Roughness of different surface treatments on lithium disilicate ceramics

Abstract

Relevance of the problem: Ceramic restorations require efficient surface treatment after hot pressing technique and final occlusal reduction. After these procedures surfaces become rough. Roughness leads to surface damage which causes increased bacteria adhesion and wear of antagonist teeth. Aim of the work: To determine which lithium disilicate ceramic treatment develops smoother surface and to ascertain if it is possible to polish the surface sufficiently after surface reduction. Material and methods: Twenty 10 mm x 4 mm disc-shaped wax specimens were modeled using CAD/CAM system (ZIRKONZAHN M5, South Tyrol, Italy) and then milled. Wax was changed to lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent AG, Schaan, Liechtenstein). Specimens were divided into two groups by surface treatment method. P group specimens (n=10) were polished and G group specimens (n=10) were glazed. Then surface reduction was made using 40μm diamond bur and the intraoral polishing imitation was performed using polishing system (NTI CeraGlaze P336, P3036, P30036, NTI-Kahla GmbH, Germany). After every procedure mean surface roughness (Ra) was estimated with profilometer (Ambios Technology Inc., XP-Plus 200 Stylus, USA) and analyzed with scanning electron (Hitachi S-3400N VP-SEM, Singapore) and optical (Nikon Eclipse LV150, USA) microscopes. Statistical analysis was performed using SPSS 20.0. Roughness compared using Student t, Mann-Whitney and Wilcoxon tests. Results: P group Ra after polishing was 1,532±0,729μμm, G group after glazing - 2,519±1,513μm. G group Ra after surface reduction was 2,585±0,529μm, P group - 2,685±0,538μm. G group Ra after intraoral polishing imitation was 1,983±1,220μm, P group - 1,611±0,685μm. There is statistically insignificant (p>0,05) difference between the average surface roughness of P and G groups after all the procedures. Regardless of the initial sample preparation method, statistic