The direct traumatising effect of the Stout-Obwegeser wire ligature splint on the marginal periodontium is minimal and need not be considered. The increase in depth of pockets, in the index of sulcus bleeding and in tooth mobility is due to poor oral hygiene. In 16 patients (orthodontic operation and jaw fractures) periodontal measurements were obtained on 369 teeth in 30 jaws before application of the splint, 1 and 6 weeks later and as 6 weeks after removal of the splint. All gingival indices determined were at first raised. The last measurements however showed, better values than those at the beginning of treatment. Inflammatory changes regressed near all teeth whether they were included in a ligature or not. This appears to prove that oral hygiene alone is decisive. The question whether the "curettage" effect of splint application has a therapeutic action is left open.