Marginal adaptation of zirconium dioxide copings: influence of the CAD/CAM system and the finish line design.
BACKGROUND
Marginal adaptation is essential for the long-term success of dental restorations. Studies comparing the marginal gaps of computer-aided design/computer-aided manufacturing (CAD/CAM) restorations made from conventional and digital impressions are limited.


OBJECTIVE
The purpose of this study was to evaluate the marginal adaptation of zirconium dioxide copings made with 2 different CAD/CAM systems, the Lava All-Ceramic System (scanning definitive dies made with conventional impressions) and the Lava Chairside Oral Scanner (scanning directly from the prepared tooth). In addition, the influences of 2 different finish line configurations were also compared.


METHODS
Forty human molar teeth were prepared to receive complete crowns. Twenty were prepared with a 90-degree round shoulder and the other 20 with a 45-degree chamfer finish line. Zirconium dioxide copings were fabricated by using CAD/CAM technology. The specimens were randomized; they included 10 teeth with round shoulder and 10 with chamfer finish lines with the Lava All-Ceramic System, and 10 teeth with round shoulder and 10 with chamfer finish lines with the Lava Chairside Oral Scanner. The marginal gaps were measured at 5 points on each side with stereomicroscopy at 40× magnification. Data were analyzed with 2-way ANOVA (α=.05).


RESULTS
The mean values of the measured marginal gap for the round shoulder group were 52.66 μm with the Lava All-Ceramic System and 14.98 μm with the Lava Chairside Oral Scanner. The mean values for the chamfer group were 64.06 μm for the Lava All-Ceramic System and 18.45 μm for the Lava Chairside Oral Scanner. Differences were identified when the marginal gaps between the specimens with different CAD/CAM systems were compared. However, differences in the finish line design were identified only between the round shoulder and chamfer with the Lava All-Ceramic System.


CONCLUSIONS
Restorations fabricated with the Lava Chairside Oral Scanner displayed smaller marginal gaps than those made with the Lava All-Ceramic System. Nevertheless, all marginal gaps were within the range of clinical acceptability for both groups.
Doctoral student, Department of Prosthodontics, International University of Catalunya, Barcelona, Spain, Department of Prosthodontics, Autonomous University of Nuevo León, Nuevo León, Mexico. Electronic address: r_euan@hotmail.com.
Raúl
R
Euán
Professor, Department of Prosthodontics, International University of Catalunya, Barcelona, Spain.
Oscar
O
Figueras-Álvarez
Professor, Chairman of Department of Prosthodontics, International University of Catalunya, Barcelona, Spain.
Josep
J
Cabratosa-Termes
Professor, Department of Endodontics, Autonomous University of Tamaulipas, Tamaulipas, Mexico.
Rogelio
R
Oliver-Parra
D017076:Computer-Aided Design; D003442:Crowns; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D006801:Humans; D008422:Materials Testing; D003765:Models, Dental; D013499:Surface Properties; D013674:Technology, Dental; D019231:Tooth Preparation, Prosthodontic / Q000379:methods; D015040:Zirconium / Q000737:chemistry*
D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide