Most people will tell you that they have heard of plaque, but few would be able to explain its composition and the role it plays in dental disease. Now, plaque is a soft, adherent film that collects on the surfaces of teeth. Seventy percent of it is made up of germs (bacteria, fungi and viruses). The remaining thirty percent is called the matrix which is actually the framework that holds it together.Plaque is found in all mouths and makes up part of the natural flora (parasites) of the body. The most common sites where plaque is found are occlusal pits and fissures (the biting surface of back teeth), cervical (neck) margins of teeth and in periodontal pockets (the sack of gum that surrounds each tooth). Patients can be made aware of plaque in their mouths by using a disclosing solution or tablets.
Plaque is a major causative factor in gingival (gum) and periodontal disease and a contributory agent of tooth decay. In fact, most dental problems that we human beings face are due to plaque. Even in people with good tooth-brushing skills, one would need to brush and floss approximately every 3 minutes in order to prevent plaque from forming.
In a healthy mouth, there is a natural balance of bacteria, but when illness or antibiotics (for example) upset the balance of the mouth’s flora, or when teeth are not cleaned often and/or appropriately, plaque matures. Waste products from the bacteria, enzymes and toxins then cause the inflammatory response in the gingival tissues leading to gingivitis. Depending on a person’s response, gingivitis can progress to periodontitis (chronic gingivitis).
In recent years, dental plaque has been recognised as a biofilm. The concept of a biofilm is of huge importance not only to dentistry, but also to the wider medical world and many sectors of industry. Since the 1990s, there has been a huge amount of research into biofilms, which reflects our growing understanding of their importance.
A biofilm, in simple terms, is a thin layer of bacteria that adheres to a surface. Over ninety-five percent of bacteria in nature exist in a biofilm state as opposed to living independently. Contact lenses, rocks in rivers and aspirator tubing in the dental surgery are all examples of surfaces colonised by biofilms. Within a biofilm, bacteria are not just sitting alongside one another passively; they are communicating, interacting and gaining benefits from one another. In other words they act as a team. This is what makes a biofilm so virulent, resilient and difficult to manage.
Bacteria being the most common germ found in plaque biofilm can be classified into groups in a number of ways, including whether they need oxygen (aerobic) or not (anaerobic) to survive. The majority of bacteria in a healthy mouth come from the oxygen-dependent species which live in areas of the mouth where oxygen is readily available. When resistance is lowered, they can give rise to sore throats and other illnesses, but are less harmful than their non-oxygen-dependent relatives.
Bacteria that need oxygen (aerobic) feed on sugar from the human diet, and in doing so, produce sticky substances that enable other more harmful germs to attach themselves, causing plaque to become more dense and harmful to tissues. On the other hand, anaerobic bacteria can cause far more disease when producing their poisons because they do not need oxygen to survive so they can penetrate deep in the gums. So, in event of an oral infection, the dentist needs to prescribe drugs to kill both the bacteria on the surface and those that penetrate deeply.
Dr. BERTRAND R. STUART D.D.S