A study of calibration has been made in students of the "Colégio Estadual Carlos Maximiliano Pereira dos Santos'' in São Paulo, Brazil, applying the GTI Index of Lowell Smith that estimates the needs of gengival treatment. The aim of the work to which we have proposed ourselves was to test the GTI INDEX and check, its applicability and effectiveness. The percentage of agreement found beetween examinators was of 70%. For the examinator A 76% was found, and for the examinator B the agreement was 73%.
