Background: The phenomenon of vapor lock, characterized by the formation of gas bubbles, poses challenges in achieving effective cleaning and debridement during endodontic treatments. This study aimed to evaluate the presence of vapor lock and to quantify its volume in the root canal system. Methods: Ten single-rooted teeth were selected, and their root canals were shaped using the Protaper Next system and irrigated with 5% NaOCl and 17% EDTA. Then, the canals were irrigated with a solution made of contrast medium (8 M cesium chloride solution) mixed in equal proportions with 5% sodium hypochlorite. CBCT scans were performed to analyze the presence and volume of bubbles in different canal thirds. Statistical analysis was conducted to compare the number of bubbles and the percentage of space occupied by them. Results: The results demonstrated the presence of vapor lock in all treated teeth, with a higher concentration of gas bubbles in the apical canal third. The formation of gas bubbles hindered the cleaning and debridement procedures, particularly in the apical region. Conclusions: This study provides evidence of the occurrence of vapor lock and highlights the importance of enhancing the cleaning phase in endodontic treatments to minimize bubble formation or eliminate them once formed. These findings contribute to a better understanding of the challenges posed by vapor lock and suggest avenues for optimizing endodontic procedures.