Cannizzaro 2008a.

Methods	Trial Design: randomised, parallel group trial Location: Pavia,Italy (private practice) Number of centres: one Recruitment period: November 2004 to December 2005 Funding source: "No commercial support was received by the investigators"
Participants	Inclusion criteria: patients with edentulous mandibles allowing the placement of 2 implants at least 10 mm long and with a diameter of 3.7 mm. For implants to be immediately loaded, a primary implant stability of 48 Ncm had to be achieved at insertion Exclusion criteria: general contraindications to implant surgery, poor oral hygiene and motivation, substance abuse, pregnancy or lactation, uncontrolled diabetes, and any systemic diseases likely to compromise implant surgery, need for augmentation procedures, lack of opposite occluding dentition/prosthesis, psychiatric problems Age at baseline: immediate 62 (44‐72); early 61 (36‐80) Gender: M25/F35 Number randomised: 60 Number evaluated: 60 (after 1 year)
Interventions	Comparison: Immediate versus early loading Gp A (n = 30) Immediate loading: 2 implants, placed with a flapless procedure, supporting a bar and an overdenture immediately (same day) Gp B (n = 30) Early loading: 2 implants, placed with a flapless procedure, supporting a bar and an overdenture loaded early (6 weeks) Zimmer SwissPlus (Zimmer, Carlsbad, Ca, USA) non‐submerged solid titanium screws were used Duration of follow‐up: 1‐year
Outcomes	Prosthesis/implant failures, Osstell, patient satisfaction, complications 1‐year data used
Notes	Sample size calculation: authors suggest that a "sample size of 300 patients pre group may be needed to detect a difference in prosthesis or implant failures"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Reported in the article: "The operator coded the selected implants sites on the forms as site number 1 and site number 2...... A computer generated restricted randomization list was created by one of the authors who was not involved in patient recruitment or treatment, and had access to the random list stored in a password‐protected portable computer (Dr Marco Esposito)"
Allocation concealment (selection bias)	Low risk	Reported in the article: "The randomized codes were enclosed in sequentially numbered, identical, opaque, sealed envelopes. Envelopes were opened sequentially only after both implants were placed, therefore treatment allocation was concealed to the investigator in charge of enrolling and treating the patients included in the trial"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Reported in the article: "Complications were assessed by the treating dentist (Dr Gioacchino Cannizzaro) who was not blinded. Two independent dentists (Dr Michele Leone and Dr Cinzia Torchio) not aware of patient allocation evaluated implant stability and peri‐implant marginal bone levels changes on periapical radiographs, respectively"
Incomplete outcome data (attrition bias) All outcomes	Low risk	All data presented
Selective reporting (reporting bias)	Low risk	All outcomes were presented
Other bias	Low risk	None detected