In 1350 client-owned dogs in North America, the association of calculus, gingival inflammation and periodontal bone loss with diet (dry food only, or other than dry food only), and with access to other chewing materials was analyzed. There were few apparent differences seen in dogs fed dry food only compared with those fed other than dry food only. There was progressively less accumulation of calculus, less gingival inflammation and less periodontal bone loss in dogs that were given access to more types of chewing materials (rawhides, bones, biscuits, chew toys) compared with dogs given access to fewer or no chewing materials. When the effects of individual chewing materials were analyzed, access to rawhides overall had the greatest apparent periodontal protective effect, and this effect was more apparent in dogs fed dry food only compared with those fed other than dry food only.