Journal of Indian Society of Pedodontics and Preventive Dentistry
Journal of Indian Society of Pedodontics and Preventive Dentistry
                                                   Official journal of the Indian Society of Pedodontics and Preventive Dentistry                           
Year : 2016  |  Volume : 34  |  Issue : 3  |  Page : 233--237

Color stability of esthetic restorative materials used in pediatric dentistry: An in vitro study


Hanisha Adusumilli1, Jogendra Sai Sankar Avula1, Pranitha Kakarla1, Sujatha Bandi1, George Manoj Kumar Mallela2, Krishna Vallabhaneni1,  
1 Department of Pedodontics and Preventive Dentistry, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh, India
2 Department of Pedodontics and Preventive Dentistry, SVS Institute of Dental Sciences, Mahbubnagar, Telangana, India

Correspondence Address:
Jogendra Sai Sankar Avula
Department of Pedodontics and Preventive Dentistry, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh
India

Abstract

Background: Children consume foods that are colorful which contain food additives that stain not only the tooth structure but also the restorations. As esthetics is of prime concern for both parents and children nowadays, long-term color stability of restorative materials is of utmost importance. Aim: To evaluate the color stability of two tooth-colored restorative materials (conventional glass ionomer cement [GIC] and giomer) when immersed in various consumable drinks and food (aerated beverage, ice candy, and health drink) at different immersion periods (low, moderate, and high). Materials and Methods: A total of 100 specimens were made with each restorative material. Ten were used as a control and remaining (n = 90) as experimental. The experimental specimens were divided into three groups based on media of immersion (n = 30 each) and were further divided into three subgroups based on immersion time (n = 10 each). The color changes (ΔE values) were measured using spectrophotometer. Results: Both the tested materials showed color change; however, conventional GIC showed greater ΔE values when compared to giomer and the samples exposed to aerated beverage resulted in highest color change. It is also noticed that greater the exposure time, higher are the ΔE values. Conclusion: Giomer showed more resistance to color change than conventional GIC with all the tested media and immersion regimes.



How to cite this article:
Adusumilli H, Avula JS, Kakarla P, Bandi S, Mallela GM, Vallabhaneni K. Color stability of esthetic restorative materials used in pediatric dentistry: An in vitro study.J Indian Soc Pedod Prev Dent 2016;34:233-237


How to cite this URL:
Adusumilli H, Avula JS, Kakarla P, Bandi S, Mallela GM, Vallabhaneni K. Color stability of esthetic restorative materials used in pediatric dentistry: An in vitro study. J Indian Soc Pedod Prev Dent [serial online] 2016 [cited 2022 May 23 ];34:233-237
Available from: https://www.jisppd.com/text.asp?2016/34/3/233/186740


Full Text

 Introduction



In the modern civilized cosmetic conscious world, well-contoured and well-aligned white teeth set the standard for beauty. Apart from esthetics, any anomalies in size, shape, color, and structure of whole or part of the dentition can also lead to problems such as decreased masticatory efficiency, speech disturbances, development of parafunctional habits, and psychological problems.[1] Thus, restoring a decayed primary teeth is a prime requisite not only for the psychological development of the child but also for the physiological development of permanent dentition.

The color, shape, and surface texture of the teeth are very important in giving a beautiful smile.[2] The demand by parents and children toward a natural appearance led to research for the development of materials that simulate natural teeth. Many restorative materials such as conventional glass ionomers, composite resins, and resin-modified glass ionomers were introduced. Recently, compomer, ormocer, and giomer restorative materials with improved properties which can be used not only for esthetic purpose but also to restore cavitated lesions in both primary and permanent dentition were developed.[3]

Color sustainability of restorative materials is necessary to assess the success or failure of the treatment. The esthetics of these materials becomes compromised when it gets exposed to the dynamic environment in the oral cavity due to the presence of microflora, saliva, and frequent intake of colored food and beverages which becomes a challenging task to dental experts.

The aim of this study is to evaluate the effect of food and beverages commonly consumed by children on the color stability of two tooth-colored restorative materials in laboratory conditions.

 Materials and Methods



The present in vitro study has been carried out in the Department of Pedodontics and Preventive Dentistry in collaboration with Quality Control Lab, Professor Jayashankar Telangana State University.

Out of the total of 200 samples, hundred samples were prepared with conventional glass ionomer cement (GIC) Type II (GC corporation ®, Tokyo, Japan) and the other with resin composite containing surface prereacted glass (S-PRG) ionomer fillers – Giomer (Beautifil II ®, Shofu Dental Corporation, Japan). Standard specimens were prepared using brass mold (6 mm inner diameter and 2 mm thickness) with GIC as specified by the manufacturer instructions in a ratio of 1.8:1 at room temperature (23°C, fold on technique) and with giomer, which is available as a single component. The materials were packed into the disks with a cement carrying instrument, covered by two mylar strips and were allowed to set by holding two glass slabs on either side of the brass mold with a constant hand pressure. Chemically activated glass ionomer is allowed to set completely, and the giomer was light cured according to the recommended exposure time of 20 s with an LED light of output 600 mW/cm 2. The prepared disks were evaluated for cracks, voids, and irregularities, and the procedure was repeated until sufficient samples were procured. All the disks were premeasured with digital weighing machine and those with mean weight of 0.12 ± 0.02 (conventional GIC) and 0.15 ± 0.02 (giomer) were considered. Markings were made on one side for better identification and then the samples were stored in distilled water for 24 h at 37°C to achieve rehydration. Before starting the immersion regime, baseline values were evaluated using spectrophotometer, with the CIELAB scale L*, a*, and b *.

The pH of the test solutions was determined with a pH meter, by placing an electrode in 5 ml of test solution, which was calibrated with standard solutions between each measurement for accuracy. The measured pH of the immersion solutions are as follows – aerated beverage (Thums Up, Coco-Cola Company) (2.96); ice candy (Orange Paddle Pop, Kwality Walls) (3.12); health drink (Horlicks, GlaxoSmithKline Consumer Healthcare) (6.98); and mineral water (6.84). The sample distribution for each material is described in [Table 1].{Table 1}

The regime of immersion followed was according to Maupomé et al.[4] For low, medium, and high immersion regime, the specimens were subjected to 1, 5, and 10 times per day lasting for 5 min distributed evenly over a 12 h period. Following the immersion regime, the samples were stored in deionized water at room temperature till further use. The test solutions were changed every day to prevent fungal contamination.

The specimens of each restorative material were stored in an airtight plastic container containing 25 ml of respective immersion media. The whole procedure was carried out for 15 days. Further, all the specimens were analyzed for change in color using a spectrophotometer [Figure 1] and was calibrated according to manufacturer's recommendation, before each measurement. Values were recorded in International commission on illumination (CIE) CIE L*a*b* which is an approximately uniform color space with coordinates for lightness, namely, white/black (L), red/green (a), and yellow/blue (b) and color change was calculated from the mean ΔL*, Δa*, and Δb* values for each specimens with the following formula.[5]{Figure 1}

Equation: ΔE* = [(ΔL*)2 + (Δa*) + (Δb*)2]½.

The whole procedure was carried out by single operator. To avoid bias, a second investigator randomly evaluated the test samples. As the interexaminer variability was not significant, the prior's results were only considered, and the values were tabulated and subjected to statistical analysis.

 Results



The mean and standard deviations were calculated by descriptive statistics and the groups were compared using ANOVA test. The P value was taken as significant when <0.05. The results depicted that in all the immersion regimes, GIC samples immersed in aerated beverage showed the highest color change followed by ice candy, health drink, and mineral water. Among the immersion regimes, high immersion groups in all the three immersion media showed highest color change when compared to other groups. The same results were observed with giomer. Comparing both the restorative materials, GIC showed the greatest color change compared to giomer which is statistically significant. Increased ΔE values were noticed with increased immersion period [Table 2].{Table 2}

 Discussion



In modern day dentistry, a major challenge of emphasis is laid over esthetics. An ideal esthetic restorative material must mimic the natural tooth in color, translucency, surface texture, and also show color stability for a prolonged period of time.[6]

GIC introduced in 1972 by Wilson and Kent has a property of low coefficient of thermal expansion, physicochemical bonding to both enamel and dentin, and the release of fluoride but are less acceptable due to poor abrasion and fracture resistance than resin-based materials.[7] On contrary giomer, a unique class of restorative material has the distinguishing feature of a stable S-PRG, which is coated with an ionomer lining incorporated in a resin matrix. This arrangement aids in the protection of the glass core from moisture, adding to long-standing esthetics, and durability of the conventional composites with ion release and recharge property.[8] These materials used in this study are well recognized by pediatric dentists as the best suited restorative materials to fulfill both restorative and preventive aspects.

Increased urbanization has led the society to revolve away from household cooking to processed food and beverages which include a wide range of coloring agents that not only increases the risk of obesity, diabetes, and cardiovascular diseases but also affect the color stability of the esthetic restorative materials. Therefore, the aim of the present study is to evaluate the color stability of two tooth-colored restoratives when exposed to different media.

Children are more attracted to food items with bright colors such as red, green, orange, and yellow. Considering this aspect, a pilot study was conducted with children in our department to note the choice of color by showing various color dice candies (pink, yellow, orange, and red) where most of them preferred orange. Thus, orange-colored ice candy was chosen as one of the immersion media.

Despite various confines, children and adolescents are consuming aerated drinks more often these days over traditional drinks such as lassi, fresh fruit juices, lime water, and coconut water.[9] Taking this into consideration, aerated drink (Thums up) was selected for this study.

Malted beverages are health drinks that are widely consumed as taste enhancers to encourage intake of milk among growing children in India.[10] Motwani and Agarwal reported from his survey that among the five brands available in Indian market (Boost, Bournvita, Complan, Horlicks, and Milo), Bournvita shared the largest market.[11] Based on this, a pilot study was designed to evaluate the color stability of conventional GIC when immersed in milk mixed with various commercially available health drinks (Boost, Horlicks, Bournvita, Maltova, and Complan) and the highest color change was noticed with Horlicks samples followed by Bournvita, Maltova, Complan, and Boost. Hence, Horlicks mixed with milk was considered as the third immersion media.

Consumption pattern put forth by Maupomé et al. was adopted as it closely resembles a real-time sipping pattern of soft drink. This immersion regime (low, medium, and high immersions) also depicts the effect of variations consumption patterns.[4]

In the present study, carbonated drink showed the highest color change among the immersion media similar to the results observed by Bansal et al.[12] The color change in the carbonated drink group could be attributed to the change in the surface roughness of the samples and low pH of the solution, which further aids in the adsorption of color onto the surface, plus cola being a brown carbonated beverage gains its color through the addition of caramel which exhibits color ranging from pale yellow to deep brown.[4],[13] Apart from staining potential, other reasons that could be attributed include the inherent acidity due to the presence of both phosphoric and carbonic acid, which tends to decrease the pH (2.96) and increase enamel decalcification, erosion, microleakage, and surface degradation of resin matrix and surface erosion of filler contents.[13]

The color change due to ice candy noticed in this study may be attributed to its low pH (3.12) and artificially added colors. Similar study by Azer et al. (2010) evaluated the effect of pH on tooth discoloration using food colorant and stated that although food/beverage pigments are associated with extrinsic staining, the degree, and type of stain are influenced by pH.[14]

The color change in health drink samples can be ascribed to the presence of cocoa solids, which was substantiated by the findings of Sangeetha et al.[15] However, the samples in the control group did not show any color change which could be due to the absence of coloring agents in water. Prabhakar et al. stated that artificial saliva and other storage media such as lactic acid, deionized water, and water did not show any significant color change.[16] In contrast, Uzun et al. stated that water also promoted slight color change.[17]

In the present study, it was also observed that discoloration of the samples are increased with time, with greatest discoloration in high-immersion regime followed by medium and low. These results are consistent with the study done by Bansal et al.[12] and Malekipour et al.[18]

Out of the two restorative materials tested, GIC showed greater color change compared to giomer in all the immersion media and immersion regimes. This could be attributed that the set material needs to be protected from salivary contamination for several hours. If not, water loss occurs making the surface weak and opaque, subsequently material shrinks, cracks, and may even debond.[19] Subsequently, the inferior values in giomer are due to the higher filler loading of 83.3 wt.% and a smaller particle size of 0.8 μm. Giomer with a smaller particle size will have a smoother surface and will retain fewer surface stains than rough surfaces. Furthermore, the lower staining susceptibility may be partly attributed to the relatively higher TEGDMA concentration.[20]

Study results by Hotwani et al. reconfirms the fact that giomer exhibits less color change when compared to resin-modified glass ionomer cement when immersed in different children beverages (Orange juice, Bournvita milk, and Coke).[20] Lack of color stability in conventional GIC could be due to the polyacid content in the material which can be explained by the degradation of metal polyacrylate salts.[21] In acidic solutions, H + ions of citric acid diffuse into the glass ionomer component that may replace and cause diffusion of metal cations to dissolve. Thus, the material presents a rough surface with voids, and the undissolved glass particles result in greater water and food colorant absorption.[22] The relative susceptibility of GIC for staining could be attributed to the porosity of the glass particles, dehydration after setting and drying, and microcracks that allow staining and discoloration of the restoration.[23]

On contrary, the color change in giomer can be attributed to its fluoride releasing property and the water soluble component that leaches out after immersion in an aqueous solution.[24] The water sorption in giomer could be due to the presence of prereacted glass polyacid zones which become as a part of the filler structure. These zones on the surface of glass filler particles appear to generate osmotic effect during water storage which leads to water absorption, swelling, and pressure which in turn implies greater the degree of water sorption, greater will be the color change.[25] Giomer containing Bis-GMA and TEGDMA are also considered to be susceptible to staining due to their increased hydrophilicity.[26]

Since it is an in vitro study, the ΔE values may be exaggerated as the role of saliva or oral clearance in retarding the long-term build-up of stains in the oral environment cannot be simulated. However, we recommend further studies to be carried out to evaluate the surface irregularities, water sorption, and dissolution of these restorative materials using temperature and pH as variables. Incentive behind this study will help the professionals to advise patients about the staining characteristics of various beverages on tooth-colored restorations. However, attention regarding certain contributing factors such as proper powder/liquid ratio, polymerization, surface protection, finishing, and polishing should be focused which will in turn help in the long-term color stability of the tooth-colored restorative materials.

 Conclusion



Based on the methodology employed and the results obtained, it may be concluded that:

Conventional GIC showed the maximum color change in all the immersion media and among all the immersion regimesAerated beverage resulted in highest ΔE values followed by ice candy, health drink, and mineral waterElevated ΔE values were noticed with increased immersion period.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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