Evaluation of marginal and internal adaptation of hybrid and nanoceramic systems with microcomputed tomography: An in vitro study

Statement of problem. The accuracy of recently introduced chairside computer‐aided design and computer‐aided manufacturing (CAD‐CAM) blocks is not well established, and marginal integrity and internal adaptation are not known. Purpose. The purpose of this in vitro study was to evaluate the marginal and internal adaptation of hybrid and nanoceramics using microcomputed tomography (&mgr;‐CT). Material and methods. The marginal and internal adaptation of 3 polymer‐infiltrated ceramic‐network (PICN) materials (Vita Enamic [VE]; Lava Ultimate [LU]; Vita Suprinity [VS]) were compared with lithium disilicate (IPS e.max.CAD, IPS). Ninety‐six specimens (48 dies and 48 crowns) were prepared (n=12 each group) using a chairside CAD‐CAM system. The restorations were scanned with &mgr;‐CT, with 160 measurements made for each crown, and used in 2‐dimensional (2D) analysis. The marginal adaptation of marginal discrepancy (MD), absolute marginal discrepancy (AMD), internal adaptation of shoulder area (SA), axial space (AS), and occlusal space (OS) were compared using appropriate statistical analysis methods (&agr;=.05). Cement volumes were compared using 3D analysis. Results. The IPS blocks showed higher MD (130 &mgr;m), AMD (156 &mgr;m), SA (111 &mgr;m) (P<.05), AS (52 &mgr;m), and OS (192 &mgr;m) than the other blocks (P<.01). The adaptation values of VS were significantly lower than those of the IPS block (P<.05). The adaption values of the LU and VE blocks were significantly lower than those of others (P<.01) but were statistically similar to one another (P>.05). IPS had the largest cement space at 18 mm3 (P<.01). Conclusions. The marginal and internal adaptation values were within a clinically acceptable range for all 3 hybrids and nanoceramics tested.