The Impact of Different Preparation Designs on Marginal Adaptation of Pressable Ceramics (An In-vitro Study)

Purpose: This study aimed to evaluate the impact of various preparation designs on marginal adaption of pressable ceramic crowns. Materials and Methods: Forty freshly extracted maxillary premolars were used. Premolars were prepared to receive crowns with two marginal designs. The samples were divided randomly into two equal groups based on the tested ceramic materials (n=20); Group E for IPS e-max press and Group C for Celtra press. Each group was subdivided into two subgroups according to the tested finish line (n = 10); Subgroups (EF) and (ES) representing deep chamfer and chisel finish line of E-max samples, respectively. Subgroups (CF) and (CS) representing deep chamfer and chisel finish line of Celtra samples, respectively. Using a stereomicroscope, each sample’s marginal gap was assessed microscopically before cementation. After Cementation, specimens were subjected to thermocycling to mimic intraoral conditions and then marginal gap was assessed microscopically. Results: Subgroup (ES) recorded the highest marginal gap mean (62.96±6.48) and subgroup (CF) recorded the lowest one (51.9±4.95). Gp (E) recoded higher marginal gap mean value (63.23± 5.38 µm) than Gp (C) (57.42± 5.07 µm). The chisel margin subgroup recoded a statistically significant higher marginal gap mean value (62.65± 5.7 µm) than the chamfer margin subgroup (57.99± 4.75 µm). Conclusion: Celtra press group (C) showed better marginal adaptation compared to IPS e-max press group (E) before/after cementation. Deep chamfer subgroups (EF) & (CF) showed better marginal adaptation compared to chisel finish line subgroups (ES) & (CS). The results were within the clinically accepted range (120 µm).