Gingivitis is a mild form of gum disease characterized by inflammation, redness, and bleeding of the gums. It is caused by bacteria that accumulate on the teeth and gums. This early stage of gum disease is often reversible with oral hygiene.
The Foundation: Dental Plaque
Dental plaque is a sticky, colorless film composed of bacteria, food particles, and saliva that forms on tooth surfaces. This biofilm accumulates along the gumline, where it can easily irritate gum tissues. If plaque is not regularly removed through daily brushing and flossing, it can harden into a calcified deposit known as tartar. Tartar provides a rough surface that makes it more difficult to clean teeth and offers an ideal environment for gingivitis-causing bacteria to thrive.
Specific Bacterial Culprits
The development of gingivitis involves a shift in the bacterial community in the mouth. In a healthy oral environment, the microbial balance is dominated by Gram-positive bacteria. As plaque accumulates and conditions change, there is a shift towards an overgrowth of Gram-negative anaerobic bacteria, which flourish in low-oxygen environments.
Early colonizers of dental plaque include species like Actinomyces and Streptococcus, that attach to the tooth surface. As plaque matures, other bacteria, such as Fusobacterium nucleatum, act as “bridge” organisms, connecting early colonizers to later, disease-associated species. Gram-negative bacteria associated with gingivitis include Prevotella intermedia, Capnocytophaga species, and Leptotrichia species. Gingivitis is the result of a complex community of these bacteria, rather than a single type, creating an imbalanced oral ecosystem.
How Bacteria Trigger Inflammation
These bacterial communities trigger inflammation in several ways. Gram-negative bacteria release substances called endotoxins from their outer cell walls. These endotoxins irritate gum tissues and initiate a localized inflammatory response. Bacteria produce enzymes that can damage the tissues of the gums.
The immune system recognizes these bacterial components and byproducts as foreign threats. This recognition activates an immune response, leading to the signs of inflammation: redness, swelling, and bleeding of the gums. The growing plaque creates an oxygen-deprived environment along the gumline, which is favorable for the growth of anaerobic bacteria that are implicated in gingivitis.
Beyond Gingivitis: The Progression of Disease
If gingivitis is left unaddressed, the inflammation can extend beyond the gums to affect the supporting structures of the teeth. This progression leads to a more severe condition known as periodontitis. Periodontitis involves the destruction of the bone and connective tissues that hold teeth in place, forming pockets around the teeth where bacteria can accumulate. This bone loss is irreversible and, if left untreated, can lead to tooth loosening and tooth loss. Therefore, early intervention and oral hygiene are important in preventing this progression.