials vs organic components and water?
## Footnote
Arnbjerg, 2014
70% inorganic, 30% organic materials and water
48
Cementum is comprised of what percentage of inorganic materials vs organic components and water?
## Footnote
Arnbjerg, 2014
65% inorganic, 35% organic materials and water
49
Identify the pathology indicated by the white arrows as seen in the study by Arnbjerg in 2014
Irregular hypercementosis
50
In Alshami's paper "Comparison of Computed Tomography Assisted 3D Cephalometric Measurements in Straight Egyptian Arabian and Thoroughbred Horses" what were the outcomes when comparing the SEAR to the TB breeds?
## Footnote
Alshami 2024 JVD
All 9 cephalometric measurements were found to be significantly greater in TB than SEAR (P < 0.05).
For the facial line: mandibular length (FL/ML) ratios TB > SEAR (P=0.002)
For the maxillary cheek teeth length: ethmoidal line ratio (Mxa/EtL), SEAR > TB (P=0.0007).
## Footnote
Difference in interincisal angle may be explained by the sig difference in age between the two groups, with the SEAR group older
51
The maxillary septal bullae lies ventral to what sinus?
## Footnote
Carmalt 2020 EVE "Intraoperative depression of the bulla of the maxillary septum as amethod of improving sinus drainage without epistaxis in horses"
courses rostro dorsally under the floor of the dorsal conchal sinus
52
What anatomy is being removed via this frontochonal flap?
## Footnote
Carmalt 2020 EVE
Maxillary septal bullae
53
What bone in the hyoid apparatus is unpaired?
## Footnote
Hartl. Correlated imaging of the equine hyoid apparatus using CT, micro-CT, and histology. Frontiers 2021.
Basihyoid
54
What joint in the hyoid apparatus is a synovial joint?
## Footnote
Hartl. Correlated imaging of the equine hyoid apparatus using CT, micro-CT, and histology. Frontiers 2021.
connection of thyrohyoid bones to thyroid cartilage of layrnx
Connections of ceratohyoid bone to epihyoid/stylo-epi when fused, and ceratohyoid to basihyoid
55
Guttural pouch endoscopy allows examination of what portions of the hyoid apparatus?
## Footnote
Hartl. Correlated imaging of the equine hyoid apparatus using CT, micro-CT, and histology. Frontiers 2021.
proximal stylohyoid and temporohyoid joint
56
Describe the path of the maxillary division of the trigeminal nerve.
## Footnote
Fairburn. Computed tomographic findings in 101 horses presented for the investigation of headshaking. EVE 2022
Exits skull at round foramen and runs cranially through pyterygopalatine fossa before entering maxillary foramen and continuing through the infraorbital canal asa infraorbital nerve
57
In RoBgardt's 2022 study "The equine dental pulp: analysis of the stratigraphic arrangement of the equine dental pulp in incisors and cheek teeth," what was the association of blood vessel density with age and what zones of the pulp had the highest blood vessel density?
## Footnote
Vet Sci 2022
Blood vessels had an increasing trend with age in the equine dental pulp
Presence of higher density of small vessels in peripheral zones and larger vessels in central zones consistent with brachydont teeth
## Footnote
Teeth of aged horses possess a similar or even higher vascularity than deciduous or young teeth → high prolonged productivity
58
In RoBgardt's 2022 study "The equine dental pulp: analysis of the stratigraphic arrangement of the equine dental pulp in incisors and cheek teeth," was there evidence for the presence of a subodontoblastic nerve plexus reaching out into the dentinal tubules?
## Footnote
Vet Sci 2022
No
presumably because dentin is exposed at the occlusal surface by physiological wear
59
In RoBgardt's 2022 study "The equine dental pulp: analysis of the stratigraphic arrangement of the equine dental pulp in incisors and cheek teeth," was a cell free zone observed in equine teeth?
## Footnote
Vet Sci 2022
No
## Footnote
Authors propose to define a subodontoblastic supportive zone with high cellularity that shows a high capacity for dentin production even in older age
60
What is a "loph" structure of a tooth?
## Footnote
Ch 1, evolution
“loph” is a complex ridge formed between cusps as enamel is worn away
61
Properly label the cusps and lophs of this maxillary cheek tooth
Ch. 1 Evolution
## Footnote
Ch. 1 Evolution
62
Properly label the cusps of this mandibular cheek tooth
## Footnote
Ch. 1 Evolution
63
Which direction do secondary dentinal tubules run?
## Footnote
Easley Textbook, ch 25
Coronal to apical
64
Which of the following statements is true regarding the enamel of incisors?
A. They contain mostly type I enamel and are less resistant to wear than cheek teeth
B. They contain mostly type II enamel and are less resistant to wear than cheek teeth
C. They contain mostly type I enamel and are more resistant to wear than cheek teeth
D. They contain mostly type II enamel and are more resistant to wear than cheek teeth
## Footnote
Easley Textbook, ch 25
B. They contain mostly type II enamel and are less resistant to wear than cheek teeth
65
What is the rate of eruption for teeth that are completely out of occlusion?
## Footnote
Easley Textbook, ch 25
0.5cm-2cm / year
66
What are the black arrows indicating in this incisor histopath image?
## Footnote
Ch 10
irregular but phasic growth of irregular cementum
67
What feature of campylorrhinis lateralis can be life threatening?
## Footnote
Ch 9
Nasal septum deviation
| Wry nose
## Footnote
All features: Diagonal incisor occlusion, Focal cheek teeth overgrowths, Nasal septum deviation, Shortening of the incisive bones
68
The prevalence of hypodontia is estimated to be:
## Footnote
Ch 9
< 1%
69
A supernumerary tooth that is characterised by a simple, usually conical shaped crown with a single root is known as which type of supernumerary tooth?
## Footnote
Ch 9
Haplodont supernumerary tooth
70
Define a Tuberculate supernumerary tooth
## Footnote
Ch 9
A tooth with complexly-shaped clinical and reserve crowns with multiple raised tubercles with deep occlusal indentations on the occlusal surface.
71
What is a connate supernumerary tooth
## Footnote
ch 9
composed of two or more tooth elements joined together, possibly arising from the fusion of two or more tooth germs or alternatively from a partial splitting of an embryonic tooth into two or more parts -- not necessarily supernumerary
## Footnote
Image from Dixon VCNA 2005 "Supernumerary teeth in the horse"
72
What developmental structures can remain visible around the apex of young adult cheek teeth?
## Footnote
Staszyk 2015 EVE "Equine dental and periodontal anatomy A tutorial review"
Dental follicle and enamel organ (before roots close) -- "eruption cysts"
## Footnote
Eruption cysts aka Prominentiae osseae transistoriae
73
What do the arrows indicate anatomically of this CT of a 306?
## Footnote
White and Dixon 2010 EVJ
Transition from pulp to subocclusal secondary dentin
74
In Froydenlund's study "Anatomical and histological study of the dorsal and ventral nasal conchal bullae in normal horses" what were the main anatomical findings noted for the VCB and DCB?
## Footnote
Froydenlund Vet Rec 2017
DCB was larger than the VCB, containing more septae, cellulae and drainage apertures.
No communications were identified between the bullae and the immediately adjacent paranasal sinuses.
75
At what age do incisors start to decrease in length?
## Footnote
Easley ch 27
13-15 yo
76
What is the range of length of infundibulum?
## Footnote
Pearce 2016 EVE
2mm - 89mm
77
What developmental pathology is noted in this maxillary cheek tooth?
## Footnote
Pearce 2016 EVE
A supernumerary infundibulum is present palatal to the normal rostral and caudal
infundibula
78
What does the term anelodont mean?
## Footnote
Easley 2022
limited growth period teeth
in reference to brachydont and hypsodont teeth continuing to develop roots after the end of crown formation
79
What is the definition of the term elodont?
## Footnote
Easley 2022
Teeth that continually grow and elongate their crown throughout all of an animal's life
occurs in rodents and lagomorphs
80
What percent of equine mandibular cheek teeth still have no root development even 12 months following their eruption?
## Footnote
Easley 2022, Kirkland 1996
~25%
81
What are the definitions of primary and secondary occlusal surfaces?
## Footnote
Easley 2022
primary occlusal surface: contains cementum over entire occclusal surface of clinical crown prior to being in wear
Secondary occlusal surface: after all occlusal cementum has worn away,with protrusion of enamel folds above dentin and peripheral cementum when in wear
82
In comparision to bracydont teeth, hypsodont teeth have a delayed termination of what stages of tooth development?
## Footnote
Easley 2022
morphogenetic and cytodifferentiative states (at their apical region)
83
What is the Tome's process and what does it do?
## Footnote
Easley 2022
A protrusion of ameloblasts that produces enamel
proximal aspect of process secretes interprismatic enamel
secretions from surface of process form enamel prisms
84
When does calcification of deciduous cheek teeth buds start and end?
## Footnote
Easley 2022
starts by 120th day of conception
Completed by 240 days
85
Disintegration of what developmental tooth structure allows peripheral cementum to be laid down?
## Footnote
Easley 2022
Enamel organ and Hertwig's epithelial root sheath
86
Why does cementum develop over the entire crown surface in equine cheek teeth?
## Footnote
Easley 2022
Because the crown of hypsodont teeth remain subgingivally within the jaws when crown formation has finished and the enamel organ starts to disintigrate
87
What is the mineral content of enamel?
## Footnote
Easley 2022
95-98%
88
What is the tissue type of origin of enamel vs dentin and cementum?
## Footnote
Easley 2022
enamel: ectoderm
dentin and cementum: ectomesenchymal
89
What type of enamel is hardest and most wear resistant and what type of enamel is most resistant to fracture?
## Footnote
Easley 2022
Type 1: hardest and most wear resistant
Type 2: most resistant to fracture
90
What is morphologic description of the structure of Type 1 enamel and where is it located?
## Footnote
Easley 2022
Composed of prisms that are oval or rounded on cross section that lie in parallel rows between plates of dense interprismatic enamel
located at amelodentinal junction (between enamel and dentin)
91
What is morphologic description of the structure of Type 2 enamel and where is it located?
## Footnote
Easley 2022
Composed soley of enamel prisms in horseshoe to keyhole shapes oriented in all three planes with no interprismatic enamel
Located on abaxial/periphery of enamel layer
92
What is morphologic description of the structure of Type 3 enamel and where is it located?
Composed of prisms completely surrounded by large quantities of interprismatic enamel in honeycomb-like structure
Inconsistently present at amelodentinal and amelocemental junctions
93
Equine enamel is composed primarily of what two types of enamel?
## Footnote
Easley 2022
Type 1 and Type 2 enamel
94
Where along the enamel folds is there the highest proportion of Type 2 enamel?
## Footnote
Easley 2022
Peripheral enamel folds in particular on maxillary cheek teeth vertical buccal ridges/cingulae
95
The highest proportions of Type 1 enamel are present in maxillary or mandibular cheek teeth and incisor enamel is almost completely composed of what type of enamel?
## Footnote
Easley 2022
Type 1 highest in maxillary CT
Incisors almost all Type 2
## Footnote
mandibular CT equal amounts of Type 1 and 2 enamel
96
What is the difference between donkey and horse type of enamel distribution patterns?
## Footnote
Easley 2022
Donkey maxillary CT have similar proportions of Type 1 and Type 2 while horse maxillary CT have more Type 1
97
What is the order of dentin occlusal layers from axial to abaxial?
## Footnote
Easley 2022
irregular secondary dentin
secondary dentin
primary dentin
98
What is the definition and purpose of enamel decussation?
## Footnote
Easley 2022
Interweaving of enamel prisms with 3D changes of direction of bundles of enamel
Adaptive process to prevent enamel fissures/cracks
Not present in Type 1 enamel
## Footnote
particularly developed in Type 2 enamel
99
At what location on equine cheek teeth is the peripheral and infundibular enamel about three times thicker?
## Footnote
Easley 2022
Sites where the enamel is parallel to the long axes of the maxillae and mandibles vs where they are perpendicular to the axis (peripheral enamel infoldings)
100
What is the length of the maturation period for equine enamel?
## Footnote
Easley 2022
18-34 months
101
What is the so called biological safety glass?
## Footnote
Easley 2022
The presence of dentin and cementum interspersed between hard but brittle enamel layers in equine teeth that helps prevent cracks and provides an irregular, self sharpening occlusal surface
102
What is the difference between irregular secondary dentin of equine teeth and tertiary dentin?
## Footnote
Easley 2022
Irregular secondary dentin has a poorly structured appearance that resembles tertiary dentin but tertiary dentin occurs in response to a pathological insult and irregular secondary dentin is laid down as part of the normal response to wear in equine teeth
103
What is the difference between reactionary and reparative tertiary dentin?
## Footnote
Easley 2022
Reactionary dentin is formed by pre-existing odontoblasts
Reparative dentin formed by previously undifferentiated connective cells of the pulp that transform into odontoblasts in response to insult
104
What type of dentin is responsible for reducing the size of the pulp horns thorughout the life of the tooth?
## Footnote
Easley 2022
Regular secondary dentin
105
In equine teeth tertiary dentin forms in response to what type of wear?
## Footnote
Easley 2022
Abrasion
## Footnote
irregular secondary dentin forms in response to physiological attrition
106
What type of dentin does not absorb pigments from foods?
## Footnote
Easley 2022
primary dentin
107
How far do equine odontoblast processes extend along the tooth?
## Footnote
Easley 2022
To the amelodentinal junction
108
What is the definition of the equine endodontium?
## Footnote
Easley 2022
refers to the intimate association between the pulp and dentin that act as a single functional unit aka pulpo-dentinal complex
109
Does primary or secondary dentin contain more intratubular dentin and which is more wear resistant?
## Footnote
Easley 2022
Secondary dentin contains more intratubular dentin and is therefore more wear resistant
110
What is the dentin production per day in the horse?
## Footnote
Easley 2022
0.5-10 micrometers per day
111
The equine common pulp chamber, with connections to all parts of the pulp, is present up to what dental age?
## Footnote
Easley 2022
2 years post eruption
112
What pulp horn numbers are in the image below?
## Footnote
Easley 2022
A.) 6
113
What pulp horn numbers are shown in the image below?
## Footnote
Easley 2022
A.) 1
B.) 2
D.) 3
C.) 4
E.) 5
114
What pulp horn numbers are shown in the image below?
## Footnote
Easley 2022
A.) 7
B.) 8
115
What pulp horn numbers are shown in the image below?
## Footnote
Easley 2022
A.) 6
116
What pulp horn numbers are shown in the image below?
## Footnote
Easley 2022
D.) 1
E.) 2
A.) 3
B.) 4
C.) 5
117
What pulp horn numbers are shown in the image below?
## Footnote
Easley 2022
A.) 7
118
In this histology image of an infundibulum what do the red arrows represent?
## Footnote
Easley 2022
Lateral branches of the central vascular channel
119
What pulp chambers are routinely connected in mandibular 07s-11s?
## Footnote
Easley 2022
mesial compartment: PHs 1 and 3
distal compartment: PHs 2 and 5
Pulp horn 4 can be part of either
## Footnote
The pulp compartment connection status of maxillary cheek teeth is unpredictable
120
How many pulp horns do maxillary and mandibular 07-10s have vs 06s and lower 11s vs upper 11s?
## Footnote
Easley 2022
maxillary and mandibular 07-10s: 5
06s and lower 11s: 6
upper 11s: 7
121
What is the correlation between subocclusal cheek teeth dentin thickness with age, Triadan position or pulp horn position?
## Footnote
Easley 2022
None
122
What is the distance of pulp horns to the mesial and idstal side of a cheek tooth?
## Footnote
Easley 2022
3-5mm
## Footnote
care must be taken during diastema widening not to expose pulps
123
In incisors, particularly maxillary, the branching pulp horns run labial or palatal to the infundibulum?
## Footnote
Easley 2022
Labial (mesial and distal branches)
124
Kirkland 1996 found that constricted/"closed" apical formamina in equine mandibular cheek teeth occur at what dental age?
## Footnote
Easley 2022
5-8 years after eruption
125
In Kirkland's 1996 study what was the morphology of the apical foramina of equine mandibular mesial roots?
## Footnote
Easley 2022
Two apical formina
## Footnote
In contrast to the delta like foramina of brachydont teeth
126
What is the definition of a detinal bridge and why are they produced?
## Footnote
Easley 2022
Pulp stones, along with tertiary dentine can form a calcified layer termed a dentinal bridge to seal off the healthy more apically situated pulp from the area of pulpar insult
## Footnote
Clinical evidence shows equine teeth to have an exceptionally high capacity for the formation of effective dentinal bridges.
127
What is the median diameter of Sharpey's fibres in the horse?
## Footnote
Easley 2022
2.5 microns
128
What do CP, BS, AVB and BT stand for in the image below?
## Footnote
Easley 2022
CP: cortical plate
BS: bony spongiosa
AVB: alveolar bone
BT: bony trabeculae
129
What do the white arrows below represent?
## Footnote
Easley 2022
Sharpey's fibers
130
How does the structure of equine cementum change adjacent to the peripheral amelo-cemental junction vs more peripherally?
## Footnote
Easley 2022
Adjacent to amelo-cemental junction: irregular hydroxyapatite crystal orientation that is similar to maxillary cheek teeth infundibular cement.
More peripherally: more regular pattern
131
Is the peripheral cementum of the clinical crown considered an inert or vital tissue?
Inert: cementoblasts lose their blood supply from periodontium but active vasculature extends from the gingiva for a few mm
132
Deposition of what dental tissue throughout life allows the prolonged eruption of hypsodont teeth?
## Footnote
Easley 2022
cementum
produced at several mm/year
133
Do maxillary or mandibular cheek teeth have more peripheral cementum?
## Footnote
Easley 2022
mandibular
## Footnote
clinical crowns have also been shown to have more peripheral cementum than reserve crowns
134
What do Pcd, Hcd, Mcd, Mstd, Encd stand for?
## Footnote
Easley 2022
Pcd: Protoconid
Hdc: Hypoconid
Mcd: Metaconid
Mstd: Metastylid
Encd: Entoconid
135
What is the average initial depth of incisor infundibula and at what age are they usually worn away by?
## Footnote
Easley 2022
10-15mm
9 years
136
What directions/routes does infundibular cementogenesis follow?
## Footnote
Easley 2022
Occlusal aspect in an apical direction
Inner aspect of infundibular enamel and proceeds in axial/central direction
137
What do Pac, Mc, Hc, Pce, Prc stand for?
## Footnote
Easley 2022
Pac: Paracone
Mc: Metacone
Hc: Hypocone
Pce: Protoconule
Prc: Protocone
138
Kilic's 1997 paper found that in addition to 24% of maxillary cheek teeth having gross caries, what percent had one or more small central defects of the infundibular cementum aka central vascular channels or central linear defects?
## Footnote
Easley 2022
65%
139
Why does the distal infundibular accessory blood supply last longer than the mesial?
## Footnote
Easley 2022
Because it is more apically located and therefore persists for a longer time than the mesial which allows the distal infundibulum to develop cementum longer
140
What developmental reasons explain why maxillary first molars have the highest prevalence of infundibular cemental hypoplasia?
## Footnote
Easley 2022
The infundibular blood supply arises solely from the occlusal aspect
09s have the shortest developmental period
141
Fitzgibbons' 2009 study of 786 extracted maxillary cheek teeth infundibula showed what relationship between age and infundibular length, surface area and infundibular length as a proportion of dental crown length?
## Footnote
Easley 2022
All progressively decreased with age
142
In Fitzgibbon's 2009 study concerning 786 extracted maxillary cheek teeth infundibula, what percent of infundibula were completely filled with cementum?
## Footnote
Easley 2022
11.7%
143
How many masticatory movements per minute are seen when eating hay vs pasture grass?
## Footnote
Easley 2022
Hay: 58-66
Grass: 100-105
144
The ratio of peripheral enamel to tooth perimeter on subocclusal transverse sections is greater in maxillary or mandibular cheek teeth?
## Footnote
Easley 2022
maxillary cheek teeth: due to infundibular enamel
## Footnote
du Toit, Dixon. "Donkey dental anatomy. Part 1." 2008
145
What is the equine deciduous dental formula?
## Footnote
Easley 2022
2 (Di 3/3, Dc 0/0, Dpm 3/3) = 24 teeth
146
What is the equine permanent teeth dental formula?
## Footnote
Easley 2022
2 (I 3/3, C 1/1 or 0/0, PM 3/3 or 4/4, M 3/3)= 36 to 44 teeth
147
What is the progression on incisor cross-sectional shape with age?
## Footnote
Easley 2022
Elliptical, round, triangular, oval
148
What is the reported prevalence of canines in female horses vs female donkeys?
## Footnote
Easley 2022
Horses: 7.8-28%
Donkeys: 17%
149
How close are canine teeth pulp cavities to the occlusal surface?
## Footnote
Easley 2022
within 5mm
## Footnote
ODY not recommended
150
What is the reported prevalence of wolf teeth in female vs male horses?
## Footnote
Easley 2022
females: 24%
males: 15%
## Footnote
range 13-32% in both sexes
151
At ~ what age do the permanent PM2, PM3 and PM4 erupt respectively?
## Footnote
Easley 2022
PM2: 2.5 years
PM3: 3 years
PM4: 4 years
152
What structure prevents the erupting permanet tooth from being resorbed during eruption?
## Footnote
Easley 2022
reduced/inactivated enamel organ
153
At ~ what age do permanent M1, M2 and M3 erupt?
## Footnote
Easley 2022
M1: 1 year
M2: 2 years
M3: 3.5 years
154
Which cheek teeth reserve crowns are always shorter and why?
## Footnote
Easley ch 7
09s and 06s because they erupt first
155
What is the eruption rate of equine cheek teeth with normal wear?
## Footnote
Easley 2022
2-3mm per year
156
What maxillary teeth are typically associated with the rostral maxillary sinus vs caudal maxillary sinus?
## Footnote
Easley 2022
Rostral max: caudal 08s, 09s, part of 10s
Caudal max: part of 10s, all of 11s
157
How far do the apices of 11s drift in horses between 6 years to over 15 years of age?
## Footnote
Easley 2022
2.83 cm (typo in textbook says 283mm but the paper says 2.83 cm)
## Footnote
Luiti 2017
158
In normal horses and donkeys respectively what percent wider are the maxillary cheek teeth rows than the mandibular?
## Footnote
Easley 2022
Horses: 23% wider
Donkeys: 27% wider
## Footnote
anisognathia. when the mouth is closed~1/3rd of the upper occlusal surface is in contact with ~1/2 lower occlusal surfaces
158
In Brown's 2008 study "Occlusal angles of cheek teeth in normal horses and horses with dental disease," what was the range of overall normal occlusal angles?
## Footnote
Vet Record 2008, Easley 2022
15-35 degrees
159
In Brown's 2008 study "Occlusal angles of cheek teeth in normal horses and horses with dental disease," do maxillary or mandibular cheek teeth have greater angulation and do the rostral or caudal mandibular and maxillary cheek teeth have greater angles?
## Footnote
Vet Record 2008, Easley 2022
Mandibular greater overall angulation
Maxillary more angled rostrally, less caudally
mandibular less angled rostrally, more angled caudally
160
What is the definition of a loph?
## Footnote
Easley 2022
Occlusal enamel ridges adjacent to hollows of dentin +/-cementum
## Footnote
occlusal surface pattern: lophodont
161
In Windley's 2009 study "Two- and three-dimensional computed tomographic anatomy of the enamel, infundibulae and pulp of 126 equine cheek teeth. Part 1: Findings in teeth without macroscopic occlusal or computed tomographic lesions," where was enamel found to be thickest and thinnest?
## Footnote
Tremaine, Eq Vet J, 2009
Thickest in areas where enamel was parallel to the long axis of the mandible or maxilla
Thinnest where the enamel formed invaginations
162
In RoBgardt's 2022 study "The equine dental pulp: analysis of the stratigraphic arrangement of the equine dental pulp in incisors and cheek teeth," what was the association of density of fibroblastic cells in incisors vs cheek teeth?
## Footnote
Vet Sci 2022
Incisors: fibroblastic cell density remained almost constant in all age groups
Cheek teeth: significantly increased with age --> may reflect a high proliferative activity of equine pulpal cells
## Footnote
Highest density in proliferative zones
163
At what age does the symphysis fuse in horses?
## Footnote
Easley 2022
2-3 months of age
164
What ancestral type of horse had shallow mandibles and maxillae and commensurately short reserve crowns and gave rise to Arabians?
## Footnote
Easley 2022
Type 1V horses
165
What ancestral types of horses gave rise to breeds with deep alveoli and long reserve crowns?
## Footnote
Easley 2022
Type 1/Mountain Pony
Type III/Forest or Marshland Horse
166
What is the origin and insertion of the digastricus muscle?
## Footnote
Easley 2022
Origin: Occipital bone
Insertion: Caudal and ventral aspect of the mandible
167
Horses obtain what percent of their energy needs from volatile fatty acids provided by bacterial fermentation which occurs in the hindgut?
## Footnote
Easley 2022
20-46%
Rest absorbed from small intestine which necessitates adequately grinding down feed
## Footnote
In ruminants, volatile fatty acids produced by bacterial fermentation provide approximately 70% of the animal’s energy needs
168
What environmental factor has been recognized as the principle driving force for the evolution of equine teeth?
## Footnote
Easley 2022
contamination of grass with exogenous silicates from soil and dust
## Footnote
not the previously thought theory that endogenous silicate phytoliths within grasses resulted in the highly abrasive properties of a grassland diet
169
Which of the following congenital abnormalities has NOT been associated with dentoskeletal malocclusions:
Limb contracture
Cleft palate
Umbilical hernia
Angular limb deformity
## Footnote
Easley ch 31
Angular limb deformity
170
What is the most common equine congenital craniofacial abnormality? % prevalence?
## Footnote
Easley ch 31
MAL2
2-5%
171
Injuries to which of the following structures is NOT associated with the development of MAL3
Nasal bones
Incisive bones
Palatine process of the maxillae
Nasal septum
## Footnote
Easley Ch 31
Nasal septum
172
Which structure is NOT involved in campylorrhinus lateralis?
Premaxillae
Frontal bone
Vomer bone
Nasal septum
## Footnote
Easley ch 31
Frontal bone
173
What genetic markers have been noted in horses and donkeys as possible areas affecting skeletal malocclusions?
## Footnote
Easley ch 9
Horses: chromosomal region ECA13 --> MAL2
Donkeys: polymorphism MATN1 --> MAL3
174
What is a noted difference in head anatomy of the donkey compared to horses?
## Footnote
El Gendy "Computed tomography and sectional anatomy of the head cavities in donkey" Anat Sc Int 2014
The shape and extent of the pharyngeal recess has a caudal elongation between the left and right guttural pouches in the donkey
## Footnote
All the anatomical structures related to the guttural
pouches resemble those in the horse otherwise
175
Where was the maxillary septum typically located in the donkey? How does it differ from the horse?
## Footnote
El Gendy "Computed tomography and sectional anatomy of the head cavities in donkey" Anat Sc Int 2014
This septum angled obliquely caudally and its rostral aspect was varied in position; it usually crossed the roots of the second and third molar teeth, approximately 4–5 cm caudal to the rostral end of the facial crest.
It's an incomplete boney septum in the donkey - complete in the horse
176
What supplies blood to the TMJ? Which vessels speficially supply the disk?
## Footnote
Easley ch 16
The blood supply to the TMJ arises from the transverse facial, superficial and deep temporal, and tympanic arteries.
The transverse facial artery supplies blood to the rostral aspect of the disc, whereas the caudal blood supply originates from the deep temporal artery.
## Footnote
Also outlined in Auer and Stick ch 103
177
What are the characteristics of the intra-articular disk of the TMJ?
## Footnote
Easley ch 16
articular surfaces are covered with fibrocartilage (NOT hyaline cartilage)
L-shaped with a caudomedial fibrous expansion - allows side to side power stroke
Concave in center (more lat-med than rostro-caudal plane)
Attaches circumferentially to mand condyle, temporal bone and joint capsule
178
How is the joint capsule reinforced anatomically for the TMJ?
## Footnote
Easley ch 16
The joint capsule is reinforced by the lateral and caudal joint ligaments
Caudal also attaches to the disk (Rodriguez EVJ 2006)
179
According to Brinkshulte's 2014 paper on sinonasal communication, what were the variations in the rostral sinonasal channel (RSC) and the caudal sinonasal channel (CSC)?
## Footnote
Brinkschulte 2014 BMC
RSC: 52% go to rostral max sinus only; 42% go to rostral max sinus and Ventral conchal sinus; 5% go to VCS only
CSC: all go to caudal max sinus
180
In Brinkschulte's 2014 study on sinonasal communications, what variation in location of the nasomaxillary aperture was noted?
## Footnote
Brinkschulte 2014 BMC
< 15yo -- located at the 09 or 10
> 15 yo -- located at the 10 or 11
## Footnote
Makes sense with mesial drift
181
In Brinkschulte's 2013 paper on sinus anatomy and volumes, that sinus was noted to sometimes be contacted but the palatal roots of cheek teeth?
## Footnote
Vet Rad US 2013 Brinkschulte
Ventral conchal sinus
182
In Brinkschulte's 2013 paper on sinus anatomy and volumes, what variation in rostral aspect of the maxillary septum was noted?
## Footnote
Vet Rad US 2013 Brinkschulte
47% at the 09
44% at the 10
2.8% at the 08 (n=1)
5.6% at the 11 (n=2)
## Footnote
The septum continued caudo-dorsally and merged with the dorsal spiral lamellae of the ventral conchal sinus.
183
According to Easley's 2022 textbook, at what years of age do dental stars on the mandibular incisors traditionally appear?
## Footnote
Chp 7
01s 5 years
02s 6 years
03s 7 years
## Footnote
stars are the red arrows, red asterisk infundibulum/cups
184
According to Easley's 2022 textbook, when are the cups of maxillary and mandibular incisors traditionally worn away respectively?
## Footnote
chp 7
Maxillary 01s 6 years, 02s 7 years, 03s 8 years
Mandibular 01s 9 years, 02s 10 years, 03s 11 years
185
What is the colloquial term for the structure demarcated by the red arrow and when does it change from oval to round and dissappear in most breeds?
## Footnote
Easley 2022, Chp 7
Enamel spot
oval to round between 5-12 years of age
Disappears between 12-18 years
186
At what ages do incisors become round on cross section?
## Footnote
Easley 2022, chp 7
01s: 9 years
02s: 10 years
03s: 11 years
187
At what ages do incisors become triangular on cross section?
## Footnote
Easley 2022 chp 7
01s: 16 years
02s: 17 years
03s: 17-18 years
188
At what age and above are incisors typically traditionally rectangular on cross section?
## Footnote
Easley 2022, chp 7
18-20+ years
189
According to Easley's textbook, at what age does a Galvayne's groove traditionally appear, extend halfway down the tooth, fully down the tooth, then back halfway up the tooth, and then completely disappear?
## Footnote
Chp 7
First appear: 10 years
Halfway down tooth: 15 years
Fully down tooth: 20 years
Halfway disappeared: 25 years
Fully disappeared: 30 years
## Footnote
Textbook does state that that the groove is inconsistent and the absence of the groove does not prove that a horse is less than 9 years old
190
What is the prevalence in canine teeth in female horses and donkeys?
## Footnote
Easley ch 5
female horses: 2-28%
female donkeys: 17.3%
191
What is the prevalence of wolf teeth and how does it vary?
## Footnote
Easley ch 5
13-32%
Females (24%) > males (14.9%)
Maxillary (10-40%) >> mandible (rare)
## Footnote
May be lost at 2.5 yo when 06 erupts
192
When are the premolar caps reported to be lost in Easley's 2022 textbook (citing Ramzan 2009)?
## Footnote
Easley ch 7
PM2 - 34.6 months
PM3 - 37.8 months
PM4 - 43.4 months
## Footnote
Upper jaw PM emerge 14 days later than mandibular counterparts
Females lose caps later than males (~38 days)
193
In Carmalt's 2017 AJVR paper on crown height of maxM1 for ageing, what age range was it most reliable in predicting?
## Footnote
Carmalt 2017 AJVR
< 10 years old
## Footnote
Overestimates by avg 0.1 yr
CT measurement correlated with rads = 0.91 (rads overestimated by 2.5 mm on avg)
194
What was the correlation with maxM1 height and age in Carmalt's 2017 AJVR paper?
## Footnote
Carmalt AJVR 2017
Height decreased with age, but rate of decrease slowed in older ages compared to younger
## Footnote
Attrition rate 2.2-4mm per year in paper
195
In Adam's 2016 study "Functional anatomy of the equine temporomandibular joint: collagen fiber texture of the articular surfaces," what conclusions were made about the relative movements of the central and lateral and medial aspects of the TMJ?
## Footnote
Arzi, Staszyk Vet J 2016
Split line patterns of central aspect of TMJ indicative of preferential rostrocaudal movement
Lateral and medial aspects split-line patterns indicate movements around a dorsoventral axis
196
In Adam's 2018 study "Functional anatomy of the equine temporomandibular joint: histological characteristics of the articular surfaces and underlining tissues," what were the three tissue layers of the articular surfaces of the TMJ?
## Footnote
Arzi, Staszyk The Vet J 2018
(1) a superficial cell-rich dense connective tissue layer
(2) a middle fibrocartilage layer
(3) a deep hyaline-like cartilage layer
197
In Adam's 2018 study "Functional anatomy of the equine temporomandibular joint: histological characteristics of the articular surfaces and underlining tissues," what were the differences between the articular disc of the mandibular condyle vs the mandibular fossa?
## Footnote
Arzi, Staszyk. The Vet J 2018
The mandibular fossa was only covered by dense connective tissue and lacked an inner core of fibrocartilage and hyaline-like cartilage meshwork and glycosaminoglycans were absent
## Footnote
Glycosaminoglycans are indicative of compressive loads
The results of this study suggest the presence of different biomechanical demands in the dorsal and ventral compartment of the equine TMJ.
198
In Smyth's 2019 study "Histologic assessment of age-related changes in the temporomandibular joints of horses," what was the association of age group with number of changes, temporal and mandibular scores, and disc scores?
## Footnote
Carmalt JAVMA 2019
Sig less changes and degrees of change within TMJs of group 1 (youngest horses) compared with group 3 (oldest horses)
Combo of temporal and mandibular scores for group 1 sig lower than groups 2 or 3
Disc scores of groups 1 and 2 were sig lower than group 3
## Footnote
The articular disks of older horses also had a decrease in cellularity, chondroid metaplasia, and chondro-osseous metaplasia, compared with results for younger horses.
