Supragingival plaque is a soft and sticky biofilm that constantly forms on the teeth. The term “supragingival” indicates its location on the visible portion of the tooth that sits above the gumline. This substance is typically colorless or can appear as a pale yellow film, making it difficult to see in its early stages. If left to accumulate, it can feel fuzzy to the tongue.
The Formation and Composition of Supragingival Plaque
The development of supragingival plaque begins just moments after a tooth surface is cleaned. The first stage is the formation of the acquired pellicle, a thin, bacteria-free layer of proteins from saliva that coats the tooth. This pellicle acts as an adhesive surface, allowing the first bacteria to attach.
These initial colonizers are predominantly gram-positive bacteria, with Streptococcus species making up a significant portion. Once attached, these early bacteria multiply and create microcolonies. As they grow, they produce a sticky extracellular matrix of polysaccharides, proteins, and lipids that provides structure to the biofilm and protects the embedded bacteria.
The composition of this plaque is about 80-85% water, with the remaining solid matter being mostly bacteria. One specific bacterium, Streptococcus mutans, plays a role in this process. It metabolizes dietary sugars and uses an enzyme to produce sticky polysaccharides. These substances allow more bacteria to join the community, leading to a thicker, more complex plaque biofilm.
Progression to Calculus and Gingivitis
When supragingival plaque is not consistently removed, it can mineralize into calculus, also known as tartar. This process occurs when the soft plaque absorbs calcium and phosphate minerals from saliva, causing it to harden. This calcification can begin in as little as a few hours, though the average time for mineralization is around 10 to 12 days.
Once formed, calculus is a hard, rough deposit firmly attached to the tooth. Unlike the soft plaque from which it originates, calculus cannot be removed by brushing or flossing at home. Its porous surface provides an ideal environment for new plaque to form and accumulate. This hardened deposit can appear yellow or brown and is most often found near salivary gland ducts, such as on the inside of the lower front teeth.
The buildup of plaque and the toxins released by its bacteria irritate the surrounding gum tissues. This irritation leads to inflammation known as gingivitis, the earliest stage of gum disease. Signs of gingivitis include red, swollen, and tender gums, and they may bleed during brushing or flossing. If left unaddressed, this inflammation can progress and cause more severe damage to the structures that support the teeth.
Removal and Prevention at Home
The management of supragingival plaque is centered on consistent and thorough mechanical removal, with proper tooth brushing being the most effective method. Using a soft-bristled toothbrush angled at 45 degrees toward the gumline helps disrupt and remove the plaque film. This should be done at least twice a day for two minutes to ensure all tooth surfaces are cleaned.
Because a toothbrush cannot effectively clean between the teeth, daily interdental cleaning is necessary for plaque control. Tools such as dental floss, interdental brushes, or water flossers remove plaque from these hard-to-reach areas. Using floss in a “C” shape against each tooth surface ensures that the plaque below the contact points of the teeth is removed. Performing this cleaning before brushing can help loosen plaque and food particles, allowing them to be brushed away more easily.
Dietary habits also influence the formation of plaque. Limiting the consumption of sugary and starchy foods and drinks reduces the fuel available to plaque-producing bacteria like Streptococcus mutans. A balanced diet and drinking plenty of water can help rinse away food particles before they contribute to the biofilm.