[aimee]

Spycar,

Not a lot of research but so far what has been published hasn’t shown a protective benefit of a “natural” diet. The following is an excerpt from “Impact of Nutrition on Dental issues in companion animals” Chandler 2014

“Proponents of natural foods or of feeding raw bones have claimed this will improve the cleanliness of teeth in pets; further claims are sometimes made that feeding commercial pet food contributes to the high prevalence of periodontal disease in domesticated cats and dogs.
However, a study in foxhounds fed raw carcases, including raw bones, showed they had varying degrees of periodontal disease as well as a high prevalence of tooth fractures (Robinson and Gorrel, 1997).
The skulls of 29 African wild dogs eating a “natural diet”, mostly wild antelope, showed evidence of periodontal disease (41 per cent), teeth wearing (83 per cent) and fractured teeth (48 per cent; Steenkamp and Gorrel, 1999).
A study in small feral cats on Marion Island (South Africa) that had been eating a variety of natural foods (mostly birds) showed periodontal disease in 61 per cent of cats, although only nine per cent had evidence of calculus (Verstraete et al, 1996).
In a study in Australia of feral cats eating a mixed natural diet there was less calculus compared to domestic cats fed dry or canned commercial food, although, again, there was no difference in the prevalence of periodontal disease between the two groups (Clarke and Cameron, 1998)

These studies show a natural diet, or one containing raw bones, does appear to confer some
protection against dental calculus, but not against the more destructive periodontal disease. There is also the risk of fractured teeth”