OBJECTIVEThis review aims to assess the relationship between initial archwire materials and pain at the initial stage of orthodontic treatment.

METHODSOn October 1, 2017, seven databases were searched electronically for studies oninitial archwire materials and pain at the initial stage of orthodontic treatment. Quality assessment was performed with bias risk assessment tools suggested by Cochrane's handbook. Data extraction of included studies was also carried out. Network Meta-
analysis was conducted using R 3.4.2 (with JAGS 4.3.0), GeMTC 0.14.3, and STATA 11.0.

RESULTSFive studies with 330 participants were included, comparing four different materials: multi-stranded stainless steel, conventional nickel-titanium, super-elastic nickel-titanium, and thermal heat-activated nickel-titanium. Two studies were at low risk of bias, one was at high risk of bias, and the remaining two were at unclear risk of bias. Network Meta-analysis results showed no statistical differences of pain among the four initial archwire materials at day 1 and day 7. However, the most painless material was most likely to be thermal heat-activated nickel-titanium on rank probability.

CONCLUSIONSOn statistical probability, thermal heat-activated nickel-titanium initial arch wires is most likely to cause the least pain at the initial stage of orthodontic treatment, compared with other materials.