Fig. 1

2D models of first mandibular molar tooth with roots and periodontium (bucco -lingual side view). Original contours developed from radiographic image of first mandibular molar tooth. a radiographic image of first mandibular molar tooth, the coordinate values at the red point were extracted. b endocrown with 2 mm occlusal clearance, (c) endocrown with 4 mm occlusal clearance. d post-core crown

Thick arrow: simulated 600 N vertical occlusal load. 1 → 2: distal root canal inner wall, 2 → 3 → 4: root outer surface. Endocrown geometrically reduced the rotation center of the crown restoration in comparison with the full crown