Aim: This in vitro study is designed to evaluate the effect of two thermal tempering protocols on the surface roughness of heat-pressed lithium silicates ceramics (LSCs).
Materials and methods: 40 LSCs discs (15×1mm) were heat-pressed and divided into 4 main groups according to type of LSCs with ten discs in each of the main groups; Gp (E): LSC (IPS e.max Press, Ivoclar Vivadent).Gp (L): LSC (GC initial LiSi Press, GC).Gp (C): Zr reinforced LSC (Celtra Press, Dentsply Sirona).Gp (A): Zr reinforced LSC (VITA Ambria, VITA Zahnfabrik). After heat pressing discs were finished and polished according to manufacturer instructions. Surface roughness of each specimen was measured using (SJ-210 surface roughness tester) for Ra(nm) parameter values and surfaces were further analyzed with AFM (ThermoMicroscope, Bruker, Santa Barbara, CA, USA). Discs of each group were subdivided equally according to thermal tempering protocol (n=5); T1 subgroup were subjected to temperature of 9%below pressing temperature, T2 subgroup were subjected to temperature of 5% below pressing temperature. Roughness measurements and AFM analysis were repeated. Data were analyzed statistically with two-way Anova tests.
Results:LSCs type had no statistically significant effect on mean Ra. Thermal Tempering also had no statistically significant effect on mean Ra. The interaction between the two variables had no statistically significant effect on mean Ra.
Conclusions: The surface roughness of LSCs after polishing are almost equal in values with no significant difference related to the type of ceramic, exposing such materials to the suggested tempering protocols have no significant effect on its surface roughness.