In this article *HOW TO RESOLVE FITTING-ISSUES WITH ZIRCONIA CROWNS, we analyzed how to solve the assembly problem of zirconia crowns, and left a preview of this article. So in this article, we focus on analyzing the causes of discomfort in zirconia crowns and three methods for removing phosphate groups.
What Can Cause Ill-Fitting Zirconia Crowns?
l Dental crown was rushed.
When crowns are rushed, errors occur, such as incorrect margins.There are gaps in the edge bonding, and saliva seeps into the crown, which can cause gum decay.
l Crown was not cemented properly.
In this case, very similar to the first, the dentist must carefully inspect the crown edges to avoid errors during the bonding process. If saliva or bacteria get into the crown, as above, there is a high chance of infection.
l Impression was questionable.
Air pockets, drag or pull marks, missing impression data, inaccurate marginal impressions and poor impression material will all affect the quality of the impression.
l Preparation anomalies.
Three Ways to Remove Phosphate Groups
Although 50 micron diameter alumina is sometimes not recommended for sandblasting interior surfaces, most manufacturers do recommend very light blasting of interior surfaces at low pressure. Be sure to consult the manufacturer's recommendations before trying this method.
n Sodium hypochlorite.
The intaglio of the crown is wiped with gauze soaked in 5% sodium hypochlorite or per hydrogen peroxide, then the restoration is removed by rinsing with water and air-drying.
When building a digital image of the patient's teeth, any irregularities are removed because milled restorations have smooth surfaces inside that will not fit irregularities or undercuts. Typically, a die spacer is used on conventional models, which creates a space of about 50-100 microns. When making zirconia restorations, ask your clinician to ensure that the computer program is set up to create a good margin while specifying the size of the space between the appropriate surface and the preparation. This simple step replicates the function of a traditional mold spacer and will prevent the zirconia crown from rocking on the face-lingual side.