How a cavity is filled

I went back in today for more work done on my teeth. This is what happens when you avoid the dentist for long periods of time. Needed 2 cavities filled on the same molar in the upper left side. Brushing the outside apparently is not the problem; I am not flossing and the result is cavities inbetween the tight spaces. Which means they had to drill straight though the tooth at an angle to get to the area of the cavity. I couldn't help but to imagine what this would look like from another point of view so I had to look it up on youtube and now it all makes sense.

*PropDental