Background and Objectives: Polymethyl methacrylate (PMMA) is currently the material of choice for denture base fabrication, that it has the advantages of good pigment wettability, high gloss and so on. Uses of natural stains (amaranth and vanilla) cheap and available in our country instead of the synthetic stains with heat cure acrylic resin denture base material for matching with natural human gingiva. Materials and Methods: Ninety samples were prepared of pink heat cure acrylic resin VertexTM material, fifteen samples with natural additives and seventy five samples with synthetic Vertex acrylic stainTM. The color of samples and gingival color of 24 healthy young participate were measured by Vita Easyshade device then compared between them. Statistical analysis was done by special designed program prepared for this study in Mat lab program 2010 that calculate the color difference between all the measurements that appeared only the (ΔE) that ≤ 6.8. Results: Results showed that (ΔE) ≤ 6.8 between some of natural and synthetic stains matched in relation to color of patients' gingiva, and some natural stains matched the color of the patients' gingiva. Conclusions: The results approved can be using the natural stains vanilla and amaranth instead of the synthetic Vertex acrylic stains that is clinically acceptable compared in relation to patients.
Key Words: Natural stains, Vanilla, Amaranth, PMMA.
Polymethyl methacrylate (PMMA) is currently the material of choice for denture base fabrication (), that it has the advantages of good pigment wettability, high gloss and so on ().
In order to obtain a natural looking restoration, there are two crucial steps in everyday dental practice; the selection of color through shade guide which will harmoniously integrate itself with surrounding biological tissue and consequently the correct reproduction of the color in the prosthesis(). Healthy gingival color ranges from pale pink and pink to dark red or purple ().
Esthetic effects are sometimes produced in a restorative material by the incorporation of colored pigments; is pigments in non metallic materials such as resin, composites, dentures acrylics, silicone maxillofacial materials and dental ceramics().
Synthetic stains are mainly chemical products, which have some toxicity(). The obtainment of coloring matter based on natural products is of considerable importance since the United States have banned the use of synthetic coloring in foods().
Grain Amaranth (Amaranthus paniculatus) () it is a natural stain that the anthocyannin is the reddish pigments in amaranth flour and vegetation appear to have great potential as a source of natural, non-toxic red dyes, this pigment is used in food industry ().
Natural vanillin (4-hydroxy-3-methoxybenzaldehyde) is one of the
most common flavor chemicals and is used in a broad range of flavors(,) it is a tropical orchid belonging to the family Orchidaceae (). Color difference (ΔE) as value for color differences became a critical in color science as well as in industries ranging from textiles to dentistry that calculated as following ():
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Vita EasyShade device is one that used For spectrophotometer measurement, this instrument provide data obtained over the range of visible wavelengths about 400 to 700 nm, captures the tristimuli HCL and subsequently calculates the values of L*, a* & b*(). MATERIALS AND METHODS One type of pink heat-cured acrylic resin denture base material Vertex TM type was used with natural (amaranth and vanilla), and synthetic stain TM additives. The samples were prepared follow the recommended manufacturers' instruction powder/ liquid ratio. Curing was carried out by using conventional water bath methods in which placing flask in a thermostatically controlled water bath for curing cycle 1.5 hours at 74oC followed by 30 minutes at 100oC (). All prepared samples were stored in distilled water at 37oC for 7 days for conditioning before testing. Ten samples were prepared to the uniform size in dimension (30x20x1.5) ±0.03 mm (length, width and thickness respectively) (), samples were divided into two groups:
First Group: Fifteen samples of natural stain additives type as follows:
1. Five samples with amaranth stain 0.1% wt/wt.
2. Five samples with vanilla additives 10% wt/wt.
3. Five samples with mixture of amaranth 0.02% and vanilla 0.08% respectively wt/wt.
Second Group: Seventy five samples prepared with synthetic stain TM additive types:
1. Fifteen samples of vertex acrylic stain TM no.210 (1%, 5%, and 10% wt/wt).
2. Fifteen samples of vertex acrylic stain TM no.220 (1%, 5%, and 10% wt/wt).
3. Fifteen samples of vertex acrylic stain TM no.230 (1%, 5%, and 10% wt/wt).
4. Fifteen samples of vertex acrylic stain TM no.240 (1%, 5%, and 10% wt/wt).
5. Fifteen samples of vertex acrylic stain TM no.250 (1%, 5%, and 10% wt/wt) as in Figure (1).
Color measurements were repeated five times for each sample and the mean of L*,a* and b* were calculated. Twenty four male (12) and female (12) dental students with age range 24±1 year. Mean of three measurements of gingival color was evaluated in the anterior region (in midpoint between free gingiva and deepest point of sulcus in central and lateral incisor regions) as in Figure (2).
Measurement color matching: (CIE L*a*b*) color difference metrics were used for the performance analysis. Measurements were done by Vita Easyshade device that showed in Figure (3) to obtain the baseline L*, a*, b* values. The information from Dr.- lng. Wolfgang Rauh , a director Business Unit - Dental Devices in VITA company "can be use Easyshade to compare different samples of resins just be comparing the reported values but that the values will not correspond to values provided by other devices and similar to resins it be possible to use it to compare different gingiva but the values will not be absolute values")(). The total color change (ΔE) between values was calculated for each pairs evaluated using the formula:
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In principle, when ΔE ≤ 3.7() the difference in color between the paired values matched are acceptable in vitro and when ΔE ≤ 6.8() the difference in color between the paired values matched are acceptable in vivo, so the two samples are nearly have same color in vivo, when color difference be detected is > 6.8 that is not acceptable and the paired samples are not matched in vivo.