Lighttransmission Through High-Densitiy-Polymers for CAD/CAM Fabrication

OBJECTIVE: Temporary restorations are an essential part of dentistry. CAD/CAM- fabrication of industrially prefabricated polymers enhances material properties compared to conventional fabrication of temporaries. Besides mechanical strength the optical properties of polymers play an important role. This study evaluates the light transmission of 7 high-density-polymers for CAD/CAM fabrication and 4 polymers from dispenser systems for chairside fabrication. METHODS: 40 disc shaped specimen (16,0 x 1,0mm) were produced from each CAD/CAM-material (A= Polycon ae; B= artbloc Temp; C= Cercon base PMMA; D= CADtemp; E= Ambarino high class; F= TelioCAD; G= Zenotec Pro Fix) and dispenser material (H= Luxatemp fluorescence, I= Protemp 4; J= Structur 2SC; K= Fixtemp c&b). After grounded / polished under standardized conditions the direct transmission coefficients tc [%] of comparable shades (A3) of all-ceramic frameworks were quantified in a spectrophotometer with an “integrating sphere” (Lambda 35, PerkinElmer) at wavelenghts (λ) of the visible spectrum (400 to 700 nm). The overall light transmission for each material was calculated as the integration of all tc values. RESULTS: A wide range of overall transmission was observed: A= 33%; B= 33%; C=38%; D= 45%; E= 46%; F= 47%; G= 54%; H= 40%; I= 41%; J= 42%; K= 46%. One-way ANOVA and following post-hoc test (Student-Newman-Keuls) revealed statistically significant differences (p= 0,05) for the overall light transmission between all materials except between A and B and E and K. As well, the spread of overall light translucency values was greater among the high-density polymers (from 33-54%) than among dispenser materials (from 40-46%). CONCLUSION: Despite having the same shade designation A3 from the manufacturers, high-density-polymers as well as chairside temporary materials show significant differences in lighttransmission. These results should be considered especially for anterior temporary restorations depend on the clinical situation either to mask discolorations or to interact with the underground.