Influence of material thickness and material type on the translucency and opalescence of lithia-based ceramics: An in vitro study

Background: By incorporating zirconia into the glass matrix, zirconia-reinforced lithium silicate (ZLS) ceramics combine the advantageous properties of zirconia and lithium disilicate (LDS). Previous studies have reported inconsistent results regarding lithia-based ceramics. Both material type and thickness may affect the opalescence and translucency of these ceramics.Aim: To evaluate the impact of material type and thickness on the relative translucency parameter (RTP) and opalescence parameter (OP) of lithia-based restorative ceramic materials.Materials and Methods: Specimens with thicknesses of 0.8 mm, 1.0 mm, and 1.2 mm (n = 10 per group) were prepared from IPS e.max CAD (EMX), Vita Suprinity PC (VS), and Celtra Duo (CD). After surface polishing, optical properties, including RTP and OP, were evaluated. Data were analyzed using two-way ANOVA (α = .05).Results: At a thickness of 0.8 mm, the EMX and VS groups showed significantly higher mean RTP values than the CD group (p < .001). At thicknesses of 1.0 mm and 1.2 mm, the EMX group demonstrated significantly higher mean RTP values than the VS and CD groups (p < .05). Significant differences in OP were observed among the groups at all thicknesses (p < .05). The VS group exhibited significantly higher mean OP values than the EMX and CD groups (p < .001), while the CD group showed significantly higher mean OP values than the EMX group (p < .05).Conclusion: Increasing material thickness resulted in reduced RTP values. Only the VS group exhibited a significant thickness-related change in OP values. Both RTP and OP were significantly influenced by material type.Keywords: computer-aided design; ceramics; lithium; dental materials; esthetic dentistryIntroduction