Comprehensive tracking and reporting features of any online advertising platform.
Google Adwords can deliver results very quickly. This is a huge advantage in situations where you need new patients fast or you have a great service/offer that you want to push out before your competitors. Most other alternatives require development of creatives and other lengthy work upfront which can take weeks.
Using the Google Search network, you can advertise to people who are looking for a dentist in your city. These people are highly interested in dental treatment and you can offer your service to them by advertising on google for relevant keywords. What is even more impressive is that you can exclude keywords to avoid showing your ad for irrelevant keywords. For e.g. if you do not treat children you can add keywords like children, kids, paediatric etc. as negatives to ensure that anyone who is searching for paediatric dentists does not see your ad!