1. Recommended bone height with reference to the placed implant. The crest of the bone should rest somewhere within the trumpet flare of the implant neck for a "corking" effect to ward off soft tissue invasion.
2. Gingival height or thickness determines above bone crest in mm increments.
3. Implant silhouettes on the overlay match all the current implant sizes available both in diameter and length.  The numbers beneath each silhouette denote the top diameter (e.g 3.5mm) by length (e.g 11mm)
4. Constant numbers are derived from subtracting the length of the implant silhouette below bone height line from the pilot drill length from tip to collar stop.
   
   
   
   So then: 21mm - 10mm (that amount of the 11mm implant actually in bone in the ideal situation) = 11 the Constant number below the 3.5 X 11 implant silhouette.
5. Pilot Drill Guide Height Formula - The constant number for the silhouette implant chosen minus the gingival thickness equals the pilot drill guide cylinder height. The gingival thickness can most often be seen on an excellent P.A. film, so its thickness can be measured with the overlay using the 1mm increment gingival height dashed lines.  The ridge top bone sounding measurement should confirm this tissue thickness number.

It can be seen then that the Omni-TightT overlay is very important and extremely useful for the M/D aspect of the site.