I've had this happen before but the last time I went to the dentist I didn't have any problem. This is pure speculation but I'm wondering if the cleaning (especially scraping at the gumline) could possibly let some bacteria loose into the bloodstream causing an immune reaction. This could account for any general malaise or flu type symptoms. My reasoning on this is that the main difference between my previous visits and my most recent one is that now I'm on an antibiotic based treatment. My dentist also told me that my gums had much less swelling than they did previously when they measured the depths of the gums at each tooth. He showed me the before and after chart and all the numbers had gone down by one or two. He attributed the better gums to the antibiotics I'm on and also mentioned they often prescribe antibiotics before major work on people because of the bacteria that's released, especially those with heart trouble etc...

NorCalJim