CAD/CAM Block Selection Calculator

Required Length adds a fixed 0.5mm milling clearance to each side of Restoration M-D Length, and it responds only to that one dimension -- Restoration B-L Width never changes it, because the calculator checks each of the three restoration dimensions against a candidate block independently. Block Material first narrows which catalog of blocks is even considered -- Lithium Disilicate and Zirconia draw from the e.max CAD ceramic block list, while Composite/PMMA draws from a separate Telio CAD list that adds a long-span block (B55) not available in the ceramic line. Recommended Block is then found by walking that list from smallest to largest and picking the first one whose length, width, and height all fit the green-state blank -- the restoration with clearance for lithium disilicate and PMMA, or that same size scaled up roughly 25% for zirconia to account for sintering shrinkage (see below), and with the length dimension multiplied by Units to Nest for a simple end-to-end nesting model; if nothing on the list fits, it reports "Custom / oversize needed" rather than silently recommending an undersized block. Cost per Unit rises directly with Block Cost and falls as Units to Nest goes up, since the same block price gets divided across more restorations -- nesting more units from one block is what actually reduces the effective cost per restoration here. Material Utilization and Material Waste are unaffected by Block Cost entirely; they compare the green-state blank's own volume (already scaled for zirconia shrinkage) to the selected block's volume, independent of price. Zirconia (green state) applies a 1.25x linear ENLARGEMENT factor to Green State Length, Width, and Height to compensate for sintering shrinkage -- that is a different number from the material's linear SHRINKAGE percentage.

Enlargement and shrinkage are measured against different baselines: milling 25% larger (green-state / final = 1.25) corresponds to a linear shrinkage, during firing, of only 20.0% (1 minus 1/1.25), matching VITA's published ~20% linear shrinkage figures for zirconia. Don't read a competing product's published enlargement factor as a shrinkage percentage either -- Zirlux publishes its enlargement factor as "1.21 (21%)," where the 21% is also an enlargement percentage, not a shrinkage percentage; the true linear shrinkage at that enlargement factor is closer to 17.4%. Real published linear shrinkage for zirconia milling typically falls in roughly the 16-21% range depending on the specific material and manufacturer -- lithium disilicate and composite/PMMA blocks apply no such oversizing since they aren't sintered, and that same green-state size (identical to the clearance-adjusted restoration for those two materials) is what Recommended Block and Material Utilization are actually checked against. Material selection should also weigh flexural strength and restoration span, which this calculator does not compute directly: published approximate biaxial flexural strengths run roughly 140 MPa for feldspathic glass-ceramics like VITABLOCS Mark II, ~185 MPa for IPS Empress CAD, ~130 MPa pre-crystallized rising to ~530 MPa after crystallization for IPS e.max CAD (lithium disilicate), ~210 MPa rising to ~370 MPa after glazing for Celtra Duo, and roughly 850-1350 MPa for zirconia depending on generation (VITA YZ XT ~850 MPa, YZ ST ~1200 MPa, YZ T/HT ~1350 MPa). Materials below zirconia's strength are generally contraindicated for bridges of any span; lithium disilicate is the only glass-ceramic on this list with any bridge indication at all, and even then it's limited to 3-unit bridges with a second-premolar terminal abutment. Confirm material choice against your restoration's span and load requirements separately from the sizing math here.