The Effect of Orthodontic Forces on Calcitonin Gene-related Peptide Expression in Human Dental Pulp

Abstract Introduction The purpose of this study was to quantify the effect of moderate and severe orthodontic forces on calcitonin gene-related peptide (CGRP) expression in healthy human dental pulp. Methods Thirty human dental pulp samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, teeth were divided into 3 groups of 10 premolars each: (1) the control group: healthy premolars without application of orthodontic forces; (2) the moderate force group: a 56-g force was applied to the premolars for 24 hours; and (3) the severe force group: a 224-g force was applied to the premolars for 24 hours. All dental pulp samples were processed, and CGRP was measured by radioimmunoassay. Results Greater CGRP expression was found in the severe force group followed by the moderate force group. The lower CGRP values were for the control group. The Kruskal-Wallis test showed statistically significant differences between groups ( P < .0001). Least significant difference (LSD) post hoc tests showed statistically significant differences in CGRP expression between the control group and the severe force group ( P < .0001) but not with the moderate force group ( P = .06). Differences between the moderate and severe force groups were statistically significant ( P < .0001). Conclusions CGRP expression in human dental pulp increases when teeth are submitted to severe orthodontic forces.