SOrry to rain on your parade, but the only logical explanation is pure coincidence. Dental hygienists, at least in the US, are trained to deliver excellent healthcare and mostly what they do is appreciated by the mass majority of patients. If you had a tooth that was loose, the highest liklihood is that you have (and had prior to the DH visit) periodontal disease. Treating this is sometimes an unpleasent albiet necessary experience. Just like the physician that diagnoses hypertension or diabetes didn't cause these diseases in their patients, your dentist or dental hygienist did not cause your periodontal disease. Perhaps sitting down with your dentist or another one, preferably a periodontist, and having a thorough discussion on the severity of your problems and how to solve them would enable you to keep your teeth. Otherwise, untreated periodontal disease ultimately causes the teeth to loosen up and fall out. I have 3 dental hygienists that work for me, and over a month period, they probably see 400 patients. If I had one patient a month that felt like you, it would be rare.   I am not trying to protect your dentist or dental hygienist. Maybe they are real jerks and are in fact not competent. I just wanted to share the more likely possibilities for your own good.