Processing of phosphate cement
Phosphate cement is mixed with a metallic cement spatula on a cool surface, such as a glass plate. The mixing temperature should be room temperature. The powder is mixed into the liquid.
The consistency for placing crowns and bridges should be creamy, whereas a firmer consistency is required for underfilling. For an underfilling, the phosphate cement is inserted into the tooth with a suitable tamper or Heidemann spatula. After approx.
7-8 minutes the phosphate cement is cured. Nevertheless, patients should not eat any sticky or hard food on the new denture for one day after the placement of crowns and bridges with phosphate cement to guarantee complete curing. Excess cement residues must be removed, otherwise the gums may become inflamed.
What problems can occur when using phosphate cement?
In some studies and investigations, one reads about concerns regarding the use of phosphate cement on vital (i.e. non-rooted) teeth. While the cement is still hardening, the phosphoric acid is active and can irritate odontoblasts (cells of the dental nerve) on free dentin surfaces. As a result, these cells retreat further into the tooth interior (to the pulp) and irritant dentin is formed.
In addition, the phosphate cement can dissolve at the crown margins over a longer period of time and thus create a cavity into which plaque and food residues can settle, thus attacking the tooth underneath the crown and, in the worst case, destroying it unnoticed. In addition, cement residues should be thoroughly removed after insertion, otherwise gum inflammation in this area can quickly occur. Phosphate cement is also not very suitable as a temporary abutment because of its low flexural strength.
It can break off quickly under load and, like all cements, can be washed out. Moreover, phosphate cement does not have an adhesive bond to dentin. Allergies to components of phosphate cement are possible, but are very rare.
In most cases, phosphate cement is well tolerated.If, after the insertion of a new crown or bridge with phosphate cement, symptoms such as reddening of the oral mucosa, itching or burning in the oral cavity occur, then you should consult your dentist. An allergic reaction could occur.
