(a).
| Author | Year | Study type | Study type 2 | Follow-up mean (range) | Surgical intervention (surgical guide) | Implant system | Implant type | Abutments |
|---|---|---|---|---|---|---|---|---|
| Abbas H. et al. | 2017 | Prospective | Case series | 4 years (nr) | Flapless (nr) | Implasa Höchests | Two pieces | Ball attachments |
| Aunmeungtong W. et al. | 2016 | Prospective | rct | 1 year (nr) | Flapless (lab template) | pw plus | Two pieces | Equator |
| El-Sheikh AM et al. | 2012 | Prospective | Case series | 2 years (nr) | Flap (nr) | Straumann | Two pieces | Locator abutment |
| Jawad S. et al. | 2017 | Prospective | rct | 6 months (nr) | Flap (nr) | Astra | Two pieces | Ball attachments |
| Ma et al. | 2016 | Prospective | rct | 7.6 years (1-10 years) | Flap (nr) | Nobel/southern | Two pieces | Ball attachments/u shape bar |
| Marcello-Machado et al. | 2018 | Prospective | Cohort | 1 year (1 year) | Flap (nr) | Neodent | Two pieces | Equator |
| Morneburg | 2008 | Prospective | Cohort | 6 years (1-9 years) | Flapless (lab template) | Microplant, Komet Brasseler Group | Two pieces | Magnetic/o-ring |
| Müller F. et al. | 2015 | Prospective | rct | 5 years (3-6 years) | nr | Straumann | Two pieces | Locator abutment |
| Zweers et al. | 2013 | Retrospective | Cohort | 3 years (nr) | Flap (lab template) | Straumann | Two pieces | Ball/locator |