The Survival Rate of All-Ceramic Single-Tooth Restorations in a Non-University Setting

This article by Offer et al evaluated the long-term survival of IPS Empress 2 and IPS e.max restorations with up to 15 years of follow-up. The study evaluated the survival of 1132 posterior restorations and the effect of variables such as the type of glass ceramics, patients' age and sex, tooth type (premolars and molars), tooth vitality, restoration type (complete and partial coverage), cementation mode (self-adhesive vs non–self-adhesive resin cements), and bruxism. Out of the 1132 restorations, 15 failed, described as bulk fractures. The authors did not include the replacement of restorations due to other reasons (such as caries, endodontic treatment, etc) as failures. Out of 15 failures, 3 were IPS e.max and 12 were IPS Empress 2 restorations. The overall reported survival rate was 98.7% after 15.4 years. The factors that had a significant effect were tooth vitality, with a higher failure rate in endodontically treated teeth, patient age, with higher failures in the older age group, type of restoration, with a higher failure rate in the onlay type (quoted as “partial crowns”), and type of cement, with higher failures in self-adhesive resin cements. However, the type of ceramics, patient sex, tooth position, and bruxism had no effect on the survival of these restorations.

This article certainly holds value and adds clinical evidence to the performance of lithium disilicate glass-ceramic restorations. It is one of the few studies that compared the survival of IPS Empress 2 restorations with that of IPS e.max restorations. Most importantly, this study showed the effect of bruxism on lithium disilicate restorations in posterior teeth. Although there is a widespread opinion that lithium disilicate would not have sufficient mechanical properties to withstand occlusal forces in the posterior dentition, it has been disproved in the series of our publications, where IPS e.max restorations in posterior teeth performed similarly to those in the anterior dentition. The current article demonstrated that, even in bruxer patients, lithium disilicate restorations perform successfully over a period of 15 years. This study has some limitations, such as the retrospective approach and the lack of reported confounding variables. Endodontically treated teeth showed lower survival rates than vital teeth. It would have been interesting to analyze the foundation restorations and their overall influence. The major question that the authors had was why the survival was calculated without accounting for time in service and dropouts, which can be described as an error in the evaluation.

Overall, this article adds more evidence to the clinical reliability of lithium disilicate glass ceramics and their performance in posterior teeth. It breaks down the clinical variables and accounts for important factors such as bruxism.