Unsplinted Attachments and Patient-Reported Outcome Measures (PROMs) in 2-Implant-Retained Mandibular Overdentures: A Systematic Review

Table 2

Excluded studies with reasons.

Sr. no.	Authors	Year	Reason for exclusion
1	Patil et al. [18]	2020	Only Locator attachments compared
2	Burns et al. [19]	2011	Compared directly with splinted attachments
3	Zygogiannis et al. [20]	2018	Compared directly with splinted attachments
4	Schincaglia et al. [21]	2016	No patient-related outcome
5	Scala et al. [22]	2012	Not involving 2-implant-retained overdentures
6	De Kok et al. [23]	2011	Compared directly with implant-supported fixed prosthesis
7	Akoglu et al. [24]	2011	Only ball attachments compared
8	Büttel et al. [25]	2012	Study type not RCT
9	Sun et al. [26]	2014	Not standardized attachments used
10	Ribeiro et al. [27]	2015	No patient-related outcome
11	Bryant et al. [28]	2014	Only ball attachments compared
12	Salman et al. [29]	2019	Only Locator attachments compared
13	Della Vecchia et al. [30]	2017	No patient-related outcome
14	Uçankale et al. [31]	2010	Compared directly with splinted attachments
15	Grandi et al. [32]	2012	Study type not RCT
16	Elsyad et al. [33]	2013	Compared directly with splinted attachments
17	Schuster et al. [34]	2020	Only Equator attachments compared
18	Giannakopoulos et al. [35]	2017	Only Locator attachments compared
19	Kappel et al. [36]	2016	Compared directly with splinted attachments
20	Geckili et al. [37]	2010	Only Locator attachments compared
21	Hasan et al. [38]	2016	Not involving 2-implant-retained overdentures
22	Pan et al. [39]	2010	Only ball attachments compared