A recent study by faculty and students at the Medical University of South Carolina (MUSC) College of Dental Medicine found clinically acceptable marginal fits, regardless of the quality of the preparation, with restorations fabricated with the E4D System, D4D Technologies announced in a press release.
There was a statistically significant correlation between the marginal fit and the quality of the preparation, however, according to the study authors, from the MUSC College of Dental Medicine (Journal of Prosthetic Dentistry, November 2012, Vol. 108:5, pp. 310-315).
The investigators used preparations placed in three categories (excellent, fair, or poor) and fabricated 75 ceramic crowns with the E4D Dentist system. They then examined the marginal gap values for each category. The results showed that the presence or absence of common preparation errors was a predictor of the quality of marginal fit.
Citing previous studies, the investigators stated that "most authors agree that marginal openings of less than 120 µm are in the range of clinical acceptability with regard to longevity." The mean marginal gap of the E4D fabricated crowns was significantly better in all categories, they added: 38.5 µm for the excellent preparations, 58.3 µm for the fair preparations, and 90.1 µm for the poor preparations.