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

Table 1 Search strategy of the current systematic review

Search strategy
1	“Dental Implantation”[Mesh] OR ((dent* OR oral* OR mouth* OR stomatology*) AND implant*)
2	flap*
3	“Randomized Controlled Trial”[Mesh] OR “Prospective Studies”[Mesh] OR “Retrospective Studies”[Mesh] OR random* OR control* OR prospective OR retrospective
4	1 AND 2 AND 3

Table 2 Characteristics of the included studies

Ref.	Study design	Participants			Intervention						Outcomes				Follow-up	Loss (%)a
		Number of patients	Mean (range) age	Gender	Number of implants	Implant type, system and size	Implant location	Guided or free-hand	Tools for flapless surgery	Prostheses	Implant survival rate (%)	Marginal bone loss (mean ± SD, mm)	Complication rate (%)	Other measures
Bömicke et al[26], 2017	RCT	38 (F: 19; C: 19)	53 (21-70)	Female: 22; Male: 16	38 (F: 19; C: 19)	One-piece (NobelDirect Groovy, Nobel Biocare) and two-piece (NobelReplace Tapered Groovy, Nobel Biocare), Ø 4.3-5.0 × 10.0 mm	Posterior mandible	Guided	Punch	Single-crown	F: 95%; C: 100%	F: 1.34 ± 1.19; C: 0.67±0.37	F: 32%; C: 31%	Prosthesis failure; PPD; PI; GI	3 yr	3 (8%)
Cannizzaro et al[27], 2008	RCT	40 (F: 20; C: 20)	39 (18-64)	Female: 21; Male: 19	108 (F: 52; C: 56)	Two-piece (Tapered SwissPlus, Zimmer Dental), Ø 3.7-4.8 × 10.0-14.0 mm	Maxilla and mandible	Guided	Drill	Single-crown	F: 100%; C: 100%	NR	F: 19%; C: 16%	Prosthesis failure; postoperative oedema and pain; analgesic consumption; implant stability quotient	3 yr	0 (0%)
Cooper et al[28], 2014	PC	113 (F: 68; C: 45)	43	Female: 66; Male: 47	113 (F: 68; C: 45)	Two-piece (OsseoSpeed, Dentsply Implants), Ø 3.5-5.0 × 11.0-17.0 mm	Maxilla except the molars	NR	NR	Single-crown	NR	NR	NR	Mucosal zenith position	5 yr	19 (17%)
Froum et al[29], 2017b	RCT	60 (F: 30; C: 30)	NAb	Female: 35; Male: 25	60 (F: 30; C: 30)	One-piece (NobelDirect, Nobel Biocare), Ø 4.3-5.0 × 10+ mm	Maxilla and mandible	Guided	Punch	Single-crown	F: 100%; C: 100%	F: 0.36 ± 0.63; C: 0.23 ± 0.95	NAc	PPD; BoP; interproximal papilla levels	8.6 yr	32 (53%)
Jesch et al[30], 2018	RC	7783	NR	NR	18945(F: 17517; C: 1428)	Two-piece (ANKYLOS, Dentsply Implants), Ø 3.5+ × ? mm	Maxilla and mandible	NR	Punch	Implant-support prostheses	F: 93%; C: 92%	NR	NR	None	10 yr	7018 (90%)
Maló et al[31], 2015	PC	41 (F: 20; C: 21)	46 (19-79)	Female: 22; Male: 19	72 (F: 32; C: 40)	Two-piece (NobelSpeedy Groovy, Nobel Biocare), Ø 4.0 × 10.0-15.0 mm	Maxilla and mandible	Free-hand	Drill	Single-crown or fixed partial prostheses	F: 97%; C: 100%	F: 1.60 ± 1.22; C: 1.14 ± 0.49	F: 29%; C: 11%	None	3 yr	8 (20%)
Naeini et al[32], 2018d	PC	49	53 (20-79)	Female: 27; Male: 22	53 (F: 28; C: 25)	Two-piece (Brånemark system, Nobel Biocare), Ø 3.3-5.0 × 7.0-18.0 mm	Maxilla and mandible	Free-hand	Drill	Single-crown	F: 100%; C: 100%	F: -0.89 ± 0.96; C: 0.49 ± 1.12	F: 5 (22); C: 4 (15)	PI; BI; PPD	6-9 yr	13 (27%)
Oliva et al[33], 2010	PC	378	48 (19-80)	Female: 227; Male: 151	831 (F: 323; C: 508)	One-piece (CeraRoot type 11, 12, 14, 16, and 21, Oral Iceberg), Ø 3.5-4.8 × ? mm	Maxilla and mandible	Guided	NR	Implant-support prostheses	F: 99%; C: 93%	NR	NR	None	3.4 yr	0 (0%)
Pisoni et al[4], 2016	RCT	45	61	Female: 6; Male:39	76 (F: 42; C: 34)	Two-piece (SLA standard, Straumann), Ø 4.1 × ? mm	Posterior maxilla and mandible	Guided	Punch	Implant-support prostheses	F: 100%; C: 100%	F: 0.20 ± 0.76; C: 0.17 ± 0.94	NR	None	3 yr	5 (11%)
Prati et al[34], 2016	PC	60	56 (25-72)	Female: 26; Male:34	132 (F: 66; C: 66)	Two-piece (PrimaConnex, Keystone Dental), Ø 3.5-5.0 × ? mm	Maxilla and mandible	Free-hand	Drill	Single-crown	F: 97%; C: 98%	F: 1.22 ± 0.87; C: 1.23 ± 0.88	F: 0%; C: 0%	PI; SBI; BoP; Microtopographic observations	3 yr	0 (0%)

^aThe loss to follow-up was reported at the patient level;

^bThe age range at baseline was not available in this study; however, the patients after an 8.5-year follow-up had a mean age of 56.8 (range 37-75) years;

^cThe exact number of complications in each study group (i.e., flapless and conventional groups) was not available in this study, and the overall number of complications was reported to be 16 cases of biological complications and 11 cases of technical complications;

^dThe articles reported the long-term clinical performance of participants from a previously published clinical study with a short (e.g., one-year) follow-up; thus, some baseline information was extracted from the previous paper. SD: Standard deviation; F: Flapless (intervention) group; C: Conventional (comparison) group; NR: Not reported; NA: Not available; RCT: Randomised controlled trial; PC: Prospective cohort study; RC: Retrospective cohort study; PPD: Pocket probing depth; PI: Plaque Index; GI: Gingiva Index; BoP: Bleeding on probing; BI: Bleeding Index; SBI: Sulcus Bleeding Index.

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.