The periodontium refers to the specialized tissues that surround and support your teeth, holding them firmly in place within the jawbone. This system is important for maintaining oral health and allows for proper chewing and speaking. The term comes from Greek words meaning “around the tooth,” accurately describing its location and purpose. These tissues constantly adapt to the forces exerted on your teeth during daily activities like biting and chewing, and rely on this regular stimulation to preserve their structure and functions.
The Gingiva
The gingiva, commonly known as your gums, is the visible soft tissue that wraps around the neck of each tooth and covers the underlying alveolar bone. Healthy gingiva appears coral pink and has a firm, stippled texture. Its function is to act as a protective barrier, sealing off the internal structures of the periodontium from bacteria and physical trauma.
The gingiva is composed of an outer epithelial layer, which is keratinized, and an inner network of dense connective tissue. This tissue includes the free gingiva, which forms a collar around the tooth; the attached gingiva, which is firmly bound to the bone; and the interdental gingiva, which fills the spaces between adjacent teeth. The free gingiva creates a shallow groove, the gingival sulcus, between itself and the tooth.
The Periodontal Ligament
The periodontal ligament (PDL) is a thin, fibrous connective tissue that surrounds the root of the tooth, connecting it to the alveolar bone. It is composed of bundles of strong collagen fibers, primarily type I and III, known as Sharpey’s fibers, which embed directly into both the cementum and the alveolar bone.
The PDL performs multiple functions. It acts as a suspensory mechanism that allows for minor tooth movement within its socket without causing damage. It also functions as a shock absorber, distributing and absorbing the forces generated during chewing, which helps protect the tooth and surrounding bone. The PDL contains sensory nerve endings, allowing you to perceive pressure and touch on your teeth, and it supplies nutrients to the cementum and bone. It also plays a role in the repair processes of the periodontium.
The Cementum
Cementum is a specialized, calcified tissue that covers the entire root surface of a tooth, extending from the cemento-enamel junction (where the enamel meets the cementum) to the root’s tip. While it shares some similarities with bone, cementum is avascular, meaning it does not contain blood vessels or nerves. It is also softer than dentin, the layer it covers.
The function of cementum is to provide an attachment site for the periodontal ligament fibers, firmly anchoring the tooth to the surrounding alveolar bone. Sharpey’s fibers from the PDL embed into the cementum. There are two types of cementum: acellular cementum, found closer to the crown and primarily anchoring the tooth, and cellular cementum, found nearer the root tip, which contains cells called cementocytes and can adapt to wear on the tooth surface.
The Alveolar Bone
The alveolar bone is the part of the jawbone that surrounds and supports the roots of your teeth, forming the tooth sockets, also known as alveoli. This living tissue constantly undergoes remodeling, adapting its structure in response to forces and changes within the mouth. It provides primary structural support for the teeth, ensuring their stability during functions like chewing and speaking.
The alveolar bone consists of two main types of bone tissue: a dense outer layer called compact bone, and a spongy, porous inner layer called cancellous bone, which contains a network of bony trabeculae and marrow spaces. This bone also houses the blood vessels and nerves that supply the tooth and the periodontal ligament. The continuous remodeling process involves specialized cells: osteoblasts, which form new bone; osteoclasts, which resorb old bone; and osteocytes, which regulate bone metabolism.