Translucency of Resin Modified Glass Ionomer Restoratives

Objectives:   This in vitro study evaluated the translucency of resin modified glass ionomer cements (RMGIs) compared to leading composites over time.

 

Methods:  

Materials tested were Riva LC A2 (1, SDI), Fuji II LC A2 (2, GC America), Riva LC HV A2 (3, SDI), Photac-Fil Quick Aplicap A2 (4, 3M ESPE), Ketac  Nano A2 (5, 3M ESPE), and Filtek Supreme Ultra composite shades A2B, A2E, WE  (6, 7, 8, 3M ESPE).              

 

Triplicate disks (n=24) were fabricated from each product by dispensing material into a 16mm diameter stainless steel mold, which was covered and compressed with a mylar strip and glass slide on both sides. The molds were light cured for 1min on each side (SDI Radii Plus), and the thickness of the disks were measured (1.00±0.05mm).  The disks were stored at 37șC in de-ionized water prior to measurement of their opacity.  Opacity was measured using the contrast ratio (CR) method with an XRite spectrometer in an integrating sphere geometry.  The CR was obtained by comparing the sample against a black glass background and white tile.  Water was placed between the disk and substrate to obtain good optical contact.  Measurements were made one hour after preparation, followed by 3 and 10 days.

 

Results:

The opacities were analyzed using ANOVA and Multiple Range Test (LSD, 95% confidence level, p-value < 0.05).

Table 1: Opacity (CR ± SD)
Group	1	2	3	4	5	6	7	8
1 hour	36.76 ± 1.91	47.81 ± 0.26	45.63 ± 1.71	50.36 ± 0.74	47.39 ± 1.29	40.64 ± 1.88	33.11 ± 1.18	29.19 ± 0.48
3 days	31.96 ± 0.65	42.91 ± 1.56	38.35 ± 2.10	39.83 ± 1.68	56.14 ± 2.55	40.58 ± 1.60	33.44 ± 0.67	28.38 ± 0.68
10 days	29.65 ± 0.80	42.74 ± 3.00	34.99 ± 1.22	33.54 ± 2.20	54.06 ± 3.42	39.70 ± 1.32	31.92 ± 0.21	28.31 ± 0.79

 

Conclusions:    Group 1 is the most translucent of the RMGIs tested.   Three days after cure, the opacity of group 1 is similar to group 7 composite.  All the RMGIs except group 5 reduce opacity slightly during the first few days after cure.  If the RMGIs are used to replace enamel, the reduction in opacity will make the underlying tooth structure slightly more visible.