Dentist question

[jniff101]

So I recently took my son to the children's dentistry of the lakes region. First off I absolutely love them! They are amazing with my kids and the place is set up just for kids. It's awesome! Here is my dilema... For the first time after his cleaning today I was told that he has 2 cavities, these will be the first and only cavities he has and he is 8 years old. They say that they are on the adult molars and they are there with no fault on his part. Apparently the enamel never grew over the tooth right and made a tiny pit that got food in it and caused an infection. Now they want to give him laughing gas, Novacaine and then drill into the teeth. I am feeling like this isn't necessary. I am having a hard time believing this is something that needs to be done. Am I wrong? Should I get a second opinion? If so I have no idea where to go because I felt like this was the best place.