Antony van Leeuwenhoek, in the 17th century observed plaque on his teeth, under a microscope,and saw many bacteria, which was the first to be reported about them. He tested the plaques from the mouths of two men who had never cleaned their teeth in their life time and found an unbelievably large numbers of such bacteria.
The dental plaque or the deposit on the teeth which is reinforced by the mineral content of the saliva to form calculus, makes the plaque more difficult to be removed and creates a protective shield for bacteria. This can be considered as a bio film on the teeth that facilitates the growth of bacteria, there is an inverse relationship between oral bacteria in the dental plaque and hygiene.
Oral hygienic procedures such as brushing, flossing and frequent descaling, limit the spread and number of bacteria on the dental plaque. Disease causing bacteria, which constitutes to a less proportion of the total bacterial population, when accumulated in the gaps between the teeth or in those regions where normal brushing won’t reach, grow in number produce chemicals, toxins and enzymes that irritate and cause inflammation of gingiva at the base of the teeth leading to swollen and bleeding gums, bad breath and decay of teeth, together contribute to the occurrence of the most common disorder of the oral cavity, gingivitis.
Many factors such as use of tobacco, diabetes, age, dry mouth, fungal and viral infections, and poor oral hygiene aggravate gingivitis. If left untreated it progress to periodontitis, in which destruction of the periodontal ligament, loss of supporting bone and ultimately tooth loss occurs.