Internal Hex Tube and Screw System

Tube & Screw

The hex screw is a high fusing precious alloy.  It  can be shortened as needed, as long as the hex profile is maintained.  The countersunk collar is a non-oxidizing, high fusing precious alloy.  The conical hex screw perfectly fits the countersunk collar, efficiently distributing forces and creating a hygienic seal on the occlusal surface.

The sleeve is also a high fusing precious alloy, and the fixation screw holds the sleeve in place during casting, reducing the risk of molten alloy flowing into it.

Always use the largest and longest screw for the space available.  The bonding technique for the tube is the most accurate method of incorporation.

Complete Tube and Screw Attachment.

Includes Tube, countersunk Collar, Fixation screw, and final Hex screw.

Four different options:

1.2mm Short   

1.2mm Long 

1.4mm Short    

1.4mm Long     

 

Fixation Screw

Thread the fixation screw into the tube prior to investing and casting to protect the threads from inflow of alloy.  Remove the screw after devesting.  Available in both 1.2mm and 1.4mm sizes. 

The fixation screw can be destroyed at temperatures above 1400 °C and by excessive overheating of the casting alloy.

Hex Screw

For fixing primary and secondary parts in the mouth.  Screw can only be reduced by a maximum of 1mm on the occlusal.

Countersunk Collar

For casting on in the secondary part with precious or semi-precious alloy.  Non-oxidizing, copper-free precious alloy.  Casting-on recommended. Can also be laser-welded or soldered.

Tube & Screw Thread Cutter (tap)

If the screw channel is tight, or has bubbles, use the proper size end thread cutter to calibrate, or refine, the screw rest.  Use with the socket key.

1.2mm size    

1.4mm sizes   

Tube & Screw Hex driver

Used to thread in the original screw and complete any necessary adjustments.

Tube & Screw Socket Key

Used to hold the thread cutter during adjustments to the tube's threads.

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 dentition. 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 / 752F for 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 (2552-2714ºF).   After devesting, carefully unscrew the fixation screw from the sleeve without bending it. If the fixation screw is frozen in the casting, fresh 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.

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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. 

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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.