## 4 Discussion
### Limitation  
There are several limitations to our research. Firstly, the canal irrigant was mixed with a contrast medium at a 1:1 ratio. Although the physical characteristics of the contrast medium used are similar to those of sodium hypochlorite, this change in irrigant composition could result in intrinsic changes in its physical properties, such as density, viscosity, surface tension, and contact angle at the root canal walls [41]. This alteration in irrigant composition may affect the formation and behavior of gas bubbles.  
Furthermore, the cleaning procedure itself can introduce changes to the tooth tissues. It has been observed that the root canal dentin surface becomes less hydrophilic and exhibits a higher irrigant contact angle compared to intact dentin [29]. These changes can influence the behavior of gas bubbles within the canal.  
Another limitation is that once the gas bubbles are formed, they do not maintain a fixed position. The movement of these gas bubbles within the canal can be attributed, in part, to the thickness of the fluid film between the bubble and the canal wall, which is affected by the surface tension and other factors [28,30]. This dynamic nature of gas bubble movement adds complexity to the study of vapor lock.  
Furthermore, the authors did not take into account the use of different delivery systems for irrigants other than a classic 30G metallic irrigation needle.  
Finally, another limitation is that no power analysis was conducted to establish the exact number of samples; the standard deviation values obtained in this research could be related to the reduced sample size. Further research with a larger sample size will be needed.  
It is important to acknowledge these limitations as they can introduce potential biases and affect the interpretation of the results. Future research should consider addressing these limitations and exploring additional factors that may influence the formation and behavior of gas bubbles in the root canal system.  
The important point of this article is that it presents a quantitative analysis of the vapor lock phenomenon during endodontic treatments. The study demonstrates the presence of gas bubbles, particularly in the apical third of the root canal system, which hinder the cleaning and debridement procedures. The findings highlight the need for clinical strategies to improve the cleaning phase and reduce vapor lock formation. The authors suggest techniques such as irrigation activation, proper maintenance of apical patency, or the use of negative pressure irrigation to minimize bubble formation.  
For further research, it would be valuable to investigate the impact of different irrigation protocols and techniques on vapor lock formation and its consequences. Comparative studies can be conducted to evaluate the efficacy of various cleaning methods in different anatomical complexities in the root canal system. Additionally, exploring the effects of different irrigants and their compositions on vapor lock formation would contribute to the optimization of endodontic treatment outcomes. Long-term studies assessing the clinical implications of vapor lock, such as the success rates of endodontic therapies, could provide valuable insights.