Once again, the number of days until the oral wound completely healed was recorded. The two groups' gum samples were compared. Which research method was used

Experimental

Explanation:

Experimental research methodology involves manipulation of a certain variable in order to understand the effect of that variable on the outcome of the research. For instance, a health related research might manipulate or change the medication given to a group and record its affects and then gives them another medication to understand the affect of the second medication on their health outcomes. Here, a similar situation has been provided and therefore, it is an experimental research.