Table 2B Summary of descriptive characteristics of included Randomized Clinical Trial Studies (n = 4)

Slot & al. 2014

RCT (1 year follow-up)

N = 66

Group A with 4 implants (n = 33) vs. group B with 6 implants (n = 33)

-Arch: maxilla and mandible for each patient;

-Distal extension: no but mesial extension : 8 mm;

-Material: titanium;

- Cross-sectional shape: egg-shaped bar;

-Width: 2.19 mm;

-Distance bar/mucosa: 2 mm

- Use of abutments: yes

-Other informations: milled bar; two bars; splinted bar but unsplinted between the medial implants;

-Peri-implant bone level (long cone paralleling technique)

-Plaque Index by Mombelli 1987

-Calculus index (0 or 1)

-Peri-implant inflammation by Löe and Sillness 1963

-Bleeding Index: Mombelli 1987

-Probing Pocket Depths: 4 sites

-Mean of bone loss in group A: 0.35 (SD: 0.31)

-Mean of bone loss in group B: 0.46 (SD: 0.34)

-Plaque Index: group A = 0; group B = 0

-Calculus Index: group A = 0; group B = 0

-Gingival Index: group A = 0; group B = 0

-Bleeding Index: group A = 0; group B = 1

-Probing depth in mm: group A = 4.8; group B = 4.4

-Implant losses in group A = 0

-Implant losses in group B = 1

Gibreel & al. 2017

RCT (1 year follow-up)

N = 60

-Group A : with clips (n = 30) vs. group B : resilient liner (n = 30)

-Arch: maxilla

-Distal extension: no;

-Material: titanium;

- Cross-sectional shape: round

-Width: no information;

-Distance bar/mucosa: no information;

-Use of abutments : yes

Other informations: two bars in the same jaw; gold clips or resilient soft liner; instant adjusted bar

- Modified Plaque Index by Mombelli 1987

-Modified Bleeding Index: Mombelli 1987

-Probing Pocket Depths: 4 sites

-Modified Plaque Index,

- > anterior implants: group A = 0.88(0.043); group B = 0.12(0.01)

-> Posterior implants: group A = 0.97(0.063); group B = 0.12(0.007)

-Modified Bleeding Index,

- > anterior implants: group A = 0.22(0.01); group B = 0.015(0.02)

-> Posterior implants: group A = 0.27(0.01); group B = 0.019(0.03)

-Probing Pocket Depths,

- > anterior implants: group A = 1.91(0.073); group B = 0.63(0.056)

-> Posterior implants: group A = 2.13(0.073); group B = 0.82(0.078)

-2 implant failures in GI.

Slot & al. 2019

RCT (1 year follow-up)

N = 66

Group A with 4 implants (n = 33) vs. group B with 6 implants (n = 33)

-Arch: maxilla and mandible for each patient;

-Distal extension: no but mesial extension : 8 mm;

-Material: titanium;

- Cross-section shape: egg-shaped bar;

-Width: 2.19 mm;

-Distance bar/mucosa: 2 mm

- Use of abutments: yes

-Other informations: milled bar; two bars; splinted bar but unsplinted between the medial implants;

-Peri-implant bone level (long cone paralleling technique)

-Plaque Index by Mombelli 1987

-Calculus index (0 or 1)

-Peri-implant inflammation by Löe and Sillness 1963

-Bleeding Index: Mombelli 1987

-Probing Pocket Depths: 4 sites

-Mean of bone loss

->group A: 0.58(SD: 0.51)

->group B: 0.60(SD: 0.58)

-Plaque Index:

-> group A, 0 = 62.1%, 1 = 20.7%, 2 = 17.2%, 3 = 0

->group B,

0 = 51.6%, 1 = 25.8%, 2 = 22.6%, 3 = 0

-Calculus Index:

-> group A, 0 = 96.6%, 1 = 3.4%

->group B,

0 = 96.8%, 1 = 3.2%

-Gingival index:

-> group A, 0 = 48.3%, 1 = 41.4%, 2 = 10.3%, 3 = 0

->group B,

0 = 54.8%, 1 = 41.9% 2 = 3.3%, 3 = 0

-Bleeding Index:

-> group A, 0 = 51.7%, 1 = 37.9%, 2 = 10.4%, 3 = 0

->group B,

0 = 38.7%, 1 = 41.9%, 2 = 19.4%, 3 = 0

-Probing depth in mm: group A = 4.3(1.0); group B = 4.2(0.8)

-Implant losses in group A = 0

-Implant losses in group B = 1

Ibrahim et al. 2022

RCT (1 year follow-up

N = 30

Group A with 4 vertical implants (n = 15)

Group B with 2 vertical anterior implants and 2 posterior implants tilted 30° distally (n = 15)

-Arch: mandible;

-Distal extension: 7 mm;

-Material: no information;

- Cross-sectional shape: Hader bar;

-Width: no information;

-Distance bar/mucosa: 2 mm

- Use of abutments: yes

-Other informations: resin clips

-Peri-implant bone level (CBCT)

-Plaque Index by Mombelli 1987

-Gingival Index by Mombelli 1987

-Probing Pocket Depths: 4 sites

For the anterior implants

-Peri-implant bone level:

For the anterior implants

-> group A = 0.50 mm

-> group B = 0.47 mm

For the posterior implants

-> group A = 0.90 mm

-> group B = 0.45 mm

-Plaque Index:

For the anterior implants

-> group A = 3

-> group B = 1

For the posterior implants

-> group A = 1

-> group B = 0

-Gingival Index:

For the anterior implants

-> group A = 0

-> group B = 0

For the posterior implants

-> group A = 0

-> group B = 1

-Probing Pocket Depths:

For the anterior implants

-> group A = 2.30 mm

-> group B = 1.80 mm

For the posterior implants

-> group A = 1.85 mm

-> group B = 1.56 mm