Dental plaque

The most common diseases to affect the teeth once they have erupted are related to dental plaque, a dense accumulation of micro-organisms on the tooth surface. These diseases have been responsible for the majority of tooth loss in human populations for many thousands of years. Reviews of plaque biology include those of Lehner (1992), Marsh and Martin (1992).

The tooth surface as a habitat for micro-organisms

The lips, palate, cheek, tongue and gums are colonized by bacteria, fungi, yeasts, viruses, protozoa and other microbes, but their ability to adhere is limited by constant shedding of the mucosa (page 260) surface. Teeth are unique in their hard, non-shedding surface, which allows luxuriant microbial communities to build up especially in fissures, approximal areas and gingival crevices, protected from the rinsing and sweeping of saliva, lips, cheek and tongue. Saliva and gingival crevice fluid (page 260) coat the crown surfaces with an organic layer known as pellicle, and the predominant plaque organisms are bacteria with specialist mechanisms for adhering to it. Plaque bacteria also obtain their nutrients mainly from saliva and gingival crevice fluid (GCF), including proteins, peptides, amino acids and glycoproteins (page 227), which can all be broken down by the combined forces of different bacteria. The human diet passing through the mouth is a less important source of nutrients, but plaque bacteria do metabolize the fermentable carbohydrates (starches and sugars) and casein, a protein that is found in milk and dairy products.