BASIC DENTAL ANATOMY
Understanding the anatomy of dental tissues and periodontal structures is fundamental to the clinical practice of dentistry.
Enamel
Enamel is the hardest and most mineralised tissue in the body.
It is the outermost layer of the crown.Pulp-dentin complex
The bulk of the crown and root consists of dentin, a substance slightly harder than bone but weaker than enamel. Dentin is tubular in structure and is produced by highly specialised cells called odontoblasts, which are located at the periphery of the pulp. These cells continuously make dentin throughout the life of a tooth, therefore causing the pulp cavity to narrow with age (Fig. 13.1). The pulp is a highly vascular structure containing nerves, blood vessels, loose connective tissue and odontoblasts. The pulp cavity in the crown is called the pulp chamber and in the root, the root canal. If the pulp becomes non-vital, dentin production ceases and the pulp cavity fails to narrow.
Cementum
Cementum is an avascular, highly mineralised and largely structureless tissue covering the root surface.
Fig. 13.1. Graphic demonstrating the activity of the pulp-dentin complex during the normal aging of a canine tooth (increasing age from left to right). Note the narrowing of the pulp cavity as more dentin is formed over time. (Graphic © Courtney A. White 2016, provided by Cornell University College of Veterinary Medicine, Dentistry and Oral Surgery Section.)
Periodontium
The periodontium consists of four tissues that help to hold a tooth within the jaw. These structures are: the gingiva, periodontal ligament, cementum and alveolar bone (tooth socket). The periodontal ligament attaches between the alveolar bone and the cementum on the surface of the roots. Radiographically, the periodontal ligament space is visible as a distinct radiolucent line around the tooth roots.
In health, the alveolar bone margin should reach within 1-2 mm of the cementoenamel junction (CEJ) of the tooth. An exception to this exists in the Tasmanian devil (Sarcophilus harrisii), where the enamel covers only the coronal two-thirds of the crowns of the canine and incisor teeth (Fiani 2015).Detailed descriptions of dental development and eruption and dental anatomy of Australian mammals can be found in Vogelnest and Woods (2008), Fiani (2015), Kido et al. (2018), Landy et al. (2021) and King and Coulson (2023). The dental formulae of Australian mammal groups are provided in Table 13.1 and dental charts for selected species or taxonomic groups are provided in Appendix 5.
Table 13.1. Dental formulae of selected Australian mammal groups and species
| Species | Dental formula |
| Polyprotodont marsupials1 | |
| Dasyuridae | I 4/3, C 1/1, P 2-3/2-3, M 4/4 |
| Bandicoots and the bilby (Macrotis lagotis) | I 5/3, C 1/1, P 3/3, M 4/4 |
| Numbat (Myrmecobius fasciatus) 2 | I 4/3, C 1/1, P 3/3, DP 1/1, M 4/4 |
| Diprotodont marsupials1 | |
| Koala (Phascolarctos cinereus) | I 3/1, C 1/0, P 1/1, M 4/4 |
| Possums, gliders and cuscus | I 3/1, C 1/0, P 1-3/1-3, M 4/4 |
| I 3/1, C 0-1/0, P 1-2/1-2, M 4/4 | |
| Wombats | I 1/1, C 0/0, P 1/1, M 4/4 |
| Eutherian mammals | |
| Flying-foxes (Pteropus spp.)3 | I 2/2, C 1/2, P 3/3, M 2/3 |
| Rodents4 | I 1/1, C 0/0, P 0/0, M 2-3/2-3 |
| Dingo (Canis familiaris) | I 3/3, C1/1, P4/4, M2/3 |
| Otariidae5 | I3/3, C1/1, Post canines 5-6/5 |
| Phocidae5 | I 2-3/2-1, C1/1, Post canines 5/5 |
1Fiani 2015; 2Cooper 2011; 3Clarke 2003; 4Breed and Eden 2008; 5Hillson 2005
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- REFERENCES
- Vogelnest L., Portas T. (Eds.). Current Therapy in Medicine of Australian Mammals. CSIRO,2025. — 848 p., 2025
- Swellings Involving the Head