Comparision of tooth alignment and pain perception of different sizes of nickle-titanium archwires in the initial phase of fixed orthodontic treatment : randomized clinical trial

Abstract

Background: Orthodontic treatment uses arch wires to force the teeth. The placement of the primary archway leads to pain and discomfort in the patient due to the release of biochemical intermediates and the occurrence of transient pulpitis, periodontal ligament contraction and mechanical damage to soft tissues. Orthodontic pain, in addition to causing a discomfort to the patient during treatment, can be an important factor in discouraging patients from taking orthodontic treatment. The purpose of this study was to compare the severity of pain caused by Ni-Ti arches in different sizes in the first stage of fixed orthodontic treatment. Methods: In this double blind randomized clinical trial, 81 patients (three groups 27) were randomly assigned in to the study. First, second and third study groups received 0.12 inch Superelastic NiTi archwires (Highland Metals USA), 0.14 inch Superelastic NiTi archwires (Highland Metals, USA) and 0.16 inch Superelastic NiTi archwires (Highland Metals, USA) as their first archwires, respectively. The amount of pain experienced by the patient were evaluated using a visual analogue scale. The patient was asked to determine the severity of pain at specified intervals (immediately, 3 hours, 24 hours, and 3 days after archiving). The patients also described the severity of the pain experienced as qualitative (no pain, low pain, moderate pain, or severe pain). Results: The results showed that immediately after the first Arch Wire placement, the highest pain intensity was related to Arch Wire 0.12 inches and the lowest pain intensity was related to Arch Wire 0.016. Four weeks after Arch Wire placement, the highest pain intensity was related to Arch Wire 0.16 and the lowest pain severity was related to Arch Wire 0.14. Eight weeks after Arch Wire placement, the highest pain was related to Arch Wire 0.16 and the lowest pain was related to Arch Wire 0.12. In addition to the characteristics of archives, internal factors, subjectivity, and previous experience of pain and morale of patients were effective in the reported pain intensity. Conclusion: The overall pattern of pain was similar in 3 types of arch wires, and there was no significant difference between the arch wires of 0.12, 0.14 and 0.16 nickel-titanium in the severity of post-placement pain. The overall pattern of pain at the moment of arch-wiring placement was zero and within 24 hours of placement it was maximized and gradually decreased over the course of three days.