Effect of experimentally induced occlusal trauma on substance P expression in human dental pulp and periodontal ligament

Introduction: The purpose of this study was to quantify the effect of occlusal trauma experimentally induced with occlusal interferences on substance P (SP) expression in healthy human dental pulp and periodontal ligament. Methods: Twenty-eight human dental pulp and periodontal ligament samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, occlusal trauma was induced with experimental occlusal interferences in half of these premolars by placing a resin block over their occlusal surface and submitting patients to chew gum for 30 minutes. The remaining healthy premolars were extracted without occlusal trauma and served as a control group. All dental pulp and periodontal ligament samples were processed, and SP was measured by radioimmunoassay. Results: There was 45% and 120% greater SP expression in dental pulp and periodontal ligament, respectively, of teeth with experimentally induced occlusal trauma. Paired t test showed statistically significant differences for both human dental pulp and periodontal ligament (P = .02 and P < .001, respectively) of teeth submitted to occlusal trauma when compared with control group values. Conclusions: SP expression in human dental pulp and periodontal ligament increases when teeth are submitted to occlusal trauma experimentally induced with occlusal interferences.