An in vitro study measuring marginal gaps of inlay restorations fabricated from different CAD-CAM materials after thermocycling

Abstract

Background: Many monolithic machined materials have been introduced and provided a suitable mechanical and physical properties for inlay restorations. However, there is shortage in the studies evaluating the marginal adaptation using these materials.

Purpose: This study aimed to compare the effect of fabricating inlay restorations from 3 different CAD-CAM materials on marginal gaps before and after thermocycling.

Materials and methods: Sixty human premolars were randomly divided into 3 groups (n = 20) according to the material used: (e.max CAD, Ivoclar AG, Schaan, Liechtenstein), (HC, Shofu, Koyoto, Japan) and (Brilliant Crios, Coltene, Altstätten, Switzerland) (n = 20). A scanning electron microscope (SEM) (JSM- 6510 lv, JEOL, Tokyo, JAPAN) was used to for measuring the marginal gaps after cementation of inlay restorations. The magnification was adapted to 250x. Marginal gaps were revaluated with SEM after thermocycling. The temperatures of baths were 5 and 55 °C was applied for a total of 5000 cycles. All data were statistically analyzed by using ANCOVA to demonstrate if there were any statistically significant differences between the gap measures after thermocycling of the three independent (unrelated) groups. A Bonferroni adjustmen was used to perform post hoc analysis (α = 0.05).

Results: Post-intervention marginal gap was statistically significantly lower in group EX (110.8 μm) which was statistically significant compared with group SF (112.5 μm) (mean difference=-1.768, P = .007) and group BR (113 μm) (mean difference=-2.272, P = .001), however, in. comparing SF and BR groups, there was no significant difference (mean difference=-0.5, P = .770).

Conclusions: Thermocycling affected the marginal gaps of composite based restoration and resin-modified ceramics widely. However, it had a very small effect on glass ceramics marginal adaptation.

Clinical implications: The marginal gaps of CAD-CAM inlays varied according to material used (ceramic based, combination, or resin based). Thermocycling has a minor effect on the marginal adaptation of lithium disilicate glass-ceramic inlays, where it affected the margin of resin-modified ceramic and composite based inlays greatly. Using lithium disilicate glass-ceramic might improve the clinical longevity of inlay restored teeth.

Keywords: CAD-CAM; Ceramics; Inlay; Margin; SEM.

Fig. 1

 A–C, SEM measurements at magnification x250 of marginal gaps for CAD-CAM, computer aided design and computer-aided manufacture endocrown restorations in 3 groups (EX, SF, and BR) (A, B, and C are showing measurements for 3 groups before thermocycling)

Fig. 2

 A–C, SEM measurements at magnification x250 of marginal gaps for CAD-CAM, computer aided design and computer-aided manufacture endocrown restorations in 3 groups (EX, SF, and BR) (A, B, and C are showing measurements for 3 groups after thermocycling)

Fig. 3

Grouped Scatterplot for marginal gap

Fig. 4

Simple scatterplot predicted values versus standardized residuals