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. 2017 Dec 20;2017(12):CD009606. doi: 10.1002/14651858.CD009606.pub2

Nicolaisen 2016.

Methods 3‐year follow‐up, single centre, parallel randomised trial
Participants 34 patients in need of replacement of a second premolar or first molar
A convenience sample was obtained from the clinic at the Department of Dentistry, Aarhus University, Denmark and by referral from private practitioners in the Aarhus area
Inclusion criteria:

  • moderate to large fillings in the teeth neighbouring the edentulous area

  • vertical dimensions at the treatment site allowing for a 2‐mm occlusal reduction, maintaining a 4‐mm preparation (in height) without risk of compromising the surrounding tissues


Exclusion criteria

  • general diseases

  • allergy to materials used in this study

  • malocclusion

  • manifest parafunctional habits (bruxism or clenching) or temporomandibular joint disorders

  • apical lesion at the abutment teeth (examined with periapical radiographs using paralleling technique), endodontic treatment of abutment teeth performed < 6 months prior to enrolment

  • insufficient oral hygiene

  • periodontally involved abutment teeth (bleeding on periodontal probing and probing pocket depth > 4 mm)

  • present caries activity or history of high caries incidence

  • present or prior xerostomia

  • major dental treatment (prosthodontic, endodontic, orthodontic, or implant treatment; or extractions) within the last 3 month comprehensive treatment need, patients with fewer than 20 teeth or removable denture
Interventions Group 1: test group (n = 17) all‐ceramic (AC) FDPs with a zirconia framework
Group 2: control group (n = 17) metal‐ceramic (MC) FDPs with a high‐noble metal framework
Tooth preparation:

  • AC‐FDPs 0.8 mm deep circumferential chamfer

  • MC‐FDPs 1 mm shoulder on facial aspect, 0.6 mm deep chamfer remaining circumference

  • both groups 2.0 mm to 2.5 mm occlusal tooth reduction with 120 degree occlusal cusp indentation. Axial convergence 15 degrees, supragingival finish line (when possible)


Impressions and lab work:

  • single step, 2‐phase impression with silicone (Extrude Wash and Heavy, Kerr) and customized tray (Novo Tray, Dansk Ædelmetal)

  • impressions poured with high‐strength dental stone (Nova Die Stone, BK Giulini)

  • metal frameworks cast with high noble gold‐platinum (Au‐Pt) alloy (BioPontoStar, BEGO), lost wax technique, veneered with VITA VM 13 ceramic (VITA Zahnfabrik)

  • stone dies of AC‐FDP preparations scanned with laboratory scanner (3Shape), zirconia frameworks milled (Medical Scan und Designcenter, BEGO) from presintered zirconia blocks (BeCe CAD Zirkon+, BEGO), veneered with VITA VM 9 (VITA Zahnfabrik)


Try‐in and cementation:

  • occlusal adjustment and corrections before the final glace firing

  • both groups cemented with resin‐enhanced glass ionomer cement (Ketac Cem Plus, 3M ESPE)


FDPs were examined at baseline, 6 months, 1, 2, and 3 years
Outcomes

  • Failure (loss of FDP)

  • Technical complications (ceramic veneer chipping fracture, marginal ditching or discolourations, loss of retention, framework fracture, or post/core fracture not leading to failure/replacement of FDP)

  • Biological complications (presence of plaque, pocket probing depth as measured to the nearest mm, bleeding on periodontal probing, marginal bone level on bite‐wings, post‐cementation pain, dental caries, apical periodontitis on periapical radiographs, and abutment or root fracture).

  • Modified California Dental Association (CDA) assessment system for surface, colour, anatomical form, marginal integrity (most severe score for each parameter recorded for the individual FDP)

  • Functional and aesthetic satisfaction changes in oral health‐related quality of life (OHRQoL) using the Oral Health Impact Profile (OHIP‐14) after insertion of FDPs
Notes  
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Unclear risk Not known. Quote: "The patients were randomly allocated..."
Allocation concealment (selection bias) Unclear risk Not known
Blinding of participants and personnel (performance bias) 
 All outcomes Unclear risk Not known
Blinding of outcome assessment (detection bias) 
 All outcomes High risk Quote: "The evaluations were performed by the operator and another clinician who had not been involved in the treatments"
Incomplete outcome data (attrition bias) 
 All outcomes Low risk No dropouts
Selective reporting (reporting bias) Low risk None known
Other bias Low risk None known