Matrix metalloproteinases (MMPs) are enzymes capable of degrading collagen hybrid layer and consequently cause failure of adhesive restorations. Objectives: investigate the effect of the application or not of chlorhexidine (CHX), a nonspecific inhibitor of MMPs in the dentin bond strength of different adhesive systems: conventional three-step, two steps self-etching and one step after aging in 100% humidity at 37 ° C for 24 hours and 8 months. Methods: this study used 99 healthy human teeth, divided into nine groups (n = 11), who had their leaflets removed and cavity preparation class I occlusal 5x4x3mm. Each tooth was treated and subdivided into 24 hours and 8 months without prior application of CHX and 8 months with the use of CHX, and then they were restored with composite resin polymerized. After 24 hours, the teeth were sectioned into sticks in a cutting machine, and according to the aging period, were submitted to the microtensile test. Results: statistical methods of Mann-Whitney and Kruskal-Wallis followed by Dunn's posttest were applied and it was observed that: 1) the microtensile strength was different among the three types of adhesives used, without using CHX in both periods (p <0.001), as the conventional adhesive achieved a performance significantly better than the self-etchings (p<0.05); 2) the two-steps self-etching showed significantly higher resistance than the single-step (p <0.05); 3) the use of CHX maintained the microtensile strength, when compared to 24 hours, being the results superior to the groups of 8 months without CHX, when were used the adhesive and self-etching conventional two-step (p = 0.001) and 4 ) the use of CHX did not significantly affect the resistance of the single-step self-etching adhesives (p = 0.395). Conclusions: aging causes a fall in bond strength of tooth-restoration, that CHX is able to maintain this strength even after aging, and that the conventional adhesive system provides the best results in bond strength when compared with self-etchings.