Anatomy and Development Flashcards
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
Maximum length 2-4 years
decrease rapidly after 13-15 years
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
Indentations: mesial and distal
Enamel reaches further on labial surface
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
Upper: middle
Lower: corner
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
3.5 years
In Sahara’s 2014 paper “Development of Coronal Cementum in Hypsodont Horse Cheek Teeth,” how was the resorption of enamel evaluated with histochemistry?
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
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?
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
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
4-5 months old
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
female Quarter horses of show lineage
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
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
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
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
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?
4 yro: 5-33mm
16 yro: 2-24mm
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
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
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
Lower bars due to relatively straight profile vs curve of maxillary bars and facial crest
The TMJ and eyeball were not useful reference points
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
Crown height and crown width were either not correlated or poorly correlated with root length
Crown height was poorly correlated with total length
In Hole’s 2016 study “Dimensions of 65 Extracted Equine First Premolar Teeth,” what measurements were statistically significantly correlated?
JVD 2016
Total tooth length was correlated with root length
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
Median total length: 21mm
Median root length: 13mm
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
1.5 and 11.7 mm in upper
0.7 and 6.7 mm in lower incisors.
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
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
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
COL1, COL3
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
3.3:1
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
Rostral infundibulum
09s
The rostral infundibulae were significantly more frequently affected by higher grades of caries than the caudal infundibulae
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
182 (91%)
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
72% of infundibulae without occlusal caries
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
73% erupted maxillary first premolars
Average age at time of examination 15 months
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%
20-23 months old 100%
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?
JVD 2019
Males 67%
Females 77%
stat sig fewer males than females
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%)
What developmental disorder is depicted?
EVE 2020 Dixon
Dental dysplasia
abnormal buccal protrusion composed mainly of dentine and peripheral enamel
What developmental disorder is depicted here?
EVE 2020 Dixon
Dental dysplasia
No infundibulum, abnormal distribution of pulp horns
More prone to central wear with no INF
What is the most common supernumerary tooth in the horse? Least common?
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
What is the least common dental disorder in the horse?
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).
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?
Frontiers 2019
2% (13/650) foals had an overjet
69% (9/13) spontaneous regression
31% (4/13) control foals developed overjet
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?
Frontiers 2019
PiMx/PiMn, Mna/ML
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?
Frontiers 2019
Long lines improved accuracy
most accurate measurements: FL-facial, EtL-ethmoidal cephalometric lines
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
Frontiers 2020
C) Period of greatest decrease in clinical crown IIA < 13-15 years had constant tooth length ratios
A) obtuse interincisal angle
B) third incisor length was shown
D) age estimates NOT recommended
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?
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
In Kau’s 2020 paper “Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns,” can the interincisal angle determine age?
Frontiers 2020
No - authors do not recommend, not accurate
Define hetertopic polydontia and dentigerous cyst
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
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?
Frontiers 2021
presence of the radiopaque contrast material in the discotemporal joint (yellow)
discomandibular joint (blue)
varying amounts outside the joints (white)
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?
Frontiers 2021
No communication in non-diseased TMJs
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”?
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.
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?
Journal of Biomechanics 2019
Rostral region
The disc also exhibits increasing GAG content and compressive stiffness with increasing age
What is the definition of syndesmosis?
Verwilghen Vet Sciences 2022
A non-synovial joint
Think of the sutures between facial bones
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.
When do the facial bone sutures close?
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.
In equine hypsodont dentition, three types of peripheral cementum are defined according to their order of appearance. What are the 3?
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
Enamel is comprised of what percentage of inorganic materials vs organic components and water?
Arnbjerg, 2014
96-98% inorganic, 2-4% organic materials and water
Dentin is comprised of what percentage of inorganic materials vs organic components and water?
Arnbjerg, 2014
70% inorganic, 30% organic materials and water
Cementum is comprised of what percentage of inorganic materials vs organic components and water?
Arnbjerg, 2014
65% inorganic, 35% organic materials and water
Identify the pathology indicated by the white arrows as seen in the study by Arnbjerg in 2014
Irregular hypercementosis
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?
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).
Difference in interincisal angle may be explained by the sig difference in age between the two groups, with the SEAR group older
The maxillary septal bullae lies ventral to what sinus?
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
What anatomy is being removed via this frontochonal flap?
Carmalt 2020 EVE
Maxillary septal bullae
What bone in the hyoid apparatus is unpaired?
Hartl. Correlated imaging of the equine hyoid apparatus using CT, micro-CT, and histology. Frontiers 2021.
Basihyoid
What joint in the hyoid apparatus is a synovial joint?
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
Guttural pouch endoscopy allows examination of what portions of the hyoid apparatus?
Hartl. Correlated imaging of the equine hyoid apparatus using CT, micro-CT, and histology. Frontiers 2021.
proximal stylohyoid and temporohyoid joint
Describe the path of the maxillary division of the trigeminal nerve.
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
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?
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
Teeth of aged horses possess a similar or even higher vascularity than deciduous or young teeth → high prolonged productivity
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?
Vet Sci 2022
No
presumably because dentin is exposed at the occlusal surface by physiological wear
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?
Vet Sci 2022
No
Authors propose to define a subodontoblastic supportive zone with high cellularity that shows a high capacity for dentin production even in older age
What is a “loph” structure of a tooth?
Ch 1, evolution
“loph” is a complex ridge formed between cusps as enamel is worn away
Properly label the cusps and lophs of this maxillary cheek tooth
Ch. 1 Evolution
Ch. 1 Evolution
Properly label the cusps of this mandibular cheek tooth
Ch. 1 Evolution
Which direction do secondary dentinal tubules run?
Easley Textbook, ch 25
Coronal to apical
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
Easley Textbook, ch 25
B. They contain mostly type II enamel and are less resistant to wear than cheek teeth
What is the rate of eruption for teeth that are completely out of occlusion?
Easley Textbook, ch 25
0.5cm-2cm / year
What are the black arrows indicating in this incisor histopath image?
Ch 10
irregular but phasic growth of irregular cementum
What feature of campylorrhinis lateralis can be life threatening?
Ch 9
Nasal septum deviation
Wry nose
All features: Diagonal incisor occlusion, Focal cheek teeth overgrowths, Nasal septum deviation, Shortening of the incisive bones
The prevalence of hypodontia is estimated to be:
Ch 9
< 1%
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?
Ch 9
Haplodont supernumerary tooth
Define a Tuberculate supernumerary tooth
Ch 9
A tooth with complexly-shaped clinical and reserve crowns with multiple raised tubercles with deep occlusal indentations on the occlusal surface.
What is a connate supernumerary tooth
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
Image from Dixon VCNA 2005 “Supernumerary teeth in the horse”
What developmental structures can remain visible around the apex of young adult cheek teeth?
Staszyk 2015 EVE “Equine dental and periodontal anatomy A tutorial review”
Dental follicle and enamel organ (before roots close) – “eruption cysts”
Eruption cysts aka Prominentiae osseae transistoriae
What do the arrows indicate anatomically of this CT of a 306?
White and Dixon 2010 EVJ
Transition from pulp to subocclusal secondary dentin
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?
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.
At what age do incisors start to decrease in length?
Easley ch 27
13-15 yo
What is the range of length of infundibulum?
Pearce 2016 EVE
2mm - 89mm
What developmental pathology is noted in this maxillary cheek tooth?
Pearce 2016 EVE
A supernumerary infundibulum is present palatal to the normal rostral and caudal
infundibula
What does the term anelodont mean?
Easley 2022
limited growth period teeth
in reference to brachydont and hypsodont teeth continuing to develop roots after the end of crown formation
What is the definition of the term elodont?
Easley 2022
Teeth that continually grow and elongate their crown throughout all of an animal’s life
occurs in rodents and lagomorphs
What percent of equine mandibular cheek teeth still have no root development even 12 months following their eruption?
Easley 2022, Kirkland 1996
~25%
What are the definitions of primary and secondary occlusal surfaces?
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
In comparision to bracydont teeth, hypsodont teeth have a delayed termination of what stages of tooth development?
Easley 2022
morphogenetic and cytodifferentiative states (at their apical region)
What is the Tome’s process and what does it do?
Easley 2022
A protrusion of ameloblasts that produces enamel
proximal aspect of process secretes interprismatic enamel
secretions from surface of process form enamel prisms
When does calcification of deciduous cheek teeth buds start and end?
Easley 2022
starts by 120th day of conception
Completed by 240 days
Disintegration of what developmental tooth structure allows peripheral cementum to be laid down?
Easley 2022
Enamel organ and Hertwig’s epithelial root sheath
Why does cementum develop over the entire crown surface in equine cheek teeth?
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
What is the mineral content of enamel?
Easley 2022
95-98%
What is the tissue type of origin of enamel vs dentin and cementum?
Easley 2022
enamel: ectoderm
dentin and cementum: ectomesenchymal
What type of enamel is hardest and most wear resistant and what type of enamel is most resistant to fracture?
Easley 2022
Type 1: hardest and most wear resistant
Type 2: most resistant to fracture
What is morphologic description of the structure of Type 1 enamel and where is it located?
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)
What is morphologic description of the structure of Type 2 enamel and where is it located?
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
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
Equine enamel is composed primarily of what two types of enamel?
Easley 2022
Type 1 and Type 2 enamel
Where along the enamel folds is there the highest proportion of Type 2 enamel?
Easley 2022
Peripheral enamel folds in particular on maxillary cheek teeth vertical buccal ridges/cingulae
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?
Easley 2022
Type 1 highest in maxillary CT
Incisors almost all Type 2
mandibular CT equal amounts of Type 1 and 2 enamel
What is the difference between donkey and horse type of enamel distribution patterns?
Easley 2022
Donkey maxillary CT have similar proportions of Type 1 and Type 2 while horse maxillary CT have more Type 1
What is the order of dentin occlusal layers from axial to abaxial?
Easley 2022
irregular secondary dentin
secondary dentin
primary dentin
What is the definition and purpose of enamel decussation?
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
particularly developed in Type 2 enamel
At what location on equine cheek teeth is the peripheral and infundibular enamel about three times thicker?
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)
What is the length of the maturation period for equine enamel?
Easley 2022
18-34 months
What is the so called biological safety glass?
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
What is the difference between irregular secondary dentin of equine teeth and tertiary dentin?
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
What is the difference between reactionary and reparative tertiary dentin?
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
What type of dentin is responsible for reducing the size of the pulp horns thorughout the life of the tooth?
Easley 2022
Regular secondary dentin
In equine teeth tertiary dentin forms in response to what type of wear?
Easley 2022
Abrasion
irregular secondary dentin forms in response to physiological attrition
What type of dentin does not absorb pigments from foods?
Easley 2022
primary dentin
How far do equine odontoblast processes extend along the tooth?
Easley 2022
To the amelodentinal junction
What is the definition of the equine endodontium?
Easley 2022
refers to the intimate association between the pulp and dentin that act as a single functional unit aka pulpo-dentinal complex
Does primary or secondary dentin contain more intratubular dentin and which is more wear resistant?
Easley 2022
Secondary dentin contains more intratubular dentin and is therefore more wear resistant
What is the dentin production per day in the horse?
Easley 2022
0.5-10 micrometers per day
The equine common pulp chamber, with connections to all parts of the pulp, is present up to what dental age?
Easley 2022
2 years post eruption
What pulp horn numbers are in the image below?
Easley 2022
A.) 6
What pulp horn numbers are shown in the image below?
Easley 2022
A.) 1
B.) 2
D.) 3
C.) 4
E.) 5
What pulp horn numbers are shown in the image below?
Easley 2022
A.) 7
B.) 8
What pulp horn numbers are shown in the image below?
Easley 2022
A.) 6
What pulp horn numbers are shown in the image below?
Easley 2022
D.) 1
E.) 2
A.) 3
B.) 4
C.) 5
What pulp horn numbers are shown in the image below?
Easley 2022
A.) 7
In this histology image of an infundibulum what do the red arrows represent?
Easley 2022
Lateral branches of the central vascular channel
What pulp chambers are routinely connected in mandibular 07s-11s?
Easley 2022
mesial compartment: PHs 1 and 3
distal compartment: PHs 2 and 5
Pulp horn 4 can be part of either
The pulp compartment connection status of maxillary cheek teeth is unpredictable
How many pulp horns do maxillary and mandibular 07-10s have vs 06s and lower 11s vs upper 11s?
Easley 2022
maxillary and mandibular 07-10s: 5
06s and lower 11s: 6
upper 11s: 7
What is the correlation between subocclusal cheek teeth dentin thickness with age, Triadan position or pulp horn position?
Easley 2022
None
What is the distance of pulp horns to the mesial and idstal side of a cheek tooth?
Easley 2022
3-5mm
care must be taken during diastema widening not to expose pulps
In incisors, particularly maxillary, the branching pulp horns run labial or palatal to the infundibulum?
Easley 2022
Labial (mesial and distal branches)
Kirkland 1996 found that constricted/”closed” apical formamina in equine mandibular cheek teeth occur at what dental age?
Easley 2022
5-8 years after eruption
In Kirkland’s 1996 study what was the morphology of the apical foramina of equine mandibular mesial roots?
Easley 2022
Two apical formina
In contrast to the delta like foramina of brachydont teeth
What is the definition of a detinal bridge and why are they produced?
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
Clinical evidence shows equine teeth to have an exceptionally high capacity for the formation of effective dentinal bridges.
What is the median diameter of Sharpey’s fibres in the horse?
Easley 2022
2.5 microns
What do CP, BS, AVB and BT stand for in the image below?
Easley 2022
CP: cortical plate
BS: bony spongiosa
AVB: alveolar bone
BT: bony trabeculae
What do the white arrows below represent?
Easley 2022
Sharpey’s fibers
How does the structure of equine cementum change adjacent to the peripheral amelo-cemental junction vs more peripherally?
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
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
Deposition of what dental tissue throughout life allows the prolonged eruption of hypsodont teeth?
Easley 2022
cementum
produced at several mm/year
Do maxillary or mandibular cheek teeth have more peripheral cementum?
Easley 2022
mandibular
clinical crowns have also been shown to have more peripheral cementum than reserve crowns
What do Pcd, Hcd, Mcd, Mstd, Encd stand for?
Easley 2022
Pcd: Protoconid
Hdc: Hypoconid
Mcd: Metaconid
Mstd: Metastylid
Encd: Entoconid
What is the average initial depth of incisor infundibula and at what age are they usually worn away by?
Easley 2022
10-15mm
9 years
What directions/routes does infundibular cementogenesis follow?
Easley 2022
Occlusal aspect in an apical direction
Inner aspect of infundibular enamel and proceeds in axial/central direction
What do Pac, Mc, Hc, Pce, Prc stand for?
Easley 2022
Pac: Paracone
Mc: Metacone
Hc: Hypocone
Pce: Protoconule
Prc: Protocone
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?
Easley 2022
65%
Why does the distal infundibular accessory blood supply last longer than the mesial?
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
What developmental reasons explain why maxillary first molars have the highest prevalence of infundibular cemental hypoplasia?
Easley 2022
The infundibular blood supply arises solely from the occlusal aspect
09s have the shortest developmental period
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?
Easley 2022
All progressively decreased with age
In Fitzgibbon’s 2009 study concerning 786 extracted maxillary cheek teeth infundibula, what percent of infundibula were completely filled with cementum?
Easley 2022
11.7%
How many masticatory movements per minute are seen when eating hay vs pasture grass?
Easley 2022
Hay: 58-66
Grass: 100-105
The ratio of peripheral enamel to tooth perimeter on subocclusal transverse sections is greater in maxillary or mandibular cheek teeth?
Easley 2022
maxillary cheek teeth: due to infundibular enamel
du Toit, Dixon. “Donkey dental anatomy. Part 1.” 2008
What is the equine deciduous dental formula?
Easley 2022
2 (Di 3/3, Dc 0/0, Dpm 3/3) = 24 teeth
What is the equine permanent teeth dental formula?
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
What is the progression on incisor cross-sectional shape with age?
Easley 2022
Elliptical, round, triangular, oval
What is the reported prevalence of canines in female horses vs female donkeys?
Easley 2022
Horses: 7.8-28%
Donkeys: 17%
How close are canine teeth pulp cavities to the occlusal surface?
Easley 2022
within 5mm
ODY not recommended
What is the reported prevalence of wolf teeth in female vs male horses?
Easley 2022
females: 24%
males: 15%
range 13-32% in both sexes
At ~ what age do the permanent PM2, PM3 and PM4 erupt respectively?
Easley 2022
PM2: 2.5 years
PM3: 3 years
PM4: 4 years
What structure prevents the erupting permanet tooth from being resorbed during eruption?
Easley 2022
reduced/inactivated enamel organ
At ~ what age do permanent M1, M2 and M3 erupt?
Easley 2022
M1: 1 year
M2: 2 years
M3: 3.5 years
Which cheek teeth reserve crowns are always shorter and why?
Easley ch 7
09s and 06s because they erupt first
What is the eruption rate of equine cheek teeth with normal wear?
Easley 2022
2-3mm per year
What maxillary teeth are typically associated with the rostral maxillary sinus vs caudal maxillary sinus?
Easley 2022
Rostral max: caudal 08s, 09s, part of 10s
Caudal max: part of 10s, all of 11s
How far do the apices of 11s drift in horses between 6 years to over 15 years of age?
Easley 2022
2.83 cm (typo in textbook says 283mm but the paper says 2.83 cm)
Luiti 2017
In normal horses and donkeys respectively what percent wider are the maxillary cheek teeth rows than the mandibular?
Easley 2022
Horses: 23% wider
Donkeys: 27% wider
anisognathia. when the mouth is closed~1/3rd of the upper occlusal surface is in contact with ~1/2 lower occlusal surfaces
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?
Vet Record 2008, Easley 2022
15-35 degrees
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?
Vet Record 2008, Easley 2022
Mandibular greater overall angulation
Maxillary more angled rostrally, less caudally
mandibular less angled rostrally, more angled caudally
What is the definition of a loph?
Easley 2022
Occlusal enamel ridges adjacent to hollows of dentin +/-cementum
occlusal surface pattern: lophodont
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?
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
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?
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
Highest density in proliferative zones
At what age does the symphysis fuse in horses?
Easley 2022
2-3 months of age
What ancestral type of horse had shallow mandibles and maxillae and commensurately short reserve crowns and gave rise to Arabians?
Easley 2022
Type 1V horses
What ancestral types of horses gave rise to breeds with deep alveoli and long reserve crowns?
Easley 2022
Type 1/Mountain Pony
Type III/Forest or Marshland Horse
What is the origin and insertion of the digastricus muscle?
Easley 2022
Origin: Occipital bone
Insertion: Caudal and ventral aspect of the mandible
Horses obtain what percent of their energy needs from volatile fatty acids provided by bacterial fermentation which occurs in the hindgut?
Easley 2022
20-46%
Rest absorbed from small intestine which necessitates adequately grinding down feed
In ruminants, volatile fatty acids produced by bacterial fermentation provide approximately 70% of the animal’s energy needs
What environmental factor has been recognized as the principle driving force for the evolution of equine teeth?
Easley 2022
contamination of grass with exogenous silicates from soil and dust
not the previously thought theory that endogenous silicate phytoliths within grasses resulted in the highly abrasive properties of a grassland diet
Which of the following congenital abnormalities has NOT been associated with dentoskeletal malocclusions:
Limb contracture
Cleft palate
Umbilical hernia
Angular limb deformity
Easley ch 31
Angular limb deformity
What is the most common equine congenital craniofacial abnormality? % prevalence?
Easley ch 31
MAL2
2-5%
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
Easley Ch 31
Nasal septum
Which structure is NOT involved in campylorrhinus lateralis?
Premaxillae
Frontal bone
Vomer bone
Nasal septum
Easley ch 31
Frontal bone
What genetic markers have been noted in horses and donkeys as possible areas affecting skeletal malocclusions?
Easley ch 9
Horses: chromosomal region ECA13 –> MAL2
Donkeys: polymorphism MATN1 –> MAL3
What is a noted difference in head anatomy of the donkey compared to horses?
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
All the anatomical structures related to the guttural
pouches resemble those in the horse otherwise
Where was the maxillary septum typically located in the donkey? How does it differ from the horse?
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
What supplies blood to the TMJ? Which vessels speficially supply the disk?
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.
Also outlined in Auer and Stick ch 103
What are the characteristics of the intra-articular disk of the TMJ?
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
How is the joint capsule reinforced anatomically for the TMJ?
Easley ch 16
The joint capsule is reinforced by the lateral and caudal joint ligaments
Caudal also attaches to the disk (Rodriguez EVJ 2006)
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)?
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
In Brinkschulte’s 2014 study on sinonasal communications, what variation in location of the nasomaxillary aperture was noted?
Brinkschulte 2014 BMC
< 15yo – located at the 09 or 10
> 15 yo – located at the 10 or 11
Makes sense with mesial drift
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?
Vet Rad US 2013 Brinkschulte
Ventral conchal sinus
In Brinkschulte’s 2013 paper on sinus anatomy and volumes, what variation in rostral aspect of the maxillary septum was noted?
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)
The septum continued caudo-dorsally and merged with the dorsal spiral lamellae of the ventral conchal sinus.
According to Easley’s 2022 textbook, at what years of age do dental stars on the mandibular incisors traditionally appear?
Chp 7
01s 5 years
02s 6 years
03s 7 years
stars are the red arrows, red asterisk infundibulum/cups
According to Easley’s 2022 textbook, when are the cups of maxillary and mandibular incisors traditionally worn away respectively?
chp 7
Maxillary 01s 6 years, 02s 7 years, 03s 8 years
Mandibular 01s 9 years, 02s 10 years, 03s 11 years
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?
Easley 2022, Chp 7
Enamel spot
oval to round between 5-12 years of age
Disappears between 12-18 years
At what ages do incisors become round on cross section?
Easley 2022, chp 7
01s: 9 years
02s: 10 years
03s: 11 years
At what ages do incisors become triangular on cross section?
Easley 2022 chp 7
01s: 16 years
02s: 17 years
03s: 17-18 years
At what age and above are incisors typically traditionally rectangular on cross section?
Easley 2022, chp 7
18-20+ years
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?
Chp 7
First appear: 10 years
Halfway down tooth: 15 years
Fully down tooth: 20 years
Halfway disappeared: 25 years
Fully disappeared: 30 years
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
What is the prevalence in canine teeth in female horses and donkeys?
Easley ch 5
female horses: 2-28%
female donkeys: 17.3%
What is the prevalence of wolf teeth and how does it vary?
Easley ch 5
13-32%
Females (24%) > males (14.9%)
Maxillary (10-40%)»_space; mandible (rare)
May be lost at 2.5 yo when 06 erupts
When are the premolar caps reported to be lost in Easley’s 2022 textbook (citing Ramzan 2009)?
Easley ch 7
PM2 - 34.6 months
PM3 - 37.8 months
PM4 - 43.4 months
Upper jaw PM emerge 14 days later than mandibular counterparts
Females lose caps later than males (~38 days)
In Carmalt’s 2017 AJVR paper on crown height of maxM1 for ageing, what age range was it most reliable in predicting?
Carmalt 2017 AJVR
< 10 years old
Overestimates by avg 0.1 yr
CT measurement correlated with rads = 0.91 (rads overestimated by 2.5 mm on avg)
What was the correlation with maxM1 height and age in Carmalt’s 2017 AJVR paper?
Carmalt AJVR 2017
Height decreased with age, but rate of decrease slowed in older ages compared to younger
Attrition rate 2.2-4mm per year in paper
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?
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
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?
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
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?
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
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.
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?
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
The articular disks of older horses also had a decrease in cellularity, chondroid metaplasia, and chondro-osseous metaplasia, compared with results for younger horses.
