AK I'm not sure you had your question about staying in hospital or dentist questions answered?

Cisplatin hits pretty hard. They give you hydration (just a bag of saline) in a drip for the two days after the Cisplatin to flush it through the kidneys. Staying in hospital isn't usually necessary, but there may be cases for elderly people or people who live a long distance away for it to be beneficial. In most cases I saw they only admitted people who had complications (diabetes, constipation etc).

Your brother is lucky not to need any teeth extracted. Its a tough period for the mouth in general, and seeing a dentist for a checkup and fluoride treatment is important. The last thing he wants is to have a toothache and need a filling when his mouth is full of ulcers etc. Best to get it sorted before treatment starts.