Objectives: This study aimed to compare the knowledge attained by third-year dental students in physical ergonomics altering live lectures and videos in teaching. The second aim was to investigate implementation of the theoretical knowledge on ergonomics into practice. Material and methods: Forty-five students divided into two groups attended a live lecture (45 min) or viewed videos (45 min). After the first teaching session, the groups changed parts. All students answered a questionnaire with 13 true or falsequestions on ergonomics at baseline and immediately after both teaching sessions. Friedman's test and Wilcoxon signed rank test were used to compare questionnaire scores of the student groups. Additionally, we photographed 17 randomly selected students 3 months after baseline during a simulation workshop on endodontics. We analyzed the photographs for ergonomic postures using a specific 12-point checklist. Results: At baseline, no difference in the knowledge between the two groups was discovered, when both scored 72%. After the first teaching session, significant improvement in both groups (p < .05) was found; and there was no statistically significant difference in the scores between the groups (88% in the lecture-first and 82% in the video-first group). After the second teaching session, the scores were similar in both groups. Overall all improvement in both groups was significant (p < .001). The photograph analysis showed half of the postures being in accord with the ergonomic guidelines. Conclusions: Both live lectures and videos showed similar outcomes in teaching ergonomics. Implementation of the knowledge on ergonomics is insufficient. Videos provide an easy-to-organize alternative to live lectures in teaching dental ergonomics. New means are needed to have dental students implement their knowledge on ergonomics into practice.