In general, when i brush and floss at bedtime does a bacteria biofilm actually form on teeth by the morning? and, if not removed, night time brushing will not really remove it as it has turned to hard tarter/plaque?

The bacteria and plaque form over a period of time, especially if you have poor oral hygiene. Brushing and flossing at night and in the morning will control the build up of both. Flossing after snacks also helps as well as a healthy diet. Make sure you see a dentist for cleanings at least twice or more a year.

Bacteria layer on your teeth constantly, each layer contributing to the activity in the next layer. The final layer produces digestive enzymes that literally eat your gums. Brushing and flossing 2x/day disrupts this plaque, preventing end-product formation. Tarter forms when areas go uncleaned for long periods of time, and calcium precipitates out of saliva and imbeds in plaque. Go 2 Dentist.