air pockets
A tooth can have a cavity or many cavities. Teeth will have cavities. A better way to say it may be 'The dentist filled the cavities in her teeth' rather than trying to say 'The dentist filled the teeth's cavities.'
No, they are not.
The ventricles are the fluid-filled cavities of the brain.
ventricles
sinuses.
Vacuoles
Frontal Sinuses.....
They're a site for bacterial growth.
anterior pituitaryThe Thyroid Gland
Pus filled cavities are called abscesses and are treated with surgical drainage of the pus and antibiotics.
dural sinuses
The ventricles are fluid filled cavities of the brain.