How do I prevent lock-on?
After you have lined the crown shell and placed it back on the patient's preparation, ask the patient to bite down gently for occlusion. Allow the temporary crown to set in the patient's mouth for about 20-30 seconds, then remove it. Repeat the process of removing and replacing the crown while the resin is curing. This prevents lock-on as well as creates space for the cement.
What are the crown and bridge forms made of?
The shells are made of a high-impact polycarbonate polymer and can be lined with either a hybrid acrylic resin or auto-mix bisacryl resin.
Does the resin generate excessive heat?
No. This resin generates very little exotherm. The technique requires a small amount of material and the short contact time due to lifting the shell off and on during curing period reduces the chance for exothermic reaction.
How much shrinkage is there with this resin?
Very little, and unlike other methacrylates, this resin cures in very few minutes and results in minimal shrinkage or distortion. The thicker the acrylic mixture, the less shrinkage and shorter curing time.
Can I add to the DirectCrown® resin?
Yes, this is a significant advantage of the DirectCrown® System. Material will bond to itself so relining, adapting is a snap.
DirectCrown® Crown & Bridge Materials
How do I finish the crown?
An acrylic bur can be used to modify the crown shell and margins as well as adjust for occlusion. A rubber wheel can be used to polish the temporary to ensure a smooth surface formation. A light-cured varnish can be used for added short term surface treatment.
Can I use other resins to line the shell?
Yes, we recommend DirectCrown® resin because of the chemical bond that occurs between the two materials. Jet, Snap and Alike are methacrylates and will bond to the polymer shell.
Will auto-mix bisacryl materials work with the shells?
Yes. Because of the oxygen inhibiting layer associated with auto-mix materials, a surface treatment is required to create a mechanical surface for adherence. Sterngold and Sultan both offer a varnish that can be brushed on and light-cured to create the bond between auto-mix and crown shell. Clinicians have also created mechanical surface roughening with air-abrasion and have used small holes in the shell to provide sufficient retention.
Will light cure acrylic work?
Yes, it will cure through the shell.