Study	Reason for exclusion
Gaasemyr 1977	This trial examined a nylon, non‐absorbable suture material (supramid).
Hemsley 1997	Trial registration; it was not clear that the trial took place. We have carried out further searches to try to locate any publications from this study and have attempted to contact the author but have had no response.
Ketcham 1994	Not a randomised controlled trial. The methodological quality of the study was poor in that no scientific principles were applied to the randomisation process and therefore, results could be subject to bias.
Marques 2001	This study was reported in a brief abstract with no clear information on study methods. Results were not reported by randomisation group. We attempted to trace the authors for further information on study methods and results but had no response.
Tompkins 1972	Unable to obtain additional information such as method of randomisation, or results (which were not presented in a suitable form to include in this review).
Uslu 1992	In this 3‐arm trial there was a mixture of materials used within arms (e.g. catgut and silk) and different techniques were used in different arms.
Wikoff 1992	Abstract only. Unable to obtain additional information or data from trialists, therefore unable to include the study in this review.