Make FreeBSD read the slice table and partition table again

[Bahman Kahinpour]

Hello
When I destroy the partition table with the following command:
# dd if=/dev/zero of=/dev/ad1 bs=1k count=10
The entries /dev/ad1s1a, ... still exist in /dev. This means that the
kernel has not found out that the slices and partitions do not exist
anymore.
How may I make the kernel read the slice/partition table again?
Something like modprobe command in Linux?
Thanks in advance