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Transcript

Dental Anatomy

By Laura Hunter (laura.hunter@glasgow.ac.uk)

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Introduction

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Intended Learning Outcomes

This online lesson will cover gross anatomy and radiographic anatomy of the teeth of the carnivores and ruminants. FP1029: Describe and identify the normal structure and topography of the digestive system and relate this to diet.Content ILO: Recognise features of dental anatomy in the common domestic species.

Carnivore Dental Anatomy

Comparative Dental Anatomy

Tooth Anatomy

Index

Tooth Anatomy

Activity:1) Identify the regions of the tooth labelled in this image. 2) Which nerve innervates the mandibular teeth in the carnivore?3) Which nerve innervates the maxillary teeth in the carnivore?

Infraorbital nerve

Inferior Alveolar Nerve

Neck

Root

Clinical Crown

Anatomic Crown

Tooth Structures

Activity:1) Identify the different structures labelled A-D in the image.2) Which of these structures is produced by odontoblasts?3) What is the normal pocket depth of the gingival sulcus in the dog?4) What is the normal pocket depth of the gingival sulcus in the cat?

D

A

B

C

Dentine

Enamel

Pulp Cavity

Cementum

Less than 0.5mm

Less than 3mm

A - Dentine

Dental Radiography

This image is an enlarged radiograph of the 1st mandibular molar of a dog. The crown (covered in enamel) and one of the roots have been labelled (this tooth has two roots). Indicated is the area of the apical foramen of one of the roots - this is the opening that allows nerves and vessels to enter the tooth. Central region of the tooth is the pulp cavity - this is large in this case as these teeth are from a young dog. The other labelled features are the lamina dura - the thin layer of dense bone that lines the tooth socket - and the periodontal space between the tooth root and the lamina dura. This periodontal space appears darker than the surrounding structures as it is occupied by the peridontal ligament (which is soft tissue opacity, rather than the mineralised opacity of the tooth and jaw). This is usually a thin layer around the tooth root(s) as seen here - when periodontal disease is present, this space widens.

Canine Upper & Lower Jaw Radiography

The teeth of the upper jaw are identified in the top radiograph. Note that the incisors are superimposed.

The teeth of the lower jaw are identified in the bottom radiograph.

Radiography Questions

Radiography remains the most common modality for imaging the dentition due to its widespread availability and excellent resolution of bony/mineralised structures (like the teeth and jaw bones). You will learn more about this in BVMS3!a) What occupies the narrow lucent space around the tooth root indicated by 1? b) Which tooth is indicated by 2? c) What is the opening indicated by 3 that allows nerves and vessels to enter the tooth? d) Is this radiograph from a young or old?

Periodontal Ligament

Mandibular molar 1

Apical Foramen

Young - wider pulp cavity

Triadan Numbering System (Carnivore)

Dog

Cat

This image shows the complete set of adult/permanent teeth from a dog. Note the marked variation in shape of the teeth (in terms of number and size of root, number of cusps on occlusal surface, etc) - this can be related to the main functions for the individual teeth.

Permanent Teeth - Dog

The image on the left shows the maxillary/upper teeth in place in the skull. The image of the right shows a different skull with the right teeth (and the left incisors) removed. Note how the individual tooth sockets mimic the root shape of the teeth.1) Which maxillary teeth in canine are triple rooted?2) Which maxillary tooth is also known as a carnassial tooth? 3) Using the triadan system, what would be the correct numeric identifier for the left maxillary 3rd premolar?

Maxillary Teeth

premolar 4 (08), molar 1 (09) and molar 2 (10)

108 & 208 (4th premolar)

207 (2 = left upper arcade, 07 = third premolar)

The image below shows the mandibular (lower) teeth of a dog in situ.1) Which mandibular teeth are triple rooted?2) Using the triadan system, what would be the correct numeric identifier for the right mandibular 3rd molar?3) Which mandibular tooth is also known as a carnassial tooth?

Mandibular Teeth

There are no triple rooted teeth in the mandible.

411 (4 = right mandibular, 11 = third molar)

309 & 409 (left and right 1st molar)

Maxillary Teeth - Cat

The top image shows a different skull with the right teeth (and the left incisors) removed. Note how the individual tooth sockets mimic the root shape of the teeth.The bottom image shows the maxillary/upper teeth in place in the skull. Activity:1) Which tooth in the upper jaw is the only triple rooted tooth in the cat?2) What is the term used to describe the slicing ability of the feline premolars and molars?3) Which upper teeth are missing in the cat when compared to dog dentition?

Premolar 4 (108 & 208)

Secodonty

Premolar 1 (05) and Molar 2 (10)

The image below shows the mandibular (lower) teeth of a cat in situ.1) Which lower teeth are missing in the cat when compared to dog dentition?2) Which mandibular tooth is also known as a carnassial tooth?3) What is the dental formula for the adult cat?

Mandibular Teeth - Cat

Cats do not have lower premolar 1 (05) & 2 (06), or molar 2 (10) & 3 (11).

309 & 409 (left and right 1st molar)

3-1-3-1 3-1-2-1

This image is a close-up of the tooth sockets (alveoli) for the upper (maxillary) 4th premolar and molars in a dog. Note the layer of compact (fairly smooth) bone lining the socket - this is the lamina dura. Between the lamina dura and the root of the tooth would sit the periodontal ligament - this would serve to hold the tooth in place in the alveolus. If infection reaches into the periodontal space (periodontal disease), the periodontal ligament can break down, leading to loosening and eventual loss of the tooth.

Tooth Socket

Triadan Numbering System (Equine)

Equine Dental Anatomy

Activity:1) Identify the structures labelled in these images.2) Which tooth is also referred to as the 'wolf' tooth?3) From which substance is the dental star formed? 4) Which structure overlaps the pulp cavity?

Dental star (younger horse)

Dental star

Enamel

Cup/ infundibulum

Premolar 1

Secondary dentine

Infundibulum

Canine

Equine Cheek Teeth

This is an image of some mandibular cheek teeth in the horse. The different structures that make up the occlusal surface of the tooth have been labelled. Activity:1) Identify the 4 structures labelled in the image.2) Which of these 4 structures wears the slowest?3) Name the structure that is present in the maxillary cheek teeth and not the mandibular cheek teeth.

Cementum

Primary Dentine

Enamel

Secondary Dentine

Enamel

Two Infundibula

Bovine Dentition

Ruminants lack upper incisors and canines in both the temporary and permanent dentition - instead the dental pad is present. Lower (mandibular) canine resembles the incisors (and is often referred to as the 4th incisor). Cheek teeth (hypsodont, with delayed closure of the root to allow maximal reserve crown to be developed to compensate for the dental erosion caused by the herbivorous diet) increase in size from rostral to caudal. These images show the incisors and cheek teeth in a bovine skull - note that when the jaw is closed the upper (maxillary) teeth sit slightly lateral to the lower teeth, with the surfaces sliding over each other to grind the ingested material.

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General anatomy: Chapter 3 - p98-105Carnivore: Chapter 11 - p369-372Equine: Chapter 18 - p502-506Ruminant: Chapter 25 - p641-643Porcine: Chapter 32 - p741-744

Further Reading

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