PhD researcher explores zirconia durability

Dental Tribune International

Thu. 10. October 2024

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MALMÖ, Sweden: Although complication rates for zirconia restorations are low, technical problems like loss of retention are significant owing to the ceramic’s growing popularity. There is, therefore, a great clinical need to understand the causes of these complications. Dr Minh Le, a PhD candidate at Malmö University, investigated key factors affecting the adhesion of zirconia posterior tooth-supported single crowns, seeking to improve long-term clinical outcomes and reduce common issues with retention failure. His findings highlight the importance of surface pretreatment and cementation procedures in ensuring durable retention.

To explore how adhesion between zirconia and dentine might be improved to enhance the longevity of zirconia restorations, Dr Le devised a research project made up of four interlinked studies. The first took place in the laboratory and examined surface treatments on various kinds of zirconia materials. The results showed that adhesion to the tooth is improved if the surface of the zirconia is sandblasted before cementation with an MDP-based resin cement.

After this laboratory-based study, a systematic review and meta-analysis were then conducted that focused on how the type of cement used affects the survival of tooth-supported zirconia crowns. This study found that such crowns exhibit a survival rate of at least three years, regardless of the type of cement used.

The third study was a three-year follow-up of a randomised, controlled clinical trial in which general dentists treated patients with three types of ceramic crowns on posterior teeth. The results showed that the restorations were overwhelmingly successful, complications were rare and the patients were satisfied with the quality. The crown survival rate was 98.8% by the end of the follow-up period.

The final study was an experimental laboratory study in which primers and cements from two different cement systems were used together to evaluate the bond strength between zirconia and the tooth. The results showed that it is important to use products from the same cement system to achieve a reliable bond.

The central finding of the thesis has been to underline the durability and quality of zirconia crowns, provided that all preparatory and technical procedures are undertaken carefully and accurately. In a university news release, Dr Le said: “We have seen dental crowns have a very good survival rate, regardless of the type of cement used. According to the systematic review and meta-analysis we did, 99% had a survival rate of at least three years.”

The PhD thesis, titled Retention of Zirconia-Based Restorations: Studies on Adhesive Cementation of Translucent Zirconia Crowns, is available to download here.