Dental biofilm, commonly known as dental plaque, naturally forms in the human mouth. This sticky, colorless film is a community of microorganisms encased in a self-produced protective matrix, adhering to tooth surfaces. While a normal biological process, dental biofilm can become problematic if not regularly managed, directly impacting oral health.
Understanding Dental Biofilm
Dental biofilm is a community of microorganisms, including bacteria, fungi, and viruses, that attach to surfaces. These microorganisms are embedded within an extracellular polymeric substance (EPS) matrix, consisting of polysaccharides, proteins, and nucleic acids. This matrix provides structural stability and protection, allowing it to thrive in the oral cavity.
Biofilm formation begins immediately after teeth are cleaned. An acquired pellicle, a thin, acellular layer of salivary proteins and glycoproteins, coats the tooth surface. Pioneer bacteria, such as Streptococcus sanguinis, then reversibly attach to this pellicle. This is followed by irreversible attachment, where bacteria firmly anchor and form microcolonies.
As initial colonizers establish, secondary colonizers adhere through co-aggregation. Bacteria then proliferate, producing the EPS matrix that encapsulates the growing community. This maturation leads to a thick, three-dimensional layer of dental plaque. If left undisturbed, this soft, sticky plaque can mineralize due to calcium phosphate deposition from saliva, transforming into a hard, crusty substance known as calculus or tartar.
Impact on Oral Health
Dental biofilm impacts oral health, contributing to several common conditions. Dental caries, or cavities, are a primary issue. Certain bacteria within the biofilm, notably Streptococcus mutans and Lactobacilli, metabolize dietary sugars. These bacteria produce organic acids, such as lactic acid, which diffuse into tooth enamel and dentin. This acidic environment causes demineralization, dissolving calcium and phosphate ions from the tooth structure. Frequent and prolonged acid attacks lead to enamel breakdown and cavity formation. Consistent acid presence also selects for more acid-tolerant bacteria, exacerbating demineralization.
Biofilm accumulation near the gumline can trigger gingivitis, an inflammatory condition of the gums. Bacteria in the plaque irritate gingival tissues, leading to an immune response. This inflammation manifests as redness, swelling, and bleeding of the gums, often noticed during brushing or flossing.
If gingivitis is left unaddressed, it can progress to periodontitis, a more severe gum disease. This involves destruction of supporting bone and tissues around teeth. In periodontitis, the biofilm’s microbial composition shifts to more pathogenic bacteria, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, which thrive in low-oxygen gum pockets. This chronic inflammation leads to breakdown of the periodontal ligament and resorption of the alveolar bone, potentially resulting in tooth loosening and loss.
Dental biofilm also contributes to halitosis, commonly known as bad breath. Anaerobic bacteria within the biofilm, especially those in tongue crevices and periodontal pockets, produce volatile sulfur compounds (VSCs). These compounds, including hydrogen sulfide and methyl mercaptan, are byproducts of protein degradation and cause the unpleasant odor.
Managing Dental Biofilm
Effective management of dental biofilm involves consistent home care and professional interventions. Daily mechanical removal is the primary method for controlling biofilm. Brushing teeth at least twice a day with a soft-bristled toothbrush and fluoride toothpaste is recommended. Brush at a 45-degree angle to the gums, using short, tooth-wide strokes to cover all surfaces. After brushing, spit out excess toothpaste but avoid rinsing, allowing fluoride to remain on teeth for maximum protection.
Cleaning between teeth is equally important, as bristles cannot reach narrow spaces where food and plaque accumulate. Daily flossing or interdental brushes remove plaque and food debris, preventing decay and gum disease. Interdental brushes are effective for larger spaces or orthodontic appliances. While not a replacement, antimicrobial mouthwashes can suppress bacterial adhesion and offer anti-gingivitis and cariostatic properties.
Professional dental care complements daily home routines. Regular check-ups and cleanings allow dentists and hygienists to remove hardened biofilm (calculus) that home care cannot remove. If gum disease has progressed and deep pockets have formed, scaling and root planing may be performed. Scaling removes plaque and tartar from above and below the gumline, while root planing smooths root surfaces to deter bacterial accumulation and encourage gum reattachment.