Impact of Recycling of Two Different Pressed Ceramic Crowns on the Marginal Adaptation and Fracture Resistance

Objective: the aim of this study was to impact of recycling of two different pressed ceramic crowns (IPS e.max Press & Celtra Press) on the marginal adaptation and fracture resistance. Materials and methods: Fifty pressable (50) ceramic crowns with various concentrations were constructed. They were divided into two groups (n=25 in each group) according to the ceramic material construction. For standardization of the preparation, a Computerized Numerical Control (CNC) Lathe-cut machine was used. all samples were subjected to thermocycling (Proto tech: Version 2.1a, Portland, Ore.USA). Then, universal testing machine (Instron Universal testing machine model 3345, England) was used for fracture resistance evaluationResults:Regarding marginal gap of IPS e.max Press subgroups before thermocycling, Subgroup (I) recorded the least marginal gap, while subgroup (V) recorded the largest marginal gap. Regarding marginal gap of Celtra-press subgroups before thermocycling. Subgroup (III) recorded the least marginal gap while subgroup (V) recorded the largest marginal gap. Fracture resistance values of IPS e.max Press Subgroups were greater than recorded for their respective Celtra-press subgroups. RConclusions: Recycling techniques showed better fracture resistance values than pressable techniques, The addition of zirconia to lithium disilicate ceramics did not improve the fracture resistance of celtra press compared to IPS e.max Press.Recycling of Pressable processing techniques showed better vertical marginal gap distance for both ceramic materials used. Thermocycling resulted in significant increase in the vertical marginal gap distance for both ceramic types.