SEM Evaluation of Marginal Adaptation E-Max Crowns Manufactured by Printing-Pressed and Milling

Dental crown marginal adaptation is a matter of the success of dental restoration treatment. Nowadays, there are many technological ways for crown manufacturing, such as tridimensional printing of an exactly desired shape through CAD-assisted systems and the appropriate shape milling of a predesigned bulk crown. Both methods are developed for patient benefits. The current research aims to investigate the marginal adaptation of E-Max crowns manufactured by printing-pressed and milling methods. The in vitro cementation procedures were effectuated on healthy teeth extracted for orthodontic purposes according to the standard procedures and the marginal adaptation was investigated with SEM microscopy. The restoration overview was inspected at a magnification of 100x and the microstructural details at 400x. The integrity of marginal adaptation was properly inspected in identical samples on segments of 2 mm from each buccal, palatal, distal and mesial side. The obtained results reveal a good marginal adaptation for all samples, with some particularities. The statistical analysis shows that the best values of the marginal adaptation were obtained for vestibular/buccal and palatal sides of the teeth being situated around 90-95%, while the values obtained for distal and mesial sides are slightly lower such as 80-90%. Furthermore, it was observed that the milled crowns presents better marginal adaptations than the printed-pressed ones, sustained by the statistical p < 0.05. This indicates that the milling process allows a better fit of the crown to the tooth surface and preserves the integrity of the bonding cement layer.