How to resolve dental fitting issues with zirconia?

Zirconia crown is one of the most popular dental restorations due its strength, life-like aesthetics and durability to withstand forceful chewing and grinding. With proper care and good oral hygiene zirconia crowns can last for a patient’s lifetime. However, zirconia crowns disadvantages are due to its newness; some dentists hesitate from using them. A well-crafted crown, but an inexperienced dentist can result in fitting issues on zirconia crowns.

How to fix ill-fitting issues on zirconia crowns?

1. If the crown is debonding then try altering your cementation process.
2. Most clinicians test out the fit of the zirconia crown within the patient’s mouth even before cleaning the tooth with pumice.
3. Clinicians oftentimes fail to decontaminate the intaglio surface of the zirconia restorations thoroughly causing the bonding procedure to fail.
4. Since zirconia bonds with phosphate groups, it is crucial to properly remove the phosphate groups so that the oxide sites can successfully bond within the patient’s mouth.

Three ways to remove phosphate groups

• Sandblasting: Most manufacturers recommend sandblasting gentle in-tooth internal surfaces with low pressure.
• Sodium hypochlorite: Use gauze soaked with 5% concentration sodium hypochlorite or full hydrogen peroxide solution and wipe the intaglio of the crown. After wiping, wash the restoration with water and air dry the restoration.
• Ivoclean: Apply proprietary solution like Ivoclean to the intaglio surface of the crown for 20 seconds before rinsing. Let the crown dry naturally and it is now ready to bond.

Issues with facial-lingually

1. Even though some of these crowns have a close-fitting margin they can have facial lingual issues which can be due to irregularities within the dental image of the patient’s teeth being removed. In contrast, the milled restorations with smooth surfaces will not fit over undercuts or irregularities of the patient.
2. To overcome the facial lingual issue the dentist must set the computer program to create the well-fitting margins while also specifying the space size between the surface of the fit as well as the prep site.
3. This simple step imitates the function of a conventional die-spacer which will also prevent crowns from rocking facial-lingually.

Reasons your zirconia crowns are ill fitted.

Below are some of the reasons why your zirconia crowns are ill fitted:

1. The dental crown was made in a rush, leaving no time for designing, zirconia crown grinding Or contouring the finishing accurately. Incorrect margins can create holes as an entry for saliva and bacteria to enter the crown which can result in damage to the natural crown, tooth decay and periodontal issues.
2. The fitting procedure was improper or was not cemented appropriately. The errors during the procedure such as a gap in the crown or loose fillings allows saliva and bacteria to enter leading to tooth decay and infection.
3. The wrong impression taking procedure can cause inaccurate marginal impressions, missing impression data and poor impression material affecting the quality of zirconia tooth production.
4. Error during preparation.