# Content Analysis of YouTube Videos That Demonstrate Periapical Radiography
## 3 Results  
The web links and coded data extracted from the 21 videos on demonstration of periapical radiography are listed in Supplementary Table S1. The oldest one was uploaded on 2 July 2009 and its caption stated that the original air date of that recorded video was actually 2 August 1972 ([[https://www.youtube.com/watch?v=TQZQCywto38](https://www.youtube.com/watch?v=TQZQCywto38)]([https://www.youtube.com/watch?v=TQZQCywto38](https://www.youtube.com/watch?v=TQZQCywto38)) (accessed on 26 July 2022)). Meanwhile, the most recent one was uploaded on 6/5/2021. Year 2016 had the highest number of videos uploaded (\(n=6\)). There was no obvious trend in the number of videos uploaded against year, though it seemed that most of them have been uploaded to YouTube since 2015 (Figure 2). Nine of the videos were uploaded by dental school channels, 7 by individual key opinion leaders (KOLs) such as dentists or dental hygienists, and 5 by dental suppliers. The majority of the videos (71.4%) demonstrated periapical radiography with digital imaging (10 of them using intraoral sensor, 5 using phosphor plate), while the remaining 28.6% of the videos used traditional films. All but one video involved an adult patient. Child patient was involved in one video only. About 90.5% of the videos (\(n=19\)) demonstrated paralleling technique, whereas 9.5% (\(n=2\)) of them demonstrated bisecting angle technique. For patient preparation, less than a quarter of the videos (23.8%) explicitly asked the patient to remove (or showed the actual removal of) metallic objects from the patient's head and neck region (Table 1). Meanwhile, 81.0% of the videos explained procedures to the patient. Lead apron and thyroid collar were worn by patients in 33.3% and 71.4% of the videos, respectively. For machine preparation, only 28.6% of the videos showed the selection of correct radiation dose (e.g., according to body size, and tooth type), and 52.4% of them used a rectangular collimator. For receptor placement procedures, most of the videos (85.7%) showed to the audience which side of the receptor should face the X-ray beam (Table 2). Meanwhile, all videos using digital imaging covered their receptor with a plastic barrier for infection control. All 6 videos using traditional films showed the film packet being inserted into the patient's mouth directly, with none of them using ClinAsept (or equivalent)--a plastic barrier that additionally covers the film packet. Only 3 videos (14.3%) demonstrated that the orientation dot should be placed on the occlusal side. Two videos did not use a receptor holder, and they were both demonstrating the bisecting angle technique. For the 19 videos using a receptor  
Figure 2: Number of YouTube videos uploaded each year that demonstrated periapical radiography. holder and demonstrating the paralleling technique, all of them assembled the holder correctly. However, it should be noted that for one video that demonstrated mandibular posterior periapicals, in one scene the aiming ring was actually covering the maxillary posterior region ([[https://www.youtube.com/watch?v=4k3](https://www.youtube.com/watch?v=4k3) RR6 VvxFK]([https://www.youtube.com/watch?v=4k3](https://www.youtube.com/watch?v=4k3) RR6 VvxFK), the problematic scene began at 3:01 (accessed on 26 July 2022)). Most of the videos (71.4%) did not apply a cotton roll to facilitate the stable placement of the receptor holder. Five videos placed a cotton roll on the opposing teeth to help stabilize the biteblock. One video demonstrated putting a cotton roll on the incisal edge of the tooth to be radiographed, stating that this act could help \"prevent cutting off the incisal edge of the tooth\" on the resultant image. Most of the videos pushed the aiming ring close to the patient's face, showed parallelism between the collimator and the receptor holder in both vertical and horizontal dimensions, kept the receptor unbent within the oral cavity, and showed the patient having a stable bite onto the biteblock.