Biological width in dentistry refers to a naturally occurring space around teeth that is fundamental for maintaining healthy gums and ensuring the success of various dental treatments. Maintaining the integrity of this natural space is important for preventing complications and ensuring the longevity of dental work.
Understanding Biological Width
Biological width is defined as the combined vertical dimension of two distinct soft tissue attachments that naturally adhere to the tooth surface directly above the alveolar bone: the junctional epithelium and the supracrestal connective tissue attachment. The junctional epithelium forms a seal around the tooth, while the supracrestal connective tissue attachment consists of fibers that anchor the gum to the tooth root.
Early studies from 1961 described these dimensions, with the connective tissue attachment averaging about 1.07 mm and the epithelial attachment about 0.97 mm. This combination results in an average biological width of approximately 2.04 mm. While this 2.04 mm measurement is a widely accepted average, individual variations exist, with biological width ranging from about 0.75 mm to 4.3 mm. This space acts as a protective barrier, sealing off the underlying bone from the oral environment.
Why Biological Width is Crucial
The existence and proper maintenance of the biological width are significant for periodontal health. This space acts as a natural protective zone, preventing bacteria and irritants from reaching the underlying bone that supports the teeth. When this barrier is intact, it helps to create a healthy environment for the gums.
This protective function helps to prevent inflammation in the gum tissues. By keeping harmful substances away from the bone, it plays a role in reducing the risk of gum recession and preventing the loss of alveolar bone, which can compromise tooth stability. Respecting this natural space is foundational for long-term dental health.
When Biological Width is Compromised
When the biological width is invaded or violated, the body responds with an inflammatory reaction. This often occurs due to poorly designed or incorrectly placed dental restorations, such as fillings or crowns that extend too far below the gum line and impinge upon this space.
Such an invasion can lead to various symptoms and issues. Patients might experience chronic inflammation, characterized by redness, swelling, and bleeding gums around the affected tooth. Persistent irritation can also cause localized pain, gum recession, and a loss of the underlying bone structure. The body attempts to re-establish the biological width, sometimes by resorbing bone to create the necessary space, which can contribute to these negative outcomes.
Dental Procedures and Biological Width
Dentists consider biological width during various dental procedures. In restorative dentistry, when placing crowns, veneers, or fillings, professionals aim to ensure the margins of these restorations do not impinge on this natural space. Placing restorative margins too close to the bone can lead to inflammation and bone loss.
If a tooth has suffered a fracture or deep decay near the gum line, or if a previous restoration has violated the biological width, specific procedures may be necessary. Crown lengthening is a common surgical procedure designed to re-establish or create adequate biological width. This involves adjusting the gum tissue and sometimes the underlying bone to expose more tooth structure, allowing for proper restoration placement while maintaining healthy gum tissue. Orthodontic extrusion, which slowly moves the tooth out of the bone, is another method used to correct biological width violations by relocating the attachment away from the restorative margin.