Discussion
handedness, influence motor learning, learning gain, a learning gain
The results of this study show that for dental students, the greatest learning gains were observed after training with the DH in both, knot tying and suturing and techniques (see table 1 Students in the preclinical and clinical study sections did not differ significantly in the parameters studied except for the learning gain in their knot tying technique. Here, the students in the clinical study section showed an increase in learning (see table 2 To answer the question of who benefited most from training, a subgroup analysis by learning gain was performed. Most students with a learning gain in knot tying technique and suturing technique (≥4 OSATS points) received DH training (46.4% and 45.7%, respectively) (see table 3 Surprisingly here, more than half of the students with inferior training of the knot tying or suturing technique in terms of training with the NDH or AT were able to achieve a learning gain with their DH (≥4 OSATS points) (53.6% and 54.3%, respectively; see also table 3 Thus, learning gains seem to have been achieved here regardless of the type of training. This could be due to the structured feedback that students in all three groups received prior to training to enable correct execution of the procedure [The learning gain after training of the DH is most likely due to independent practice, as during practice learners did not receive corrective feedback from a teacher [The students with the lower learning growth started at a higher level with their knot tying technique prior to training when compared to the students with a greater learning growth (see table 3 Before and after training, students self-assessed their competence in knot tying and suturing techniques. Correlation analysis showed no relevant correlations between self-assessments and OSATS scores before or after training in the DH, NDH, and AT groups (data not shown). Studies on the predictive value of self-assessment are very heterogeneous. Some studies found a correlation between self-assessment and external assessment [A possible limitation of the present study lies in the fact that not all causes that influence motor learning have been captured [Future studies that investigate the efficiency of the learning gain with the DH as a result of successive repetitions with the DH during training could use the CUSUM curve method to show the learning effect over consecutive repetitions over time. Indeed, handedness is a relevant issue in the operating room, as many surgical instruments such as scissors have been optimized for right-handers. An interesting question for further studies would therefore be how quickly and effectively left-handers can learn with their right hand to perform surgical steps as well as primary right-handers using instruments optimized for right-handers.