In vitro evaluation of the marginal and internal discrepancies of different esthetic restorations

Objective: this study examined the fit of two types of all-ceramic single crowns and indirect composite resin full coverage crowns. material and methods: thirty intact human mandibular first premolars were selected for this study and prepared using a machine to standardize the dimensions and randomly divided into 3 groups. slip cast (ic) (in-ceram zirconia,vita zahnfabrik),copy-milled zirconia (cm) (ice,zirkonzahn) and indirect composite resin crowns (neco,heraeuskulzer,hanau,germany),(n=30,10 per group) were fabricated according to each manufacturer's recommendations. before cementation,discrepancies were measured at the marginal zone in each crown. crowns were then cemented with g-cem capsule self-adhesive luting cement (gc corporation,tokyo,japan). four positions were marked for each zone (mid-facial,mid-mesial,mid-distal,and mid-lingual) and three measurements were made at each of the four positions yielding to a total of 12 measurements per crown before and after cementation. the measurements were performed at a different magnification using a stereo microscope (sz11,olympus,japan). marginal,axial and occlusal zone discrepancies (μm) were evaluated after cementation. the data were statistically analyzed using two-way anova and tukey's test. results: before cementation,significantly less marginal discrepancies were noted compared with after cementation in all groups (p<0.05). no significant differences were found within each zone (marginal= ic: 84.2,neco: 95.22,cm: 84.22; axial= ic: 54.22,neco: 64.2,cm: 55.22; occlusal= ic: 119.97,neco: 129.18,cm: 121.15) in the three crown systems (p>0.05). occlusal zone discrepancies were significantly higher than those of the marginal and axial zones in all groups (p<0.05). conclusions: slip cast and copy-milled zirconia crowns showed comparable fit to composite resin crowns in all marginal,axial and occlusal areas.