Iorio‐Siciliano 2020.

Study characteristics
Methods	Trial design: randomised, parallel‐group trial Location: Naples, Italy Number of centres: single centre, University of Naples Federico II, Naples, Italy Recruitment period: not stated Funding source: self‐funded
Participants	Inclusion criteria: patients aged ≥ 18 years, required extraction of maxillary or mandibular posterior single‐ or multi‐rooted tooth and committed to replacement with dental implant after 6 months; full mouth plaque and bleeding scores of less than 25%; presence of at least 2 mm of keratinized tissue; sound socket walls, signed consent form Exclusion criteria: any medical condition that contraindicate surgery; pregnant or lactating women; smoking; periodontally compromised; acute abscess, third molars Age at baseline: 38.9 ± 10.1 (test group A); 43.6 ± 14.2 (test group B); 38.4 ± 13.2 (control group) years Gender: M 22/F 18 Smokers: 0 Teeth extracted: single‐ and multi‐rooted posterior teeth Number randomised (participants/sites): 45/45 Number evaluated (participants/sites): 40/40
Interventions	Comparison: ARP (grafting material) versus ARP (grafting material) versus extraction alone Test group A: (n = 12 extraction sockets) bovine‐derived xenograft with 10% collagen (Bio‐Oss Collagen, Geistlich Biomaterials, Wolhusen, Switzerland) + resorbable collagen membrane (Bio‐Gide, Geistlich, Biomaterials, Wolhusen, Switzerland) Test group B: (n = 13 extraction sockets) bovine‐derived xenograft (Bio‐Oss, Geistlich Biomaterials, Wolhusen, Switzerland) + resorbable collagen membrane (Bio‐Gide, Geistlich, Biomaterials, Wolhusen, Switzerland) Control group: (n = 15 extraction sockets) extraction alone Surgical technique: flap, no primary closure Type of socket: 4‐wall socket Duration of follow‐up: 6 months
Outcomes	Width and height of alveolar ridge, thickness of buccal wall Method of assessment: periodontal probe, caliper
Notes	Sample size calculation: reported The sample size was calculated with a power of 80% and an alpha level of 0.05. The calculations were based on previous literature and assumed mean horizontal bone difference of 17.3 ± 16.4% between test and control groups. A total of 15 participants per group was required based on possible dropouts
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization procedure was performed by single examiner using a commercially available computer software package"
Allocation concealment (selection bias)	Low risk	Quote: "Allocation was performed after tooth or root extraction by opening an opaque envelope"
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "The principal investigator and co‐investigators were not masked"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Number and reasons for withdrawals were reported. It does not seem that the lost data had affected the results. 5 dropouts were recorded; 2 participants had medical reasons, 1 was pregnant, 1 moved to another town, and 1 was not compliant with the research protocol
Selective reporting (reporting bias)	Low risk	All outcomes appear to be reported
Other bias	Low risk	None detected