Bacteria and food can cause tooth decay. It starts out as plague; a clear (usually sticky) substance forming on the teeth and in some cases gums which are as a result of bacteria the feed on sugar from food consumed.
As the bacteria breed on the tooth they secrete acids that attack the teeth which eventually starts eroding the tooth enamel, destroying them and causing tooth decay.
This degenerates and goes on to cause pains, infections and in some cases completely eat the tooth which would have to be taken out in the end.
1. Eating food with high sugar content and carbohydrate
Foods high in sugar as well as starchy ones are the most common cause of tooth decay. After eating these foods, one should make sure the tooth are brushed to kill the chances of bacteria breeding on them.
2. Skipping regular brushing and flossing
Going without brushing twice daily (in the morning and last at night) will leave tooth decayed as it would become the perfect breeding ground for bacteria.
Brushing daily, flossing and getting regular dental checks help prevent tooth decay.
3. Low Fluoride
Fluoride keeps gives tooth resistance to acids caused by plagues and generally makes them stronger where this is absent, the tooth will be prone to decay.
Fluoride are present in toothpastes and water.
Smokers ( and even second hand smokers) stand a great risk of having enamels and gum eroded which eventually leads to tooth decay.
5. Dry mouth
A dry mouth or one without enough saliva leaves the tooth at a greater risk of decay where otherwise saliva would have helped to 'wash away' sugar that ends up causing bacteria.