Dental Assistant Practice Exam

What is the primary cause of tooth decay (caries)?

1. Fluoride exposure

2. Activity of bacteria and acids in dental plaque

3. Excessive sugar consumption

4. Overbrushing teeth

The correct answer is: Activity of bacteria and acids in dental plaque

The primary cause of tooth decay, also known as dental caries, is the activity of bacteria and acids in dental plaque. When sugars and carbohydrates are consumed, it provides food for bacteria that reside in dental plaque, a sticky film that forms on teeth. As these bacteria metabolize sugars, they produce acids as byproducts. These acids can demineralize the tooth enamel, leading to the formation of cavities. While excessive sugar consumption contributes to the overall process by providing more substrate for bacteria, it is the resultant acid production by these bacteria that directly causes tooth decay. Fluoride exposure can actually help to prevent tooth decay by enhancing the remineralization of enamel and making it more resistant to acid attacks, rather than being a cause of decay itself. Overbrushing teeth typically does not lead to decay and is more closely associated with dental abrasion or damage to the gums than with caries formation. Thus, the key driver of the tooth decay process is indeed the harmful activity of bacteria and the acids they generate in dental plaque.