“…However, two retrospective CS evaluated this comparison (Cordaro et al, 2005; Eliasson et al, 2007). The second PICO question (the efficacy of multi‐unit tooth‐supported fixed prostheses in patients with stage IV periodontitis) was studied in 18 investigations, including one RCT (Budtz‐Jorgensen & Isidor, 1987; Budtz‐Jørgensen & Isidor, 1990; Budtz‐Jorgensen et al, 1985; Isidor & Budtz‐Jorgensen, 1990), one CCT with split‐mouth design (Freilich et al, 1991), four prospective CS (Cortellini et al, 1999; Li et al, 2016; Nyman & Lindhe, 1979; Yi et al, 2001) and twelve retrospective CS (Baumer et al, 2011; Baumer et al, 2020; Brägger et al, 2011; Graetz et al, 2013; Guarnieri & Ippoliti, 2019; Heschl et al, 2013; Karlsson et al, 1995; Lundgren et al, 1975; Muller et al, 2013; Nyman et al, 1975; Quirynen et al, 1999; Yi et al, 1996; Yi, Ericsson, Carlsson, & Wennström, 1995). One investigation compared FPDs connecting teeth, implants, or teeth and implants with or without cantilevers (4 treatment arms for the purpose of this review) (Brägger et al, 2011), while another study included subjects receiving FPDs, removable partial dentures or no prosthetic treatment at all (for the purpose of the present review only data from the groups with FPDs and no prosthetic treatment were considered for the analysis) (Muller et al, 2013).…”