Groenendijk 2004

Methods	Randomised, split‐mouth study. Patients and outcome assessors blind. No withdrawals.
Participants	Adults edentulous. 12 enrolled and results given for 12.
Interventions	2 groups. About 0.7 microlitre 0.2% chlorhexidine (Corsodyl) injected into the inner part of 3i Titamed fixture versus physiologic solution. Abutments immediately connected afterwards. Recall every week. Study duration: 6 weeks.
Outcomes	Microbiological count, gingival index by Loe and Silness, crevicular fluid flow rate, modified plaque index by Mombelli each week for 6 weeks. 6‐week data used.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Two implants per patient were randomly allocated to the test group and two to the control group". Written to the author: no reply.
Allocation concealment (selection bias)	Unclear risk	Written to the author: no reply.
Blinding (performance bias and detection bias) All outcomes	Low risk	"The clinical measurements were done by the prosthodontist. Neither the prosthodontist, the patient, nor the microbiologist was informed about which fixture was in the test or control group".
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up.
Selective reporting (reporting bias)	Unclear risk	No reply from author.
Other bias	Unclear risk	Unclear if there was any commercial funding.
Blinding of the patient?	Low risk	"Neither the prosthodontist, the patient, nor the microbiologist was informed about which fixture was in the test or control group".