12 February 2023

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What is the best material to perform the endocrown?

Simona Chirico

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Today, the endocrown is an increasingly widespread type of restoration in the clinical practice of the dentist. This type of indirect restoration aims to preserve as much as possible of the residual dental tissue of the endodontically treated teeth, which are often destroyed by the carious process that affected them. There are various types of materials used to perform this type of restoration. Among these we have: leucite, lithium disilicate, lithium silicate reinforced with zirconia, monolithic zirconia. But which of these has a better mechanical behavior?

Materials and methods

A study conducted by Nereu Roque Dartora and a team from University of Ribeirão Preto in Brazil aimed to answer this question. The study was published in The Journal of Prosthetic Dentistry in January 2021. 

Sixty mandibular human molars were endodontically treated, prepared for endocrowns and divided into four groups (n=15) according to the following various ceramic systems: leucite-based glass-ceramic (LC group), lithium disilicate-based glass-ceramic (LD group), glass- ceramic based on zirconia-reinforced lithium silicate (LSZ group) and monolithic zirconia (ZR group). 

After adhesive bonding, the specimens were subjected to thermomechanical loading and then to fracture resistance testing in a universal testing machine. The failure mode of the specimens was qualitatively evaluated. Three-dimensional FEA was performed to evaluate the stress distribution in each group. Data were analyzed by using a 1-way ANOVA and the Tukey HSD test (a=.05). 

Results

Statistically significant differences among the groups were observed (P<.05). The outcomes of the LC, LD and LSZ groups were similar but different from those of the ZR group. 

The LC and LD groups had a higher ratio of restorable failures, while LSZ and ZR had more nonrestorable failures. Fractographic analysis indicated a regular failure pattern in the ZR group and irregular failure patterns in the other groups. Three-dimensional FEA revealed similar values and stress pattern distributions among the groups. 

Conclusions

The mechanical performance of monolithic zirconia was better than that of the other ceramic endocrowns considered in this research; however, monolithic zirconia presented a higher rate of catastrophic tooth structure failure. 

Clinical significance

Even if monolithic zirconia has the best mechanical behavior, as demonstrated by the study, it is important to choose the material based on the patient's clinical conditions. For example, I would suggest observing the antagonist but also the relationship with the adjacent teeth, with the aim of always being as conservative as possible.

Nereu Roque Dartora et al. “Mechanical behavior of endocrowns fabricated with different CAD-CAM ceramic systems.” J Prosthet Dent. 2021 Jan.;125(1):117-125. doi: 10.1016/j.prosdent.2019.11.008. Epub 2020 Feb 10.