The clinical performance of the newly developed all-ceramic systems on the posterior teeth and the mechanism of failure are relatively unknown. Objectives: This study reports the results of prospective clinical evaluation and elemental analysis of three ceramic systems {non-layered, experimental hot-pressed ceramic (EC)1, Procera-AllCeram (PA)2 and metal ceramic (PFM)3} over 3-year period. Methods: A total of 90 posterior crowns were randomized into three groups equally in 48 patients and assessed over 3 years using modified USPHS criteria. Clinical images were taken after using staining dye to highlight surface changes. The data were analyzed using Kruskal-Wallis non-parametric statistical test and subsidiary follow up Mann-Whitney was performed with Bonferroni correction. Crowns that developed cracks were removed and the surfaces analyzed. Quantitative and qualitative element analysis was performed on contact and non-contact areas using SEM, back-scattered imaging and energy-dispersive spectroscopy. Results: USPHS evaluation showed visible roughness, wear and deformity in PA crowns at the region of occlusal contact after 36 months. A number of PA showed chipping of the layering material, whereas EC and PFM showed less changes clinically. One PA crown was rated Delta and removed due to fracture while one EC was rated Charlie and removed due to crack propagation after 36 months. Kruskal-Wallis showed a highly significant difference (p<0.0005) in alpha scores in between the three crown systems. Mann-Whitney showed all the groups were significantly different. Elemental analysis showed a difference in chemical composition between contact and non-contact areas in EC and PA with disappearance and change in the weight % of some elements after 3 years. Conclusions: EC showed a comparable clinical performance with PA crowns, but improved durability according to USPHS criteria. Chemical analysis suggests that there is preferential elemental loss in EC and changes in weight % for PA and EC.
1: Ivoclar-Vivadent, 2: NobelBiocare/Ducera, 3: Panadent/Ivoclar.