The aim of the study was to investigate the effects of Botox injection therapy, with or without wearing thermoformed occlusal splints, in patients with sleep apnea and nocturnal bruxism and to determine their degree of satisfaction after completing the therapy. The selected patients (n = 36, 24 female and 12 male) with sleep apnea and nocturnal bruxism were divided into two groups. The first group of 18 patients (G1) was treated by injecting Botox (Allergan) into the masseter muscle. The 18 patients in the second group (G2) benefited from associated therapy represented by Botox injections in masseter muscle and the wear of thermoformed occlusal splints. Four monitoring sessions were realized: at baseline, at three weeks, at three months, and at six months after the effectuation of treatments. The associated therapy (Botox and thermoformed occlusal splints) presented much better results over time in decreasing the sleep apnea and nocturnal bruxism symptoms than the one represented only by injections with Botox, but Botox injections presented a rapid relief of both disease signs. Patient satisfaction after the applied treatments was very good, but in patients with associated therapy, it was better after six months than in first-group patients.