Effects of different food colorants and polishing techniques on color stability of provisional prosthetic materials

The colour stability of 3D-printed, non-invasive restorations after 24 months in vivo - esthetically pleasing or not?

OBJECTIVES

The aim of the present prospective study was to evaluate the colour stability of 3D-printed non-invasive restorations after 24 months in vivo.

METHODS

The study included 29 patients, who received 3D-printed restorations made of a computer-aided design (CAD) / computer aided-manufacturing (CAM) hybrid material (n = 354). Restoration colour of 190 restorations was measured using a spectrophotometer. By applying the CIELAB system, *L (lightness), a* (red-green) and b* (blue-yellow) values were recorded. An evaluation of the colour differences (ΔE) after 6, 12 and 24 months was conducted.

RESULTS

Analysis of colour differences of 3D-printed restorations showed continuous discolouration of the restorations. After one year 34 % and after two years 18 % of the restorations were rated alpha or bravo, indicating no or hardly visible colour change. After two years, 54 % of the evaluated restorations yielded a colour difference with ΔE > 6.8 (delta). More than 82 % of the evaluated restorations showed values between ΔE 3.8 - 6.8 (charlie) and ΔE ˃ 6.8 (delta) after two years.

CONCLUSIONS

3D-printed non-invasive restorations showed an overall reduced colour stability after 24 months in vivo.

CLINICAL SIGNIFICANCE

The present study provides first clinical data regarding 3D-printed restorations. These restorations are recommended for a wearing time of about 6 months.

Comparison of Various Surface Treatment Procedures on the Roughness and Susceptibility to Staining of Provisional Prosthodontic Materials

Esthetically pleasing temporary prostheses are often necessary for extended periods in a variety of clinical scenarios. Adjustments to the occlusion or margins are commonly needed before cementing the temporary prosthesis. Therefore, it is clinically necessary to repolish the rough surface to avoid biological and esthetic issues associated with rough surfaces. The purpose of this in vitro study was to assess and compare the impact of various polishing protocols on the surface roughness and color stability of three resin materials used for provisional crowns. A total of 150 specimens were fabricated from auto-polymerizing polymethyl methacrylate, bis-acryl composite, and Methyl methacrylate-LC resin using a stainless steel mold. Each material group was divided into five groups (n = 10) based on the applied surface treatment: positive control group (G1): no roughening or surface treatment, Negative control group (G2): acrylic bur-roughened surface without any polishing, the different surface treatment groups of silicon carbide and aluminum oxide stone polishing (G3), diamond-coated rubber twist (G4), and Surface Glaze (G5). An optical profilometer was used to assess the surface roughness of all samples. After undergoing 6000 cycles of thermocycling followed by immersion in a coffee solution for 15 days at 37 °C, color parameters were measured using a spectrophotometer both before and after a storage period to evaluate color differences. A two-way ANOVA test with α = 0.05 significance level was carried out to determine the impacts of both the materials utilized and the polishing protocol. Among the three types of resin examined, the bisacryl group exhibited superior surface quality in positive control groups, while PMMA resin demonstrated higher polishability. The diamond-coated rubber twits resulted in lower Ra values of 0.36 (0.01) µm, 0.52 (0.11) µm, and 0.28 (0.05) µm for PMMA, BAMA, and MMLC resins, respectively. The application of photo-polymerized surface glaze led to a plaque accumulation threshold of 0.2 µm across all resin groups. The greatest mean color change occurred in the negative control group, indicating a propensity for more staining on rougher surfaces. The Bisacryl resin exhibited higher ΔE values, whereas PMMA showed better color stability. The lowest ΔE values were found when the surface glaze was applied to all of the provisional crown resins. Untreated Bisacryl resin exhibited the lowest Ra values, while PMMA resins demonstrated superior surface morphology after polishing. PMMA provisional crown resins showed increased resistance to staining. The use of surface glaze enhanced both smoothness and color stability on the surfaces.

Comparative Evaluation of Mechanical Properties and Color Stability of Dental Resin Composites for Chairside Provisional Restorations

Resin composites have become the preferred choice for chairside provisional dental restorations. However, these materials may undergo discoloration, changes in surface roughness, and mechanical properties with aging in the oral cavity, compromising the aesthetics, functionality, and success of dental restorations. To investigate the color and mechanical stability of chairside provisional composite resins, this study evaluated the optical, surface, and mechanical properties of four temporary restoration resin materials before and after aging, stimulated by thermal cycling in double-distilled water. Measurements, including CIE LAB color analysis, three-point bending test, nanoindentation, scanning electron microscopy (SEM), and atomic force microscopy (AFM), were conducted (n = 15). Results showed significant differences among the materials in terms of optical, surface, and mechanical properties. Revotek LC (urethane dimethacrylate) demonstrated excellent color stability (ΔE00 = 0.53-Black/0.32-White), while Artificial Teeth Resin (polymethyl methacrylate) exhibited increased mechanical strength with aging (p < 0.05, FS = 68.40 MPa-non aging/87.21 MPa-aging). Structur 2 SC (Bis-acrylic) and Luxatemp automix plus (methyl methacrylate bis-acrylate) demonstrated moderate stability in optical and mechanical properties (Structur 2 SC: ΔE00 = 1.97-Black/1.38-White FS = 63.20 MPa-non aging/50.07 MPa-aging) (Luxatemp automix plus: ΔE00 = 2.49-Black/1.77-White FS = 87.72 MPa-non aging/83.93 MPa-aging). These results provide important practical guidance for clinical practitioners, as well as significant theoretical and experimental bases for the selection of restorative composite resins.

Color stability of CAD-CAM hybrid ceramic materials following immersion in artificial saliva and wine

PURPOSE

To examine the color stability of 3D-printed and milled, interim, and definitive, restorative materials after immersion in artificial saliva and wine for 1, 3, and 6 months.

MATERIAL AND METHODS

The study used a 2 × 5 factorial design with 10 subgroups, including 2 immersion liquids (artificial saliva and wine) and 5 manufacturing technology and restorative material combinations (n = 10). Color measurements were taken using a contact-type digital spectrophotometer (CM-2600d Spectrophotometer; Konica Minolta Healthcare Americas Inc) before immersion and at 1 month (T1), 3 months (T3), and 6 months (T6) after immersion. The CIE2000 system was used to calculate quantitative measurements of color differences in ΔE00, and comparisons were made to the acceptability threshold (AT) and perceptibility threshold (PT). Repeated measures of ANOVA (α = 0.05) were used to compare differences in color changes between manufacturing technology/restorative material-immersion liquid combinations at T1, T3, and T6.

RESULTS

To compare the effect of immersion liquid and time on the manufacturing technology/restorative material groups, the ΔE00 values were compared to the PT of 0.8 and the AT of 1.8. Wine caused significant color changes in ΔE00 values beyond the PT and AT values in all groups at all time intervals, except for the AT value of milled definitive crowns (hybrid nano-ceramic material). Wine immersion caused significant ΔE00 for all manufacturing technology/restorative material groups at all time intervals (1 month, 3 months, and 6 months) when compared to artificial saliva immersion (all p < 0.001).

CONCLUSION

Upon exposure to artificial saliva, 80%-100% of samples from all groups remained within the acceptable and perceptible color change thresholds. The wine had significant chromogenic effects on all tested restorative materials, however, the milled definitive crowns (hybrid nano-ceramic material) showed the greatest color stability. For patients with heavy wine consumption, 3D-printed definitive crowns (hybrid ceramic-filled material) may show discoloration exceeding acceptable and perceptible color change limits.

Effects of surface glazing on the mechanical and biological properties of 3D printed permanent dental resin materials

Purpose This study aimed to determine the surface glazing effect on the mechanical and biological properties of three-dimensional printed dental permanent resins.Methods Specimens were prepared using Formlabs, Graphy Tera Harz permanent, and NextDent C&B temporary crown resins. Specimens were divided into three groups: samples with untreated surfaces, glazed surfaces, and sand-glazed surfaces. The flexural strength, Vickers hardness, color stability, and surface roughness of the samples were analyzed to identify their mechanical properties. Their cell viability and protein adsorption were analyzed to identify their biological properties.Results The flexural strength and Vickers hardness of the samples with sand glazed and glazed surfaces were significantly increased. The color change was higher for surface untreated samples than that for the samples with sand-glazed and glazed surfaces. The surface roughness of the samples with sand-glazed and glazed surfaces was low. The samples with sand-glazed and glazed surfaces have low protein adsorption ability and high cell viability.Conclusions Surface glazing increased the mechanical strength, color stability, and cell compatibility, while reducing the Ra and protein adsorption of 3D-printed dental resins. Thus, a glazed surface exhibited a positive effect on the mechanical and biological properties of 3D-printed resins.

Biaxial flexural strength of different provisional restorative materials under chemo-mechanical aging: An in vitro study

PURPOSE

Durability is a critical factor for the success of long-term provisional restorations. This study evaluated the effect of different storage media and cyclic loading on the biaxial flexural strength of different types of provisional materials.

MATERIALS AND METHODS

Discs (N = 360, 10 × 2 mm) were prepared from different provisional materials; conventional (Protemp 4, Tuff-Temp, Tempron), CAD-CAM milled (VITA CAD-Temp, breCAM.multiCOM), and 3D-printed (Nextdent C&B MFH) (n = 60). Each material group was subdivided into four subgroups according to the storage media (n = 15): nonaged, artificial saliva, mouthwash, and coffee. The specimens in storage media were placed in an incubator at 37°C for 4 weeks followed by 60,000 simulated chewing cycles. Biaxial flexural strength test was done. Data were analyzed using two-way ANOVA. Weibull distribution parameters were estimated.

RESULTS

Both the material and aging protocol showed a significant effect on the biaxial flexural strength. Both Protemp 4 and Nextdent C&B MFH showed a significantly higher biaxial flexural strength before and after aging compared to all other materials. Protemp 4 and Tuff Temp showed a significant decrease in strength with aging. CAD-CAM materials showed higher Weibull moduli.

CONCLUSIONS

The 3D-printed polymethylmethacrylate provisional material presents with both greater biaxial flexural strength and increased durability against chemical and mechanical aging compared to conventional and CAD-CAM milled provisional materials tested.

Comparison of light transmittance and color changes between polyurethane and copolyester retainer materials after staining and destaining

BACKGROUND

Retainers are the only effective approach to prevent orthodontic relapse. The aim of this study was to compare the changes in color and light-transmittance of rough and smooth thermoformed polyurethane and copolymer retainer samples after staining in different solutions and destaining with different approaches.

METHODS

Four hundred copolyester (Essix® ACE) and 400 polyurethane (Zendura®) samples with different surface textures, smooth and rough, were stained in 4 different solutions (n = 100 per solution) over 28 days. Each of the four groups of 100 stained samples of each material was subdivided into 5 groups of 20 samples and subjected to different destaining solutions. Light transmittance and color changes were evaluated using a spectrometer and a spectrophotometer. Mean differences were compared using a two-way analysis of variance (ANOVA) and posthoc multiple comparison tests at P = 0.05.

RESULTS

No significant differences in light transmittance were found between both untreated materials. Both materials were stained in a similar fashion and showed no significant differences between two materials after staining. Coffee and tea stained both materials more significantly than wine, but there was a significant difference of changes of color and light transmittance between rough and smooth surfaces during the destaining in coffee- and tea-stained samples of copolyester material. All destaining solutions were effective at removing all stains on the samples. The surface roughness of the material plays a significant role in the ability of the materials to be destained, demonstrating a more significant greater effect on cleaning rough samples for improvements in light-transmittance and greater changes in color.

CONCLUSIONS

This study concluded that the surface of materials plays a significant role in the material destaining and staining. In addition, the different polymers used for retainer fabrication exhibited different responses during the destaining process depending on types of stains.

Evaluation and Assessment of the Colour Stability of Modified Polymethyl Methacrylate Denture Base Materials and Polyether Ether Ketone in a Cast Partial Denture Framework: An In-Vitro Study

Background One of the frequent aesthetic issues patients confront is the loss of colour and lifeless appearance of the dentures of the base materials of their dentures after regular use. This leads to a lack of motivation to use the denture regularly. Due to the drawbacks of conventional PMMA, polyether ether ketone (PEEK) and newer polymethyl methacrylate (PMMA)-based materials have now started being used in cast partial denture frameworks due to their superior physical and biological properties. The lack of long-lasting colour is one of the main reasons for the repeat of dental prostheses. Hence, the need for the study is to help clinicians decide which would be the most suitable denture base material to be used based on colour stability. Aim To assess and compare the colour stability of PEEK, polyan, and biodentaplast denture base materials (DBMs) upon staining with distilled water, tea, coffee, and turmeric solutions after one day, seven days, and 30 days. Methods A total of 20 cuboidal specimens were constructed and immersed in distilled water, tea, coffee, and turmeric (five specimens of each material in each solution, a total of 60 specimens): Group 1: PEEK, Group 2: polyan, Group 3: biodentaplast. All specimens were subjected to colour measurements before exposure to beverage solutions, after 24 hours, on the seventh day and 30th day with a colour reflectance spectrophotometer with computer software. A one-way ANOVA test followed by post hoc Tukey's honestly significant difference (HSD) was performed for comparison of colour stability between the DBMs, revealing a significant difference between PEEK and polyan and PEEK and biodentaplast. Polyan showed the highest delta E values, followed by biodentaplast and PEEK. A two-way ANOVA test, followed by Tukey's HSD post hoc, was done to compare the staining ability of various staining solutions. Turmeric had the highest delta E values, followed by coffee, tea, and distilled water. Data were assessed using Statistical Product and Service Solutions (SPSS, version 23) (IBM SPSS Statistics for Windows, Armonk, NY) software. Results The highest mean delta E value at T1 was seen in biodentaplast immersed in turmeric (12.3900+/-0.442), and the least value at T1 was obtained for PEEK immersed in distilled water (0.4460+/-0.036). The highest mean delta E value at T2 was seen in polyan immersed in turmeric (13.0160+/-0.28962), and the least value at T2 was obtained for PEEK immersed in distilled water (0.5860+/-0.051). At T3, the highest mean delta E value was seen in polyan immersed in turmeric (16.8600+/-0.49845), and the least value at T3 was obtained for PEEK immersed in distilled water (0.700+/-0.037). Conclusion PEEK had the highest colour stability when compared with polyan and biodentaplast.

Effect of Different Disinfecting Agents on Surface Roughness and Color Stability of Heat-cure Acrylic Denture Material: An In Vitro Study

AIM

The current study aimed to determine the impact of three different disinfectants on the surface roughness and color stability of heat-cure acrylic denture material.

MATERIALS AND METHODS

Using a stainless-steel mold, disc-shaped wax patterns with dimensions of 10 mm in diameter and 2 mm thick (in accordance with ADA Specification No. 12) were created and prepared for a total of 75 acrylic samples. Dimensions of all 75 acrylic samples were checked with a digital Vernier caliper. About 25 samples of denture base material were immersed in three different chemical disinfectants: Group I: immersed in chlorhexidine gluconate solution, group II: immersed in sodium hypochlorite solution, and group III: immersed in glutaraldehyde solution. All samples were scrubbed daily for 1 minute with the appropriate disinfectant and submerged for 10 minutes in the same disinfectant. Between disinfection cycles, samples were kept in distilled water at 37°C. Color stability was measured using a reflection spectrophotometer. Surface roughness values were measured by a profilometer at baseline following 15 days and 30 days.

RESULTS

After 15 days, the color stability was better in chlorhexidine gluconate solution group (4.88 ± 0.24) than sodium hypochlorite solution (4.74 ± 0.18) and glutaraldehyde solution group (4.46 ± 0.16). The mean surface roughness was less in glutaraldehyde solution group (2.10 ± 0.19), followed by chlorhexidine gluconate solution group (2.48 ± 0.09) and sodium hypochlorite solution group (2.64 ± 0.03). After 30 days, the color stability was significantly better in chlorhexidine gluconate solution group (4.40 ± 0.02), followed by sodium hypochlorite solution (4.06 ± 0.16) and glutaraldehyde solution group (3.87 ± 0.17). The mean surface roughness was significantly lesser in glutaraldehyde solution group (2.41 ± 0.14), followed by chlorhexidine gluconate solution group (2.94 ± 0.08) and sodium hypochlorite solution group (3.02 ± 0.13).

CONCLUSION

In conclusion, the color stability was significantly better in chlorhexidine gluconate solution group than sodium hypochlorite solution and glutaraldehyde solution group. But the surface roughness was significantly lesser in the glutaraldehyde solution group, followed by the chlorhexidine gluconate and sodium hypochlorite solution group.

CLINICAL SIGNIFICANCE

The maintenance of the prosthesis requires the use of a denture disinfectant; therefore, it is crucial to select one that is effective but would not have a negative impact on the denture base resin's inherent characteristics over time. How to cite this article: Kannaiyan K, Rakshit P, Bhat MPS, et al. Effect of Different Disinfecting Agents on Surface Roughness and Color Stability of Heat-cure Acrylic Denture Material: An In Vitro Study. J Contemp Dent Pract 2023;24(11):891-894.

Effect of khat extract on color stability of digitally and manually fabricated provisional restorations: an in vitro comparative study

BACKGROUND

The aim of this in vitro study was to evaluate the effect of khat extract on the color stability of five different provisional restorative materials (PRMs).

METHODS

In this study, 50 specimens were fabricated from five different PRMs with different techniques. Twenty specimens were digitally fabricated of poly-methyl methacrylate (PMMA) CAD/CAM milling and 3D printing PRMs, while the other thirty specimens were manually fabricated of three different PRMs: PMMA self-cured (SC) acrylic resin, light-cured (LC) composite, and Bis-acrylic SC composite. Milling and 3D printing machines were used to fabricate the digital specimens, while the manual specimens were fabricated using a metallic mold. The material was placed in the mold, covered by a polyester stripe, and held between two glass slabs with a constant load for 30 s. After setting, the specimens were removed and checked. Ten disc-shaped specimens with 2 ± 0.3 mm thickness and 10 ± 0.3 mm diameter were prepared from each of the tested PRM. Then all the specimens were polished. Five specimens of each PRM were immersed in khat extract, while the other five were immersed in distilled water medium as a control group. The color measurements were recorded before and after 1 and 7 days of immersion using a spectrophotometer. The immersion media were renewed every 24 h and kept along with the specimens at 37 °C. The T test, paired T test, and ANOVA analysis of variance were used to analyze the results. The Bonferroni test was used for post-hoc multiple comparisons.

RESULTS

The interaction between the tested PRMs, the media, and the duration of immersion time was statistically significant (p < 0.05). PMMA CAD/CAM milling PRM was the most stable in color, and this was statistically significant (p < 0.05). The LC composite PRM composite was the least stable in color and was statistically insignificant (p > 0.05) when compared to the 3D printing and Bis-acrylic SC composite PRMs, respectively.

CONCLUSIONS

This study demonstrated that khat extract medium has a high staining ability on the tested PRMs. CAD/CAM milling PRM was the most stable in color and could therefore be used as a long-term provisional. The increase in immersion time was a significant factor in the color change of the tested PRMs. The color of the 3D-printed PRM was the most affected over time.

The effect of different staining solutions on the color stability of temporary crown materials

Background

The esthetic expectations of patients are increasing by the day. That is why it is important to minimize the color changes in the oral cavity in both the temporary and permanent restorations.

Aim

This study was carried out to compare the time-dependent color changes of polished and unpolished temporary crown materials prepared by different methods in various solutions.

Materials and Methods

Half of the two different temporary restoration materials prepared with a diameter of 10 mm and a thickness of 2 mm were polished, and half were not polished. The ΔE* values of the samples kept in various solutions were recorded. Data were statistically evaluated by using variance analysis (ANOVA) and a Tukey HSD multiple comparison test.

Results

It was determined that the material type, the solution, the interaction between the material types and the surface treatment, and the interaction between the surface treatment and the solution were statistically significant for color change (p < 0.001).

Conclusion

The most significant color change in the inter-material evaluation was observed in chemically polymerized polymethyl methacrylate. In the evaluation between beverages, the highest color change was found in sugared coffee, and the lesser color change was observed in polished samples.

Clinical Evaluation of Low-shrinkage Bioactive Material Giomer Versus Nanohybrid Resin Composite Restorations: A Two-year Prospective Controlled Clinical Trial

This study evaluated the clinical performance of low-shrinkage bioactive resin composite compared with a conventional nanohybrid resin composite. A total of 35 patients (18 males, 17 females; mean age: 29±9 years old) received, randomly, 35 pairs of fillings restored with either low-shrinkage bioactive material employing Giomer filler technology (Beautifil II LS, Shofu Inc, Kyoto, Japan) or conventional nanohybrid resin composite (Clearfil Majesty Posterior, Kuraray, Japan) in Class I and Class II cavities. Two operators made all the restorations using the corresponding adhesive resins: FL-Bond II (Shofu Inc) and Clearfil SE Bond (Kuraray), according to each manufacturer's instructions. Two calibrated operators evaluated the restorations two weeks after placement (baseline), at six months, and at one and two years using FDI criteria (Scores 1-5). Data were analyzed using the McNemar test (α=0.05). Mean observation time was 27.4 ± 4.1 months (min=20.8; max=33.7). In both groups, according to FDI criteria, the restorations were mostly rated with best scores (Score 1 or 2) for biological, functional, and optical parameters. For one filling in the group restored with nanohybrid resin composite, a small and localized secondary caries lesion was observed and monitored at the one- and two-year follow-ups. One restoration in the low-shrinkage Giomer restorative group was accepted as a failure due to retention loss. Over the two-year follow-up, both the Giomer and the nanohybrid resin composite restorations' performance was clinically acceptable.

In vitro comparison of the color degradation of two computer-aided design/computer-aided manufacturing provisional materials: A 12-month simulation

Aim

This study evaluated the color aging of two computer aided design/computer aided manufacturing (CAD/CAM) provisional materials of different compositions (polymethyl methacrylate and composite resin) after exposure to thermal aging and immersion in coffee for 3, 6, and 12 intraoral months.

Setting and Design

The current in vitro study was conducted from September to December 2021 at the Craniofacial laboratory at the Saint Joseph University in Beirut, Lebanon.

Materials and Methods

The shades of 2.0 mm thick, 10.0 mm in diameter disk shaped specimens of VITA CAD Temp® and Ceramill® TEMP were measured using the VITA Linearguide 3D MASTER® and a conversion table to extract the CIE LFNx01aFNx01bFNx01 values on a white background (n = 30).

Statistical Analysis Used

The color differences ΔE at 3, 6, and 12 months were calculated and analyzed by repeated measures ANOVA followed by Bonferroni multiple comparisons, univariate analyses, and one sample t tests.

Results

The mean ΔET1/T0, ΔET2/T0, and ΔET3/T0 values were significantly higher than the cutoff values for acceptability and perceptibility for the VITA CAD Temp® and the Ceramill® TEMP groups. In addition, the increase in ΔE overtime was significantly greater in the Ceramill® TEMP group compared to the VITA CAD Temp® group.

Conclusions

The Ceramill® TEMP changed color more and faster than the VITA CAD Temp®. In addition, whether at 3, 6, or 12 months, the color variations of both materials are not only perceptible but also unacceptable compared to the initial shade.

The Effects of Staining and Cleaning on the Color and Light Transmittance Changes of a Copolyester Retainer Material with Different Surface Textures

This study evaluated the efficacy of different cleaning methods with respect to changes in the color and light transmittance of both rough and smooth thermoformed, copolyester retainer specimens, after staining in different solutions. Four hundred copolyester sheets (Essix ACE) specimens were fabricated over molds with different surface textures, smooth and rough. The specimens were stained in four different solutions (n = 100 per solution) over 28 days; then, each of the four groups of 100 stained specimens was sub-divided into five groups of 20 specimens and subjected to a different destaining solution. The specimens were sub-divided with half subjected to an additional ultrasonic cleaning procedure. Light transmittance and color changes were analyzed using a spectrometer/integrating sphere assembly and a spectrophotometer. Mean difference comparisons were performed using appropriate statistical tests at p = 0.05. All five destaining solutions proved to be effective at removing coffee and tea stains. The surface roughness of the retainer material plays a significant role in the ability of cleaning solutions to remove stains, demonstrating a greater effect on cleaning rough specimens with respect to improvements in light transmittance and greater changes in color. Additionally, an ultrasonic cleaning unit generally enhanced the ability of all five solutions to clean the tea-stained specimens. However, the enhancements were only significant for light transmittance.

Influences of Toothbrushing and Different Toothpastes on the Surface Roughness and Color Stability of Interim Prosthodontic Materials

The surface properties and color stability of interim crown materials may vary depending on the toothbrushing procedure. This study aimed to investigate the effects of toothbrushing and different toothpastes on the surface roughness (Ra) and color stability of different interim crown materials. Disc-shaped specimens were prepared from four interim crown materials (Tab 2000 (ChPM), Imident (LaPM), Protemp 4 (ChDM), and Telio-CAD (CadPM)). Specimens were divided into four subgroups for the control group (Cnt) and for simulated toothbrushing with distilled water (Dw) or with two different toothpastes (whitening toothpaste (WTp), activated charcoal toothpaste (ACTp)). The specimens’ Ra values were measured before and after 10,000 cycles of toothbrushing. The color parameters were measured and the color differences (ΔE00) were calculated. Data were statistically analyzed by two-way analysis of variance (ANOVA) and Tukey’s HSD tests. A significant increase in the Ra values was observed after toothbrushing, except for the LaPM_Dw, ChDM_Dw, and all the CadPM specimens (p < 0.05). Toothbrushing with toothpastes increased the ΔE00 values of all ChPM and ChDM interim materials (p < 0.05). Before and after all toothbrushing procedures, the CadPM specimens had smoother and ChPM specimens had rougher surfaces than the other interim materials. The two tested toothpastes had similar effects on the Ra of all interim materials. Non-perceivable color changes were seen only with the CadPM_Dw group.

Effect of post-curing time on the color stability and related properties of a tooth-colored 3D-printed resin material

This study investigated the effect of post-curing time on the color stability and related properties, such as degree of conversion (DC), surface roughness, water contact angle, water sorption (W_sp), and water solubility (W_sl) of 3D-printed resin for dental restorations. The 3D-printed specimens were divided into four groups according to the post-curing time (0, 5, 10, and 20 min). Color changes (ΔE₀₀) of the specimens immersed in aging media were measured using a spectrophotometer at different aging times. The DC of the resin was measured using a FTIR. The surface roughness (Ra) of the resin immersed in coffee was measured at different aging times. Water contact angle was evaluated using the sessile drop method, and W_sp and W_sl were tested according to the ISO 4049:2019. The ΔE₀₀ values of the specimens immersed in coffee and red wine decreased with increasing post-curing time. As the post-curing time increased up to 10 min, the DC increased and water contact angle decreased. The Ra value of the group without post-curing (0 min) increased gradually for 30 days, except between 7 and 15 days. However, when the post-curing time increased to greater than 10 min, no apparent change in Ra value was detected. The W_sp and W_sl of the group without post-curing were significantly lower and larger than that of the other groups, respectively. The longer the post-curing time of the tooth-colored 3D-printed resin, the better the color stability. The post-curing time of the 3D-printed resin affected the DC, surface roughness after aging in the staining media, water contact angle, water sorption, and water solubility.

Influence of Different Beverages on the Color Stability of Nanocomposite Denture Base Materials

BACKGROUND

The effect of beverages on nanocomposite denture base materials is neglected. Therefore, this study aimed to investigate the influence of different beverages (coffee, tea, cola, and mineral water) on the color stability of nanoparticles-modified denture base materials (DBMs).

MATERIALS AND METHODS

A total of 280 specimens (n = 10/group) were prepared from heat-polymerized acrylic resin modified with different concentrations (3% and 7%) of zirconium dioxide (nano-ZrO2), titanium dioxide (nano-TiO2), and silicon dioxide (nano-SiO2) nanoparticles, while 0% was taken as a control. Color change (∆E) of the specimens was evaluated after simulating 6-month immersion time in four commonly used beverages, coffee, tea, cola, and mineral water, as experimental groups. Color stability was measured using a spectrophotometer, and then values were converted to National Bureau of Standards units (NBS units). The one-way ANOVA test was applied to compare color change (ΔE) results followed by Bonferroni's post hoc test (α = 0.05).

RESULTS

The results showed that the heat-polymerized acrylic resin modified with different types of nanoparticles showed lower color changes after being immersed in beverage solutions compared to the unmodified group (P < 0.001), so the color stability of heat-polymerized acrylic resin was significantly enhanced by the addition of several nanoparticles; nano-ZrO2 showed the lowest ΔE followed by nano-TiO2 and then nano-SiO2. Regardless of the filler type, 3% concentration showed lower mean ΔE than 7% concentration. Regarding the beverage solutions, the greatest color change was found in the coffee group followed by tea and cola, while water showed the least changes.

CONCLUSION

Modification of heat-polymerized acrylic resin with certain amounts of nano-ZrO2, nano-TiO2, and nano-SiO2 may be useful in improving color stability.

Comparative evaluation of color stability of three commercially available provisional restorative materials: An in vitro study

Aim:

Esthetics of the provisional restorations is of prime importance to the patients especially in long term in the esthetic zone. Discolouration of these restorations may result in patient dissatisfaction and an additional expense for their replacement. LuxaCrown provisional material being new in market and claimed to be semi-permanent by the company needs to be evaluated for its colour stability. This in vitro study was aimed to evaluate and compare the colour stability of three provisional restorations using three pigmented solutions.

Setting and Design:

In vitro - comparative study.

Materials and Methods:

LuxaCrown, Protemp4, Heat cure PMMA were evaluated. 40 specimens of each material were divided into four groups of ten specimens each. Each group was stored in three staining solutions and artificial saliva. Colour values of each specimen were measured before immersion, after one day, one week, one month, three months and six months with a spectrophotometer.

Stastistical Analysis Used:

One way ANOVA, Post Hoc Tukey Test, Bonferonni Test.

Results:

Least colour change was seen in Heat Cure PMMA followed by Protemp4 and highest colour change was seen in LuxaCrown when immersed in artificial saliva, tea and coffee. Whereas in turmeric, Heat Cure PMMA showed the least colour change followed by LuxaCrown and highest colour change was seen in Protemp4 at all time intervals except day one, where LuxaCrown was higher than Protemp4.

Conclusion:

Heat cure showed the best results as compared to Protemp4 and LuxaCrown in terms of colour stability at all time periods.

The Effects of Beverages and Surface Treatments on the Color Stability of 3D-Printed Interim Restorations

PURPOSE

To evaluate the color stability of 3D-printed interim restorations with different surface treatments while immersed in various staining solutions or beverages (artificial saliva, tea, coffee, and wine) for 6 months.

MATERIAL AND METHODS

An acrylic tooth was prepared for an all-ceramic full-coverage restoration. A laboratory scanner was used to digitize the prepared abutment tooth. A virtual all-ceramic full-coverage restoration was designed on the digitized abutment tooth using a laboratory CAD/CAM software. Eighty abutment teeth and interim restorations were 3D-printed with tooth-colored photopolymerizing resin. The restorations were randomly allocated into two different groups: Polish and Optiglaze. For the Polish group, interim restorations were finished and polished with aluminum oxide finishers/polishers. For the Optiglaze group, one layer of nanofilled, light-polymerizing protective coating was then applied. The 80 printed interim crowns were divided into 4 different groups depending on where they would be immersed: Artificial saliva, coffee, wine, and tea. After the sample allocations, there were 8 experimental groups. Each group was allocated with 10 specimens. Color measurements were obtained using a digital spectrophotometer in conjunction with The CIE L*a*b* system before the immersion and 6 months after the immersion. Two-way analysis of variance (ANOVA) was used to test the effects of surface treatment, immersion liquid, and their interaction on ΔE at 6-month post-immersion. Fisher's protected least significant differences (LSD) was used as post hoc test to compare groups differences (α = .05).

RESULTS

There were significant effects of surface treatment [F(1,72) = 13.39, p = 0.000], immersion liquid [F(3,72) = 74.18, p = 0.000], and their interaction [F(3,72) = 16.33, p = 0.000] on ΔE at 6-month post-immersion at the α = .05 level. The polish group showed significantly higher ΔE than the Optiglaze group when immersed in coffee (p < 0.001) and wine (p = 0.015). The Optiglaze group showed significantly higher ΔE than the polish group that was immersed in artificial saliva (p < 0.001). The wine group showed higher ΔE than all other immersion liquid groups for both polish and Optiglaze surface treatments (p < 0.001 for all comparisons). ΔL* showed a reduction that was significantly higher than the 2.0 acceptability threshold in the wine-polish (p < 0.001) and wine-Optiglaze (p < 0.001) groups. ΔE showed a color change that was significantly higher than the perceptibility and acceptability thresholds for all the groups under polish surface treatment (p < 0.001). ΔE also showed a color change that was significantly higher than the perceptibility and acceptability thresholds for artificial saliva, tea, and wine under Optiglaze surface treatment (p = 0.004).

CONCLUSIONS

3D-printed interim restorations showed significant discoloration after 6-months immersions in the artificial saliva and common beverages (including tea, coffee, and wine). Among all the chromogenic beverages, red wine caused the most significant discoloration on the interim restorations. When 3D-printed interim restorations are needed for extended intraoral service, nano-filled, light polymerizing protective coating can reduce the restoration discoloration caused by chromogenic beverages. The protective effect is most significant against coffee.

Alcohol and light-polymerizing glaze effect on the physical and mechanical properties of a bisacrylate composite resin before and after immersion in chlorhexidine gluconate

STATEMENT OF PROBLEM

The use of 0.12% chlorhexidine gluconate (CHX) may damage bisacrylate composite resin interim restorations, but whether they can be protected with an application of alcohol and/or the use of a glaze is unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of applying a 70% alcohol solution on the physical and mechanical properties of a bisacrylate composite resin, with and without the application of a light-polymerizing glaze subjected to 0.12% CHX twice a day for 7 days.

MATERIAL AND METHODS

Forty specimens of an autopolymerized bisacrylate composite resin were divided into 4 groups (n=10): Group C (without alcohol, without glaze), Group G (without alcohol, with glaze), Group A (with alcohol, without glaze), and Group AG (with alcohol, with glaze). All specimens were submitted to in vitro treatment with 0.12% CHX for 7 days, and tests of color alteration (ΔE₀₀), microhardness, roughness, and surface were performed initially and after treatment. Data were submitted to analysis of variance (ANOVA) and the Tukey HSD test (α=.05).

RESULTS

Group A had the lowest mean value of ΔE₀₀ with a significant statistical difference from Group C. The groups with alcohol presented higher microhardness mean values compared with groups without alcohol in both periods of analysis, except for the groups with glaze in the final period. Group C showed higher mean roughness values in comparison with Group A in both periods. Group AG presented higher mean roughness values than Group G. Surface energy values did not vary significantly among groups, except between Groups C and A in the final period.

CONCLUSIONS

The application of alcohol optimized the properties of the autopolymerized bisacrylate composite resin analyzed, with and without the application of glaze. Overall, the use of CHX changed the microhardness and roughness when the glaze was applied.

The colour stability of crystallized acetyl resin material in comparison to other restorative materials. An in-vitro study

AIM

To investigate the colour stability of Crystalized Acetyl Resin, in comparison to three other aesthetic restorative materials, when immersed in different staining aqueous solutions.

MATERIALS AND METHODS

Fifteen disc-shaped specimens each, of the four materials tested, were immersed in either DW or 4 staining solutions. CIE L*a*b* values were recorded using a digital spectrophotometer on a weekly basis for 4 weeks. Data were compared using three- way/two-way ANOVA along with auto-regressive model.

RESULTS

Two-way Anova indicates that there is a significant colour change in all materials over time when immersed in the different staining solutions. Auto-regressive model showed that the colour change in each successive week was statistically significant (P < 0.001).

CONCLUSION

The most staining solution affecting the materials during this study was black coffee. Within the limitation of this study, Acetyl Resin was the most colour stable material among the other materials.

Color stability of provisional restorative materials with different fabrication methods

PURPOSE

The aim of this study was to investigate and compare the color stability of provisional restorative materials fabricated by 3D printing, dental milling, and conventional materials.

MATERIALS AND METHODS

For the experimental groups, two commercially available 3D-printing provisional resins (E-Dent 100; EnvisionTEC GmbH, Germany & VeroGlaze™; Stratasys®, USA), two dental milling blocks (PMMA Disk; Yamahachi Dental Co., Japan & Telio®CAD; Ivoclar Vivadent AG, Liechtenstein), and two conventional materials (Alike™; GC Co., Japan & Luxatemp automix plus; DMG, Germany) were used. The water sorption and solubility test were (n=10, respectively) carried out according to ISO4049:2000 (International Standards Organization, Geneva, Switzerland). For the color stability test (n=10), coffee and black tea were used as staining solutions, and the specimens were stored for 12 weeks. Data were analyzed by one-way ANOVA and Tukey's HSD using SPSS version 22.0 (SPSS Inc. Chicago, IL, USA) (P<.05).

RESULTS

Alike and Veroglaze showed the highest values and Luxatemp showed the lowest water sorption. In the color stability test, the ΔE of conventional materials varied depending on the staining solution. PMMA milling blocks showed a relatively low ΔE up to 4 weeks, and then significantly increased after 8 weeks (P<.05). 3D-printed materials exhibited a high ΔE or a significant increase over time (P<.05).

CONCLUSION

The degree of discoloration increased with time, and a visually perceptible color difference value (ΔE) was shown regardless of the materials and solutions. PMMA milled and 3 D-printed materials showed more rapid change in discoloration after 8 weeks.

Optical properties of bisacryl-, composite-, ceramic- resin restorative materials: An aging simulation study

OBJECTIVE

Compare optical properties of a bisacryl-, composite-, and ceramic-resin restorative materials pre and post artificial aging.

METHODS

Bisacryl-resin (LuxaCrown [LC], DMG), resin-composite (Filtek Supreme Ultra, [Filtek SU] 3M ESPE), and ceramic-resin (Enamic, VITA Zahnfabrik) specimens were prepared. The L*, C*_ab , and h_ab values were measured pre and post artificial aging to determine color stability (CIEDE2000) and changes in contrast ratio (CR), transmittance block, and relative translucency parameter. The datasets were analyzed using 2-way ANOVA followed by pairwise comparisons.

RESULTS

Color difference data showed a significant interaction between materials and treatments [F(6:60) = 375.04, P < .0001] with Enamic being most color stable material and coffee having most effect on color stability. CR data showed a significant interaction between materials and treatments [F(6:60) = 4.12, P = .0016]. LC showing most change in CR values with coffee treatment. Change in transmittance blocked by Filtek SU and LC was greater for coffee treatment than that by each of the other treatments (P < .0001). Filtek SU and LC, coffee produced a greater decrease in relative translucency than that each of the other treatments (P < .0001).

CONCLUSIONS

Resin-based materials demonstrate optical properties that encourage their use for direct/indirect restorative options. Color stability and translucency of these materials are proportionally related.

CLINICAL SIGNIFICANCE

Understanding the optical properties of resin-based materials provides help in material selection and provides insight into clinical performance and esthetic longevity. The optical stability of certain bisacryl-resin is better than what was previously determined for these restorative materials.

The color stability and wear resistance of provisional implant restorations: A prospective clinical study

Objectives

The aim of the present clinical study was to determine the stability of color and resistance against abrasion and attrition of provisional single implant restorations.

Material and Methods

A group of 16 patients were treated with provisional crowns made of Telio CAD. Shortly before the insertion the crowns were photographed and scanned using a 3D‐laser scanner. After 8 weeks of clinical usage, the crowns were photographed and scanned again. The vertical occlusal wear and color changes between the restorations were measured.

Results

The occlusal plane of the original crown showed a statistically significant reduction of 0.052 mm ± 0.037 mm 8 weeks after placement (p < .05). For the stability of color, a change in red, green and blue was described. All three scopes (red, green and blue) showed a statistically significant reduction (p < .05).

Conclusions

This prospective clinical study showed that Telio CAD experienced a significant occlusal reduction and color change after an intraoral placement of 8 weeks.

Effect of acidic beverages on surface roughness and color stability of artificial teeth and acrylic resin

PURPOSE

The aim was to evaluate the effect of four acidic beverages on the roughness (Ra) and color change (ΔE_ab) of two brands of artificial teeth and a heat-polymerized acrylic resin (HPAR) for use in a prosthetic base.

MATERIALS AND METHODS

All materials were divided into 5 groups, according to the used acidic beverage (artificial saliva - control, red wine, orange juice, coke-based, and lemon juice-based soft drink). The immersion process was divided into two stages: T1 - immersion in the acidic solutions for 10 minutes for 14 days; T2 - after T1, the samples were immersed in grape juice for 14 days. The Ra of the samples was evaluated in a rugosimeter and the ΔE_ab in a spectrophotometer, before and after the immersions. The analysis of variance of one (ΔE_ab) and two factors (Ra) and Tukey were performed (α=.05).

RESULTS

There was a statistical difference for roughness after immersion (T1) for Trilux and Tritone teeth, regardless of the acid solution. For Trilux teeth, all acid solutions increased Ra (P<.05). For Tritone teeth, only the coke-based soft drink did not statistically change Ra. Grape juice (T2) altered Ra only of artificial teeth (P<.05). The color was changed for all materials, after T1 and T2.

CONCLUSION

In general, the acidic solutions changed the Ra and ΔE_ab of HPAR and artificial teeth after T1. The grape juice altered the roughness only of the artificial teeth, promoting a clinically acceptable color change in the materials.

Color stability of nanohybrid composite resins in drinks

Aim: The objective of this study was to evaluate the effects of solutions on the color stability of nanohybrid composite resins. Methods: The experimental sample consisted of 90 composite specimens (Beautifil II; Z350XT; Premisa), divided into three subgroups (n=10) according to the solutions (matte tea; lemon flavor isotonic drink; artificial saliva). The specimens were immersed in the solutions (5 mL/specimen) while stirring for 5 minutes, four times a day, with 1-hour intervals, repeated for 15 days. The color of the specimens was analyzed before (baseline) and after the 15th day of cycling using the CIELAB system. Data were analyzed using the two-way analysis of variance (ANOVA) and Tukey’s test (α=5%). Results: Different behaviors were observed among resins. Beautifil II presented the highest color change (∆E=4.18) and less color stability, statistically different from the others (p<.05). The solutions also presented different behaviors. The lemon flavor isotonic drink (∆E=3.95) promoted the highest color change, statistically different from saliva (∆E=2.75; p<.05). The interaction between Beautifil II and isotonic drink became even more evident and significant (p<.05). Conclusion: The isotonic drink is the solution that most affected the resins, and Beautifil II presents the worst color stability.

Long-term stainability of interim prosthetic materials in acidic/staining solutions

OBJECTIVE

To evaluate the long-term color stainability, translucency, and contrast ratio (CR) of different resins used to fabricate interim prostheses after immersion in acidic/staining solutions.

MATERIALS AND METHODS

A total of 160 specimens were divided into 16 groups (n = 10) according to the material (heat-polymerized acrylic resin [HPAR], auto-polymerized acrylic resin [APR], nanoparticulated bis-acrylic resin [BR], and prefabricated poly(methyl methacrylate) block for CAD/CAM [CADR]) and immersion solutions (artificial saliva, cola beverage, coffee, and red wine). A spectrophotometer was used before and after each immersion period (7, 14, 28, 90, and 180 days). Color differences (CIEDE2000 and CIELab) were calculated. A three-way repeated-measures analysis of variance and Bonferroni test (α = .05) were used.

RESULTS

After 180 days, the APR presented the highest value for coffee and the CADR presented the smallest value for the cola (P < .001). For the CR, the highest values were obtained at 180 days for BR in coffee (1.35) and wine (1.18) (P < .001). Higher translucency parameters were obtained in the BR and CADR in the initial, 14, 28, and 90 days (P < .001).

CONCLUSIONS

From the greatest to the smallest staining potential, the solutions were classified as: wine > coffee > cola beverage > saliva, while for the materials as: APR > BR > HPAR > CADR.

CLINICAL SIGNIFICANCE

The knowledge of the long-term optical behavior of interim prosthetic materials is important for clinicians to decide which material to use to match the dietary intake of their patients and their esthetic demands. Prefabricated blocks for CAD/CAM systems have been shown to maintaining their optical characteristics even after a long period of immersion in acidic/staining solutions.

Influence of a light-activated glaze on the adhesion of Streptococcus sanguinis to the surface of polymers used in fabrication of interim prostheses

AIM

This study aimed to investigate the adhesion of Streptococcus sanguinis to the surface of interim prostheses that were treated or not treated with a light-activated glaze, and subjected or not subjected to a thermocycling procedure.

METHODS

36 specimens of each resin were divided into 4 groups: heat-activated acrylic resin; chemically-activated acrylic resin; bis-acryl composite resin (Protemp; 3M ESPE); and bis-GMA (Charisma; Heraeus Kulzer). Half of the specimens underwent application of glaze and the other half underwent mechanical polishing. Specimens were randomly distributed into groups (N = 9) with and without thermocycling (2000 cycles). Surface energy, roughness and microbiological analyses were performed.

RESULTS

Groups treated with glaze showed lower roughness when compared with the same groups without glaze treatment, before and after thermocycling, except for the bis-acryl groups after thermocycling. Surface energy values were higher in the groups treated with glaze, except the bis-acryl group before and after thermocycling. After thermocycling, the values of bacterial adhesion decreased numerically, with the exception of the chemically-activated acrylic resin group treated with glaze and the heat-activated acrylic resin group without glaze treatment.

CONCLUSION

The application of glaze and the thermocycling do not influence, in a statistically significant manner, the bacterial adhesion on polymer surfaces.

Color stability of repairs on bis-acryl resin submitted to thermal aging and immersion in beverages

OBJECTIVE

Defects/bubbles can occur during the manufacture of bis-acryl resin provisional restorations, requiring repair or new prosthesis. This study evaluated the color stability of bis-acryl resin specimens repaired, aging, and immersioned in beverages.

MATERIAL AND METHODS

Eighty disks were made of bis-acryl resin. Twenty disks were not repaired (BCR), 20 disks were repaired with the same bis-acryl resin (BCR-BCR), 20 disks were repaired with flowable resin (BCR-FR), and 20 disks received an adhesive layer prior to flowable resin repair (BCR-AFR). Coordinates L*a*b* were obtained. Ten disks from each group were thermocycled (5000 cycles) and the others were immersed in coffee with sugar (n = 5) and cola-based soft drinks (n = 5) for 7 days. Color, lightness, chroma, and hue differences were calculated by the CIEDE2000 formula, analyzed by two-way analysis of variance. Multiple comparisons were made with the Tukey's HSD test (α = .05).

RESULTS

BCR-FR group presented the highest color differences (5.6) between groups repaired (P < .001). BCR-BCR group showed the smallest color differences (0.9) after aging (P = .003), but the greatest variation between T₀ and T₁ (about 1 ΔE). BCR-ARF immersed in coffee showed the greatest color differences (20.6) (P < .001).

CONCLUSIONS

Aging and immersion altered the colorimetric behavior of repairs, especially after the use of coffee.

CLINICAL IMPLICATIONS

Repairs are indicated when defects and bubbles are present in the surface of the bis-acryl resin provisional restorations after its manufacture. However, they may present noticeable color changes, especially when the use of coffee is frequent.

"Comparative Evaluation of the Effect of Three Polishing Agents on Staining Characteristics of Provisional Restorative Material:" An in vitro Study

Aim:

The present study aimed to evaluate the effect of three various polishing agents on provisional restorative material on immersion in a staining solutions.

Objectives:

The objective of the study is (1) To evaluate the effect of pumice on staining characteristics of provisional restorative material before and after immersion in chlorhexidine. (2) To evaluate the effect of aluminum oxide paste on staining characteristics of provisional restorative material before and after immersion in chlorhexidine. (3) To evaluate the effect of diamond paste on staining characteristics of provisional restorative material before and after immersion in chlorhexidine. (4) To compare and assess the outcome of three polishing agents on staining characteristics of provisional restorative material.

Materials and Methods:

Sixty samples (10 mm × 2 mm) were fabricated of bis-acryl composites (Protemp™ 4) by utilizing a metal mold. The samples were grouped into three groups (n = 20), and various polishing agents were used, including pumice, aluminum oxide paste, and diamond polishing paste. The samples that were not exposed to any polishing agent served as the control group. The samples were kept in a water bath for a day at 37°C and were stained with chlorhexidine mouthwash. The color of all specimens was measured with a spectrophotometer before and after polishing, and color changes (ΔE) were calculated.

Results:

By using one-way ANOVA, significant difference was found in mean color change in three polishing materials (F = 4.44, P = 0.016). By using Tukey test, statistically significant difference was found among pumice and aluminum oxide paste (P = 0.027), among pumice and diamond paste (P = 0.041) and no significant difference was found among aluminum oxide paste and diamond paste (P = 0.985).

Conclusion:

Pumice exhibited less staining which was statistically significant when compared with aluminum oxide paste and diamond paste. Hence, it can be considered the most efficient polishing agent.

A Comparison of the Color Stability of Conventional and CAD/CAM Polymethyl Methacrylate Denture Base Materials

Objective

The aim of this study was to evaluate the color stability of a heat polymerized resin, an auto-polymerizing resin, a urethane dimethacrylate resin and a CAD/CAM PMMA block resin stored in different storage media.

Materials and methods

60 disc-shaped specimens (15×2 mm) were fabricated for each group. A total of 240 disc-shaped specimens were thermal-cycled for 5,000 cycles. Then specimens were randomized into 4 groups (n= 15) according to storage media: coffee, coke, red wine and distilled water (control group). The color measurement of each sample was performed using a spectrophotometer before and after storage (after 7 and 30 days), and color changes (ΔE) were calculated.

Results

All the denture base materials demonstrated dissimilar color changes after stored in the different storage media in both evaluation stages. In all storage media, CAD-CAM denture base resins showed the minimum in color change. In all denture base resins, red wine showed a higher degree of color change than coke or coffee.

Conclusion

The color stability of CAD-CAM denture base resins is better than any of the other kind of denture base resins. The color change values of all groups except Eclypse stored in red wine had clinically detectable values.

Surface degradation of composite resins under staining and brushing challenges

Background/purpose

The primeval evaluation of the properties of composite resins with different compositions that impact clinical behavior is very important in guiding use in clinical settings. The aim of this study was to evaluate color stability (ΔE) and Knoop microhardness (KHN) of composite resins containing different compositions.

Materials and methods

Forty-five disks were made composite resins: Filtek Z350 XT/3MESPE and Beautifill II/SHOFU and divided into 3 subgroups: Control - immersed in artificial saliva; OB - brushing with Oral B 3D White; CT - brushing with Colgate Total 12. The OB and CT groups had the disks brushed daily with 120 cycles after immersion in coffee solution (10 min) for a period of 30 days. ΔE and KHN was obtained at baseline and after the treatments. Data were analyzed ANOVA and Tukey tests (p < 0.05).

Results

ANOVA revealed significant differences for ΔE and KHN. ΔE: the highest mean was observed in Beautifil II composite resin group, which differed significantly from Z350 group. For the Beautifil II, the treatments were significantly different from each other. For the Z350, the control group showed significant differences in relation to OB e CT groups. KHN: the highest mean was observed in Z350 group, which differed significantly from Beautifil II group. For Z350, the control group showed significant differences in relation to OB e CT groups. For Beautifil II, the treatments did not differ significantly among themselves.

Conclusion

The composite resin containing fluoride in the composition showed higher color alteration (ΔE) and lower Knoop microhardness (KHN), thus demonstrating that composition is an important factor in the clinical performance of esthetic restorative materials.

Polishing Methods' Influence on Color Stability and Roughness of 2 Provisional Prosthodontic Materials

PURPOSE

To evaluate the roughness and color change of a conventional acrylic resin and a bis-acryl resin, submitted to different types of polishing and exposed to a staining solution.

MATERIALS AND METHODS

One hundred specimens were manufactured from an autopolymerizing conventional acrylic resin (Duralay, shade 66) (n = 50) and a bis-acryl resin (Protemp 4, shade A3) (n = 50) according to the manufacturers' instructions. Specimens were subdivided into 10 groups (n = 10), according to the type of resin and polishing method, including no-polishing (control groups for acrylic resin [tungsten bur finishing] and bis-acryl resin [cotton and alcohol]), Enhance System, Edenta kit, Labordental kit, and sandpaper. The specimens were immersed in a staining solution (coffee at 60°C) for 7 days. Surface roughness was evaluated before the first immersion (baseline - Ra1) and after 7 days (Ra2). The color change (∆E) was determined after 24 hours (∆E1) and 7 days (∆E2), by CIE L^* a^* b^* scale. Data were statistically analyzed with 3-way ANOVA for repeated measures test and Tukey test (α = 0.05).

RESULTS

According to 3-way ANOVA test, material, polishing techniques, and polishing*material factors exhibited statistically significant influence (p < 0.0001) on the roughness, and, for color change, material, polishing techniques, time, polishing*material, and material*time factors were statistically significant (p < 0.0001). The polishing techniques successfully reduced the surface roughness of acrylic resin groups, when compared to control (p < 0.001), but for bis-acryl resin, results were not different from the control group (Enhance: p = 0.954, Edenta: p = 0.866, sandpaper: p = 0.366, Labordental: p = 0.945). Surface roughness was not affected by the immersion in staining solution for 7 days. Color change of acrylic resin groups after 24 hours and 7 days of immersion exhibited a clinically acceptable value (ΔE < 3.7) with the exception of the Enhance group, and all bis-acryl resin groups exhibited a clinically unacceptable color change value (ΔE > 3.7) independent of polishing technique and time interval (∆E1 and ∆E2).

CONCLUSIONS

Roughness of both materials was similar when the polishing techniques studied were performed, although Ra values were superior to the clinically acceptable values (0.20 µm), and were not affected by the immersion protocol studied; however, when esthetics are critical, the selection of material type is more important than the surface treatment technique used, and bis-acryl resin was more susceptible to clinically unacceptable color change after immersion in a staining solution.

Coloration of provisional restoration materials: a comparison of the effects of mouth rinses and green tea

Purpose

The present study aimed to evaluate the color stability of provisional restorative materials stored in different mouth rinses and green tea extract for 14 days.

Materials and methods

Forty cylinders of fixed provisional restoration material of 15-mm diameter and 2-mm thickness were prepared. The samples were separated into four storage solutions (three different mouth rinses and green tea) (n=10). The values of L*, a*, and b* were determined before and after storage in the solutions using a spectrophotometer, and the ΔE* value was calculated. The effect of mouth rinses and green tea extract on the color change of provisional restoration materials was determined with one-way analyses of variance. The Tamhane multiple comparison analysis was used to determine the differences between the groups (p<0.05).

Results

The color stability of the provisional restoration materials varies depending on the solution. Listerine mouth rinse showed more color change than Sensodyne or Colgate did. Minimal color change was found in the green tea solution.

Conclusion

The effect of mouth rinses on the color stability of fixed temporary restorative materials is remarkable. As green tea shows less color change, it can be suggested as an alternative to mouth rinses.

Characterization of Bis-Acryl Composite Resins for Provisional Restorations

This study investigated the in vitro performance of the commercial bis-acryl composite resins Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) and ProviPlast (PVP, Biodinamica). Characterization involved optical (color stability, translucency parameter, fluorescence), surface (roughness, morphology and elemental composition), physical-chemical (viscosity, polymerization kinetics) and mechanical analyses (Poisson ratio, biaxial flexural strength, flexural modulus). Most tests were carried out after 24 h, but optical and mechanical analyses were carried out after storage in water at 37 °C for 1, 15, and 30 days. Data were statistically analyzed (a=0.05). Most results were material dependent. SYS and PT4 showed stability in color and translucency over time. All materials had similar or higher fluorescence than human enamel. SC2 and PVP showed rougher surfaces than the other bis-acryl composites. Smaller filler particles were observed on the surface of PT4 and PVP compared with the coarser particles from ST2 and SYS. Viscosity readings indicated a thixotropic behavior for all tested materials. SYS had the lowest and PT4 the highest degree of C=C conversion after 10 min. In the polymerization kinetics, PT4 had the highest maximum polymerization rate and reached earlier the transition between polymerization autoacceleration and autodeceleration. PT4 and SYS had significantly higher flexural strength and modulus than ST2 and PVP for most storage times. Results for Poisson ratio varied between materials. Longer storage periods were generally associated with higher frequency of catastrophic failures in the flexural tests. In conclusion, the performance of bis-acryl composite resins varied largely among materials.

Color stability of a bis-acryl composite resin subjected to polishing, thermocycling, intercalated baths, and immersion in different beverages

OBJECTIVE

To evaluate the color of a bis-acryl resin after polishing, aging, and colorants.

MATERIALS AND METHODS

From the 140 disks obtained, 35 were not polished (NP), 35 were polished with 3-μm (3P), 35 with 3- and 1-μm (1P), and 35 with 3-, 1-, and 0.5-μm sized particles (05P). Five disks of each group were thermocycled for 20, 100, and 200 cycles. Sixty disks were thermocycled and kept in beverages (tea, wine, and coffee) after four cycles. Sixty disks were immersed in the beverages for 24 hours, a week, and a month. The coordinates L*a*b* were measured and the color differences were analyzed by ANOVA. The lightness, chroma, and hue differences were evaluated by repeated measures ANOVA. Comparisons were made with Tukey's test (α = 0.05).

RESULTS

Similar behaviors were observed between 3P and 05P groups (1.53 and 1.95ΔE₀₀ ) (P < .05). The NP group submitted to 200 cycles showed the biggest color differences (3.02) (P = .003). The greatest color differences were observed in the NP group submitted to immersion in coffee (8.30) and wine (7.93) (P < .05).

CONCLUSIONS

The polished surfaces were the least stained. Coffee and wine provided the greatest color changes, both for baths and immersions.

CLINICAL SIGNIFICANCE

Polishing of provisional surfaces restorations made of bis-acrylic resin is essential to minimize staining caused by aging and use of colorants, regardless of the particle size present in the polishing paste. The contact with coffee and red wine should be avoided, especially for clinical times greater than 1 week.

Effect of different polishing methods on surface roughness of provisional prosthetic materials

Purpose:

To evaluate the surface roughness of bis-acrylic and acrylic resins submitted to different methods of polishing.

Materials and Methods:

Fifty samples of each provisional restorative material (Structur 2, Protemp 4, Duralay, and Dencrilay) were fabricated (10 mm × 2 mm) and divided into five groups (n = 10): (1) positive control group – polyester strip; (2) negative control – unpolished; (3) abrasive tips (Exa-Technique-Edenta); (4) goat hair brush and diamond polishing paste; and (5) silicone tips (Enhance). Each material was mixed and polymerized according to manufacturer's instructions. The parameter evaluated was the arithmetic mean of the surface roughness (Ra) determined using the rugosimeter SJ 301 (Mitutoyo, Japan). The data were analyzed with two-way analysis of variance (post hoc Tukey's test) (P < 0.05).

Results:

The lowest surface roughness values (0,22–0,90 μm) were observed in the Group 4 – goat hair brush and diamond paste, while the highest values (1,17–1,44 μm) were found in the Group 5 – silicone tips (enhance), with statistically significant differences between them, except for Dencrilay acrylic resin. There was statistically significant difference between bis-acrylic and acrylic resins in the Groups 1, 2, and 4.

Conclusions:

Within the limitations of this study, it was concluded that the most effective polishing system was the goat hair brush with diamond paste for both bis-acrylic and acrylic resins. The bis-acrylic resins exhibited significantly smoother surfaces than the acrylic resins.

The Effect of Different Storage Media on Color Stability of Self-Adhesive Composite Resin Cements for up to One Year

The aim of this study was to analyze the long-term color stability of eight self-adhesive composite resin cements (SACRCs) after storage in diverse media for up to one year. 480 discs (diameter: 12 mm/thickness: 1.0 ± 0.05 mm) were fabricated (n = 60/SACRC): (1) BeautyCem (BEA); (2) Bifix SE (BIF); (3) Clearfil SA Cement Automix (CLE); (4) RelyX Unicem 2 Automix (RXU); (5) SeT (SET); (6) SmartCem 2 (SMC); (7) SoloCem (SOC); and (8) SpeedCEM (SPC). After polishing, specimens were immersed in (a) red wine (RW); (b) curry-solution (CU); (c) cress-solution (CR); and (d) distilled water (DW) at 37 °C and measured after 7, 28, 90, 180, and 365 days for color differences (ΔE) and water absorption (WA). Non-aged specimens were used as baselines. After 365 days, all of the discs were polished and their ΔE was measured. Data were analyzed using Kolmogorov-Smirnov, partial-eta-squared/η_P², 3-/1-way ANOVA with Tukey-HSD post-hoc test (α = 0.05). Significant differences occurred between all SACRCs for WA (p ≤ 0.003), except in RXU and in SET and in ΔE (p ≤ 0.002), except in SET and SPC. The significantly highest WA presented in SOC; the lowest showed in BEA. Significant ΔE differences and a decrease after polishing between all storage media were found (p < 0.001) with highest values for RW, followed by CU, CR, and DW. The lowest ΔE was measured for CLE, followed by SOC, BIF, RXU, BEA, SPC, SET, and SMC (p < 0.001) and increased significantly during aging. The highest ΔE decrease presented in BEA. SACRCs showed an increase in WA/ΔE within total aging time. Discoloration could not be removed completely by polishing. SACRCs need to be carefully selected for restorations in the esthetical zone with visible restoration margins. Polishing can significantly reduce the marginal discoloration.

Kinetic and equilibrium profile of the adsorptive removal of Acid Red 17 dye by surfactant-modified fuller's earth

In the present study, fuller's earth (FE) was modified with sodium dodecyl sulfate for removal of Acid Red 17 (AR 17) dye from aqueous solutions. The surfactant-modified FE and FE were characterized by a Fourier transform infrared spectrometer, thermogravimetric analyzer and scanning electron microscope. Batch adsorption experiments were carried out as a function of contact time, pH, initial concentration of AR 17 and adsorbent dosage. About 99.1% adsorption efficiency was achieved within 60 min at adsorbent dose of 0.1 g for initial dye concentration of 1,000 mg L^-1 at pH 10. The adsorption data were well fitted with the Dubinin-Radushkevich isotherm model implying physisorption as the major phenomenon for adsorption. The kinetic data were analyzed using four kinetic equations: pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich equations. The rates of adsorption confirmed the pseudo-second-order kinetics with good correlation value (R² = 0.999). The results indicate that the modified adsorbent can effectively be used for the removal of AR 17 from wastewater with high absorption capacity of 2164.61 mg g^-1.

Evaluation of color stability of different temporary restorative materials

AbstractIntroductionTemporary restorative materials are widely used, however, little is know about their color stability.Objectiveto evaluate the color stability of the following temporary restorative materials: acrylic and bis-acrylic resins after immersion in pigmenting solutions for different periods of storage.Material and methodFour materials were tested (Dêncor/Clássico, Protemp 4/3M ESPE; Structur 2 SC/Voco; Luxatemp AM Plus/DMG) and 30 test specimens (15 mm in diameter and 2 mm thick) per material were fabricated. They were divided according to the storage medium (artificial saliva, saliva + cola type soda, and saliva + coffee) and storage time intervals (2, 5, 7 and 15 days). Color measurements were made before and after immersions, with use of a spectrophotometer, by means of the CIE L*a*b* system. The data were analyzed by the analysis of variance and the Tukey Test, at a level of significance of 5%.ResultAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). When bis-acrylic resins were compared no significant difference was observed between the resins Structur and Luxatemp (p=0.767). As regards solutions tested, coffee showed the highest color change values (p<0.001), and the longer the storage time interval, the greater was the color change in all the temporary restorative materials analyzed (p<0.001).ConclusionAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). Coffee caused the greatest color change, and immersion time was determinant in color stability of the temporary materials analyzed.

Evaluation of staining susceptibility of resin artificial teeth and stain removal efficacy of denture cleansers

OBJECTIVE

To assess the staining susceptibility of four acrylic resin (Ivostar, SR Vivodent PE, Major Dent, Integral) and a nanocomposite resin (Veracia) artificial teeth and to evaluate the stain removal efficacy of denture cleansers.

MATERIALS AND METHODS

Sixty maxillary incisors of each brand (total = 300) were divided into three groups according to staining solution as coffee, red wine and tea. Baseline color measurements were performed with a spectrophotometer. Specimens were immersed in staining solutions for 14 h (2 h × 7 days) and then second color measurements were performed. Each group was further divided into four sub-groups according to denture cleanser as Corega tabs, Fittydent, NaOCl (0.5%) and distilled water (control) (n = 5). Specimens were immersed in denture cleansers for 8 h and third color measurements were made. Thus, the weekly simulation period was completed. This cycle was repeated 12 times to simulate a 3-month time period and measurements were performed at the end of the 4th, 8th and 12th cycles. ΔE values were calculated and data were analyzed with 3-way repeated measures ANOVA and Bonferroni tests.

RESULTS

Significant color differences were found among the teeth and staining solutions, but all of the color differences were in the clinically acceptable range (ΔE < 5.5). Integral showed the highest ΔE values for all solutions, while Ivostar and Vivodent demonstrated the lowest ΔE values for red wine and tea solutions. There was no significant difference among the denture cleansers in terms of stain removal efficacy.

CONCLUSIONS

Cross-linked acrylic (Integral) and nanocomposite (Veracia) resin teeth were more susceptible to staining. Denture cleansers were efficient on stain removal from artificial teeth.

Physical properties of polyamide-12 versus PMMA denture base material

OBJECTIVES

Polyamide-12 (PA) is a flexible material suited for denture bases and clasping. This study investigated its potential aging effects with a focus on surface roughness, color stability, and elasticity.

METHODS

PA specimens (Valplast) of 40×10×2 mm and equally measuring PMMA specimens (Palapress) as control were fabricated. Color changes after storage in air, water, coffee, and red wine (n=10) were measured using the CIE L*a*b* color specification. Elasticity after thermocycling (1000, 3000, and 7000 cycles,  n=15) was measured by three-point bending testing. Mean surface roughness (Ra) was determined after storage in the liquids mentioned above and thermocycling (n=10).

RESULTS

Tukey's HSD test (P<0.05) revealed statistically significant color changes of PA in red wine (ΔE=4.27 after 12 days, ΔE=6.90 after 12 days) and coffee (ΔE=3.93 after 36 days) but no color changes in PMMA. Elastic modulus of PA was 845 MPa and not affected by thermocycling (Tukey's HSD test,  P>0.81). Dry specimens showed significantly decreased elasticity (P<0.001). Mean surface roughness (PA 0.20  μ m, PMMA 0.28  μ m) did not change significantly after thermocycling or storage (Mann-Whitney U-test,  0.16<P<0.65).

SIGNIFICANCE

PA exhibited a higher susceptibility to discoloration than PMMA. Neither surface roughness nor elasticity of PA was altered by artificial aging.

Citotoxicity of food dyes sunset yellow (E-110), bordeaux red (E-123), and tatrazine yellow (E-102) on Allium cepa L. root meristematic cells

The objective of this study was to evaluate the cytotoxic effect of the food dyes sunset yellow, bordeaux red, and tartrazine yellow on the cellular cycle of Allium cepa L. Each dye was evaluated at the doses of 0.4 and 4.0 mL, at the exposure times of 24 and 48 hours in root tip cells of Allium cepa L. Slides were prepared and cells were analyzed during the whole cell cycle for cellular aberrations totaling 5,000 total cells for each dose evaluated. The mitotic index was calculated, and statistical analysis was performed using the Chi-squared test (p < 0.05). The results showed that the three dyes used under the evaluated doses and exposure times were cytotoxic to the cells of the system-test used. Further cytotoxicity studies should be conducted for additional results and a proper evaluation of the effect of these three dyes on a cellular level.