Color Change Evaluation of Denture Soft Lining Materials in Coffee and Tea

Effect of Extrinsic Pigmentation on Dimensional Stability, Hardness, Detail Reproduction, and Color of a Silicone

OBJECTIVE

 The aim of the study is to evaluate the effect of extrinsic pigmentation on the dimensional stability, hardness, detail reproduction, and color of a silicone after thermocycling.

MATERIALS AND METHODS

 Sixty samples of MDX4-4210 silicone (Dow Corning Corporation Medical Products) with intrinsic pink pigment (H-109-P, Factor II) and intrinsic opacifier (TiO) were fabricated. Two groups were created: Group 1-only intrinsic pigmentation (H-109P, Factor II + TiO) (Control); and Group 2-intrinsic (H-109P, Factor II + TiO) and extrinsic (Tan FE - 215, Factor II) pigmentation. The following tests were performed for each group: dimensional stability, Shore A hardness, detail reproduction, and color. Readings for the tests were taken before and after thermocycling (2,000 cycles). For dimensional stability and hardness, two-way analysis of variance (ANOVA) was used. One-way ANOVA was used for the color test. In case of significant statistical difference, the Tukey test was applied (p <0.05). All samples achieved the same detail reproduction score, therefore, no statistical evaluation was performed.

RESULTS

 For the dimensional stability test, comparing the initial time with the final time, there was a significant contraction in both groups after thermocycling. For the hardness test, comparing the time points, only group 1 showed a significant reduction in hardness after thermocycling. Groups 1 and 2 scored 2 for the detail reproduction test, before and after thermocycling. Comparing group 1 with group 2, there was no significant difference for color change.

CONCLUSION

 Based on the tests performed, extrinsic pigmentation did not show a negative effect on silicone, and therefore it can be indicated. The results of the dimensional, hardness, detail reproduction and color evaluations of the MDX4-4210 silicone were clinically acceptable in all cases in the groups with and without extrinsic pigmentation.

Antifungal Efficacy of Ocimum Basilicum Essential Oil in Tissue Conditioner Against Candida Albicans: An In vitro Study

Tissue conditioner is used to condition inflamed mucosa induced by denture stomatitis. However, the drawback of the aging tissue conditioner is increased surface roughness, thus enhance microbial adhesion. Ocimum basilicum is known for its antimicrobial effects but its use in liners has not been investigated. Aims: This study aimed to determine the antifungal efficacy of ocimum basilicum essential oil (OBEO) when incorporated into tissue conditioner against C. albicans and the effect on the properties.

Subject and Methods

The antimicrobial activities were determined using disc diffusion, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). After incorporation into tissue conditioner, the color difference and surface roughness were evaluated after one day. The surface morphology and the antibiofilm activity were assessed on day 1 and day 14.

Results

The zone of inhibition of OBEO on Sabouraud Dextrose agar was significantly wider than nystatin and deionized water (P=0.000) with the MIC and MFC values were 1.25% and 5%. Both OBEO concentrations incorporated into tissue conditioner, there was no significant difference of color changes in the light-dark character (P=0.102) and surface roughness (P=0.920) when compared to the control group. As for adherence at days 1 and 14, both concentrations of OBEO in tissue conditioner show significantly reduced adherence of C. albicans compared to the control group (P=0.000).

Conclusion

OBEO exhibited significantly better antifungal activity against C. albicans when compared to nystatin and deionized water and resulted in no significant color changes, better surface roughness and lesser adherence of C. albicans toward the tissue conditioner.

Colour Stability of 3D-Printed and Prefabricated Denture Teeth after Immersion in Different Colouring Agents—An In Vitro Study

This study investigated the colour stability of three dimensional (3D)-printed and conventional denture teeth after immersion in different colourants. A total of 60 artificial maxillary central incisors were selected from three types of materials: 3D-printed dental resin (NextDent, 3D Systems, Soesterberg, The Netherlands), prefabricated acrylic teeth in Ivostar Shade (Ivoclar Vivadent, Schaan, Liechtenstein), and SpofaDent Plus in shade A2 (SpofaDental, Jičín, Czechia). These were immersed in four types of colourants at room temperature (23 °C ± 1 °C), including artificial saliva (pH = 6.8) as a control group, coffee, red wine, and Coca-Cola (n = 5). The temperature and the pH of the colouring agents were maintained throughout all immersion periods. After 7 days (T1), 14 days (T2), and 21 days (T3), the ∆E values were measured with a SpectroShade Micro (SpectroShade, Oxnard, CA, USA) spectrophotometer. Their means were then calculated and compared by two-way ANOVA. The independent factors, immersion time and different staining solutions, as well as the interaction between these factors, significantly influenced ΔE. The highest and the lowest mean ∆Es were recorded for prefabricated teeth in red wine, and 3D-printed teeth in artificial saliva, respectively. All the specimens demonstrated an increased colour change at T1 compared to T3, and the difference in mean ∆E was statistically significant.

Color Stability Determination of CAD/CAM Milled and 3D Printed Acrylic Resins for Denture Bases: A Narrative Review

The aim of this paper is to review the available literature on the different methods for color stability determination of CAD/CAM milled and 3D printed resins for denture bases. The methodology included applying a search strategy, defining inclusion and exclusion criteria and selecting studies to summarize the results. Searches of PubMed, Scopus, and Embase databases were performed independently by three reviewers to gather the literature published between 1998 and 2022. A total of 186 titles were obtained from the electronic database, and the application of exclusion criteria resulted in the identification of 66 articles pertaining to the different methods for color stability determination of CAD/CAM acrylic resins for denture bases. Color change in dental materials is clinically very important for the dental operator, as it determines the clinical serviceability of the material. Discoloration of the denture bases can be evaluated with various instruments and methods. Dental resins may undergo color changes over time due to intrinsic and/or extrinsic factors. The extrinsic factors are considered the more frequent causes of color changes. According to a number of studies, CAD/CAM fabricated acrylics have achieved better color stability than the conventional PMMA (polymethyl methacrylate) resins.

Effect of Food Colorants on Color of Denture Base Acrylic Resins

Background:

Acrylic resin has been successfully used for complete denture fabrication for many years. Color stability is very crucial clinical properties for dental materials, and color change may be an indicator of aging or damaging of materials.

Aim and Objectives:

This study has been designed to determine the color stability of heat cure denture base acrylic resins in commonly consumed solutions causing stains.

Methodology:

Four hundred disc samples of four commercially used heat cure denture base resins (Trevalon®, DPI®, Veracril®, and Pyrax®) were fabricated (100 in each group). These were checked for any change in optical density by immersing them in four different staining solutions (tea, coffee, turmeric, and betel leaf, i.e., paan) and synthetic saliva for 1-month synthetic saliva was taken as control. The denture cleansers were also evaluated for their efficacy determined by their ability to remove the stains caused by the staining solutions.

Results:

It was observed that Trevalon® showed least change in optical density and coffee illustrated the maximum potential for staining the denture base resins and is the most difficult to be removed using a denture cleanser.

Conclusion:

It can be concluded that Trevalon® demonstrated maximum color stability. Among the staining solutions, coffee caused maximum stains.

Analysis of Color and Hardness of a Medical Silicone with Extrinsic Pigmentation after Accelerated Aging

Objective  The aim of this study is to evaluate the color alteration and shore A hardness of a medical silicone with extrinsic pigmentation, before and after accelerated aging.

Materials and Methods  Twenty samples (Silastic Q7–4735) were made with an intrinsic pigmentation. This intrinsic pigmentation was composed of a pink pigment (H-109-P, Factor II) and an opacifier (ZnO). All samples had standardized dimensions (45-mm diameter and 2-mm thickness). Half of the 20 samples manufactured subsequently received an extrinsic pigment (Tan FE–215, Factor II). Therefore, two groups were created ( n = 10): Group 1, group with intrinsic pigmentation and without extrinsic pigmentation (control) and Group 2, group with intrinsic and extrinsic pigmentation. Samples were submitted to color and Shore A hardness tests, before and after 1,008 hours of aging.

Statistical Analysis  Color alteration data were submitted to Student’s t -test ( α = 0.05). Shore A hardness data were submitted to two-way analysis of variance and Tukey test ( α = 0.05).

Results  The incorporation of the extrinsic pigment on the silicone did not affect its color (ΔE) when the two groups were compared ( p = 0.232). Regarding the hardness test, the interaction between group and period did not interfere with the hardness results( p =0.599). However, the period factor showed that there was a reduction in the hardness of the silicone after aging ( p < 0.05).

Conclusion  In this study, all the hardness and color results of the silicone used were clinically acceptable, regardless of the presence of extrinsic pigmentation.

Long-Term Soft Denture Lining Materials

Long-term soft denture lining (LTSDL) materials are used to alleviate the trauma associated with wearing complete dentures. Despite their established clinical efficacy, the use of LTSDLs has been limited due to the unfavorable effects of the oral environment on some of their mechanical and performance characteristics. The unresolved issue of LTSDL colonization by Candida albicans is particularly problematic. Silicone-based LTSDL (SLTSDL) materials, which are characterized by more stable hardness, sorption and solubility than acrylic-based LTSDLs (ALTSDLs), are currently the most commonly used LTSDLs. However, SLTSDLs are more prone to debonding from the denture base. Moreover, due to their limitations, the available methods for determining bond strength do not fully reflect the actual stability of these materials under clinical conditions. SLTSDL materials exhibit favorable viscoelastic properties compared with ALTSDLs. Furthermore, all of the lining materials exhibit an aging solution-specific tendency toward discoloration, and the available cleansers are not fully effective and can alter the mechanical properties of LTSDLs. Future studies are needed to improve the microbiological resistance of LTSDLs, as well as some of their performance characteristics.

Comparative evaluation of color change between two types of acrylic resin and flexible resin after thermo cycling. An in vitro study

Evaluation of the effect of different beverages (tea with sugar, coffee with sugar, and Pepsi), and immersion time cycles (2, 4, and 12 weeks) on color change property, and dimensional change of Vertex Dental BV, Netherlands heat cured acrylic resin, recently modified Vertex Dental BV, Netherlands heat cured acrylic resin with additive (20 % banana oil), and Valplast(®) flexible resin (FR) denture base materials by using artificial saliva cycle. The total samples of this study for color, and dimensional changes were 360 samples, divided into three groups according to the type of the material, Vertex Dental BV, Netherlands heat cured acrylic resin, modified heat cured acrylic resin (Vertex with additive 20 % banana oil), and Valplast(®) FR groups, each group contains 120 samples. The thermal cycling used in this study was as follows: The samples were incubated in distilled water at 37 ± 1 °C for 2 days for conditioning. Then, the samples were immersed in beverage solutions for 10 min daily at 50 ± 1 °C temperature for tea, and coffee with sugar, while for Pepsi at 20 ± 1 °C. Then, the samples were immersed in artificial saliva at 37 ± 1 °C for 5 h, and 10 min. This cycle was repeated three times daily, and then the samples were immersed in distilled water at 22 ± 2 °C room temperature for 8 h at night. This cycle was repeated for 2, 4, and 12 weeks. At the end of each time period, the immersed samples were tested to evaluate the color change property. Descriptive statistics, ANOVA, and Duncan's multiple range tests were used to analyze the collected data. The results of this study showed that, in comparison between the materials at different times for colors L*a*b* properties, there were significant differences at P ≤ 0.05 except in color b* at 12 weeks, which showed no significant difference at P > 0.05 between materials. And there was a significant difference in dimensional change at P > 0.05 for different beverages, and times of immersion. The largest color, and dimensional changes were observed in the Valplast(®) FR, whereas tea was found to be the most chromatic agent, and showed unaccepted color change (ΔE ≤ 3.7) in vitro study as compared with coffee, Pepsi, and artificial saliva solutions.

Effect of different solutions on color stability of acrylic resin-based dentures

The aim of this study was to evaluate the effect of thermocycling and immersion in mouthwash or beverage solutions on the color stability of four different acrylic resin-based dentures (Onda Cryl, OC; QC20, QC; Classico, CL; and Lucitone, LU). The factors evaluated were type of acrylic resin, immersion time, and solution (mouthwash or beverage). A total of 224 denture samples were fabricated. For each type of resin, eight samples were immersed in mouthwashes (Plax-Colgate, PC; Listerine, LI; and Oral-B, OB), beverages (coffee, CP; cola, C; and wine, W), and artificial saliva (AS; control). The color change (DE) was evaluated before (baseline) and after thermocycling (T1), and after immersion in solution for 1 h (T2), 3 h (T3), 24 h (T4), 48 h (T5), and 96 h (T6). The CIE Lab system was used to determine the color changes. The thermocycling test was performed for 5000 cycles. Data were submitted to three-way repeated-measures analysis of variance and Tukey's test (p<0.05). When the samples were immersed in each mouthwash, all assessed factors, associated or not, significantly influenced the color change values, except there was no association between the mouthwash and acrylic resin. Similarly, when the samples were immersed in each beverage, all studied factors influenced the color change values. In general, regardless of the solution, LU exhibited the greatest DE values in the period from T1 to T5; and QC presented the greatest DE values at T6. Thus, thermocycling and immersion in the various solutions influenced the color stability of acrylic resins and QC showed the greatest color alteration.

Color changes of autopolymerized silicone or acrylic soft denture reliners: the effect of accelerated aging

The aim of this in vitro study was to investigate the effect of accelerated aging on the color stability of six autopolymerized silicone and acrylic soft reliners. Ten specimens for each material were fabricated. Initial color was measured with a tri-stimulus colorimeter. One set of five specimens was placed in distilled water at 37 °C under dark for 15 days, while the remaining were subjected to photoaging initially for 1 and then for 6 days. Color changes (ΔE) then calculated. Data were analysed by ANOVA, Tukey and t tests at a = 0.05. All the reliners after storage in water showed ΔE ranged from 2.8 (Mucopren Soft) to 7.9 (Vertex Soft). After accelerated aging for 1 day, ΔE ranged from 4.6 (Vertex Soft) to 12.4 (Eversoft) whereas after 6 days from 1.7 (Ufigel SC) to 11.8 (Eversoft). All the reliners showed perceptible ΔE except Ufigel SC in 6 days aging and clinically unacceptable ΔE except Sofreliner S and Vertex Soft after aging for 1 day. Eversoft showed the highest discoloration after aging.

Characteristics of denture thermoplastic resins for non-metal clasp dentures

Six thermoplastic resins and conventional acrylic resin were examined to characterize their mechanical and physical properties, water sorption, solubility, flexural strength, modulus of elasticity, tensile strength and color stability. Thermoplastic resins for non-metal clasp dentures exhibiting low water sorption and solubility offer hygienic advantages. Since they have a low modulus of elasticity and are easily manipulated, these materials make it possible for larger undercuts to be used for retention compared to acrylic resin. Not all of the thermoplastic resins tested fractured after the bending test in contrast to the conventional denture base resin, which fractured when tested beyond its proportional limit. It was also found that clinically noticeable staining may occur on the polyamide resins and polyethylene terephtalate resins.

Denture Cleansers, Soft Lining Materials and Water Temperature: What is the Effect?

Aim

To investigate the effect of water temperature, in association with four denture cleansers, on the colour and surface roughness of five soft lining materials.

Method

Two silicone soft lining materials (Molloplast B and Sofreliner) represented the heat-cured, laboratory-based and chairside materials that are available. The wide range of chairside, acrylic resin-based, temporary soft lining materials was represented by Coe-Soft, Viscogel and Eversoft. An alkaline hypochlorite (Dentural) and three effervescent peroxide solutions with a range of active pH values (Steradent Active Plus, pH 6; Steradent Extra Strength, pH 3; Superdrug Fresh, pH 11) were selected as the cleansers. The denture cleansers were used at two temperatures: 55 °C (manufacturers’ recommended temperature) and 80 °C. The colour of the specimens was evaluated using a colorimeter and the surface roughness was assessed using a three-dimensional, non-contact surface profilometer. This study reported on the effect of using both the higher temperatures and the recommended temperature on the colour and roughness of permanent and temporary soft lining materials.

Results and Conclusion

The results of the study showed that the temperature of the water used with denture cleansers might have a detrimental effect on the colour and surface roughness of some permanent and temporary soft lining materials.