Absolute disk read/write interrupts and sector caching

I'm writing a DOS utility (primarily targeting MS-DOS 5.0-7.0) which uses int 25h/26h to modify a FAT16 partition, including the FATs and root directory entries. Ideally I'd like to be able to use this partition immediately afterwards without rebooting. There won't be any open files from this drive at the time, but I'm worried about DOS caching sectors (in particular, the FAT itself) and not…