Effect of extraoral aging conditions on the color stability of high temperature vulcanizing and room temperature vulcanizing maxillofacial silicone elastomers: An in vitro study (original) (raw)
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Brazilian Oral Research, 2009
One of the greatest challenges faced by buccomaxillofacial prosthetists is to reproduce the patient's exact skin color and provide adequate esthetics. To reach this objective, professionals must use materials with easy characterization and that maintain color over long periods of time. The objective of this study was, thus, to evaluate the color stability of two types of silicones, Silastic 732 and Silastic MDX4-4210. Twenty-four test specimens were made from each type of silicone and were divided into a colorless group and groups intrinsically pigmented with ceramics, cosmetics or iron oxide. The specimens were submitted to an accelerated system of aging for non-metallic materials. Readings were carried out initially and after periods corresponding to 163, 351, 692 and 1,000 hours of aging, using a reflection spectrophotometer analysis, and color alterations were calculated by the CIE L*a*b* system. The data were submitted to variance analysis and Tukey's test at a 5% level of probability. The results demonstrated that, irrespective of the period of time analyzed, all the materials underwent some type of chromatic alteration (∆E > 0). The test specimens made with Silastic 732 and MDX4-4210, without pigmentation, presented the lowest color alteration values after 1,000 hours of aging. Of the pigments, ceramic presented the lowest color alteration values and cosmetic powder presented the highest values. Thus, it may be concluded that the materials without the incorporation of pigments presented similar color alteration values, and did not differ statistically. The cosmetic powder used in this study was the pigment that most altered the color of the test specimens.
BMC Oral Health, 2019
Background: The inherent colour change in maxillofacial silicone elastomers becomes perceptible 6-12 months after fabrication. Determining the factors that accelerate the degradation of the prosthesis can help the clinicians increase its life span. Therefore, the aim of the study was to investigate the effect of time passage, processing temperature, and molding-stone colour on the colour change of maxillofacial silicone elastomers after darkroom storage for 6000 h. Methods: A total of ten study molds, each incorporating ten specimen gaps were fabricated using five different colors of dental stones. The gaps were filled with coloured Cosmesil M511 maxillofacial silicone elastomer. Five of the study molds, one of each stone color, were processed at room temperature (25°C) for 24 h while the remainder were vulcanized at 100°C for 1 h. Two stainless-steel molds were also fabricated to obtain a total of twenty controlgroup specimens of the same dimensions that were processed under the same conditions as the study molds. Colour measurements of the vulcanized silicone samples were performed using a Konica Minolta spectrophotometer. Initial measurements were obtained after the blocks were removed from the molds and the final measurements were recorded 6000 h after storage in the dark at 25°C and 40% relative humidity. The CIEDE2000 colour-difference formula was used to measure the changes in the colour. One-way and two-way ANOVA, and an independent-sample t-test were used for statistical assessments. Results: For every group, the colour change exceeded the perceptible thresholds. Thus, either the vulcanization temperature or the colour of the molding stone has a significant effect on the colour change over time. Those samples vulcanized in green and white molding stones at 100°C exhibited a significantly higher ΔL*, Δa*, and Δb* values relative to the samples vulcanized at room temperature. Conclusion: The molding-stone colour and vulcanization temperature both affect the degree of colour change after storage in a dark environment. The L*, a*, and b* values for the maxillofacial silicone elastomers are influenced by the direction of the increase or decrease according to the selected colour. This effect varies as the temperature increases.
Aim: The aim of the study was to evaluate the color stability of maxillofacial silicone elastomer (Cosmesil M511) after exposing them to five different human and environmental aging conditions. Material and methods: Sixty disk-shape maxillofacial silicone Cosmesil M511 (Principality Medical Ltd., South Wales, UK) (Part A: Part B = 10:1) specimens were prepared and equally divided into 5 groups. Dark room (control) (group A),outdoor weathering (group B), acidic perspiration (group C), neutral soap (group D) and disinfectant (group E) along with subgroups in each groups dark brown, medium brown and light brown using the principality skin shade P416, P406 and P418. The conditioning period for Group A, B, C are 3 months; group D and E for 30 hours. Color change (ΔE) was measured at the end of the conditioning period using spectrophotometer. Data was analysed with One-way analysis of variance (ANOVA) and Tukey's Post – Hoc tests. The probability value .05 is considered as significant level. Results: Four of the five treatment conditions induced perceivable color change (ΔE > 3). Specimens stored in outdoor weathering (Group B) condition for 3 months exhibit high (ΔE = 5.68), which was greater (p < 0.05) than that produced by disinfectant (Group E) (ΔE = 5.37). All groups exhibited detectable color change expect for dark room (Group A). Conclusion: There is inherent color stability of the three skin shades (dark brown, medium brown and light brown) which added to the overall color change of the silicone prosthesis. Visual perceptible and clinically unacceptable color change occurred when exposed to various extra oral aging conditions expect dark room condition. It can be said Cosmesil M511 have color instability under extra oral aging conditions.
Color changes in dry-pigmented maxillofacial elastomer resulting from ultraviolet light exposure
Journal of Prosthetic Dentistry, 1995
Five dry pigments and one maxillofacial elastomer were, evaluated for color changes (ΔE) resulting from prolonged exposure to two types of ultraviolet light. The elastomer, pigments, and pigmented elastomers were subjected to each ultraviolet light source for 400, 600, and 1800 hours, and ΔE color shifts were determined. The unpigmented elastomer underwent minimally perceptible color change after 600 hours of exposure to both types of ultraviolet light. Two pigments underwent substantial color change after 400 hours, whereas the remaining three pigments remained color stable after 1800 hours. It was concluded that for the materials tested, early color changes in a prosthesis may be the result of degradation of certain ultraviolet light-susceptible pigments, whereas longer term color shifts may be caused by color changes within the elastomer.
The Journal of Indian Prosthodontic Society, 2017
Context:Surveys have reported color fading as the most frequent reasons patients given for disliking their prostheses.Aim:The aim of the study is to compare the color variation between two maxillofacial silicone elastomers after subjecting them to extraoral aging conditions.Subjects and Methods:A total of 80 samples were made from M511 Maxillofacial Rubber (Part A: Part B = 10:1) and Z004 Platinum Silicone Rubber (Part A: Part B = 1:1) and divided into two main Groups A and B (40 each). These main groups were then subdivided into five subgroups (A1B1, A2B2, A3B3, A4B4, and A5B5) (n = 8); outdoor weathering, acidic perspiration, sebum (for 6 months), and neutral soap and disinfectant (for 30 h), respectively. Baseline L*a*b* values were recorded. The samples were subjected to the extraoral aging conditions, and the L* a*b* values were recorded after the aging period using a spectrophotometer.Statistical Analysis:The intergroup comparison was done by Kruskal–Wallis test, whereas the intragroup comparison was done by Mann–Whitney test.ResultsAll groups exhibited visually detectable, mean color differences that ranged from 3.06–5.21, except for A4B4. There was no statistical significance between the two materials when subjected to extraoral aging conditions.Conclusions:Visually perceptible and clinically unacceptable color changes occur when exposed to various extraoral aging conditions except for neutral soap solution immersion, for which values of Δ E* were clinically acceptable (ΔE < 3). It can be said for all practical purposes, clinically, the choice between M511 Maxillofacial Rubber (Part A: Part B = 10:1) and Z004 Platinum Silicone Rubber (Part A: Part B = 1:1) would yield more or less the same results, with unacceptable norms in terms of color stability under extraoral aging conditions.
Journal of Esthetic and Restorative Dentistry, 2015
Purpose: To evaluate the effect of different in vitro aging methods on color change (CC) of an experimental dental resin-based composite using CIELAB (ΔEab) and CIEDE2000 (ΔE00) color-difference formulas. Materials and Methods: The CC was evaluated with a spectrophotometer (CM700d, Konica Minolta,Tokyo, Japan) according to the CIE chromatic space. Disk-shaped specimens (Φ = 5 × 1 mm thick) (N = 10) were submitted to different in vitro aging methods: 30 days of water aging (WA); 120 hours of ultraviolet light aging (UVA); or 300 hours of an accelerated artificial aging (AAA) method with cycles of 4 hours of UV-B light exposure and 4 hours of moisture condensation to induce CC.The temperature was standardized at 37°C for all aging methods. CC was evaluated with ΔEab and ΔE00 formulas. Differences in individual Lab coordinates were also calculated. Data for the individual color parameters were submitted to one-way analysis of variance and Tukey's test for multiple comparisons (α = 0.05). Results: All in vitro aging methods tested induced CC, in the following order: WA: ΔEab= 0.83 (0.1); ΔE00 = 1.15 (0.1) < AAA: ΔEab = 5.64 (0.2); ΔE00 = 5.01 (0.1) < UVA: ΔEab = 6.74 (0.2); ΔE00 = 6.03 (0.4). No changes in L* or a* coordinates were ≥1; the methods with UV aging showed a yellowing effect due a large positive change in b*. Conclusions: All in vitro aging methods tested induced a CC, but to different extents. Changes in color followed similar trends, but with different absolute values when calculated with the CIELAB and the CIEDE2000 formulas.
BMC Oral Health, 2017
Background: Colour degradation is a major problem in maxillofacial silicone elastomers. Recent studies have focused on colour stability and the mechanical properties of the silicone elastomers. A colour match is also essential for the acceptance of the prosthesis by the patient. The aim of this study is to assess the colour degradation of the silicone elastomer after being moulded in different colours of dental stones at two different vulcanization temperatures. Methods: Five different colours of dental stones were used to fabricate a total of 120 silicone blocks using a Cosmesil M511 maxillofacial silicone elastomer. Vulcanization was completed at two different temperatures (25 and 100°Celsius). Colour measurements were obtained with a Conica Minolta spectrophotometer. The CIEDE2000 formula was used to calculate the colour differences (ΔE00). Two-way ANOVA, one-way ANOVA with Bonferroni corrected post-hoc p values and independent samples t-test were used for the statistical analyses. Results: High temperature vulcanization causes lightening of the maxillofacial silicone elastomers without regard to the dental stone colour (p = 0.001). Specimens moulded in green stone lightened least at room temperature (p = 0.999). Compared to the control group, at high temperature, all specimens moulded in coloured dental stones darkened significantly (p < 0.001 for white, blue and yellow; p = 0.006 for green; p = 0.045 for reddish-brown). In the high temperature group, the shift to a green chroma was significant in the white, yellow and green dental stones groups (p = 0.001, p = 0.002, p < 0.001, respectively). The mean b* of the high temperature control group was higher than that of the room temperature control group (p < 0.001). The only ΔE00 score lower than the perceptibility threshold for dental materials (ΔE00 = 1.30) was between the room temperature control group and the room temperature green dental stone group (ΔE00 = 0.96). Conclusions: Green and blue dental stones cause less colour degradation in silicone elastomers. Reddish-brown dental stones cause the most colour degradation in silicone elastomers. At 100°C, the colour of the silicone elastomer lightens and yellows even if the elastomer is vulcanized in a stainless steel mould. White, yellow and reddish-brown dental stones make the silicone elastomer appear more yellow even if the elastomer is vulcanized at room temperature.
Ultraviolet radiation-induced color shifts occurring in oil-pigmented maxillofacial elastomers
The Journal of Prosthetic Dentistry, 1999
Col oration of an extraoral maxillofacial prosthesis (EMFP) is typically achieved through the use of either oil-based or dry rare-earth pigments. The pigments are combined into the elastomer before polymerization, and final customization is enhanced by painting a thin layer of pigmented adhesive onto the surface of a prosthesis. More information is needed regarding the color stability of various pigments, pigmented elastomers, and pigmenting methods to develop more color stable EMFP materials.
The Journal of Contemporary Dental Practice, 2020
Aim: To evaluate the change in color of the maxillofacial silicone after curing using a mobile phone colorimeter application. Materials and methods: A two-piece metal mold was fabricated. Twenty five samples were made using M511, maxillofacial silicone. A jig was prepared to hold the mobile phone at a fix distance from the samples. The color was measured for each sample in terms of HSV (hue, saturation, value) with the mobile phone colorimeter application after manipulation and after polymerization of the samples. Data were statistically analyzed using the Student's paired t test and the software used in the analysis was SPSS 22.0 version. Results: The mean difference of hue was 1.32 ± 2.71, with p value 0.053. Mean differences in saturation was 0.72 ± 2.01, with p value 0.066. Mean differences in value were 2.16 ± 3.11, with a p value 0.002. The measure of value showed statistically significant differences (p < 0.05). Conclusion: There was a significant change in the value of the color of the maxillofacial silicone after polymerization. Clinical significance: Increasing the value of the color by 2-3% at the time of manipulation of the maxillofacial silicone with the use of a mobile phone colorimeter application can help the clinician to reproduce the same color in the final prosthesis after curing to achieve a predictable esthetic outcome for a facial prosthesis.