Table 2A Summary of descriptive characteristics of included Observational Studies (n = 1)

Heschl & al., 2011

Retrospective study (5 years follow-up)

39 patients with 4 implants each

Only one group, each subject with 4 implants

-Arch: mandible;

-Distal extension: max 12 mm;

-Material: no information;

-Cross-sectional shape : Dolder bar;

- Width: no information

- Distance bar/mucosa : no information

-Use of abutments : yes

-Other informations: splinted bar, gold copings

-Marginal bone loss (long cone paralleling technique),

- Plaque Index Mombelli 1987

-Bleeding Index Mombelli 1987

-Probing pocket depth

-Peri implantitis and mucositis Löe & Silness 1963

-Mean of bone loss = 1.44(0.78)

-Plaque Index = 0.5(0.5)

-Calculus Index = 0.5(0.3)

-Gingival Index = 0.7(0.4)

-Bleeding Index = 1.3(0.6)

-Probing depth in mm = 3.8(0.6)

-Implant fails = 1

-Implant losses = 1