Long-term clinical performance of flapless implant surgery compared to the conventional approach with flap elevation: A systematic review and meta-analysis

Table 3 Quality assessment and risk of bias of the included non-randomised studies

Study	Coding Manual for Cohort Studies	Newcastle-Ottawa Scale
Cooper et al[28], 2014	Selection
	(1) Representativeness of the exposed cohort	*
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	*
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	*
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	*
	Total Scale	******** (8)
Jesch et al[30], 2018	Selection
	(1) Representativeness of the exposed cohort	*
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	-
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	-
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	-
	Total Scale	***** (5)
Maló et al[31], 2015	Selection
	(1) Representativeness of the exposed cohort	*
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	*
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	*
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	*
	Total Scale	******** (8)
Naeini et al[32], 2018	Selection
	(1) Representativeness of the exposed cohort	-
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	*
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	-
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	-
	Total Scale	***** (5)
Oliva et al[33], 2010	Selection
	(1) Representativeness of the exposed cohort	*
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	*
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	-
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	*
	Total Scale	******* (7)
Prati et al[34], 2016	Selection
	(1) Representativeness of the exposed cohort	-
	(2) Selection of the non-exposed cohort	*
	(3) Ascertainment of exposure	*
	(4) Demonstration that outcome of interest was not present at start of study	*
	Comparability
	(1) Comparability of cohorts on the basis of the design or analysis	-
	Outcome
	(1) Assessment of outcome	*
	(2) Was follow-up long enough for outcomes to occur	*
	(3) Adequacy of follow-up of cohorts	*
	Total Scale	****** (6)

The following coding instructions were applied for the Newcastle-Ottawa Scale (NOS), which are also available on the NOS website (http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp): SELECTION: (1) a: Truly representative of the average edentulous participants in need of implants in the community *; b: Somewhat representative of the average edentulous participants in need of implants in the community *; c: Selected group of users, e.g. nurses, volunteers; d: No description of the derivation of the cohort; (2) a: Drawn from the same community as the exposed cohort *; b: Drawn from a different source; c: No description of the derivation of the non-exposed cohort; (3) a: Secure record (e.g. surgical records) *; b: Structured interview *; c: Written self-report; d: no description; (4) a: Yes*; b: No. COMPARABILITY: (1) a: Study controls for the most important factor *; b: Study controls for any additional factor *. OUTCOME: (1) a: Independent blind assessment *; b: Record linkage *; c: Self-report; d: No description; (2) a: Yes (≥ three-year follow-up period for outcome of interest) *; b: No; (3) a: Complete follow-up, i.e., all subjects accounted for *; b: Subjects lost to follow-up unlikely to introduce bias, i.e., follow-up rate ≥ 80%, or description provided of those lost *; c: Follow-up rate < 80% and no description of those lost; d: No statement. Note: A study can be awarded a maximum of one star for each numbered item within the SELECTION and OUTCOME domains. A maximum of two stars can be allotted for the COMPARABILITY domain.