Standard CAD/CAM Milling and Layered Sintering Protocol of Zirconia Restorations
Jun 24, 2026
Leave a message
Zirconia restorations serve as universal all-ceramic material for anterior and posterior teeth. Digital milling and staged sintering determine flexural strength, translucency and dimensional stability, matching tetragonal and tetragonal-cubic composite zirconia blanks. Pre-sintered zirconia blank is the mainstream raw material, requiring two-stage thermal treatment: low-temperature bisque firing and high-temperature full densification after milling. Milling QC parameters: spindle speed stabilized at 28000–32000r/min, rough feed rate 0.8mm/s, finish feed 0.4mm/s with 0.08mm finishing allowance to eliminate internal microcracks from cutter extrusion. Multi-unit long bridges limit single segment within 3 units with intermediate support pillars; milled blanks cool naturally for 30min before demolding to avoid thermal cracking. Standard staged firing curve: bisque firing at 900℃ holding 30min to remove cutting coolant and organic binder; densification heating rate 5℃/min, peak 1450℃ soaking 120min, cooling rate controlled ≤8℃/min. Rapid cooling triggers detrimental surface martensitic transformation and strength degradation. High-translucency zirconia lowers peak temperature by 15–20℃ to retain light-permeable tetragonal crystals. Post-sinter surface treatment: 50μm alumina sandblasting at 0.2MPa exclusively on internal bonding surface; occlusal and labial surfaces avoid coarse blasting to preserve surface crystal integrity. For veneering porcelain, bonding agent pre-firing precedes layered dentin and incisal porcelain firing with secondary peak 100℃ lower than main sintering temperature to prevent substrate shrinkage distortion.
Send Inquiry