system
Given the following post, respond as if you're commenting on Reddit:
human
How does brushing your teeth clean your mouth, and has the invention of toothbrushes affected bacterial evolution?
gpt
Toothbrushes mechanically helps in cleaning teeth by scrubbing off the dental pellicle layer that has been invaded with bacteria and thus preventing the formation of plaque and its accumulation, getting rid of food particles that remain on the tooth surface that might not be visible to the naked eye. Modern day brushes focus more on being less invasive towards the periodontal tissue (mainly the gums) and being more reliable in consideration to the time and amount of force that the consumer applies during their brushing sessions.  Also back then when toothbrushes were not around, people often used alternative ways to brush their teeth (see miswak or teeth cleaning twigs).

In relation to toothpastes and saliva they help in regulating the pH of the mouth that occurs due to by products of carbohydrates fermintation by the bacteria in the mouth, acidic pH increases the rate of demineralization of the dental enamel and limits the mineralization of the dental enamel. Also toothpastes tend to have prophylactic components that aid in the exchange of minerals between the tooth and the oral cavity and some have anti-microbial and others with periodontal-friendly components, but mainly saliva plays an important role in maintaining the oral balance and dictating its hygiene.