Fixed orthodontic appliances cause pain and disturbance in somatosensory function

Abstract

This study aimed to assess the short-term effects of orthodontic pain on quantitative sensory testing (QST) in subjects receiving fixed orthodontic treatment. Twenty patients and 12 healthy volunteers (as controls) participated. All 20 patients had bonded AO self-ligating brackets, with a 0.014 super elastic nickel-titanium arch wire placed in the brackets. Pain [self-reported on a visual analog scale (VAS)], and thermal and mechanical thresholds, were tested at six time points--before (baseline), and 2 h, 24 h, 7 d, 14 d, and 30 d after, force application--in the treatment group. The attached gingiva adjacent to the left upper central incisor (21 gingiva) was hypersensitive to cold stimuli (i.e. increased cold detection thresholds were detected) in the treatment group. The pressure pain thresholds of the left upper central incisor (21) and 21 gingiva were significantly reduced. Our results suggest clear signs of sensitization of the trigeminal nociceptive system up to 1 month after force application and orthodontic pain. Quantitative assessment of somatosensory function may help to provide a better understanding and profiling of the underlying neurobiological mechanisms related to orthodontic pain.

The effect of orthodontic separator and short‐term fixed orthodontic appliance on inflammatory mediators and somatosensory function

“…Shen et al. found a hypersensitive to cold and hyposensitive to pressure at the site of the tooth movement up to 1 month after orthodontic force was applied . Both studies found some somatosensory alteration intraorally which diverge from the extraoral examination of the present investigation.…”

“…In contrast to previous investigations, which applied either elastic separator around the first molars or fixed orthodontic appliance to induce pain, we examined both methods of stimulating orthodontic tooth movement. Patients reported a moderate pain intensity 24 hour‐aBB and only mild pain intensity following elastomeric separator which was expected since the separator only stimulate two contiguous teeth in contrast to fixed appliance which stimulates all teeth on the arch.…”

“…Only two studies in humans and one animal model assessed possible somatosensory alterations following orthodontic treatment. Bilateral mechanical and thermal hypersensitivities following orthodontic tooth movement (OTM) were found in rats, with peaks reached on postoperative day‐1.…”

“…Patients were asked to mark a vertical line crossing the horizontal line corresponding to their pain intensity. Pain intensity measurement was the distance between the beginning of the horizontal line, corresponding to 0 cm, to the vertical line, drawn by the patient …”

“…Inflammation can also alter nerve function, and it has been shown that the release of IL‐1β and TNF‐α induce inflammatory hyperalgesia, characterised by a decrease in the nociception threshold and increase neuronal membrane excitability, which can lead to somatosensory alterations . Quantitative sensory testing (QST) is a standardised battery of psychophysical tests that can reliably assess the somatosensory function and has been extensively applied to the oro‐facial region .…”