This is a normal and necessary part of every dog's life. Puppies between the ages of 2 and 6 months chew to relieve the pain of teething. Dogs, in particular young dogs, are very oral when investigating new items. Young dogs, up to a year, also chew for teething reasons even though their permanent teeth are in. This is because they have not fully set in the root and it relieves them to chew.
Some dogs start to chew all of a sudden because of dental problems.
A trip to the veterinarian will take care of dental chewing. What starts out as a dental problem or investigator chewing can soon become habit. There are a variety of other reasons why dogs chew, from the dog being bored to having fun to relieving stress. This problem is not a dog that chews but what the dog chews. The problem occurs when the dog chews the couch or your shoes instead of his chew toys.