Lang Jet Adjusters Characterizing & Staining Liquid, 10 mL · Grey

• Temporary Crown Material — A self-polymerising acrylic is made from pre-polymerised powder and liquid monomer. A composite provisional material uses bis-acryl resin, a hydrophobic material similar to bis-GMA, and comes auto-polymerised, dual-polymerised or light-polymerised.
• Temporary C&B Accessories — Liquids, kits, temporary cement, stain and mixing tips rather than the crown material alone.
• Mixing Tips — The tips a cartridge of provisional material is dispensed through, and the refills filed with them.

A review lists the drawbacks of the acrylic as high polymerisation shrinkage, release of residual monomer and ready staining. The same review notes that its contraction and the heat given off while it sets can interfere with the state of the mouth.

Materials containing no methyl methacrylate were introduced to reduce tissue toxicity and thermal irritation. In one laboratory study the self-curing acrylic gave off significantly more heat than the bis-acrylic composite, and took about twice as long to reach its peak temperature.

Span: in a study of provisional materials, fracture of a long span restoration under considerable chewing force was described as more likely than fracture of a short span. How long it stays in: a review notes that provisionals are usually worn for a short time, but complex rehabilitations can keep them in place for a prolonged period.

What it has to do while it is in: cover exposed dentine, prevent unwanted tooth movement, maintain function, allow oral hygiene and prevent gingival overgrowth. Provisional restorations also allow the appearance, the occlusal vertical dimension and the new occlusal scheme to be tested before the final work.