The problem posed to the yeast manufacturer, however, is not as simple as just adding air during the fermentation process. If the concentration of sugar in the fermentation growth media is greater than a very small amount, the yeast will produce some alcohol even if the supply of oxygen is adequate or even in abundance. This problem can be solved by adding the sugar solution slowly to the yeast throughout the fermentation process.
Human teeth are made up of four different types of tissue: pulp, dentin, enamel, and cementum. The pulp is the innermost portion of the tooth and consists of connective tissue, nerves, and blood vessels, which nourish the tooth.
Bacteria are abundant in the mouth and are commonly found in saliva and dental plaque (a thin film that forms on teeth and gums). If the seal between the tooth and the filling breaks down, food particles and decay causing bacteria can work their way between the worn filling and the tooth. These bacteria can not be removed easily with a toothbrush or other means and decay may develop along the edge of the filling or underneath it.