Introduction Postoperative delirium has a multifactorial origin in the perioperative period. We postulate that the use of bispectral index (BIS), decreases the necessary amount of intraoperative drugs decreasing the incidence of pop delirium in patients with neurocognitive deficit Objective: To determine whether BIS in patients with neurocognitive deficits reduces delirium in the postanesthetic care unit, since its use would reduce the amount of anesthetics administered. Method Quantitative study of randomized intervention in patients between 16 years and 60 years undergoing dental treatment under anesthesia. We managed a group A, patients with the BIS device, group B, patients without the BIS device. The anesthetic technique uses medicines of habitual use. In the post anesthetic care unit, the RASS and CAM-ICU scales were applied every 30 minutes until discharge. Results Regarding hyperactive delirium, the presentation was similar in both groups (p = 0.19). Through the evaluation scales it was found that patients in group B had hyperactive delirium with a longer duration compared to group A. There is no association of anesthetics and delirium because it is multifactorial. Conclusion BIS does not reduce postoperative delirium but limits its duration, which is an effective cost to reduce the times in post anesthetic units. The delirium evaluation instruments are not fully applicable in this type of population, so conclusions can not be drawn regarding the usefulness of BIS in delirium.