Aoife B Monk, Jayne E Harrison, Helen V Worthington, Annabel Teague

Pain is a common side effect of orthodontic treatment. It increases in proportion to the amount of force applied to the teeth, and the type of orthodontic appliance used can affect the intensity of the pain. Pain during orthodontic treatment has been shown to be the most common reason for people wanting to discontinue treatment, and has been ranked as the worst aspect of treatment. Although pharmacological methods of pain relief have been investigated, there remains some uncertainty among orthodontists about which painkillers are most suitable and whether pre-emptive analgesia is beneficial. We conducted this Cochrane Review to assess and summarize the international evidence relating to the effectiveness of analgesics for preventing this unwanted side effect associated with orthodontic treatment. The objectives of this review are to determine:- the effectiveness of drug interventions for pain relief during orthodontic treatment; and- whether there is a difference in the analgesic effect provided by different types, forms and doses of analgesia taken during orthodontic treatment. Cochrane Oral Health's Information Specialist searched the following databases: the Cochrane Oral Health Trials Register (to 19 June 2017), the Cochrane Central Register of Controlled Trials (CENTRAL;the Cochrane Library 2016, Issue 7), MEDLINE Ovid (1946 to 19 June 2017), Embase Ovid (1980 to 19 June 2017) and CINAHL EBSCO (Cumulative Index to Nursing and Allied Health Literature; 1937 to 19 June 2017). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched on the 19 June 2017 for ongoing studies. We placed no restrictions on language or date of publication when searching the electronic databases. We included randomized controlled trials (RCTs) relating to pain control during orthodontic treatment. Pain could be measured on a visual analogue scale (VAS), numerical rating scale (NRS) or categorical scale. Two review authors independently screened the search results, agreed the studies to be included and extracted information from the included studies regarding methods, participants, interventions, outcomes, harms and results. We planned to resolve any discrepancies or disagreements through discussion. We used the Cochrane 'Risk of bias' tool to assess the risk of bias in the studies. We identified 32 relevant RCTs, which included 3110 participants aged 9 to 34 years, 2348 of whom we were able to include in our analyses. Seventeen of the studies had more than two arms. We were able to use data from 12 trials in meta-analyses that compared analgesics versus control (no treatment or a placebo); nine that compared non-steroidal anti-inflammatories (NSAIDs) versus paracetamol; and two that compared pre-emptive versus post-treatment ibuprofen for pain control following orthodontic treatment. One study provided data for the comparison of NSAIDs versus local anaesthetic.We found moderate-quality evidence that analgesics effectively reduced pain following orthodontic treatment when compared to no treatment or a placebo at 2 hours (mean difference (MD) -11.66 mm on a 0 to 100 mm VAS, 95% confidence interval (CI) -16.15 to -7.17; 10 studies, 685 participants), 6 hours (MD -24.27 mm on a VAS, 95% CI -31.44 to -17.11; 9 studies, 535 participants) and 24 hours (MD -21.19 mm on a VAS, 95% CI -28.31 to -14.06; 12 studies, 1012 participants).We did not find any evidence of a difference in efficacy between NSAID and paracetamol at 2, 6 or 24 hours (at 24 hours: MD -0.51, 95% CI -8.93 to 7.92; 9 studies, 734 participants; low-quality evidence).Very low-quality evidence suggested pre-emptive ibuprofen gave better pain relief at 2 hours than ibuprofen taken post treatment (MD -11.30, 95% CI -16.27 to -6.33; one study, 41 participants), however, the difference was no longer significant at 6 or 24 hours.A single study of 48 participants compared topical NSAIDs versus local anaesthetic and showed no evidence of a difference in the effectiveness of the interventions (very low-quality evidence).Use of rescue analgesia was poorly reported. The very low-quality evidence did not show evidence of a difference between participants taking ibuprofen and participants taking paracetamol (relative risk (RR) 1.5, 95% CI 0.6 to 3.6). Nor did we find evidence of a difference between groups in likelihood of requiring rescue analgesia when ibuprofen was taken pre-emptively compared to after treatment (RR 0.8, 95% CI 0.3 to 1.9).Adverse effects were identified in one study, with one participant developing a rash that required treatment with antihistamines. This was provisionally diagnosed as a hypersensitivity to paracetamol. Analgesics are more effective at reducing pain following orthodontic treatment than placebo or no treatment. Low-quality evidence did not show a difference in effectiveness between systemic NSAIDs compared with paracetamol, or topical NSAIDs compared with local anaesthetic. More high-quality research is needed to investigate these comparisons, and to evaluate pre-emptive versus post-treatment administration of analgesics.