1. The Anatomy, Physiology and Morphology of Teeth
By Dr. Juliana Mathews

2. Tooth Anatomy The crown: consists of enamel, dentine and pulp
The root:
has a root canal with blood vessels and nerves
covered by cementum and held together by periodontal fibres
embedded in the alveolar bone
Enamel:
white hard covering over the crown of the tooth
no nerve or blood supply
cannot heal or repair like bone or dentine
Dentine:
covered by enamel on the crown and cementum on the roots
protects the pulp

3. Tooth Anatomy continued
Pulp:
Consists of nerves, blood vessels and connective tissue
Found in pulp chamber and root canal
Anastomoses between venules and arterioles
Cementum:
Covers the dentine of the root
Attached to the periodontal ligament
No nerve supply

4. Tooth Anatomy continued
Periodontium:
Alveolar process: bony extensions of the maxilla and mandible that support teeth
Cortical Plate: dense outer layer of bone covering the spongy (cancellous) bone
Periodontal ligament :
Periodontal fibres attach the roots to the alveolar bone
has a nerve and blood supply
provides an elastic cushion between the tooth and bone
Gingiva: covers the teeth and the alveolar process

5. Dentine
Enamel
Dentinal Tubules
Cementum
Pulp
Alveolar Process
Cortical Plate
Spongy Bone
Periodontal Ligaments

6. Root Canal System
Pulp chamber is found on the coronal part of the tooth
Reduces in size with age due to secondary dentine due to physiological or pathological reasons
Orifices to the root canal are found on the floor of the pulp chamber
Canals taper towards the apex
The narrowest part of the canal is found at the apical constriction, which opens out as the apical foramen and exists to one side i.e. 0.5mm-1mm from the anatomical apex
New layers of cementum are constantly being laid down, therefore the centre of the foramina deviates from the apical centre
Lateral canals can develop between the main body of the root canal and the periodontal ligament space
Accessory canals can develop in the apical region forming the apical delta
Lateral and Accessory canals develop due to a break in the “Hertwigs” epithelial root sheath or during the development, the sheath grows around the existing blood vessel
Lateral canals can be impossible to instrument and can compromise obturation

9. Root canal system continued
Some roots can have more than one canal and they don’t always merge
Single rooted teeth that have a single canal can end in a single foramen. Some have an apical delta and have a single canal but many exits
Multi- rooted teeth commonly have multiple foramina and each root can have two or three canals. Some canals merge before their exit and some can leave the root independently
Eg. Some maxillary second premolars can have two roots (usually are single rooted) or a single root with 2 canals
Eg. The mesio-buccal root of the maxillary first molar can have two canals (usually one canal present)

10. The complexity of the root canal

11. Physiology of the Dental Pulp
Nerve fibres:
consist of sensory (afferent) fibres, sympathetic fibres and parasympathetic fibres
sensory fibres pass through the apical foramen and end at the peripheral pulp
sensory nerve fibres originate from the trigeminal ganglion
C –fibres:
Unmyelinated, high threshold fibres responding to mechanical, thermal or chemical stimulation
Dull, poor localized pain
A- delta fibres:
myelinated, low threshold mechano- receptors
sharp localized pain
A-beta fibres

12. Pain Inflammation of pulp develops:
Increased pulpal pressure against the sensory nerve endings
Sensitized nerves release neuropeptides and cause inflammation= Neurogenic inflammation
A-delta fibres respond to hydrodynamic stimuli
C-fibres respond to the inflammatory mediators
Pheripheral sensory nerves produce pain = hyperalgesia
Peripheral sensory nerves sprout/branch in the inflammed area but disappear as the inflammation subside
Central sensitization occurs when there is a flow of continuous pain impulses which can occur in acute and chronic states

13. The Innervation of Teeth
Trigeminal Nerve: (CN V)
Three sensory branches
Opthalmic branch supplies the orbit and forehead
Maxillary branch supplies the maxillary sinus and upper jaw teeth
Mandibular branch supplies the tongue and the lower jaw teeth
Facial Nerve: (CN VII)
Motor and sensory branches
Innervates
muscles of facial expression
taste buds of the anterior 2/3 of the tongue
salivary glands

14. Innervation of Teeth continued
Maxillary Teeth:
Anterior superior alveolar nerve: upper incisors and canines (CNV2)
Middle superior alveolar nerve: upper premolars and the mesio-buccal root of the maxillary first molar (CNV2)
Posterior superior alveolar nerve: upper molars except the mesio-buccal root of the maxillary first molar (CNV2)
Mandibular Teeth:
Inferior alveolar nerve: mandibular teeth, gingiva and lower lip unilaterally (CNV3)
Lingual nerve: anterior 2/3 of tongue and mucosa of the floor of the mouth (CNV3)
Buccal nerve: gingiva on the buccal side of posterior teeth (CNV3)

15. The Branches of the Trigeminal Nerve
Please note that these nerves innervate other structures. Look over the facial nerve and mandibular nerves and its different innervations

16. Blood supply Maxillary teeth: Mandibular teeth:
Superior alveolar artery: anterior, middle and posterior branch (Maxillary Artery)
Mandibular teeth:
Inferior alveolar artery (Maxillary Artery)
Look at the blood supply to the face

17. Tooth Morphology
Please look the additional notes for this section

18. ANY QUESTIONS