Evaluation Of Zirconia Crowns Restoring Endodontically Treated Posterior Teeth With Two Finish Line Designs And Occlusal Reduction Schemes
Condition: Gingival Inflammation
MeSH terms: Gingivitis; Inflammation
Study type: Interventional

Summary: 
      The aim of this study is to evaluate the clinical performance of two finish line designs
      (feather edge and rounded shoulder) in relation with two occlusal designs (flat and planar)
      in endodontically treated teeth restored with zirconia crowns.
    

Detailed description: 
      Several studies have been investigating the effect of preparation design and its relation to
      the marginal adaptation. Habib et al 2014 compared the accuracy of marginal and internal
      adaptation of zirconia copings fabricated on anatomic (A), semi-anatomic (SA) and
      non-anatomic (NA) occlusal surface preparations. The internal & marginal fit were measured
      under electron microscope at 9 standardized areas .The anatomical occlusal preparation had
      better marginal and internal adaptation of Zr copings. Lima et al 2018 studied the influence
      of two different occlusal preparation designs on the marginal adaptation of CAD-CAM onlay
      restorations. The conventional anatomical occlusal preparation with a 1.2-mm modified
      shoulder finish line extending on the buccal surface and modified preparation flat cuspal
      reduction without shoulder finish line. The results showed that the conventional anatomical
      occlusal preparation had significantly better marginal adaptation than that of the flat
      cuspal preparation. Succeeding these studies, it was of interest to investigate whether or
      not the occlusal scheme could influence the marginal accuracy of the CAD/CAM crowns
      fabricated with Zirconia ceramic material.

      Studies correlating between the finish line design and occlusal scheme in literature are
      scarce, with little evidence regarding their effect on precision fit properties of
      restorations. Abdullah et al 2017 evaluated the effect of using different finishing line
      designs with different occlusal surface reduction schemes on the vertical marginal fit of
      full contour CAD/CAM zirconia crown restorations. They found a direct correlation between
      both the finish line geometry and the occlusal design. In recent literature, the use of
      feather edge finish line with all ceramic restorations is a point of conflict. Fuzzi et al
      2017 studied the nanoleakage and internal adaptations of lithium disilicate and zirconia
      crowns with featheredge finish lines. They recommended only zirconia with this finish line
      configuration due to its high fracture resistance when used in thin sections. Thus, the
      current study was conducted to examine this finish line effect on the marginal precision fit.
      Our hypothesis is there will be no difference in the clinical performance between the flat
      occlusal scheme with feather edge or rounded shoulder finish line and the planar occlusal
      scheme with rounded shoulder finish line configuration.

      The rationale for carrying out the trial:

      The influence of different tooth preparation designs can affect the success of the full
      coverage restorations. Still, there is no available research dealing with the effect of
      finishing line designs in combination with different occlusal reduction schemes on the
      marginal fit of full contour zirconia crowns.
    

Intervention name(s): Abutment with flat occlusal reduction with feather edge finish
Intervention type(s): Other
Intervention description(s): Non vital teeth require a full coverage restoration to withstand the functional stresses and prevent any further destruction of tooth/crown complex. The zirconia all-ceramic crowns yield a high flexure strength and are used as an esthetic alternative to ceramo-metallic crowns. Several studies linked the effect of preparation designs to the survival of the restoration. Others, studied the effect of the finish line geometries as deep chamfer and shoulder on the marginal integrity of restorations. The feather edge finish line is used with zirconia crowns with limited data regarding its success. However, there is no presented research dealing with the effect of finishing line designs in combination with different occlusal reduction schemes on the marginal fit of full contour zirconia crowns.
Other intervention name(s): Experimental: Abutment with flat occlusal reduction with shoulder finish line
Intervention MeSH terms: Salicylic Acid
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Zirconia,; occlusal scheme,; endodontically treated teeth,; finishline designs.