Don't miss a digital issue! Renew/subscribe for FREE today.
×
Compendium
May 2016
Volume 37, Issue 5
Peer-Reviewed

Results

The median and percentiles of the values obtained for ΔE1* in the groups tested are presented in Figure 5. No statistical differences were observed among ΔE* found for all the groups tested (P = .701).

Similarly, the median and percentiles of the values obtained for ΔE2* in the groups tested are presented in Figure 6. No statistical differences were observed among ΔE* found for all the groups tested (P = .704). When comparing the values of ΔE* obtained for each group in pairs (ΔE1* and ΔE2*), no statistically significant differences were found (P = .646, P = .169, P = .508, and P = .05, respectively, for groups I, II, III, and IV).

The means and standard deviation for ΔE3* are shown in Figure 7. No statistically significant differences were observed among groups (P = .312).

Figure 8 shows the values of ΔE3* obtained for each specimen and allows the visualization of their relationship with the values indicated by the horizontal lines, which express the cutoff points for the color variation imperceptible to the human eye accepted by different authors (ΔE = 2.0, ΔE = 3.3, and ΔE = 5.5).8,10 Considering that 3.3 is the most accepted value of ΔE in the literature for visible color changes, 45% of the specimens tested showed color variance higher than this value (ΔE* > 3.3).2,8,9,15

Discussion

The final shade of the veneer depends not only on the color, opacity, and thickness of the ceramic, but also on the color of the underlying tooth and the color and thickness of the resin cement.5,16 The type of illuminant and substrate, as well as the thickness of the material, should always be considered, because they all influence the final color of ceramic restorations.17

The results of the present study revealed that the colors obtained with the ceramic in position were similar for all try-in materials (P = .701) and resin cements (P = .704) tested (Figure 5 and Figure 6, respectively). Therefore, using 0.6-mm-thick ceramic veneers, no differences in the final color were observed for any shades of try-in material or resin cement assessed. Two possible reasons for this are: (1) the cement and try-in paste layer thickness employed; (2) the thickness of the ceramic discs (0.6 mm) used. However, new studies are necessary to investigate the magnitude of color alterations with different thicknesses of ceramic veneers, as well as with different resin cements and try-in materials.

Comparing the groups in pairs (trial × cementation), no statistically significant differences were found for the optical behavior at these two moments (P = .646, P = .169, P = .508, and P = .05 for groups I, II, III, and IV, respectively). These results indicated similarity between colors generated by use of different resin cements’ shades and correspondent try-in pastes’ shades. Similarly, Xing et al10 reported that the color of resin cements and their corresponding try-in pastes had high agreement.

Analyzing the values found for ΔE3* (Figure 7), no statistically significant differences in color change were observed between the try-in materials and the corresponding shades of cured resin cements among groups (P = .312). These results disagree with those reported by Alghazali et al,8 who found statistically significant difference between the color achieved using the try-in paste and the same shade of cured resin cement. Further studies involving different brands of resin cements and ceramic veneers are indicated.

The cutoff to visible color change should be considered when using ΔE* to evaluate this parameter. Xing et al10 affirmed that ΔE* values higher than 2.0 may be considered as perceptible color change, whereas Chang et al18 considered this value as the gold standard. Ruyter et al15 found that 3.3 units of color difference have been considered unacceptable by 50% of observers. However, more recently, another in vivo study has presented the clinically acceptable threshold to be ΔE* 5.5 units.19 Nevertheless, the most widely accepted value for ΔE* in the literature is 3.3 units for visible color change.2,8,9,15,16,20

Considering that in the present study the results found for ΔE3* represent the color change, in numeric values, between the results obtained for the trial and after cementation, and acknowledging each cutoff point, the following situation has resulted: 70% of specimens presented ΔE3* values higher than 2.0; 45% presented ΔE3* values higher than 3.3; and 5% presented ΔE3* values higher than 5.5 (Figure 8). Although no statistically significant differences were observed between the results found for the trial and after cementation for any of the groups, a difference in color may be noticeable to the human eye. This aspect should be considered in decision making during routine clinical practice.

Conclusions and Clinical Implications

No differences were found in the shades of the ceramic veneers used when tested with water-soluble gel or try-in pastes values 0, -3, and +3. Also, the different resin cements (values 0, -3, and +3) produced similar effects on the color of ceramic restorations.

No statistically significant differences were found in the values of color change among three shades of try-in paste placed underneath the ceramic discs. Considering the parameters for color change perceptible to the human eye, 45% of the ceramic restorations presented visible changes (ΔE > 3.3).

© 2024 BroadcastMed LLC | Privacy Policy