Implant-supported prostheses or abutments made of zirconia have been reported to provide a favorable response in the peri-implant tissues,
1
,2
with lower plaque adhesion,1
lower tissue inflammation,1
and better esthetics2
, 3
, 4
, 5
than titanium. The improved gingival outcome may be related to zirconia’s chemical composition because bacterial adhesion was reduced when zirconia was compared with titanium specimens with the same roughness, wettability, and topography.6
In addition, an adhesive protective barrier might be formed between zirconia and the gingiva,7
,8
helping to provide long-term stability of the peri-implant tissues.Polished zirconia without a porcelain layer, stain, or glaze seems to be the material that best interacts with gingival fibroblasts,
8
, 9
, 10
which may result in a transmucosal seal between the subgingival part of a zirconia abutment or prosthesis and mucosal tissue. Higher adhesion and proliferation of human gingival fibroblasts has been reported on zirconia and alumina surfaces without a porcelain layer 9
and accelerated human fibroblast viability on smooth zirconia surfaces.10
Although a consensus for the ideal roughness value of zirconia is lacking, it is believed that a roughness (Ra) of 0.2 μm results in less bacterial adhesion6
and that even smoother surfaces can promote higher fibroblast proliferation.9
,10
Clinical polishing protocols suggest that proper smoothness can be achieved with commercially available rubber discs and polishing pastes,11
regardless of the practitioner's experience level.12
Also, polishing conventional or translucent zirconia with diamond rubber polishers may not reduce the fracture resistance of these materials.13
- Vila-Nova T.E.L.
- Gurgel de Carvalho I.H.
- Moura D.M.D.
- Batista A.U.D.
- Zhang Y.
- Paskocimas C.A.
- et al.
Effect of finishing/polishing techniques and low temperature degradation on the surface topography, phase transformation and flexural strength of ultra-translucent ZrO(2) ceramic.
Dent Mater. 2020; 36: e126-e139
When a zirconia abutment is designed for porcelain layering or for a cement-retained crown, the finish margin determines the division between the subgingival portion of the prosthesis and the supragingival area,
14
facilitating the application of porcelain and glaze in the appropriate location. However, in monolithic screw-retained prostheses, it is quite difficult to characterize and glaze without applying the material to the subgingival area because of their low viscosity. Screw-retained monolithic zirconia protheses have become popular because of fewer technical complications than porcelain layered prostheses15
and fewer biological problems than cement-retained ones.16
The author is unaware of a description of a technique to prevent glaze or pigments from reaching the subgingival portion of monolithic zirconia prostheses. It is likely that to obtain a polished and nonglazed zirconia surface, a grinding and polishing process in the subgingival area is performed after conventional characterization and glazing firing cycles. However, grinding may reduce the material strength.
13
Therefore, this article describes a straightforward technique that ensures that the subgingival portion of a monolithic prosthesis in zirconia will not receive glaze or pigments.- Vila-Nova T.E.L.
- Gurgel de Carvalho I.H.
- Moura D.M.D.
- Batista A.U.D.
- Zhang Y.
- Paskocimas C.A.
- et al.
Effect of finishing/polishing techniques and low temperature degradation on the surface topography, phase transformation and flexural strength of ultra-translucent ZrO(2) ceramic.
Dent Mater. 2020; 36: e126-e139
Technique
- 1.Delimit the gingival margin in the monolithic zirconia prosthesis (Ceramill Zolid FX Multilayer; Amann Girrbach AG) (Fig. 1), which can be performed on the definitive cast.
![Figure thumbnail gr1]()
Figure 1Monolithic zirconia screw-retained implant-supported crown with delimited gingival margin. - 2.Below the line, apply a coat of firing support paste (IPS Object Fix; Ivoclar Vivadent AG). Adjust the paste layer with a water-moistened brush until the contour is adequate, leaving exposed only the part of the crown to be characterized (Fig. 2A).
![Figure thumbnail gr2]()
Figure 2A, Firing support paste covering subgingival area. B, Characterized and glazed crown after firing cycles. - 3.Characterize and glaze as usual, repeating firing cycles until the desired result is achieved (MiYO Liquid Ceramic Color; Jensen Dental) (Fig. 2B).
- 4.After the last glaze firing, remove the support paste. It is removed easily by hand and water. Note that the covered part has not received pigments or glaze (Fig. 3A).
![Figure thumbnail gr3]()
Figure 3A, After paste removal, note subgingival area without pigments or glaze. B, Nonglazed and noncharacterized polished subgingival zirconia after polishing with diamond-impregnated rubber discs. - 5.Polish the subgingival area with specific zirconia diamond-impregnated rubber polishing discs using light pressure and following the sequence and rotational speed recommended by the manufacturer (Diacera HP L26DCmf and Diacera HP L26DC; EVE Ernst Vetter). To achieve higher smoothness, use a polishing paste (Polish ZrO2; Renfert) (Fig. 3B).
References
- Effects of modified abutment characteristics on peri-implant soft tissue health: A systematic review and meta-analysis.Clin Oral Implants Res. 2018; 29: 118-129
- The effect of zirconia or titanium as abutment material on soft peri-implant tissues: A systematic review and meta-analysis.Clin Oral Implants Res. 2015; 26: 139-147
- A systematic review and meta-analysis of the influence of abutment material on peri-implant soft tissue color measured using spectrophotometry.Int J Prosthodont. 2020; 33: 39-47
- Influence of anodized titanium abutments on the esthetics of the peri-implant soft tissue: A clinical study.J Prosthet Dent. 2021; 125: 445-452
- Zirconia abutments in the anterior region: A systematic review of mechanical and esthetic outcomes.J Prosthet Dent. 2019; 121: 775-781.e1
- Adhesion of streptococci to titanium and zirconia.PLoS One. 2020; 15: e0234524
- Adhesion properties of human oral epithelial-derived cells to zirconia.Clin Implant Dent Relat Res. 2016; 18: 906-916
- Differential behavior of fibroblasts and epithelial cells on structured implant abutment materials: A comparison of materials and surface topographies.Clin Implant Dent Relat Res. 2015; 17: 1237-1249
- Influence of modifying and veneering the surface of ceramic abutments on cellular attachment and proliferation.Clin Oral Implants Res. 2008; 19: 1178-1187
- Surface structuring of zirconia to increase fibroblast viability.Dent Mater. 2020; 36: 779-786
- The effect of a polishing protocol on the surface roughness of zirconium oxide.Int J Prosthodont. 2020; 33: 217-223
- Polishing of monolithic zirconia crowns-results of different dental practitioner groups.Dent J (Basel). 2017; 5: 30
- Effect of finishing/polishing techniques and low temperature degradation on the surface topography, phase transformation and flexural strength of ultra-translucent ZrO(2) ceramic.Dent Mater. 2020; 36: e126-e139
- The novel design of zirconium oxide-based screw-retained restorations, maximizing exposure of zirconia to soft peri-implant tissues: clinical report after 3 years of follow-up.Int J Periodontics Restorative Dent. 2017; 37: 41-47
- Randomized controlled clinical trial to compare posterior implant-supported modified monolithic zirconia and metal-ceramic single crowns: one-year results.J Prosthodont. 2019; 28: 15-21
- Peri-implant diseases and biologic complications at implant-supported fixed dental prostheses in partially edentulous patients.J Prosthodont. 2020; 29: 429-435
Article info
Publication history
Published online: November 25, 2020
Identification
Copyright
© 2020 by the Editorial Council for the Journal of Prosthetic Dentistry.
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