Resin cement color stability and its influence on the final shade of all-ceramics.
OBJECTIVE
Adhesive resin cements may go through internal discoloration, which may show-through and affect the appearance of translucent all-ceramic restorations. This in vitro study evaluated the amount of resin cement color change and its effect on the final shade of the all-ceramics.


METHODS
Three different resin cements in both light and dual-cure forms were included in the study (Nexus-2/Kerr; Appeal/Ivoclar Vivadent; Calibra/Dentsply). All resin cements contained veneered (IPS Empress Esthetic, ETC1 shade, 20 mm × 1 mm ingot discs) and uncovered groups (n=10/group), all luted on white backgrounds (acetalpolyoxymethylene/Delrin(®)). Curing was performed according to ISO standards with a calibrated LED curing-light (Flashlite 1401). Samples were stored in 37°C distilled water at dark. Spectrophotometric baseline color measurements (Color Eye 7000A) were performed from the samples' top surfaces at 24h (D65 illuminator). Samples were subjected to 65 h of accelerated ageing (Atlas Ci4000). Further color measurements from the same areas were recorded in CIEL*a*b* coordinates where a ΔE data above 3 was accepted as visible discoloration (OptiviewLite-1.9software). Statistical analysis was performed using a nested random effects model and Tukey's post hoc analysis.


RESULTS
Light-cure groups showed better color stability in all three resins but only in Appeal resin cement, the dual-cure group discolored significantly more (p<0.001). More discoloration was recorded on uncovered cement groups that represented the exposed cement at the margins. There was no visible color change (ΔE>3) through the ceramic surface on any veneered group.


CONCLUSIONS
All resin cements showed varying degrees of discoloration after accelerated ageing however their actual color change was partially masked by the ceramic. Dual-cure resin cements may affect aesthetics on restoration margins if directly exposed.
Department of Cariology and Restorative Dentistry, Nova Southeastern University College of Dental Medicine, 3200 South University Drive, Fort Lauderdale, FL 33328, USA. kilinc@nova.edu
Evren
E
Kilinc
Sibel A
SA
Antonson
Patrick C
PC
Hardigan
Atilla
A
Kesercioglu
D003116:Color; D003124:Colorimetry; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D055116:Self-Curing of Dental Resins; D013053:Spectrophotometry; D013997:Time Factors
D019279:Resin Cements; D003776:Dental Porcelain