A 45-year-old man who clenches and grinds his teeth takes lisinopril for hypertension (BP 138/86 mmHg). For 3 weeks he had sharp pain on biting on his mandibular left first molar, which has a large MOD amalgam. For 2 days he has had spontaneous throbbing pain that wakes him at night. The tooth has cold pain that lingers for 40 seconds, is tender to percussion, and the periapical radiograph shows a normal periapex with a widened apical periodontal ligament space. A crack line runs from the mesial marginal ridge; probing depths are normal all round. After root-canal treatment, a full-coverage crown is planned for this heavy bruxist with limited interocclusal space. Which material is most resistant to fracture in thin sections?