Adapting and testing the oral impacts on daily performances among adults and elderly in Brazil.

To cross-culturally adapt and evaluate the psychometric properties of the oral impact on daily performance (OIDP) in Brazilians aged 50-74 years; to test the impact of oral health on 'work' and 'vigorous physical activity'.Clinical oral health indicators do not assess the perceived impact of oral health on people's lives.The study was performed through small group interviews, pilot studies and a main study with 200 people aged 50 and over. Data were collected through interviews in health centres.For content validity, 'eating' (1.00, p < 0.001) and 'speaking' (0.96, p < 0.001) obtained the highest level of agreement among experts. For criterion and construct validity, there was an inverse correlation between self-rated oral health, perceived oral treatment needs and satisfaction with oral health and OIDP score. Cronbach's alpha coefficient varied from 0.69 to 0.67 when 'work' and 'vigorous physical activities' were deleted. Test-retest reliability was 0.69 (ICC).The validation process showed that the Brazilian OIDP has the necessary basic psychometric properties to be used in the 50-74 years age group in Brazil. 'Work' and 'vigorous physical activities' had low impact on oral health. The activity 'vigorous physical activities' was not maintained in the instrument because of its low impact, while 'work' was maintained due of the increase in the 50-59 years age group in the Brazilian population.