Fracture resistance of CAD/CAM endocrowns made from different materials in maxillary premolar interproximal defects

This in vitro study aims to compare the fracture resistance of three CAD/CAM materials used in endocrown restoration of interproximal defects in maxillary premolars.

45 maxillary premolars extracted as part of orthodontic treatment were included. Following standardized root canal treatment, all teeth were prepared into Mesial-Occlusal (MO) cavity types. The samples were then randomly divided into three groups: LD [repaired with lithium disilicate glass ceramics (IPS e.max CAD)], VE [treated with polymer-infiltrated ceramics (Vita Enamic)], and LU [repaired with resin-based nanoceramics (Lava Ultimate)]. Axial static loading was applied using a universal testing machine at 1 mm/min until fracture, and fracture resistance and failure modes were recorded.

Regarding Fracture Resistance Values (FRVs), the LD group exhibited significantly higher values than the other two groups, VE (P = 0.028) and LU (P = 0.005), which showed no significant difference (P = 0.778). On the other hand, regarding failure modes, the LD group had a higher prevalence of irreparable fractures compared to the other two groups, VE (P < 0.001) and LU (P < 0.001), which showed no significant difference.

Although lithium disilicate glass ceramics exhibited higher FRVs, they had a lower repair probability. In contrast, polymer-infiltrated ceramics and resin-based nanoceramics contributed to tooth structure preservation.

For maxillary premolars with interproximal defects following root canal treatment, resin ceramic composites are recommended for restoration to enhance abutment teeth protection.