OBJECTIVE: To determine if sodium hexametaphosphate applied to monkey chow, could reduce calculus when fed to macaques. RESULTS Sodium hexametaphosphate did reduce the amount of calculus and plaque formation after 6 months and improved the health of the gingiva of the test animals compared to controls. FUTURE DIRECTIONS Test the diet in rhesus macaques. KEY WORDS Macaque, dental, sodium hexametaphosphate, diet, calculus, plaque, dental prophylaxiz