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A randomized controlled clinical trial of two types of lithium disilicate partial crowns.

PURPOSE
This randomized controlled clinical trial evaluated the behavior of lithium disilicate partial crowns by means of a novel Functional Index for Teeth (FIT).


METHODS
105 subjects in need of at least a single prosthetic restoration in posterior areas were treated with adhesive partial crowns (for a total of 170 restorations) onto natural vital abutment teeth and followed-up annually for 4 years. Subjects were randomly divided into two experimental groups: Group 1, e.max Press and Group 2, Initial LiSi Press. FIT was used for the objective assessment of outcomes including clinical and radiographic examinations. A dropout rate of 4.25% in Group 1 and 3.4% in Group 2 was recorded. FIT is made up of seven variables (interproximal, occlusion, design, mucosa, bone, biology and margins); each of them to be evaluated using a 0-1-2 score. The Mann-Whitney U test was applied for statistical analysis and the level of significance was set at P< 0.05.


RESULTS
In Group 1, five complications were recorded, and four in Group 2, with a failure rate of 6.25% and 6.17%, respectively. No statistically significant difference was found between the experimental groups in any of the assessed variables. The tested lithium disilicate material brands showed comparable clinical performances after 4 years of clinical service.


CLINICAL SIGNIFICANCE
Clinicians can use either of the tested lithium disilicate materials to make adhesively luted partial crowns.