Table 1.

Characteristics of included studies.

Study ID	Methods	Participants	Mean age (range), years	Interventions	Outcomes	Follow-up	Note
Bottini, 2012	Parallel design RCT where patients were randomly assigned to the two treatment groups	40 (17F and 23M)	22–80, mean (45–65)	Group 1: immediate implants were inserted in association with a deantigenated collagenated bone substitute of porcine origin and were maintained in place by the use of equine collagen sponge. Group 2: immediate implants were placed with no grafting material	The measurement of the buccolingual width, implant mobility, pain, suppuration, and peri-implant radiolucency	6-month	Italy
Cornelini, 2004	Parallel design RCT where patients were randomly assigned to treatment groups	20 (11F-9M)	21–60, mean 45	Group 1: immediate implants with Bio-Oss (bovine-derived porous bone mineral matrix) covered by Bio-Gide membrane (pure collagen membrane). Group 2: immediate implants with Bio-Gide membrane alone.	Proximal radiographic bone level, mucosal coverage of the implant, probing attachment level, oral hygiene status (plaque score) and soft tissue condition (mucositis score)	6-month	Country not stated
Daif, 2013	Parallel design RCT where patients were randomly divided into two equal groups	28 (18F and 10M)	22–48, mean 34	Group 1: immediate implants with pure-phase multiporous beta-TCP particles. Group 2: immediate implants with no filling materials	Bone density, implant failure, and infection	3 and 6 months after loading (implant loading three months after surgery)	Egypt
De Angelis, 2011	Multicenter parallel group RCT. Four computer-generated restricted random lists were created	80	—	Group 1: immediate implant with the bone substitute granules (Endobon®; Biomet 3i) and a resorbable collagen barrier (OsseoGuard®, Biomet 3i). Group 2: immediate implants with a resorbable collagen barrier (OsseoGuard®, Biomet 3i) alone	Implant failures, any biological or biomechanical complications, peri-implant marginal bone levels, esthetic evaluation of the vestibular and occlusal clinical pictures, and patient satisfaction	1 year after loading (implant loading after 3-4 months)	Italy
Gher, 1994	Factorial design RCT. The patients were randomly assigned to four treatment groups according to implant type and use or nonuse of DFDBA at the time of implant placement	36	—	Group 1: Titanium plasma-sprayed implant 3 without DFDBA. Group 2: Titanium plasma-sprayed implant with DFDBA. Group 3: Hydroxyapatite-coated implant 1 without DFDBA. Group 4: Hydroxyapatite-coated implant with DFDBA	Implant failure and crestal bone apposition measurements	6-month	USA
Prosper, 2003	Parallel design RCT. The patients were divided randomly into 2 groups	83	21–75	Group 1: immediate implants in combination with the use of synthetic hydroxyapatite and patients. Group 2: immediate implants combined with a bioabsorbable membrane based on polyglycolic and polylactic acid copolymers	Soft-tissue examination, implant mobility, bone loss, and implant success	Every 3 months for an overall period of 4 years	Italy