Genetic factors associated with orthodontic pain in children and adolescents: a pilot study

Abstract

Introduction: Pain is often reported as being the worst aspect of orthodontic treatment. Nearly all patients experience pain and discomfort at their teeth at some point during orthodontic treatment. Little information exists on the severity of pain in the latter stages of orthodontic treatment. In addition, no studies have investigated the role of genetic factors on pain caused by fixed appliances.

Objectives: To investigate whether demographic, clinical or genetic factors are associated with the severity of pain experienced following adjustment of fixed orthodontic appliances.

Methods: Eighty-two participants undergoing fixed orthodontic treatment were recruited. Baseline DNA was collected via blood or saliva samples. Immediately after bond-up or an adjustment of the fixed appliances, the participants used a smartphone app to record regular pain scores at their teeth over the following three days.

Results: Pain peaked approximately 19 hours after the orthodontic adjustment, then gradually returned toward baseline levels by day three. Pain on chewing was significantly greater than the resting pain at the teeth at all time points concerned. There was a significant difference in the total amount of pain at the teeth over the three days when comparing bond-ups to no arch wire changes (with or without bends placed). Gender, age, and time in treatment were not associated with the severity of pain experienced after an orthodontic adjustment. The rs931233 SNP of the HTR2A and the rs4646310 SNP of the COMT genes were significantly associated with pain severity. Haplotypes of the COMT gene also showed promising, although non-significant associations with pain severity.

Conclusions: Pain on chewing is significantly more painful compared to resting pain at the teeth after adjustment of fixed appliances. SNPs of the HTR2A and COMT gene were associated with the severity of pain following adjustment of fixed appliances. Therefore, it seems that genetic factors have a modifying effect on orthodontic pain (as is the case with many other pain conditions such as TMD, fibromyalgia, and experimental pain). Larger samples are required to investigate these associations further.