With charges such as dental fillings that can be reoccurring over a short period of time. The idea is to be able to utilize your credit card for instance for all those payments and have a gifted period (3 months for example) of interest free to pay off those dental bills.
Example: You get one filling $300 . Next scheduled filling is two weeks which is $300. Instead of spending $600 within a month, you can credit it and utilize a gifted period of interest free.