Objective: The aim of this study is to evaluate the effect of ceramic repressing on internal fit of two different pressable ceramic materials.
Materials and Methods: Two commercially available glass ceramic materials were used in this study; IPS E-max press (Ivoclar, vivadent) and Celtra press (Dentsply, Sirona). The two materials were used to fabricate veneer samples as which a total of twenty veneers were constructed .The samples for each material(n=10) were randomly divided into two equal groups; Group A: Pressed specimens (n=5) veneer shaped wax patterns were invested and heat-pressed according to the manufacturer's recommendations and Group B: Re-pressed specimens (n=5) the leftover material from 1st pressing was recovered and the buttons were adjusted to fabricate the specimens by repeated heat-pressing using the same procedures as for (A The internal gap distance between the veneers and the resin dies substance ware measured with the stereomicroscope at three preselected locations at 70× magnification.
Results: For IPS E.max or Celtra press; there was no statistically significant difference between mean values of press and repress conditions between tested groups. internal gab mean values was recorded for Celtra repress recorded (96.6±6.4) μm then E-max repress was recorded (92.6±7.6) μm , Celtra press recorded (91.8±2.8) μm , E-max press recorded (91.6±5.6) μm
Conclusions: The optimum properties for lithium disilicate Press ceramic materials are obtained with the first pressing. However, multiple heat repressing could affect the microstructure and mechanical properties but with no statistically significant difference on internal fit adaptation.