People with an "internal" locus of control believe that ability and effort are important factors in affecting what happens to them, whereas those with an "external" locus of control believe that this is more a matter of luck or fate. Patients whose oral health was rated as being "good" scored in a more internal fashion on a locus of control questionnaire than patients whose oral health was "moderate" or "poor," suggesting that locus of control beliefs are important in the design of preventive programs on a personalized basis.