Root canal cleaning plays an important role in endodontics. In most cases, root canal cleaning is performed using irrigants, such as sodium hypochlorite or EDTA (ethylenediaminetetraacetic acid). The efficacy of these irrigants may be compromised by different phenomena, such as vapor lock. Different methods can be used to overcome this problem; in this paper, we compare the efficacy of two such methods: manual dynamic agitation (MDA) and passive ultrasonic irrigation (PUI). We shaped 50 endo training blocks, which were divided into two groups of 25 samples each, into MDA or PUI groups. In both groups, the vapor lock was produced by delivering a watery solution using a disposable syringe with a tip-opened needle. Using the MDA technique, vapor lock was removed in 15/25 cases. The PUI technique produced the same results in 17/25 cases, where vapor lock was only reduced, not removed. The MDA method produced an average reduction in vapor lock of 80%, whereas the PUI method yielded a 55% reduction. The differences among groups were assessed through a Mann–Whitney U test, and the results had a p-value of 0.0013, which was considered to be statistically significant. The MDA method was able to effectively remove vapor lock. PUI, however, was only able to reduce but not remove vapor lock.