Study	Reason for exclusion
Alberti 1994	Controlled, but non‐randomised trial.
Colombo 1993	Duplicate publication (Lampertico 1994).
Fukui 1994	No untreated control group.
Genesca 1992	Duplicate publication (Viladomiu 1992).
Lee 1996	No untreated control group.
Ohnishi 1989	No untreated control group.
Ohnishi 1991	Controlled, but non‐randomised trial.
Omata 1994	Duplicate publication (Omata 1991).
Palmovic 1994	No untreated control group.
Takano 1994	No untreated control group.
Tassopoulos 1993	Controlled, but non‐randomised trial.
Vogel 1996	No untreated control group.