Influence of Contact Pro on Microhardness of a Composite

Objectives: Evaluate the microhardness of an underlying composite resin to Contact Pro (TDV), in order to verify the influence of this intermediate layer on the intensity of light produced by a halogen light curing unit. Methods:Ten measures of Knoop hardness of color A3 Charisma composite were used, with 3mm of diameter and 2 mm of thickness for each one of the 2 experimental groups, whose variable was the interposition of the Contact Pro. For standardization of the methodology, the area of the composite was protected with a black adhesive tape, that has an opening of 3mm of diameter and the tip of the light curing unit, was maintained fixed 13mm away from the surface of the composite. Results:The average hardness of the group with the Contact Pro was 71,8(± 4,07) and without it was of 30,8(±2,06). The statistical analysis using Student's t test showed significant difference (p=2,54025E-13) between the groups. Such difference can be related to the reduction of the intensity of captured light, by a radiometer used in the same previous conditions, that showed an average reduction of 100mW/cm² when the intermediary was removed. Conclusions:It may be concluded that the use of the Contact Pro increased the hardness of the composite, when compared with the group, without the intermediary, suggesting that its use is indicated in restoring situations of difficult access.