Occlusal Relationship Assesment of Monolithic Zirconia FDPs
Condition: Tooth-loss
MeSH terms: Tooth Loss
Study type: Interventional

Summary: 
      To analyze in vivo occlusal accuracy and occlusal adjustment requirement, a cross-over
      clinical trial was designed. Two 3-unit tooth-supported posterior FDPs were planned to be
      made for each patient's single missing tooth gap, one with complete analog workflow (control
      group) and the other complete digital workflow (test group). The analog workflow aims for a
      porcelain fused to metal (PFM) FDP whereas the digital workflow aims for 3-unit monolithic Zr
      FDP. PFor half of the restorations, digital impression was planned to be taken first and to
      be followed by analog impression. As for the occlusal adjustment, in half of the study sites
      monolithic Zr FDPs were planned to be tried-in first, followed by metal-ceramic FDP and vice
      versa.

      One investigator (DK) was assigned to prepare the restoration sites and deliver the FDPs. All
      monolithic Zr and all metal-ceramic FDPs were designed and fabricated by the same experienced
      dental technician. One investigator (HL), that was not involved in the treatment intervention
      was assigned to make the 3D analysis of the volumetric occlusal adjustment amount.
    

Detailed description: 
      All teeth preparations will be carried out ensuring the minimum material thickness for
      monolithic FDPs (0.8-1 mm margin thickness, 1 mm occlusal thickness) by one experienced
      investigator (DK). To prevent any possible carry-over effect, the impression acquisition
      order will be randomized.

      The control group FDPs (metal-ceramic) will be fabricated with a complete analog workflow.
      Accordingly, a polyether dual-phase impression (Impregum Penta Soft Quick and Soft Quick, 3M)
      will be taken from the restoration arch and a Polyvinylsiloxane (PVS) impression material
      will be used for the impression of the antagonist arch. Face bow transfer (Whip Mix Face bow0
      will be done. Following the stone master model (Type IV dental rock, Fuji) obtention, the
      maxillary models will be mounted to a semi-adjustable articulator based on the face bow
      record and mandibular models will be then mounted with the aid of laterotrusive and MI
      records. The MI and laterotrusive records will be taken with a PVS bite registration
      material. The Cr-Ni frameworks will be fabricated with lost-wax technique (Brand?), manually
      layered with feldspathic veneering porcelain (Vita), and glazed by one experienced dental
      technician.

      The test group FDPs (high translucent monolithic Zr) (Aidite Multilayer 3D) will be
      fabricated by a complete/model-free digital workflow. The digital quadrant impressions of the
      preparation, antagonist as well as bite registration will be obtained by the use of an IOS
      (Trios 3, 3Shape). The files will be sent to a CAD software (Dental System, 3Shape) directly
      via the communication tool (3 Shape Communicate, 3Shape). Following CAD, the high translucent
      monolithic Zr 3-unit FDPs will be computer-aided manufactured (CORITEC 350i Loader,
      imes-icore GmbH). FDPs will be high-gloss polished, glazed, and sent to the dental clinic for
      the try-in session. Monolithic Zr design and manufacturing process will be completed by one
      dental technician that is highly experienced in CAD/CAM.

      Clinical occlusal adjustment:

      A standardized occlusal adjustment strategy will be adopted and executed by one investigator
      for both control and test group FDPs. In half of the restoration sites, monolithic Zr
      restorations will be the ones to have been tried first whereas in the other half
      metal-ceramic FDPs were the first. Initially, distal and mesial approximal contact areas,
      then the internal fit will be checked and adjusted to eliminate any interferences in order to
      ensure the optimal fitting of the restorations. For the occlusal adjustment amount
      calculation, the FDPs will be fixed on the prepared teeth provisionally and scanned by an IOS
      (Trios 3, 3Shape) to record the pre-adjustment FDP volume. The occlusal contacts and
      adjustment needs were assessed while still the restorations are fixed. The occlusal
      adjustment strategy will be as follows: Under normal occlusal forces, 40-micron articulation
      paper (Arti-Check micro-thin, Bausch, Cologne, Germany) will be used and followed by
      12-micron articulation foil (Shimstock-foil, Bausch, Cologne, Germany) under strong occlusal
      force. The FDPs' occlusal contact design will be ensured to hold the articulation foil under
      strong occlusal force. Thereafter, once ensuring the FDPs to remain fixed, intraoral digital
      quadrant impressions (Trios 3, 3 Shape) will be taken by the same investigator in order to
      record the post-adjustment volume of the FDPs. After chairside finishing and polishing of the
      adjustment areas, Monolithiz Zr FDPs will be adhesively luted by a composite cement as the
      definitive restoration.

      2.4. Quantitative analysis Both .stl files (pre-and-post adjustment) will be exported in
      order to process in an inspection software (Gom Inspect 2019, GOM GmbH, Braunschweig,
      Germany). The pre-and post-adjustment .stl files will be superimposed with the surface of
      restorations excluding occlusal adjusted area. After that, they will be sectioned from the
      same planes, mesial, distal, and 3mm apical to occlusal plane. The total volume of the
      sections that will be analyzed will be measured and the quantitative volume difference of the
      sectioned parts then was Calculated three-dimensionally (3Matic, Materialise NV, Leuven,
      Belgium). The total volumetric difference in mm3 between pre-and post-adjustment .stl files
      will be calculated for each 3-unit FDP
    

Intervention name(s): Monolithic FDPs: before adjustment; Monolithic FDPs: after adjustment; Metal fused porcelain FDPs: before adjustment; Metal fused porcelain FDPs: after adjustment
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Before the occlusal adjustment, Occlusal relationship recording of the 3-unit monolithic FDPs which was fabricated following the complete digital work-flow.; After the occlusal adjustment, Occlusal relationship recording of the 3-unit monolithic FDPs which was fabricated following the complete digital work-flow.; Before the occlusal adjustment, Occlusal relationship recording of the 3-unit metal fused porcelain FDPs which was fabricated following the complete conventional manufacturing procedure.; After the occlusal adjustment, digital occlusal relationship recording was done of the 3-unit metal fused porcelain FDPs which was fabricated following the complete conventional manufacturing procedure.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: A non-randomized one-control group study
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Occlusal Relationship; Complete Digital Work-flow; Fixed Partial Denture; Fixed Dental Prosthesis