Assessment of fracture resistance, marginal and internal adaptation of endocrown using two different heat – press ceramic materials: an in-vitro study

Abstract

Background The aim of the study was evaluating of fracture resistance, marginal and internal adaptation of endocrowns using two different heat-press ceramic materials using the universal testing machine for fracture assessment and a scanning electron microscope (SEM) for marginal and internal adaptation assessment. Methods 40 extracted human mandibular first molars were collected for the study. The teeth were mounted in acrylic blocks using a dental surveyor. All teeth were endodontically treated and prepared for endocrown restorations. All samples were divided into two groups according to the material used (n = 20): group (a) for lithium disilicate glass-ceramic (IPS e.max press) and group (b) for zirconia-reinforced lithium silicate glass ceramic (VITA Ambria). Specimens of each group were subdivided into two subgroups (n = 10): subgroup (1) for assessment of fracture resistance and subgroup (2) for assessment of marginal and internal adaptation. Waxing up all teeth was done using CAD/CAM technology. Endocrowns were fabricated with the heat press method. Bonded endocrown specimens were stored at 37°C and 100% humidity for 24 h in an incubator before testing. The fracture resistance of samples was tested using a universal testing machine. Marginal adaptation and internal adaptation were assessed using a SEM. Quantities variables were expressed as mean and standard deviation using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test at (a = 0.05). Results The Vita Ambria mean values (2174.99 N±537.65) had more compressive strength than IPS e.max press mean values (1974.33 N±566.35). Considering the marginal adaptation test using SEM, there was no significant difference between both materials (P = 0.656) and there was also no significant difference between either of the materials (P = 0.855) after the internal adaptation test using SEM. Conclusion Vita Ambria endocrowns had higher compressive strength than IPS e.max press ceramic endocrowns. During the evaluation of marginal and internal adaptation, there was no significant difference between both materials and their values were within the clinically acceptable values.