46594
document
Translucency of zirconia copings made with different CAD/CAM systems . STATEMENT OF PROBLEM Zirconia cores are reported to be less translucent than glass , lithium disilicate , or alumina cores . This could affect the esthetic appearance and the clinical choices made when using zirconia-based restorations . PURPOSE The purpose of this in vitro study was to evaluate the translucency of zirconia copings for single crowns fabricated using different CAD/CAM systems , using lithium disilicate glass ceramic as a control . MATERIAL AND METHODS Using impressions made from a stainless steel complete-crown master die , 9 stone cast replicas were fabricated , numbered , and distributed into 8 ceramic ZrO ( 2 ) CAD/CAM system groups ( Lava Frame 0.3 and 0.5 , IPS e.max ZirCAD , VITA YZ , Procera AllZircon , Digizon , DC Zircon , and Cercon Base ) and to a lithium disilicate glass-ceramic control group ( IPS e.max Press ) using a simple computer-generated randomization method . From each die , the manufacturer 's authorized milling centers supplied 5 copings per group without applying any dying technique to the ceramic base material . The copings were prepared to allow for a 40-mum cement layer and were of different thicknesses according to system specifications . Translucency was measured by the direct transmission method with a digital photoradiometer mounted in a dark chamber . The light source was a 150-W halogen lamp beam . Measurements were repeated 3 times for each specimen . Data obtained were analyzed using 1-way ANOVA and the Bonferroni multiple comparison test ( alpha=.05 ) . RESULTS Among ZrO ( 2 ) copings , Lava ( 0.3 mm and 0.5 mm thick ) showed the highest ( P < .05 ) values of translucency measured as light flow units ( 3.572 + or - 018 x 10 ( 3 ) lx and 3.181 + or - 0.13 x 10 ( 3 ) lx , respectively ) . These values represent 71.7 % and 63.9 % , respectively , of the glass-ceramic control group ( 4.98 x 10 ( 3 ) lx ) . CONCLUSIONS All ZrO ( 2 ) copings demonstrated different levels of light transmission , with the 2 Lava specimens showing the highest values . Translucency of zirconia copings was significantly lower ( P=.001 ) than that of the lithium disilicate glass-ceramic control .
46595
Intervention_Pharmacological
zirconia copings
46596
Intervention_Pharmacological
lithium disilicate glass ceramic
46597
Outcome_Physical
translucency
46598
Outcome_Physical
Translucency
46599
Outcome_Other
values of
46600
Outcome_Physical
translucency
46601
Outcome_Physical
Translucency
46602
Participant_Condition
zirconia copings
46603
Participant_Sample-size
9