Yasmine EI Makawi And Nagwa Khattab,

Purpose: The Aim Of This Study Was To Evaluate The Effect Of Lithium Disilicate Endocrowns Compared To Prefabricated Zirconia Crown Used For Restoring Pulpotomized Primary Molars, On Their Fracture Resistance And To Compare The Loads To Failure These Different Ceramic Restorations With Previously Reported Posterior Occlusal Forces.

Materials and Methods: Twenty Mandibular Left Second Primary Molars Were Randomly Distributed Into Two Groups (n = 10 In Each Group) The Zirconia Crown (Nusmile Zr.) Group (Gl) And The Lithium Disilicate (IPS E.max Press) Endocrown Group (G2). In All Groups Pulpotomy Procedure Was Done Before Preparation Then Each Sample Were Prepared Based On Their Allocated Restoration, Both Zirconia Crown (Nusmile Zr.) And Endocrown (IPS E.max Press) Were Cemented By Dual-cure Resin Cement. All Samples Were Loaded To Failure By Means Of A Universal Testing Machine (Instron, USA), And Compressive Force Was Applied. The Data Were Analyzed Using One-way (ANOVA) And Tukey"s Post Hoc Significance Difference Tests. Differences Were Considered Significant At (p-c 0.05).

Results: Group Zirconia Crown (G1) Showed Significantly Higher Fracture Strength Than Group (G2) Lithium Disilicate Endocrown (p < 0.05). Conclusion: The Zirconia Crown Showed Higher Fracture Resistance Than Lithium Disilicate Endocrown. However, Both Tested Zirconia Crown And Lithium Disilicate Endocrown Withstood The Application Of Axial Occlusal Forces Greater Than The Reference Values For Posterior Occlusal Loads .