| Methods |
10‐year follow‐up, randomised, parallel‐group study |
| Participants |
320 individuals responded to an advertisement in a local newspaper. After preliminary interview, and panoramic X‐ray, 18 partially dentate patients (12 women, 6 men; age range: 37 to 70 years) in need of 1 or more 2‐ to 5‐unit implant‐supported FDPs with satisfactory oral hygiene were randomised to 2 groups
Inclusion criteria:
Exclusion criteria:
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| Interventions |
2‐ to 5‐unit implant‐supported FDPs
Group 1: 9 patients with 12 FDPs of a zirconia‐toughened alumina, 35 units (InZ)
Group 2: 9 patients with 13 FDPs of a yttria‐stabilized tetragonal zirconia polycrystal material, 31 units (DZ)
Implant insertion:
Impressions and lab work:
full arch impressions were taken using a polyether impression material (Impregum, 3M ESPE) in disposable trays with open‐tray technique. Impressions of opposing arch were taken using alginate in rigid standard stainless steel trays (Svedia, Svedia Dental Industri), interocclusal registrations in centric relation were recorded with aluminium wax (Alminax, Associated Dental Product, Kemdent Works) preparable titanium abutments (Profile BiAbutment, Astra Tech) were prepared with a cervical shoulder depth of 1.2 mm and slightly rounded inner angles. The preparations allowed a minimum occlusal thickness of 1.7 mm and minimum buccal, approximal, and lingual/palatal thicknesses of 1.5 mm. The desired angle of convergence was 15 degrees. Preparations were performed using a parallelometer. All laboratory procedures were carried out at a dental laboratory (DP Nova) that had been authorized by the manufacturers of the material systems.Minimum acceptable diameter of the connection between crown and pontic was 3 mm for anterior and premolar replacements. In cases of molar replacement, the minimum diameter for the pontic connectors was 4 mm. For FDPs with no pontics minimum diameter between connecting abutments was 3 mm after visual and radiographic inspection and approval, frameworks were veneered with porcelain and fired in calibrated furnaces. Esprident Triceram (Dentaurum) veneering porcelain was used for DZ FDPs and Vitadur Alpha (Vita Zahnfabrik) for InZ
Try‐in and cementation:
the completed FDPs were fit, adjusted, and cemented permanently with zinc phosphate cement (De Trey zinc crown and bridge Fixodont Plus, Dentsply) in 1 sitting. The occlusion was checked using GHM Hanel single‐sided occlusion foils (Hanel GHM Medizinal) and, if necessary, adjusted using fine grit diamond burs (Two striper VF grit, Abrasive Technology) in a high speed turbine handpiece cooled with copious water spray and polished with rubber points (Identoflex, Identoflex) and a polishing paste (Temrex Diamond, Temrex)
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| Outcomes |
Modified California Dental Association quality assessment system (registrations of the surface, anatomical form of the restoration, occlusion and articulation, marginal integrity, pocket depth, bleeding on probing, and mobility)
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| Notes |
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| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Quote: "Patients were randomized to the two groups by drawing lots" |
| Allocation concealment (selection bias) |
Unclear risk |
Patients were divided into 2 groups after healing of implants |
| Blinding of participants and personnel (performance bias)
All outcomes |
Unclear risk |
No information |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Examinations were performed blindly and the examiners were not aware of which material system each patient had received |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
No dropouts |
| Selective reporting (reporting bias) |
High risk |
Follow‐up visits included PD, BOP and mobility assessment but data were not reported |
| Other bias |
Low risk |
None identified |
