Effect of handedness on learning subgingival scaling with curettes: a study on manikins

The aim of the present study was to evaluate the influence of systematic manikin-head training and the effectiveness of subgingival scaling applied with hand instruments (curettes) by right- and left-handed dental students on dental chairs (traditional) designed for right-handers. A questionnaire focusing on handedness was administered to 69 voluntary dental students in the third class at the School of Dentistry during pre-participation examination. Handedness was assessed using the Turkish version of the Edinburgh Handedness Inventory. Then, 18 dental students were specially selected in 2 equal groups according to hand preference: consistent right-handers with Geschwind Scores of +100 (5 female and 4 male) and consistent left-handers with Geschwind Scores of -100 (5 female and 4 male). These two untrained dental student groups received 10 weeks manikin-head training. Subgingival scaling was performed with hand instruments (Gracey curettes) in manikin-head mounted on right-sided dental chairs. At 6 test days each dental student had to instrument 12 test teeth. Effectiveness of subgingival scaling was evaluated by adoption of a grading system. This system had scores from 0 to 3 and was defined by illustrated and described criteria. Statistical analysis was carried out with SPSS. Two groups were statistically compared on all test days. The yet-untrained left-handed dental students begin with a relatively high the mean score of 2.25, compared to the yet-trained right-handed dental students with 1.93, which was statistically significant (p > .05). The right-handed dental students reached the mean score of 0.53, whereas the left-handed dental students reached the mean score of 0.87 on test day 6. Significant differences in the mean scores were found between the two groups for overall surfaces (p < .05), the distal surfaces (p < .01), lingual surfaces (p < .01), and each group of teeth (p < .05). But there was no statistically significant difference between the 2 groups of students on all test day, except for test day 3 in terms of the mean scores for the facial and mesial surfaces (p > .05). Learning success was observed a high level in both groups through systematical training (p < .0001). The present study has documented that the left-handed dental students were less successful than the right-handed dental students in subgingival scaling, except for mesial and facial surfaces. However although training on right-sided chairs, they were quite similar to their right-handed counterparts in terms of learning success.