They do, unfortunatley. Occasionally one gets caught doing unnecessary work, but I assume that's only the tip of the iceberg. The thing I really don't trust them on is anaesthetic; I don't know whether things have improved, but they used to be notorious for overdosing people. A friend of mine had this happen, and it affected her heart. She could hear everything, but couldn't move or speak, and she's a nurse so she knew exactly what was happening. The dentist had no oxygen available, and was panicking. Fortunately, she pulled through. That was the same dentist who made me so ill that I ended up, several days later, having someone from the church arrive on the doorstep, extremely worried, wondering why I wasn't there to take my service. At the time, I was just starting to work on the sermon, thinking it was Saturday.