5 month old lab grinding his teeth

Question
My lab, is I believe going through the teething process and I hear him constantly grinding his teeth. Is it normal for dogs to grind their teeth?

Answer
No, it is not normal, but I am not sure what to say to do other than providing plenty of safe chew toys.  

The pet stores are full of toys that many dogs will quickly chew up into
pieces they could choke on or cause intestinal blockages.  If you are not
there to watch, stick to sturdy stuff such as Nylabones and Kongs.  Keep a
close eye on chew toys and quickly discard anything that is coming apart in
pieces.  Rawhide is especially bad because it swells after being swallowed.
I don't trust any of the consumable chews.  The dogs just gnaw them down to a
dangerous size too quickly.  These problems are the worst with, but not
limited to, large, aggressive chewers such as Labs.

Ropes from the pets' store quickly turn to hazardous shreds.   Ones I made
lasted much better.   Go to a hardware or home center that sells rope by the
foot.  Buy 2' of 3/4" poly rope.   Melt the ends, and tie  knots in it.   Get
them as tight as possible, put it in a vise and pound it with a hammer.  Watch
carefully, and be ready to discard when it comes apart.