Background This study aimed to assess and update the content, reliability, and information quality of content related to root canal treatment (RCTx) on YouTube and evaluate the correlation between each evaluation index. Methods YouTube was searched using two terms related to RCTx (“root canal and endodontic treatment”). A total of 240 videos (120 for each search term) were screened. Exclusion criteria were as follows: no sound or visuals, non-English, irrelevant to the search term, longer than 15 min, duplicate, or old (uploaded before 2016). After exclusion, 50 videos of “root canal treatment” and 45 videos of “endodontic treatment” were analyzed. Video length, total number of views, likes, dislikes, comments, and days since upload were recorded using descriptive video data. Viewers’ interaction, reliability and information quality of the video, and quality of video content were measured using nondescriptive video data. The interaction index and video power index were used for viewer interactions, and the modified DISCERN index, JAMA criteria, and Global Quality Score were used to assess the reliability and information quality of the video. The quality of the video content was measured using the completeness score. Results The videos of the “root canal treatment” group had a significantly higher completeness score for the etiology and symptoms (p < 0.05), and videos of the “endodontic treatment” group showed a higher interaction index, completeness score for the procedure (p < 0.05). Videos for dentists had significantly higher completeness scores for the procedure, while videos for laypersons had higher completeness scores for etiology, anatomy, symptoms, and prognosis (p < 0.05). Furthermore, the total completeness score and the interaction index of the videos for laypersons were significantly higher (p < 0.05). The videos uploaded by the university had a significantly higher modified DISCERN index (p = 0.044), and the JAMA score was significantly higher in the commercial group (p = 0.001). Conclusions Although the accuracy of videos related to RCTx was higher in videos by universities and professionals, the total completeness of YouTube videos was low regardless of the video source. Therefore, professionals should be responsible for providing more accurate and reliable videos.