An in vivo and in vitro study on the force degradation and surface morphology of the orthodontic elastic ligatures

•Force degradation of orthodontic elastic ligatures in vivo and in vitro was tested.•Novel and sample in vivo elastic ligature processing method was adopted.•Force degradation of elastic ligature was greater in vivo than in air or artificial saliva.•Increased force degradation showed a more surface morphologic change in each brand.