Biochemistry of Antibiotics in Dentistry: Effects of Antibiotics in Toothpastes and Rinses on Bacterial Growth from the Human Mouth

Over 100 million bacteria in every milliliter of saliva ranging from more than 500 different species live in our mouths, and dentists recommend we brush our teeth around two to three times a day. Toothpaste companies have developed safe rinses and pastes to prevent tooth decay and gum diseases. The purpose of this experiment was to observe the effects of different toothpastes or rinses on growth of bacteria. We hypothesized that if toothpaste with antibiotics were used to brush teeth, then there would be a decrease in population of bacteria. The hypothesis was tested by two experiments. The objective of the experiment was in order to determine the effectiveness of over the counter toothpastes and mouthwashes in preventing dental/gum diseases. Human subjects either brushed their teeth or rinsed their mouths with different toothpastes or rinses for around two minutes. Then, they will put their swab on the Petri dish. Contrary to our hypothesis, the majority of the postbrush Petri dishes had more bacteria colonies than pre-brush dishes. Toothpastes and rinses, with antibiotic and antiseptic properties, did reduce growth; however, numerous variables of eating before the experiment, the time of the day, various bacteria in different people’s mouth, and the age of the person, contributed to errors in our experiment. Working with human subjects complicates these studies. In the future, it would be useful to test the effectiveness of these agents or bacteria in isolated culture, outside the complicated environment of a human mouth.