Pre-cementation treatment of glass-ceramics with vacuum impregnated resin coatings.

Abstract

The study aimed to investigate the effectiveness of a vacuum impregnation process to eliminate the porosity at the ceramic-resin interface to optimize the reinforcement of a glass-ceramic by resin cementation. 100 leucite glass-ceramic disks (1.0±0.1mm thickness) were air-abraded, etched with 9.6% HF acid, and silanated. Specimens were randomly allocated to 5 groups (n=20). Group A received no further treatment (uncoated control). Groups B and D were resin-coated under atmospheric pressure, whereas groups C and E were resin-coated using vacuum impregnation. The polymerized resin-coating surfaces of specimens in groups B and C were polished to achieve a resin thickness of 100±10µm, while in groups D and E no resin-coating modification was performed prior to bi-axial flexure strength (BFS) determination. Optical microscopy was undertaken on the fracture fragments to identify the failure mode and origin. Comparisons of BFS group means were made by a one-way analysis of variance (ANOVA) and post-hoc Tukey test at α=0.05. All resin-coated sample groups (B-E) showed a statistically significant increase in mean BFS compared with the uncoated control (p<0.01). There was a significant difference in BFS between the ambient and vacuum impregnated unpolished groups (D and E) (p<0.01), with the greatest strengthening achieved using a vacuum impregnation technique. Results highlight the opportunity to further develop processes to apply thin conformal resin coatings, applied as a pre-cementation step to strengthen dental glass-ceramics.