| Methods |
3‐year follow‐up, multicentre, parallel, double‐blind randomised controlled trial |
| Participants |
40 patients in need of 1 maxillary or mandibular 3‐unit FDP in second premolar or molar area recruited and treated at 2 separate centres at the University of Zurich, Switzerland
Inclusion criteria:
good general health periodontally healthy (plaque indices and BOP below 20% previously to treatment) no signs or symptoms of bruxing and/or clenching abutment teeth in need of reconstruction
Exclusion criteria:
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| Interventions |
Group 1 (test group): 20 patients received a zirconia–ceramic FDP with pressed veneering ceramic
Group 2 (control group): 20 patients received a FDP with conventionally layered veneering ceramic
Tooth preparation:
abutment teeth were prepared according to the guidelines for all‐ceramic FDPs. After preparation vital teeth were treated with a dentine adhesive system (Syntac Classic, Ivoclar Vivadent AG, Schaan, Liechtenstein)
Impressions and lab work:
double‐mix technique with A‐silicone impression material (President, Coltène Whaledent, Altstätten, Switzerland/Honigum, DMG, Hamburg, Germany) impressions were poured with scan stone (Camtech‐Roc, Picodent, Witterfürth, Germany) casts scanned using CAD/CAM scanner (inEOS Scanner, Sirona, Bensheim, Germany) frameworks were designed by software (Cerec V2.6 R2005 Sirona, Bensheim, Germany) milled out of Y‐TZP partially sintered zirconia ceramic blanks (IPS e.max ZirCAD, Ivoclar Vivadent AG, Schaan, Liechtenstein) with chair‐side milling unit of the CAD/CAM system (inLab milling unit, Sirona, Bensheim, Germany), after milling frameworks were sintered to full density in a high‐temperature furnace (Nabertherm LHT02/16, Lilienthal, Germany) test group received pressed veneering ceramic (IPS e.max ZirPress, Ivoclar Vivadent AG, Schaan, Liechtenstein) control group received conventionally layered veneering ceramic (IPS e.max Ceram Margin, IPS e.max Ceram Dentin and Enamel, Ivoclar Vivadent AG, Schaan, Liechtenstein)
Try‐in and cementation:
frameworks were checked prior to veneering FDPs were adhesively cemented with resin cement (Panavia 21 TC, Kuraray, Japan) after cementation occlusion was adjusted and reshaped surfaces were polished with ceramic polishers (Komet nos. 9425, 9426, 9547, Brassele)
All FDPs were evaluated at baseline, at 6 months and at 1 and 3 years of clinical service |
| Outcomes |
Failure Technical complications assessed using modified United States Public Health Services (USPHS) criteria Biological complications analyzed at abutment teeth and analogous non‐restored teeth (probing pocket depth, plaque control record, bleeding on probing, tooth vitality (CO2)) Patient satisfaction with the aesthetic outcome and the functionality of their FDP (yes/no) |
| Notes |
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| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Quote: "Patients were randomly assigned to the treatment modality and the respective clinic by means of a random list with even and uneven numbers" |
| Allocation concealment (selection bias) |
Unclear risk |
No information available |
| Blinding of participants and personnel (performance bias)
All outcomes |
Unclear risk |
No information available concerning participants blinding |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Quote: "In order to avoid bias the FDPs were examined by two clinicians who were not involved in the reconstructive treatment" |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Quote: "Four patients (2 test and 2 control) were not available for the 3‐year examination. They did show up for the 1‐year recall and later moved away without giving notice" |
| Selective reporting (reporting bias) |
Low risk |
None known |
| Other bias |
Low risk |
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