Abstract
Background
Polishing of dental composite restorations to achieve a highly smooth and reflective surface not only enhances esthetics but also their color stability and improves resistance to staining. The objective of this study was to evaluate the effect of beverages on the color stability of nanoceramic composites polished using different techniques.
Methods
80 samples of ceram. X SphereTEC one were prepared by condensing the material into a stainless-steel split mold and divided randomly into two groups. Group I was subjected to polishing using Sof-Lex system™ disks, and Group II was kept unpolished. Each group was subdivided into four sub-groups of 10 samples each. Each subgroup samples were immersed into designated beverages (Tropicana orange juice, Coco-cola, Nescafe coffee, and distilled water) for a duration of 15mins/day for 15 days. The color of all specimens before immersion, one day, and 15 days after immersion was measured using a Spectrophotometer.
Results
Significant staining of the material was found with cola drinks and coffee compared to orange juice and distilled water. Polished material showed better resistance to staining by various beverages compared to control group.
Conclusion
Nanoceramic composites exhibited superior color stability after polishing with Sof-Lex system™. Among the beverages, coco-cola significantly altered the color of the composite.
Keywords: Dental composite, Color stability, Beverages, Operative dentistry
1. Introduction
Ever since their introduction, resin-based composites have been continuously evolving to the growing demands of esthetic dental applications. This was made possible due to the advances in polymer matrix materials and fillers, leading to the availability of composites with a wide range of properties for a variety of clinical applications. Despite these advances, discoloration over time, wear, and polymerization shrinkage leading to microleakage are the most common factors that contribute to their clinical failure.
The properties of composites are known to be influenced by various factors like type and amount of polymeric matrix material, nature, amount, size and size distribution of filler particles.1 The advent of nanotechnology resulted in a significant improvement in the qualities of dental composites with enhanced esthetic and mechanical performance compared to conventional composite materials.
Nanofillers provide superior shade, finish, texture, translucency, and gloss retention to the final restoration.2 Ceram. x SphereTEC™ one (CS) (Dentsply Konstanz, Germany) is one such light-curable, radiopaque restorative material for anterior and posterior restorations of primary and permanent teeth. CS comprises of organically modified ceramic nanoparticles and nano-fillers combined with conventional glass fillers of ~1 μm and merges hybrid composite filler technology with advanced nanotechnology resulting in nanoceramic technology.3 Overall, the filler loading of this material is about 77 wt% or 55 vol%, which imparts superior mechanical properties. Also, it offers natural esthetics with excellent handling characteristics.4
The ability of a dental material to be able to retain its original color is known as color stability. Various factors such as the nature of the composite resin as well as the characteristics of the composite such as water sorption and surface finish influence the esthetics of restoration.5 The extrinsic factors like food components, beverages and increased use of colored mouth rinses such as chlorhexidine, can have a negative effect on the esthetic quality of composite resin materials.6,7 It is documented that extrinsic discoloration has the most pronounced effect on the color stability and long term esthetics of the composite restorations.8
The color stability of dental composites has been widely investigated. The effect of variations in composition, filler size, the effect of various beverages, etc., have been extensively investigated.9, 10, 11 However, the impact of polishing techniques on the color stability of composite materials has not been studied. Hence, this study aimed to evaluate the effect of beverages on the color stability of nanoceramic composites polished using different techniques. The null hypothesis tested was that polishing techniques do not significantly influence the color stability of nanoceramic composites in storage solutions.
2. Materials and methods
A total of 80 specimens of ceram. X SphereTEC one (CS) (Dentsply, Konstanz, Germany) were prepared by packing the material into a stainless-steel split mold of 2 mm height and 10 mm diameter. The samples were then covered using a mylar strip on top of which a glass plate was placed, and light-cured on both sides using Elipar S10 LED Curing Light (3 M ESPE, ST. Paul, MN, USA) having a light intensity of 1200 wM/cm2 for 20 s. Post-curing, the samples were retrieved and divided into two groups, i.e., Group I and Group II.
The specimens in Group I were subjected to polishing using Sof-Lex system™ disks (3 M ESPE, ST. Paul, MN, USA), and specimens in Group II were left unpolished. Subsequently, the specimens in these groups were further divided into four subgroups as A, B, C, and D (n = 10). Specimens in IA and IIA were immersed in Tropicana orange juice (PepsiCo India private limited, Gurugram, India) IB and IIB were immersed in Coco-Cola (PepsiCo India private limited, Gurugram, India) IC and IIC were immersed in Nescafe coffee (Nestle, Mumbai, Maharashtra, India) and ID and IID were immersed in distilled water and were considered as control specimens (Fig. 1).
Fig. 1.
Distribution of specimens according to the groups and subgroups.
The pH of beverage solutions used during the study was measured using a pH meter (Eutech pH 700, Thermo Fisher Scientific India Pvt. Ltd., India) prior to the immersion of the prepared specimens. Nescafe coffee solution was freshly prepared and other solutions were used from fresh containers each day. All the specimens were immersed for a duration of 15 min/day for 15 days. After the immersion time, the samples were kept in distilled water for the remainder of the day at 37 °C. The color of all the specimens prior to the immersion, one day after immersion and at the end of 15 days, was measured using a Spectrophotometer (SpectrolinoGretag-Macbeth AG, Germany). It measures color in terms of L∗, a∗, b∗ values. The D50 standard illuminant from a tungsten lamp was used with a viewing angle of 2° to measure the emission light from the samples. The color measurement was carried out at three different places on each disc. The spectra of the sample with the reflectance of a white background were compared, and the difference in color was expressed based on the CIE L∗, a∗, b∗ color space system as established by International Commission on Illumination. The total color difference between the reference and test specimen, delta E, was calculated using the following formula.
2.1. Statistical analysis
All the analysis were done using SPSS version 20 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp.). A P-value of <0.05 was considered statistically significant. Intra-group comparisons were done using Repeated measures ANOVA with post-hoc Bonferroni test. Intergroup comparisons of the difference in ΔE values was done using Kruskal Wallis ANOVA with post-hoc Conover test.
3. Results
The main aim of the present study was to investigate the color stability of CS composites immersed in different beverages. The selected beverages were subjected to pH measurement and the results indicate a difference in pH. Among the beverages, Coco cola exhibited lowest pH (2.50 ± 0.01) indicating its acidic nature. Tropicana orange juice showed a pH of 3.51 ± 0.02 whereas Nescafe coffee and distilled water showed pH of 4.77 ± 0.02 and 5.85 ± 0.07 respectively. The immersion of composite resins in aqueous solutions will lead to absorption of the solution by the resin matrix of the composite. This will lead to softening of the surface of the composite as well as deposition of staining materials on or within the surface. The ability of a beverage to cause staining of composites is mainly affected by pH, exposure time and frequency, temperature as well as stain causing substances in the material.
The results of the present study indicate that polishing of CS with Sof-Lex system™ polishing discs exhibited superior color stability and no significant changes in ΔE values from the baseline through 15 days were observed for the subgroups immersed in orange juice and distilled water. However, a significant change in ΔE was observed in polished CS specimens immersed in coco-cola at the end of 15 days. Similar changes in ΔE vlaues were also observed in the specimens immersed in coffee. The color changes in specimens that were left unpolished were more pronounced. The changes in ΔE values of unpolished CS specimens immersed in coca-cola and coffee showed significant changes (Table 1).
Table 1.
Color stability of CS in different beverage groups with or without Sof-Lex system™ polishing.
| Baseline |
1 day |
15 days |
P-value | Post-hoc test | |
|---|---|---|---|---|---|
| Mean ± SD | Mean ± SD | Mean ± SD | |||
| Sof-Lex system™ polishing (Group I) | |||||
| Orange juice | 30.27 ± .36 | 30.16 ± .25 | 29.94 ± .43 | 0.124 | – |
| Coco Cola | 29.19 ± .19 | 29.16 ± .07 | 27.99 ± .30 | <0.001 | B, 1 > 15 days |
| Coffee | 30.08 ± .52 | 30.03 ± .37 | 29.30 ± .42 | 0.003 | B, 1 > 15 days |
| Distilled water | 30.11 ± .40 | 30.07 ± .64 | 29.84 ± .10 | 0.993 | – |
| No polishing (Group II) | |||||
| Orange juice | 29.77 ± .53 | 29.55 ± .52 | 29.28 ± .23 | 0.065 | – |
| Coco Cola | 29.91 ± .31 | 29.62 ± .79 | 27.06 ± .36 | <0.001 | B, 1 > 15 days |
| Coffee | 29.67 ± .59 | 29.44 ± .54 | 28.98 ± .27 | 0.007 | 1 > 15 days |
| Distilled water | 29.74 ± .33 | 29.73 ± .05 | 29.66 ± .67 | 0.804 | – |
The difference in ΔE was calculated at day 1 and day 15 and compared between the groups (with or without Sof-Lex system™ polishing disc). There were no signficant differences in the mean difference of ΔE’ s (baseline – 1 day and baseline – 15 days) between the groups polished with or without Sof-Lex system™ except for Coco-cola at 15 days. The mean difference in ΔE at 15 days was signficantly higher in group II than group I (P < 0.001) (Table 2).
Table 2.
Comparision of mean difference in ΔE among the different beverage groups at 1 and 15 days with or without Sof-Lex system™ polishing disc.
| Sub-group | Duration of exposure | Sof-Lex system™ polishing disc (Group 1) |
No polishing (Group 2) |
P-value |
|---|---|---|---|---|
| Mean ± SD | Mean ± SD | |||
| A. Orange juice | 1 day | 0.11 ± 0.49 | 0.22 ± 0.74 | 0.82 |
| 15 days | 0.33 ± 0.46 | 0.49 ± 0.53 | 0.52 | |
| B. Coco-Cola | 1 day | 0.03 ± 0.24 | 0.29 ± 0.83 | 0.22 |
| 15 days | 1.20 ± 0.38 | 2.85 ± 0.48 | <0.001 | |
| C. Coffee | 1 day | 0.05 ± 0.66 | 0.23 ± 0.57 | 0.6 |
| 15 days | 0.78 ± 0.80 | 0.69 ± 0.65 | 0.97 | |
| D. Distilled water | 1 day | 0.04 ± 0.84 | 0.01 ± 0.29 | 0.65 |
| 15 days | 0.27 ± 0.39 | 0.08 ± 0.75 | 0.47 |
Overall, results of the present study indicate that polishing of CS with Sof-Lex system™ enhances their resistance to staining by beverage solutions. Among the beverages, staining potential was found to be higher with coca-cola and coffee.
4. Discussion
The frequent reason for the replacement of tooth-colored restorative material is staining and discoloration.3 This can occur due to intrinsic or extrinsic factors. Resin dental restorative materials exposed to a variety of solutions such as tea, coffee, nicotine, cola drinks or other beverages and mouth rinses may cause staining.4 In addition, the color stability of dental restorations is also affected by the surface characteristics such as roughness. A smooth and polished surface do not tend to retain the stain and exhibit self-cleaning nature thus leading to longer color stability.
Surface treatments to achieve a smooth and polished surface have been described as an effective way to enhance the color stability of resin composite restorations.11,12 Different polishing techniques may diminish the roughness of resin composite restorations, thus increasing their color stability. However, some of the polishing steps may leave irregularities on the surfaces that may lead to the impregnation of dyes. Mylar strips are considered as “gold standard” in achieving superior surface smoothness, but their use is restricted to proximal surfaces on restorations. Furthermore, it is known that the composition of the resin matrix can influence the color stability.13
CS exhibits superior mechanical strength and reduced polymerization shrinkage owing to a higher filler loading. Higher filler loading has been achieved by utilizing different filler sizes in such a way that larger filler particles form a pre-packed grid, and the spaces in the grid are occupied by the smaller filler particle.5 A higher filler loading imparts high stability, slump resistance, and sculptability to the composite.
It exhibits thixotropic properties, which tend to show a low viscous state under force and return to a more viscous state after the removal of stress. It also exhibits less stickiness, which helps in the rapid and easy placement of the material and it can be polished easily with both silicon-based and abrasive discs with superior gloss.14
Polishing using Sof-Lex system™ disks provides considerable smoothness and glossy finish and has exhibited superior results in previous studies.12 The color changes can be assessed by using various instruments, including spectrophotometer and colorimeter. In the present study a spectrophotometer, spectrolino was used as they are considered to be more accurate than colorimeter.7
In the present study, composites stained considerably in Coco-cola and coffee beverages compared to orange juice and distilled water as depicted by lower ΔE values over 15 day challenge. The adsorption or absorption of colorants causes staining of the resins and is modulated by its water sorption rate.15 The Sof-Lex system™ polished CS specimens showed better results with minimal staining as compared to unpolished CS specimens in the present study for Coco-cola beverage at the end of 15 days.
The effect of beverages on the properties of composite resins are influenced by the amount and frequency of their intake.16, 17, 18 The staining of composite restorations is also effected by the pH, temperature as well as duration of exposure to staining solutions. In the present study, coco-cola beverage exhibited lowest pH and such a pH may affect the surface integrity of materials leading to softening of the matrix, loss of structural ions such as calcium, aluminium, and silicone from the glass filler phase.7,19, 20, 21 In addition, the composite resin restorative materials may exhibit higher water sorption in acidic media thus facilitating staining of the composite resins. Coffee exhibits higher pH than coca cola and hence the staining is less compared to coca cola.
From the clinical standpoint of view, the changes in color of the restorations would be perceptible only if delta E values are higher than 1. Considering this, the observed changes in the color in the present study are within the clinically acceptable limits. However, polishing of the CS significantly reduced the staining ability of beverages.
5. Conclusion
Polishing of nanoceramic composites with Sof-Lex system™ enhanced their color stability. Among the various beverages evaluated in the present study, coco-cola significantly altered the color of composites. However, the color change of nanoceramic composites exposed to different beverage challenge is within the clinically acceptable limits.
Conflicts of interest
Nil.
Funding
Nil.
Authors’ contributions
PS: Concept and design, data acquisition, initial draft. TPP: Study design, overall monitoring, resources, mentor, initial and final draft of the manuscript. KG: Data acquisition, mentor, study design, initial draft, final draft. KP: Data formal analysis, design, final draft
Acknowledgments
Nil.
References
- 1.Cramer N.B., Stansbury J.W., Bowman C.N. Recent advances and developments in composite dental restorative materials. J Dent Res. 2011;90(4):402–416. doi: 10.1177/0022034510381263. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Beun S., Glorieux T., Devaux J., Vreven J., Leloup G. Characterization of nanofilled compared to universal and microfilled composites. Dent Mater. 2007;23(1):51–59. doi: 10.1016/j.dental.2005.12.003. [DOI] [PubMed] [Google Scholar]
- 3.ceram.x - universal nano-ceramic restorative. https://www.dentsplysirona.com/content/dam/dentsply/pim/manufacturer/Restorative/Direct_Restoration/Composites_Flowables/Universal_Composites/ceramx_universal/ceramxuniversal_Scientific Compendium_EN.pdf
- 4.Vyver P van der. Predictable restorations using a new nano-ceramic composite – two case studies. Int Dent. 2016;6(2):1–8. [Google Scholar]
- 5.Ashok Jayalakshmi S. Factors that influence the color stability of composite restorations. Int J Orofac Biol. 2017;1(1):1. doi: 10.4103/IJOFB.IJOFB_5_16. [DOI] [Google Scholar]
- 6.Khokhar Z.A., Razzoog M.E., Yaman P. Color stability of restorative resins. Quintessence Int. 1991;22(9):733–737. [PubMed] [Google Scholar]
- 7.Powers J.M., Fan P.L., Raptis C.N. Color stability of new composite restorative materials under accelerated aging. J Dent Res. 1980;59(12):2071–2074. doi: 10.1177/00220345800590120801. [DOI] [PubMed] [Google Scholar]
- 8.Guler A.U., Yilmaz F., Kulunk T., Guler E., Kurt S. Effects of different drinks on stainability of resin composite provisional restorative materials. J Prosthet Dent. 2005;94(2):118–124. doi: 10.1016/j.prosdent.2005.05.004. [DOI] [PubMed] [Google Scholar]
- 9.Abu-Bakr N., Han L., Okamoto A., Iwaku M. Color stability of compomer after immersion in various media. J Esthetic Restor Dent. 2000;12(5):258–263. doi: 10.1111/j.1708-8240.2000.tb00232.x. [DOI] [PubMed] [Google Scholar]
- 10.Schroeder T., da Silva P.B., Basso G.R., Franco M.C., Maske T.T., Cenci M.S. Factors affecting the color stability and staining of esthetic restorations. Odontology. 2019;107(4):507–512. doi: 10.1007/s10266-019-00421-x. [DOI] [PubMed] [Google Scholar]
- 11.Ozera E.H., Pascon F.M., Correr A.B. Color stability and gloss of esthetic restorative materials after chemical challenges. Braz Dent J. 2019;30(1):52–57. doi: 10.1590/0103-6440201902263. [DOI] [PubMed] [Google Scholar]
- 12.Pala K., Neslihan T., Tuncer S., Serim M.E., Demirci M. Evaluation of the surface hardness, roughness, gloss and color of composites after different finishing/polishing treatments and thermocycling using a multitechnique approach. Dent Mater J. 2016;35(2):278–289. doi: 10.4012/dmj.2015-260. [DOI] [PubMed] [Google Scholar]
- 13.Chittem J., Sajjan G.S., Kanumuri M.V. Spectrophotometric evaluation of colour stability of nano hybrid composite resin in commonly used food colourants in Asian countries. J Clin Diagn Res. 2017;11(1):ZC61–ZC65. doi: 10.7860/JCDR/2017/22919.9193. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Bansal K., Saraswathi V., Acharya S. Effect of alcoholic and non-alcoholic beverages on color stability and surface roughness of resin composites: an in vitro study. J Conserv Dent. 2012;15(3):283. doi: 10.4103/0972-0707.97961. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Patel S.B., Gordan V.V., Barret A.A., Shen C. The effect of surface finishing and storage solutions on the color stability of resin-based composites. J Am Dent Assoc. 2004;135(5):587–594. doi: 10.14219/jada.archive.2004.0246. [DOI] [PubMed] [Google Scholar]
- 16.Al-Dharrab A. Effect of energy drinks on the color stability of nanofilled composite resin. J Contemp Dent Pract. 2013;14(4):704–711. doi: 10.5005/jp-journals-10024-1388. [DOI] [PubMed] [Google Scholar]
- 17.Doray P.G., Eldiwany M., Powers J.M. Effect of resin surface sealers on improvement of stain resistance for a composite provisional material. J Esthetic Restor Dent. 2003;15(4):244–250. doi: 10.1111/j.1708-8240.2003.tb00292.x. [DOI] [PubMed] [Google Scholar]
- 18.Catelan A., Briso A.L.F., Sundfeld R.H., Goiato M.C., dos Santos P.H. Color stability of sealed composite resin restorative materials after ultraviolet artificial aging and immersion in staining solutions. J Prosthet Dent. 2011;105(4):236–241. doi: 10.1016/S0022-3913(11)60038-3. [DOI] [PubMed] [Google Scholar]
- 19.Gönülol N., Yılmaz F. The effects of finishing and polishing techniques on surface roughness and color stability of nanocomposites. J Dent. 2012;40(SUPPL.2):e64–e70. doi: 10.1016/j.jdent.2012.07.005. [DOI] [PubMed] [Google Scholar]
- 20.Fay RM, Servos T, Powers JM. Color of restorative materials after staining and bleaching. Oper Dent. 1999;24(5):292–296. [PubMed] [Google Scholar]
- 21.Hubbezoglu I., Akaoğlu B., Dogan A. Effect of bleaching on color change and refractive index of dental composite resins. Dent Mater J. 2008;27(1):105–116. [PubMed] [Google Scholar]