Relationship between tooth type and material used in the construction of endocrowns and fracture force values: a systematic review.

OBJECTIVE: The aim of this study was to summarize the results of the endocrown (EC) studies that compared tooth preparation designs, tooth types, and ceramic material types in relation to fracture force values.

MATERIALS AND METHODS: A full literature search was conducted in Web of Science, PubMed/Medline, EMBASE, Scopus, Cochrane Library, Google Scholar, and ProQuest electronic databases. The following keywords: Endocrown [(molar(s)) or (premolar(s) or (posterior teeth)] and Ceramic materials as (Lithium disilicate glass-ceramic; Zirconia; Lava Ultimate) and (fracture strength) or (fatigue) were used. Articles were manually searched utilizing their reference lists. Study selection was not restricted or limited to the time of publication, type of tested tooth, ceramic material, and EC design.

RESULTS: A total of 34 laboratory studies published between 2008 and 2023 were included in this systemic review. Twelve studies were published in the last 3 years, the mandibular molar was examined by 14 studies, and premolars in both arches were investigated, followed by premolars in both arches. Lithium disilicate glass-ceramic (LDGC) was the most used material for EC testing, followed by LAVA Ultimate and zirconia materials. The EC design with a 2 mm extension inside the pulp (14 studies) was the most used. Fracture forces of maxillary molars or premolars were nearly equal and lower than those of mandibular molars. Differences among the fracture forces of the tested ceramic materials were marginal. EC with 2 mm deep inside the pulp showed the highest fracture force.

CONCLUSIONS: Mandibular EC molars showed the highest fracture forces, followed by maxillary premolars and molars. No differences among the EC materials in the 2- and 4-mm pulpal extension designs were found, which had higher fracture forces than other designs.