Normal Anatomy of teeth Flashcards
What is the crown?
*In a healthy state, the part of the tooth visible above the
gingival margin.
*The healthy crown is covered with a layer of enamel
*A enamel thickness of less than 1 millimetre in dogs and cats
What is the neck of the tooth?
*Not clearly demarcated area: where the crown meets root
*It does correspond with the cemento-enamel junction.
(where the cementum meets enamel )
Where is the root of the tooth?
*The root is covered by cementum.
*In health it is situated below the gingival margin and
alveolar margin.
In general the roots of dogs and cats are at least how much longer than the crowns?
one and a half times longer that the tooth crown; in many cases
much more.
In teeth with multiple roots, the area between the coronal
aspects of two adjacent roots are called the?
Furcation.
Enamel is the hardest material in the body
it is completely formed before?
The tooth
erupts and no repair is possible after
eruption.
At 8 weeks post partum, the enamel of
the permanent teeth have been
completely formed.
Enamel consist of 96% of what?
mineral
Described the pulp cavity?
This space contains the pulp and runs along
the centre of the crown and root of the
tooth.
What is the pulp chamber called in the crown and in the root? The part of this space
The pulp chamber in the crown is called the pulp chamber.
It continues as the root canal in the root.
What happens at the apical extent of the root canal?
Multiple smaller canals allows access for
blood vessels, nerves and lymphatics.
These radiating canals are called the
apical delta.
What is the apical delta?
Area at the apical end of the root canal where multiple smaller canals allow access for blood vessels, nerves and lymphatics.
An extremely intimate anatomical and
functional relationship exists between dentin
and pulp. To refer to these structures as a single organ
that consist of two distinct parts is therefore
advisable. What names are given to this organ?
Dentin-pulp Organ (or Dentin-pulp Complex)
What is likely to happen to the Dentin-pulp Organ (or Dentin-pulp Complex) if one aspect of it is damaged?
Any condition that affects one of these parts also has a profound effect on the other.
What produces Dentin?
It is produced by the cells that line the pulp cavity (odontoblasts)
Odontoblasts have processes that extend where?
They extend to the interface between dentin and enamel in the crown as well as dentin and cementum in the root.
Discuss how dentinal tubules radiate out?
Dentinal tubules radiate outwards from the pulp canal to the dentine-enamel junction in the crown and the
dentino-cemental junction in the root. The tubules create
the porous nature of dentin.
What should any injury to the dentin be considered when knowing the route of dentinal tubules?
Any injury that exposes dentin should therefore be considered to at least be potentially painful.
What is primary dentin?
primary dentin is dentin produced before the tooth erupts.
What is secondary dentin?
Secondary dentin is deposited in the direction of the pulp
by odontoblasts after the crown had erupted.
When is Tertiary dentin/reparative dentin produced?
It is produced in response to exposure of dentinal tubules.
How is tertiary/reparative dentin produced?
Tertiary dentin/Reparative is produced in response to exposure of dentinal tubules.
Signals of such injury reaches the odontoblast
layer via the sensory nerve supply. The
odontoblast respond to this insult by
producing additional dentin in the direction
of the injury.
Why is tertiary dentin darker in colour?
If the damage/wear that has triggered production of tertiary dentin ( e.g abrasion )
continues and this reparative dentin is
exposed it stains more strongly because of
this less dense nature. Reparative (or
tertiary dentin) can prevent exposure of
the pulp if the damage does not occur too
rapidly.
Why does dentin have some sensitivity?
Nerve endings from the sensory nerves in the
pulp extend along the odontoblastic processes.
This nerve supply explains the sensitivity of dentin.
What is in the pulp?
Specialised connective tissue that contains blood vessels, nerves and lymphatics and various different
cell types that enters through the apical delta
What is one of the most important functions of the pulp?
To support the cells that line the pulp canal.
(odontoblasts)
Fine processes of pulp cells extend along the
dentinal tubules that radiate outwards to eventually reach the?
Junction between dentin and enamel in
the crown (the dentino-enamel junction) or the
junction of dentin and cementum in the tooth root (the dentino-cemental junction).
Sensory nerve supply dominates the innervation of
the pulp. All sensory perception (e.g.heat cold,
pressure) of the pulp is interpreted as?
Pain
What is cementum?
Cementum is a bone like mineralised tissue
attached to the surface to the root surface.
Cells are enclosed in this mineralised
matrix.
There is no innervation or blood vessels
to this tissue.
What happens to cementum during an animals lifetime?
Cementum is maintained and possibly thickens during the life time of the
tooth.
What are all the structures involved in the periodontium?
All structures involved in attachment of tooth is included in the periodontium.
It consist of:
* Gingiva
* Periodontal ligament
* Cementum
* Alveolar bone
Is oral mucosa part of the periodontium?
NO
What is the function of Gingiva which forms part of the periodontium?
Tough, resilient tissue that forms the interface
between teeth and the oral soft tissue.
Where does the gingiva cover?
Covers the coronal aspects of the alveolar bone.
What is most of the gingiva attached to?
Most of the gingiva is firmly attached to either the alveolar bone or the cementum by way of bundles of dense collagen fibres.
How does gingiva associate with the periodontal ligament?
Gingiva extends into and form part of the periodontal ligament.
Discuss how free gingiva is attached?
Free gingiva at the gingival margin is not attached.
Where is the gingival sulcus?
The gingival sulcus is between the crown of the tooth
and free gingiva.
How is the gingiva measured?
Measured with a periodontal probe from the gingival
margin to the junctional epithelium.
What is the normal gingival sulcus depth in cats and dogs?
*1mm for small breeds up to 3 mm for large breed dogs.
*Less than 1 mm deep, normal for cats.
Discuss the location of the junctional epithelium?
The gingiva inside the gingival sulcus eventually
attaches to the tooth surface by means of the
junctional epithelium.
Where is the Mucogingival junction?
Demarcation between Gingiva and oral mucosa
What is the function of the periodontal ligament?
Attaches the tooth to the alveolus.
What is the periodontal ligament made of?
Bundles of collagen fibres (Sharpey’s fibres)
imbedded in the cementum on the root surface and
into the alveolar bone.
What do the collagen fibres that form the periodontal ligament do?
The collagen fibres act as firm
attachment of the tooth to the alveolar bone.
They also acts as shock absorbers.
What do the collagen fibres of the periodontal ligament share the space with?
The collagen fibres share the periodontal space with multiple blood
vessels, lymphatics and nerves.
What type of bone lines the alveolus?
Alveolus is lined with spongy or trabecular bone and not cortical bone.
The alveolus spongy or trabecular bone is well perforated which allows what?
Multiple blood vessels and nerves access to the periodontal space.
What is cementum?
A bone like mineralised tissue attached to the
surface of the root.
What is enclosed in the cementum?
- Cells are enclosed in this mineralised matrix (unlike dentin).
- There is no innervation or blood vessels in this
tissue.
How many premolar teeth do dogs have?
Four maxillary and four mandibular premolar teeth in the permanent dentition.
Describe the 1st premolar tooth in the dog?
The first premolar does not have a deciduous precursor
and has a single root and a conical crown with a single
cusp.
Describe the fourth maxillary premolar in the dog?
The fourth maxillary premolars (the upper carnassial
tooth) have three roots.
In dogs the first premolar has one root and the fourth maxillary has 3. How many roots do the remaining premolar teeth have?
All of the remaining premolars in dogs have two roots.
How many premolar teeth do cats have?
Cats have three maxillary and two mandibular
premolars per quadrant in the permanent
dentition.
Discuss the second maxillary premolar in the cat (206)?
The second maxillary premolar usually have
a small single cusped crown and usually a
single root, but it can be double rooted in
some individuals.
The two mandibular premolars (on each
side) both have how many roots?
The two mandibular premolars (on each
side) both have two roots.
In both cats and dogs the mandibular first molar is?
In both cats and dogs the mandibular first molar is the lower carnassial tooth. It has two large roots.
309 + 409
In cats the single maxillary molar (one on each side)
is a?
Very small tooth and have one to three roots.
In dogs the distal cusp of the mandibular first
molar has a flat occlusive surface and this part occludes onto what?
The flat occlusal surface of the first
maxillary molar
Dogs have two maxillary molars per side. Describe them?
Both have three roots, three cusps on the crowns and flat occlusal surfaces.
The mandibular second molar have two roots and
the third maxillary molar a single root.
The mandibular second molar have two roots and
the third maxillary molar a single root.
The maxillary molars with the distal cusp of the first mandibular molar and the other two mandibular molars provide?
Limited crushing
function in the caudal dentition in dog.
All
mucosa that does not form part of the keritanised and parakeratinised masticatory mucosa are referred to as?
Alveolar mucosa and covers the inside lining of the lips, the cheeks, the floor of the
mouth and the underside of the tongue and continues as the mucosal lining of the
oropharynx
According to the orientation of the collagen fibres (Sharpie’s fibres) within the
periodontal ligament, different fibre bundles can be identified at different aspects of the tooth root. List them:
*Crestal fibres: From the cementum these fibres are directed towards the gingiva
and the coronal aspects of the alveolus.
* Horizontal fibres: these fibres are directed horizontally and occurs mainly in the
mid-parts of the tooth roots.
* Obliques fibres: These fibres course in an coronal orientation from the
cementum and occurs anywhere along the root surface except apically. They are
crucial as a suspensory apparatus and for the shock absorption function of the
periodontal ligament.
* Apical fibres extends from the apical cementum to the apical part of the alveolus
and is important to anchor the tooth in the alveolus.
* Inter radicular fibres extend from the furcational alveolar bone to the cementum
in the furcation area, and is also important for anchorage.
