Understanding the periodontium: Dental assisting

The periodontium is a group of tissues that surround and support the teeth. It’s made up of several structures, including the alveolar bone, periodontal ligament, cementum, and the gingival unit. As a dental assistant, your understanding of the periodontium and its role in maintaining dental health and function will support effective patient care.

Now, imagine that the tissues of the periodontium are like the foundation of a building, that supports the teeth and anchors them in place. At the base of the periodontium is the alveolar bone that forms the tooth sockets and provides structural support for the root, or the lower part of the tooth. The alveolar bone holds the tooth in place with the help of the periodontal ligament, which acts like a flexible suspension system, allowing the tooth to withstand the forces of chewing. Covering the root of the tooth is the cementum, which serves as the attachment point for the periodontal ligament. And finally, the gingival unit, or gum tissue, surrounds the cervical portion of the tooth and forms a protective seal around it. So, similar to the foundation of a building, the periodontium stabilizes the tooth, protects it from external forces, and holds it in place.

Okay, let’s take a closer look at the alveolar bone and cementum, which are at the base of the periodontium. The alveolar bone, also known as the alveolar process, is a thick ridge of bone with a spongy core that forms the tooth sockets in the maxilla and mandible bones. A dense outer layer, called the cortical plate, provides strength and protection. The top of the tooth socket is the highest point of the alveolar bone and is called the alveolar crest, while the cavity surrounding the root of the tooth is the alveolar socket. Lining this socket is the lamina dura, a thin layer of compact bone with tiny openings that allow blood vessels and nerves to pass through. Lastly, the cementum is a thin, calcified connective tissue that covers the root of the tooth. Its main role is to provide attachment for the periodontal ligament fibers. The cementum can repair itself through the deposition of new layers over time.

Next, let’s focus on the dense connective tissue called the periodontal ligament, which has several important functions. Its supportive and protective functions involve attaching to the cementum to hold teeth in place against pressure and force, like chewing, while its sensory function helps you feel the pressure and texture when you bite into something, like a crunchy apple. It also has a nutritive function which is made possible by a network of blood vessels that supply oxygen and nutrients to the surrounding tissues. Finally, it has formative and resorptive functions, working as a repair crew to continuously remodel the alveolar bone, cementum, and collagen fibers within the ligament.

And speaking of fibers, the periodontal ligament is composed of groups of specialized fibers. The alveolar crest fibers extend from the alveolar crest to cementum in the cementoenamel junction, or CEJ, which is where the enamel-covered top of the tooth called the crown meets the cementum-covered root. They are composed of several subgroups of fibers, including horizontal fibers that resist side-to-side movement; oblique fibers that absorb most downward chewing pressure as the main attachment of the tooth; apical fibers that prevent twisting and tipping of the tooth, as well as protecting the tooth’s blood, lymph, and nerve supplies; and interradicular fibers, which are only found in multirooted teeth, like molars, and add extra support against tipping and twisting.