Scared of medical instruments

I studied in Kendriya Vidhyalaya school which was in National Police Academy campus. The campus had an hospital. I remember we kids (4-5 grade) used to go to hospital in the campus. There was a huge garbage bin in front of the hospital. There used to be weird looking medical waste in the bin. We used to find a lot of used syringes and needles. We took them and used to play with them. We then got to know that all kind of disearses are spread if we use those syringes and needles. Then we heard of AIDS. All kind of ads on AIDS were aired at that time. Looking at the ads we used to think that its spread through used blades, needles or by hugging others or kissing others. It took some time to actually understand what they meant. But once i knew it was speard using used needles, I realize that most of the doctors i met at that time used to reuse the needle.They used to clean the needle and syringe in boiling water.Who know how many diseases were speard by these doctors by reusing them.

i suppose even doctors were not aware of these precautions.

Recently i had been to a hospital for a dental checkup. I saw the doctor using some kind of dental instrument which is used to remove the tartar from the teeth. A lot of blood came off my gums while cleaning. All i was thinking was, is it safe to use that instrument? How does the doctor make sure that the instrument is not properly steralize before using? He uses the instrument everyday and might have treated hunderds of patients. And usually the doctor just uses the instrumemt and there is another person who cleans the instrument. If it were a needle of blade then we can make sure he changes it. But what about this costly instrument for which he cannot change everytime? I dont know how many of us actually think about it.

Yesterday i saw another instrument when i went to a hospital for a checkup for my grandfather. He was advised to take an endoscopy. In Endoscopy the doctor inserts a tube into your mouth and pushes it till your stomach and seeing if there is any problem. The pipe inserted is pretty thick and expensive. I am sure its not disposable after single use. I saw the person who was cleaning it was just washing it with water and some lotion. Does it 100% steralize it? i am not sure. What i mean to say is even today there are few medical instruments used in hospital which can transmit viruses or bacterias. There might be hospitals where people take proper steps to steralize. But what about small hospitals?