Gallucci 2011.

Methods	2‐year follow‐up, randomised, parallel‐group study
Participants	20 patients with 1 missing tooth in the anterior maxilla (first bicuspid to first bicuspid) and presence of 2 intact adjacent teeth Inclusion criteria: age > 21 years absence of relevant medical conditions absence of periodontal disease availability for 24 months follow‐up 1 missing tooth in the anterior maxilla (first bicuspid to first bicuspid) presence of 2 intact adjacent teeth adequate native bone to achieve implant primary stability Exclusion criteria: heavy smokers (more than 10 cigarettes/ day) adjacent implants presence of periapical radiolucency at the adjacent teeth missing adjacent teeth
Interventions	2 different types of screw‐retained single implant crowns Group 1: 10 all ceramic single crowns Group 2: 10 PFM single crowns Implant insertion: all patients received single implants in the anterior maxilla (Standard Plus, Straumann Co., Basel, Switzerland) Provisionalization: during the healing phase, all patients wore a removable interim prosthesis after implant loading all patients received a fixed screw‐retained provisional prosthesis Impressions and lab work: final impressions were taken at the implant level for the metal‐free group a screw‐retained all ceramic crown was fabricated using a blank composed of 90% alumina with glass infiltration (synOcta, InCeram blank, Ø 9 mm, height 15 mm and synOcta abutment, height 2.5 mm, Straumann Co.). The ceramic block was reduced to the desired shape and dimension. In average, a 1.5 mm space was left for the ceramic veneering. All ceramic framework was glass infiltrated to reach its optimal mechanical strength. For the ceramic veneering, alumina ceramic was applied in a stratified fashion to mimic the volumetric composition of the natural tooth for the metal‐ceramic group, a screwed retained MC crown was fabricated using a cast‐on gold coping (synOcta gold coping crown, height 4.5 mm, Ceramicor and synOcta abutment, height 2.5 mm, Straumann Co.). Desired framework shape and dimensions were waxed‐up onto the cast‐on gold coping and invested in a casting mold. Framework was casted using a high gold content alloy for PFM restorations (ISO 9693 standard). Ceramic veneering was performed in an average thickness of 1.5 mm with feldspathic ceramic
Outcomes	Failure Complication (chipping) Periodontal/peri‐implant measurements Aesthetic evaluation through pink aesthetic score (PES) and white aesthetic score (WES) VAS questionnaire for aesthetics assessed by patient, subjective aesthetic evaluation on photos by panel of clinicians
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "All participants were randomly assigned to one the two treatment options. A random permuted block system was generated by a collaborator not involved in the study. Six permuted blocks containing three test and three control subjects were generated and included in 24 sealed envelopes. A copy of the randomization sequence was preserved for accuracy assessment at the end of the study. The permuted block randomization system ensured the uniformity of the patient allocation during the clinical trial by randomly distributing three participants to the test and three participants to the control group every six treated patients"
Allocation concealment (selection bias)	Low risk	Quote: "Upon patient's enrolment, a sealed envelope was assigned by order of inclusion in the study. In order to avoid bias during the prosthodontic treatment, the individually assigned sealed envelopes were only opened after final impression taking and were subsequently sent to the dental laboratory for fabrication of the implant crowns"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "For the objective assessment at baseline, the study design was double blinded because neither the investigators nor the patients were aware of the assigned group"
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "For the objective assessment at baseline, the study design was double blinded because neither the investigators nor the patients were aware of the assigned group. For the objective measurements at CI, 1Y, and 2Y, the study design was single‐blinded being only the participants unaware of the group they were allocated. For the subjective evaluation, the trial design was double blinded. Neither the patients nor external expert clinicians were informed about the results of the randomization"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Three dropouts were recorded. Two patients moved abroad before receiving the final crowns and one patient was unreachable after completing the 1Y"
Selective reporting (reporting bias)	Low risk	None identified
Other bias	Low risk	None identified