Effect of Coloring Pigments on the Properties of Dental Zirconia-A Systematic Review and Meta-Analysis

ObjectivesThe effect of pigmentation on color, aging behavior, and mechanical properties of zirconia is debated. The purpose of the paper is to conduct a systematic review and meta-analysis of the studies that evaluated the effect of coloring pigments on the properties of zirconia.Data SourcesA systematic electronic search was conducted using MEDLINE, Scopus, Cochrane Central, and EBSCO Host. A platform-specific search strategy was employed, using MeSH keywords and text words.Study SelectionThe inclusion criteria were in vitro experimental studies that synthesized coloring pigments and evaluated their effect on zirconia. Case reports, narrative reviews, and systematic reviews were excluded. Commercially available pre-shaded zirconia, coloring liquids, and staining or glazing systems were not considered. Two investigators independently evaluated the risk of bias using modified CONSORT. Meta-analysis employed a random-effects model and assessed heterogeneity with the I-square test and continuous data with the inverse variance test.ConclusionsTransitional metal oxides are used in pre-shaded blocks and rare earth metals in coloring liquids. These pigments can alter grain size and lattice parameters, increase porosity, reduce translucency, improve aging resistance, and affect zirconia's hardness, fracture toughness, and flexural strength. They demonstrated no effect on gingival fibroblast proliferation, indicating their cytocompatibility.