Perhaps your dog just got tired of the type you were buying him.
I try to give my animals a variety of treats and chews.
I only give them to them un supervised unless I have a dog that doesn't get kicks out of ripping his toys to shreads

Try these...

www.greenies.com

They are human grade and fully digestable, great for the teeth and gums, and most dogs love em! Helps improve their breath as well.