1

2

Select the proper length and diameter of tube and screw.  Wax the primary crown, coping, implant abutment or bar.  Position the Tube into the wax pattern of the primary crown/coping/bar in a vertical position according to anatomical, functional and aesthetic principles. The sleeve should be completely surrounded by wax. A small groove can be cut around the junction between the wax and sleeve to prevent an inflow of alloy when casting (FIG 1-2). Remove any wax around the opening of the tube

Note: Check the occlusion with the countersunk collar and screw inserted. The head of the screw should not come into contact with the opposing bite. If required, the screw head can be shortened by max. 1 mm.

Casting to / soldering the Tube

3

Casting: Select the proper size investment fixation screw to retain the sleeve and protect the threads.  Oxidize the fixation screw (400 °C / 10 min.) before use.  Coat the threaded portion and part way up the shank with Liquid Colloidal Graphite. 

Thread the investment fixation screw into the tube, invest, and cast.  The tube melting range is 1400-1490ºC.   After devesting, carefully unscrew the fixation screw from the sleeve without bending it. If the fixation screw is frozen in the casting, warm sulfuric acid (or Strip-It) will dissolve the investment fixation screw after about 1 hour in a heated 30 % hydrochloric acid solution (HCL).

If flash is on threads, put thread cutter into socket key and gently clean the threads.

Soldering: The fixation screw is also used for fabricating the solder model. "Vent" the pocket hole to ensure the solder surrounds the tube completely and to prevent the solder flowing into the thread. This can be done by drilling a small hole or making a slit (Fig. 3).

Laser welding:  The sleeve can also be laser welded. Filler material of the same alloy as the primary crown material should be used to ensure a reliable weld. The laser seam should be completely sealed to prevent corrosion due to pitting.

4

5

Resin bonding: Allow a minimum of 0.3mm space for wax (metal) between the die and the waxing spacer.  Select the proper diameter and length waxing spacer and tube and screw (FIG 4 ).  Thread the fixation screw into the tube.  Lubricate the tube with either die lube or silicone.  Wax the primary unit around the tube (FIG 5 ).  Using the fixation screw as a handle, carefully remove the waxing spacer. 

6

7

Secondary unit

The secondary unit is fabricated after trimming and polishing the primary unit. This involves inserting the countersunk collar with the screw, which has already been shortened as required. The countersunk collar is integrated in the wax pattern. A small groove should be cut around the junction between the wax and countersunk collar to prevent molten alloy flowing into the ring when casting. Invest, cast and polish the unit. Note: If the countersunk collar has been properly invested without bubbles, it should be adequately retained in the investment.

Finish the secondary structure, and attach to the primary structure with the Hex screw.

The hex key is designed to ensure proper retention of the screws and safe handling intraorally. Note, retention of the screw on the hex key can be reduced while unscrewing. When the screw is almost completely undone, increase pressure to make sure it remains on the hex key. The hex key should also be secured with a cord in the drill hole provided. Cover the working area with a rubber dam to safeguard against aspiration.