Preparation Guidelines General preparation guidelines for all ceramic restorations should be followed: (Fig 1. and Fig. 2) Preparation should follow the anatomy of the tooth, providing at least the minimum thickness required for the respective restoration. A 1.0 mm axial and occlusal reduction is considered ideal for full contour zirconia restorations. (Table 1) A definitive finish line (shoulder with rounded internal line angles or chamfer) is recommended. Feather edge preparations are acceptable. (Fig. 3) All sharp edges and line angles should be rounded. Ideal Chamfer Margins TABLE 1 Minimum Zirconia Thickness - Crowns Anterior Crowns Axial Incisal/Occlusal Connector Dimensions 0.5 mm 0.5 mm n/a Posterior Crowns Axial Incisal/Occlusal Connector Dimensions 0.5 mm 0.5 mm n/a Occlusal reduction 1.0 mm ideal 0.5 mm minimum Rounded internal line angles Taper between 4° and 8° Axial reduction 0.5 mm to 1.5 mm Reduction of ≥ 0.5 mm at gingival margin Minimum Zirconia Thickness - Bridges ≥ 4 units with Anterior 3-Unit max 2 connected pontics Axial Incisal/Occlusal Connector Dimensions 0.5 mm 0.7 mm 0.7 mm 1.0 mm 0.7 mm 1.0 mm 7 mm2 9 mm2 12 mm2 0.5 mm 0.7 mm 0.7 mm 1.0 mm 0.7 mm 1.0 mm 9 mm2 12 mm2 12 mm2 Cantilever with 1 pontic Posterior Axial Incisal/Occlusal Connector Dimensions Feather Edge Margin FIGURE 1 FIGURE 2 Chamfer/shoulder preparation or feather edge Rounded internal line angles Reduction of ≥ 0.5 mm at gingival margin Axial reduction 0.5 mm to 1.5 mm Incisal reduction 0.5 mm to 2.0 mm For More Information or to Prescribe Zirlux® Contact Your Zirlux® Certified Partner Today! Figure 3 Feather edge margin ≥ 0.5 mm gingival reduction