What causes bone loss and bone disease BESIDES not brushing correctly and not flossing?

Dear Doctors--What causes bone loss and bone disease BESIDES not brushing correctly and not flossing?
I'm 74 and have been flossing every day for many many years, and brushing after eating. I also haven't had a cavity for many many years, yet my dentist tells me I have some gum disease and bone loss. Thank you.

[Jerome Tsang, DDS]

The bone loss could have happened years ago and has since stabilized.  Unfortunately the bone doesn't grow back so it may stay lower than ideal.  Gum disease is the active disease so if it isn't poor hygiene, it can be due to other risk factors such as smoking, poorly controlled diabetes, etc.  You may want to ask your dentist what he thinks it may the cause.