Transient Pain Following Orthodontic Fixed Appliances Induces Sensitization of Gingival and Periodontal Tissues

Aims: To evaluate the transient effects of orthodontic treatment on the mechanical detection threshold (MDT) and mechanical pain threshold (MPT) of the buccal attached gingiva and the pressure pain threshold (PPT) of the buccal attached gingiva and of the teeth in two directions (perpendicular and parallel). Methods: A total of 20 patients (15 females and 5 males) aged 18 to 30 years participated in the study. Perceived pain on a 0- to 10-cm visual analog scale (VAS) and MDT, MPT, and PPT scores were evaluated at two time points at the masseter muscle, gingiva, teeth, and hand (control) prior to orthodontic treatment (T0) and 24 hours after the first archwire placement (T1). Mean values and SEMs were calculated for all continuous variables. The differences between T0 and T1 of MDT, MPT, and PPT were analyzed by means of a paired Student t test. Results: The pain intensity as assessed on the VAS was 4.2 ± 1.8 cm. No significant changes in MDT or MPT were found at the hand and buccal attached gingiva (P > .06). The PPTs at the buccal attached gingiva of teeth 21, 23, 24, and 34, at teeth 21, 23, 24, and 34 (perpendicular) and at teeth 21 and 23 (parallel) were lower (ie, more sensitive) at T1 compared with T0 (P .04). Conclusion: This study indicates for the first time that pain following insertion of an archwire causes sensitization to blunt-pressure stimuli both in the attached gingiva and in the periodontal ligament. Quantitative assessment of mechanical sensitivity may provide more insights into procedural pain and allow for better monitoring and evaluation of the effects of orthodontic treatment in the future. Keywords: f ixed appliances, orthodontics, pain, pressure pain threshold, quantitative sensory testing