tObjectives. Compare failure modes and fracture origins using fractography on recovered clin-ically fractured parts of indirect resin composite endocrowns and overlay restorations onendodontically treated teeth (ETT).Methods. Four endocrowns (3 molars, 1 premolar) and one overlay (molar) adhesively lutedon ETT were recovered after fracturing during function. The time in service ranged between4 and 48 months. The composite materials were (i) CAD/CAM LAVA Ultimate (N = 1), (ii)Premise Indirect (N = 2), and (iii) Colombus (N = 2). Fractography was performed by means ofdigital microscopy and SEM. Occlusal surfaces were checked for signs of fatigue degradationand contact wear. Cuspal plane angles were measured from profiles obtained from 3D digitalmicroscope images with respect to the horizontal plane of the occlusal central crown groove.Results. All five cases showed a wedge-opening mode I fracture, splitting the crown and toothin two parts through the crown's central groove. Classic brittle fracture features (arrest lines,twist and wake hackle) were easily identified on the fracture surfaces. Multiple origins werelocated along the central groove in conjunction with the presence of fatigue cracks. Contactwear surfaces showed pitting and cracking. Cuspal plane angles were around 30–35◦, excepta 50◦palatal cusp slope for the Lava Ultimate overlay.Significance. Fractography on clinical fractures of resin composites was enlightening. Occlusalsurface fatigue degradation from cyclic loading, mode I fracture from applied masticationforces on cuspal planes, and stress concentration within the crown's central groove, indicatelimitations of use of these materials for endocrowns in posterior teeth.