Influence of two different cement space settings and three different cement types on the fit of polymer-infiltrated ceramic network material crowns manufactured using a complete digital workflow

Abstract

Objectives The study evaluates the influence of two spacer settings and three resin luting materials on the marginal and internal fit of polymer-infiltrated ceramic network (PICN) material crowns manufactured using a complete digital workflow. Methods Optical impressions of fifty identical dies were performed using the 3M scanner (software version 5.0.2). Twenty crowns were designed using Ceramill Mind (version 3.4.10.1163), from which ten with spacer setting of 50 μm (G1) and ten with 80 μm (G2). Thirty crowns (spacer setting of 50 μm) were divided into three groups corresponding to the resin materials used as follows: RelyX Unicem (RX), Variolink Esthetic (VLE), and Nexus 3 (NX3). All crowns were milled from Vita Enamic blocks. After micro-CT scanning, absolute marginal discrepancy (AMD), internal gap (IG), total cement space volume (TCV), and marginal porosities (VP) were measured. Results Significant difference was detected on the VP between the RX and NX3 group (p = 0.033). The mean values of all parameters were the following: AMD (μm)VP (mm 3 ): G1 0.26, G2 0.34, RX 0.32, VLE 0.46, NX3 0.54. Conclusions Fit of PICN material crowns was not significantly influenced by increasing the spacer settings and cementation with different resin materials. Additionally, RelyX Unicem showed significantly less porosities as compared with Nexus3. Clinical relevance Both 50 μm and 80 μm virtual spacer settings can be suggested for the manufacture of PICN crowns when Ceramill Mind (version 3.4.10.1163) is used. Furthermore, a self-adhesive system can be recommended for the cementation.

Effect of various digital cement space settings on the adaptation of CAD/CAM occlusal veneer “micro-ct evaluation”

“…CAD occlusal veneer as proposed by other authors 11,22,26) . In contrast with other studies which postulated that, an increase of the cement space does not improve the marginal fit 13,18) .…”

“…Finally, three dimples were made at the level of cemento-enamel junction on mesial, distal and buccal surfaces using round diamond bur) they Effect of various digital cement space settings on the adaptation of CAD/CAM occlusal veneer "micro-ct evaluation" were used as guides to standardize the position of the die and its corresponding occlusal veneer within the mold during scanning). Then, 30 resin master dies were made by replicating the prepared tooth using Cerec inLab 3D system (D-64625, Sirona dental system, Bensheim, Germany) and randomly distributed into 3 groups (ten samples for each) according to the cement space parameters (30, 40 and 50 µm) subsequently designed 18,26) .…”

“…4. Absolute marginal discrepancy value (AMD): The mean of two right and left distances between the margin of occlusal veneer and die margin (AMD1 and AMD2) 18,20,27) . The occlusal veneers were seated onto their corresponding dies without any luting medium 26) .…”

“…The digital data were developed using a reconstruction software (NRecon 1.6.6.0, Bruker), Cross-sections of samples were made with a distance of 9 degrees. Images were acquired from 20 slices were used to measure four sites per slice (occlusal, axial, marginal and absolute marginal discrepancy) with a total of 80 measuring values for each tooth 18,27,28) as illustrated in Figs. 3 and 4.…”

“…Moreover, the internal gap is the vertical distances from the axial and occlusal walls of preparation to the internal surfaces of the crown. In addition to that; the absolute marginal discrepancy (AMD), which is the angular combination of the extension error and marginal gap, reflects the total crown misfit in vertical and horizontal directions [17][18][19] .…”