Color stability of siloranes versus methacrylate-based composites after immersion in staining solutions

Objectives

The purpose of this study was to determine, by using a spectrophotometer device, the color stability of silorane in comparison with four methacrylate-based composites after being immersed in different staining solutions such as coffee, black tea, red wine, orange juice, and coke, and distilled water as control group.

Methods

Four restorative methacrylate-based composites (Filtek Z250, TetricEvoCeram, Venus Diamond, and Grandio) and one silorane (FiltekSilorane) of shade A2 were selected to measure their color stability (180 disk samples) after 4 weeks of immersion in six staining solutions: black tea, coffee, red wine, orange juice, coke, and distilled water. The specimen's color was measured each week by means of a spectrophotometer (CIE L*a*b* system). Statistical analysis was carried out performing an ANOVA and LSD Test in order to statistically analyze differences in L*a*b*and ?E values.

Results

All materials showed significant discoloration (p?<?0.05) when compared to the control group (immersed in distilled water). The Highest ?E observed was with red wine, whereas coke led to the lowest one. Silorane showed the highest color stability compared with methacrylate-based composites.

Conclusions

Methacrylate-based materials immersed in staining solutions showed lower color stability when compared with silorane. Great differences in ?E were found among the methacrylate-based materials tested.

Clinical relevance

Although color stability of methacrylate-based composites immersed in staining solutions has been widely investigated, this has not been done for long immersion periods with silorane-based composites.     

Patients’ Assessments of Tooth Sensitivity Increase One Day Following Different Whitening Treatments

ObjectivesThe aim of this clinical study was to compare tooth sensitivity scores and color change values before and 1 day following whitening treatments using different concentrations of whitening agents for in-office and at-home procedures.Materials and methodsA total of 60 participants divided into 3 groups were included in this study. A whitening procedure was carried out in groups using 40% hydrogen peroxide (HP) in in-office treatment, 16% and 10% carbamide peroxide (CP), respectively. Participants rated their tooth sensitivity at the baseline and 1 day following the treatment. The CIEl_ab values were recorded and color differences were calculated.ResultsWithin each of the whitening treatments, the tooth sensitivity scores significantly increased following the procedure (p<0.05). The largest significant increase in scores was noted in 40% HP in-office whitening treatment, while the lowest increase was noted in 10% CP at-home whitening treatments (p<0.05). The highest color change 1 day following the procedure was found in the 40% HP in-office whitening treatment group (3.3) and it significantly differed from both 16% CP and 10% CP at-home whitening treatments whose color difference was both 2.0, respectively (p<0.05).Conclusion1 day following the procedure, a low concentrate CP agent for at-home whitening causes the least tooth sensitivity compared to higher concentrate CP for at-home and HP for in-office agents, with the same color change efficacy as higher concentrate CP agent. In case with slight tooth sensitivity reported at the baseline, a 10% CP whitening treatment should be recommended.     

Effect of staining and whitening systems on color stability of computer aided design/computer aided manufacturing lithium disilicate glass ceramic

PurposeTo investigate the effect of coffee stain and whitening systems on the color stability of CAD/CAM glazed lithium disilicate glass-ceramics (LDGCs).Methods 68 glazed LDGC discs (12 × 10 × 2 mm) were fabricated using blocks of CAD/CAM systems (IPS e.max CAD ceramic). Baseline color was measured (CIE/L*a*b*), and specimens were randomized into four groups (n = 17). All specimens were stained (coffee solution; 24 h/d × 12) and then subjected to two whitening protocols. G1- (kept moist × 7 days); G2-positive control (brushed with distilled water, 200gm/load, 2 min twice daily × 7 days); G3- whitening toothpaste (Colgate optic white; relative dentin abrasivity = 100, 200gm/load, 2 min twice daily × 7 days) and G4-simulated at-home bleaching protocol (Opalescence,15% carbamide peroxide (CP), 6 h/day × 7 days). The study outcome was color change (ΔE) measured at baseline, after staining, and after whitening treatments. Data were analyzed using paired T-test and one-way ANOVA (α = 0.05).ResultsAll groups stained equally (p > 0.05) but were not clinically significant (ΔE ≤ 1.05). Stains were significantly (p ≤ 0.01) improved in G2 and G3 (ΔE = 0.69 and 0.63), yet were not eliminated compared to bleaching, which had the highest color improvement and completely removed the stains (ΔE = 0.72).ConclusionsGlazed LDGC was color stable after simulating one year of coffee staining. Bleaching, using 15% CP for a week, completely removed the stains and returned the LDGCs to their original shade. However, simulating eight months of brushing, regardless of the toothpaste content, improved the color outcome but didn’t remove it completely.     

The effect of curing units and staining solutions on the color stability of resin composites

This study investigated the effects of two different light curing units and two staining solutions on the color stability of a hybrid composite and a nanohybrid composite after different immersion periods. Thirty disk-shaped specimens (10 mm in diameter, 2-mm thick) were fabricated for each of the resin composites, Clearfil AP-X and Filtek Supreme. The specimens were randomly divided into two groups according to the curing unit used: Group I specimens (n = 15) were cured with a quartz-tungsten-halogen (QTH) light for 40 seconds, and Group II specimens (n = 15) were cured with a light-emitting diode (LED) unit in standard mode for 40 seconds. The specimens were incubated in 100% humidity at 37 degrees C for 24 hours. Then, the baseline color values (L*, a*, b*) of each specimen were measured with a spectrophotometer according to the CIELab color scale. After baseline color measurements, five randomly selected specimens from each group (Groups I and II) were immersed in one of two staining solutions (tea or coffee) or distilled water (control). After 1, 7 and 30 days of immersion, the color values of each specimen were remeasured and the color change value (deltaE*ab) calculated. Color changes caused by immersion in tea and coffee for 30 days were only perceptible in the Clearfil AP-X specimens cured with QTH or LED. In the Filtek Supreme specimens, coffee perceptibly stained the teeth after all immersion periods and tea stained after 30 days. Polymerization with QTH or LED did not cause any significant difference in the color stability of Clearfil AP-X or Filtek Supreme. While there were no significant differences between staining solutions in the Clearfil AP-X specimens cured with LED after one and seven days of storage and one day of storage in the QTH cured specimens, significant differences were observed between water and coffee after seven days of storage. In the Filtek Supreme specimens cured with QTH or LED, there were statistically significant differences between the staining solutions after one and seven days of storage. After 30 days of storage, no significant difference was found between tea and coffee in either resin composite cured with QTH or LED. The effect of the staining solutions (tea, coffee) on color changes in composites was immersion time and resin-material dependent.     

Effect of in-office bleaching agents on the color changes of stained ceromers and direct composite resins

Purpose. To evaluate the effect of two in-office bleaching agents on the color changes of two ceromers (Ceramage and Adoro SR) and one direct composite resin (Gradia Direct Anterior) after staining by tea and coffee. Materials and methods. Twenty-four disk-shaped specimens were fabricated for each resin material and randomly divided into three groups (n = 8). The specimens were immersed in tea, coffee or deionized water, respectively, for 7 days. Each group was then equally divided into two sub-groups (n = 4), which were subjected to two in-office bleaching agents (BEYOND and Opalescence Boost), respectively. The color of the specimens was measured by a spectrophotometer at baseline, after staining and after bleaching. The color differences (ΔE values) between baseline and after treatments were calculated. Results. Statistical analysis indicated that the staining solution had significant influence on the color change of resin composites tested (p < 0.001). The discolorations of resin composites were perceptible after immersing in tea or coffee solutions (ΔE>2.0). There was no statistically significant difference between BEYOND and Opalescence Boost in stains removal from discolored resins (p = 0.550). The color changes in ΔE value between baseline and after bleaching were less than 2.0 for all resin composite groups. Conclusions. Tea solution produces severe discoloration of three resin composites tested. The two in-office bleaching agents can effectively remove the stains from two ceromers and one direct composite resin tested in this study.     

Tooth color change due to different etching and debonding procedures

Objectives:To compare the effects of different etching techniques, 12–, 24–bladed tungsten carbide burs, and polishing discs on tooth color changes during orthodontic treatment.Materials and Methods:59 individuals (mean age: 15.20 ± 1.59 years) were divided into four groups: 37% phosphoric acid and adhesive primer was used in Groups I and II whereas self–etch primer was used in Groups III and IV for enamel preparation. After orthodontic treatment, residual adhesives were cleaned with 12–bladed tungsten carbide burs in Groups I and III, while 24–bladed tungsten carbide burs were used in Groups II and IV. All teeth were polished with medium and fine Sof–Lex XT discs (3M ESPE, St Paul, Minnesota). Color measurements were taken from upper incisors and canines at pretreatment (T0), after cleaning with tungsten carbide burs (T1) and polishing with discs (T2). Wilcoxon test was used for evaluation of L*, a*, b* changes and Kruskal–Wallis for intergroup comparison of color changes.Results:L*, a*, b* values, except a* at Groups I, II, IV, and b* at Group III, changed significantly (P < .05). Groups III and IV showed significantly different color alterations from T0 to T1 (P < .05). After polishing, tooth color alterations were not significantly different among the groups.Conclusions:In self–etch bonding groups, a 12–bladed tungsten carbide bur caused less color change than the 24–bladed tungsten carbide bur. Orthodontic treatment resulted with visible and clinically unacceptable tooth color alterations regardless of the enamel preparation and clean–up techniques. Polishing reduced the effect of tungsten carbide burs, but did not affect the total influence of orthodontic treatment on the tooth color.     

Changes on the color parameters of air‐abraded resin composite exposed to different colored beverages

Aim: To evaluate the effect of prophylaxis using sodium bicarbonate and colored beverages on the color parameters of a resin composite. Methods: Eighty specimens (Z350–3M ESPE) were randomly allocated into eight groups (n = 10), according to the combination of staining solution (artificial saliva, cola, red wine, or coffee) and air‐powder abrasion with sodium bicarbonate (either performed or not performed). Specimens were immersed in the staining solution for 48 h (two 24‐h cycles). Color evaluation was based on the CIELab system. Two measurements were carried out using a spectrophotometer (Commission Internationale de L’Eclairage L* a* b* system) before and after the immersion period. Final measurement data were analyzed by two‐way anova /Tukey’s test, and comparisons were made between initial and final measurements by anova /Dunnett’s test, with a 5% significance level. Results: Most comparisons between initial and final measurements were statistically significant. Red wine and coffee significantly affected the color parameters (L*, b*, and ΔE). However, only coffee significantly increased a* values. When compared with untreated surfaces, air‐powder abrasion resulted in alterations of b* and a* parameters, but did not affect L* and ΔE. Conclusions: Both colored beverage solutions and air‐powder abrasion can affect the color of composite resin restorations.     

Influence of food-simulating solutions and surface finish on susceptibility to staining of aesthetic restorative materials

OBJECTIVES: To determine the degree of surface staining of resin-based composites (RBCs) and glass-ionomer cements (GICs) after immersion in various stains and food-simulating solutions (FSS). METHODS: Six tooth-coloured restorative materials were used: a light-cured microfilled RBC (Durafil, Kulzer), a light-cured microglass RBC (Charisma, Kulzer), a polyacid-modified RBC (F2000, 3M/ESPE), a conventional GIC (Fuji IX, GC) and two resin-modified GICs (Fuji II LC, GC; Photac Fil, 3M/ESPE). Disk-shaped specimens were prepared and tested with either a matrix finish or polished using wet silicon carbide papers up to 2000 grit. All specimens were immersed in 37 degrees C distilled water for 1 week, followed by three different FSS (water, 10% ethanol, Crodamol GTCC) and five stains (red wine, coffee, tea, soy sauce and cola) for a further 2 weeks. Three specimens of each material for each stain were tested. Colour coefficients (CIE L* a* b*) were measured by a spectrophotometer after each treatment. The change in colour (DeltaEn) was calculated using the formula: DeltaEn=[(DeltaLn+(Deltaa(n))2+(Deltab(n))2]1/2. RESULTS: Distilled water caused no perceptible colour change as tested by ANOVA and Tukey's tests. The effect of surface finish on staining was not statistically significant (P>0.05). There was no strong interaction between FSS and stains or between FSS and materials. There was a strong interaction between surface and material, and stain and material (P<0.001). CONCLUSIONS: All materials were susceptible to staining by all stains especially coffee, red wine and tea; Fuji IX showed the least susceptibility and F2000 the greatest.     

Color stability of different denture teeth materials against various staining agents

The purpose of this in vitro study was to evaluate the color stability of two brands of porcelain teeth and three brands of acrylic denture teeth. Samples were immersed into three staining drinks as test groups and distilled water as a control. Color measurements of teeth were performed by using a spectrophotometer. Before immersion, the initial color value of each tooth was recorded. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks of immersion. Color differences were characterized using the CIE L*a*b* color space. The color stability of all teeth was significantly affected by the immersion period (p<0.0001). Instant coffee was found to be the most chromogenic agent among the solutions tested (p<0.0001). Among the materials tested, porcelain was found to be more resistant to discoloration. It was concluded that acrylic teeth showed a higher degree of color change and that the amount of color change for each group increased proportionally with time.     

The color differences of direct esthetic restorative materials after setting and compared with a shade guide

BackgroundThe authors conducted a study to evaluate esthetic restorative materials’ color differences after setting and color matching between set materials and a shade guide.Materials and MethodsThe authors evaluated 13 resin-based composites, one silorane-based composite, two polyacid-modified resin composites and one conventional glass ionomer cement. They measured the color parameters of the samples, which were 8 millimeters in diameter and 1.5 mm in thickness, before and after they were set according to the Commission International de l’Eclairage (CIE) L*a*b* color scale relative to standard illumination against a white background by means of a dental colorimeter. They also compared the final colors of the restorative materials with a shade guide.ResultsColor difference values for each restorative material ranged from 3.25 to 14.04. With the exception of Fuji IX (GC, Tokyo), Filtek P60 (3M ESPE) and Te-Econom (Ivoclar Vivadent), the restorative materials exhibited a perceptible color change after setting. Color difference values between the set materials and the shade guide tabs ranged from 1.86 to 11.83. With the exception of Filtek Supreme XT (3M ESPE) and Fuji IX, the materials exhibited a perceptible difference.ConclusionMost of the materials tested exhibited a significant color change after polymerization and did not match the shade guide tab after undergoing light curing.     

Clinical comparison of two self-directed bleaching systems

PURPOSE: This randomized clinical trial compared the clinical efficacy and tolerability of 2 marketed self-directed vital tooth-whitening systems. MATERIALS AND METHODS: Balancing for baseline tooth color, self-reported coffee/tea use, and age, 57 adult volunteers were randomized to either a whitening strip containing 6% hydrogen peroxide or a tray-based 10% carbamide peroxide/dentifrice/mouth rinse combination system. Following the manufacturer's directions, the strip group bleached twice daily for 30 minutes, whereas the tray group bleached twice daily for 20-30 minutes, preceded by tooth brushing with a whitening dentifrice and followed by mouth rinsing with a whitening solution. Treatment extended for 14 days, with evaluation at day 7 and again at day 14. Whitening response was measured objectively as L*a*b* from standardized digital images of maxillary anterior teeth. Tolerability was assessed by oral examination and subject interview. Efficacy comparisons were made using analysis of covariance, whereas tolerability was compared using the nonparametric Wilcoxon rank-sum test. RESULTS: Both treatments resulted in statistically significant (P < 0.01) improvements from baseline for all color parameters. For between-group comparisons, the 6% hydrogen peroxide strips yielded a nearly 3-fold reduction in yellowness (deltab*), a nearly 2-fold improvement in lightness (deltaL*), 2.6 times greater redness reduction (deltaa*), and a more than 2-fold change in overall color (deltaE*) compared to the tray-based combination system. Between-group comparisons were statistically significant for the all color parameters at both the day 7 and day 14 evaluations (P < 0.001). In general, 7-day use of the whitening strips provided significantly greater color improvement relative to the combination dentifrice/gel/rinse system at day 14. In addition, the groups differed significantly (P < 0.05) in bleaching tolerability severity-days, with the strip system demonstrating better overall tolerability compared to the combination system. CONCLUSIONS: The single-step 6% hydrogen peroxide strips demonstrated better overall clinical response, in terms of both tooth-whitening efficacy and tolerability, than the multiple-step tray-based combination system.     

Effect of bleaching and repolishing procedures on coffee and tea stain removal from three anterior composite veneering materials

Discolored teeth can be treated with resin veneers, but their color changes when confronted with staining solutions. Polishing procedures can provide a remedy for highly stained composites, but they tend to remove some materials as well. However, bleaching procedures are an effective, nondestructive method for solving the problem. The aim of this study was to compare the color change of three veneer composites exposed to staining solutions and to evaluate the effectiveness of a 15% hydrogen peroxide bleaching agent and three polishing systems to remove the stain. Forty‐five disks (12 × 2 mm) each of Clearfil ST® (Kuraray Co. Ltd., Osaka, Japan), Esthet‐X? (Dentsply/Caulk, Milford DE, USA), and Filtek A110? (3M ESPE, St. Paul, MN, USA) were prepared. The specimens were polished with Sof‐Lex? (3M ESPE), Enhance® (Dentsply/Caulk), or PoGo® (Dentsply/Caulk). Five specimens for each material‐polishing system combination were immersed in coffee (Nescafe® Classic, Nestle SA, Vevey, Switzerland) or tea (Earl Grey, Lipton, Blackfriars‐London, England) for 7 days. The remaining disks were stored in water. Color measurements were made with a spectrophotometer (X‐Rite® Seroice SP78, Loaner, Köln, Germany) at baseline; after 1, 3, 5, and 7 days; and after bleaching and repolishing. After 1 week, one side of the specimens was bleached with Illuminé‐office® (Dentsply De Trey GmbH, Konstanz, Germany) for 1 hour, and the other side was repolished for 30 seconds. All comparisons of color change for the polishing systems, times, and staining solutions were subjected to repeated measurements of analysis of variance. Paired t‐test was used to examine whether significant color differences (δE*) occurred during immersion at the specified time intervals (p .05). Filtek A110 was the least stained resin composite. Its color remained under a δE* value of 2 during the study. Clearfil ST exhibited the most color change after 1 week. All specimens polished with Enhance showed less staining, whereas those polished with the Sof‐Lex system demonstrated the most color change. Water did not cause a variance in the δE*. There was no difference in the staining potential of coffee and tea. Bleaching and repolishing were effective in removing the stains. The resin composites tested reversed nearly to baseline color with the bleaching and to less than values at 1 day of staining with repolishing. The coffee and tea brands tested stained the composites used in this study equally. In‐office bleaching was found to be more effective than repolishing in the restitution of the color.     

Effects of Different Over – the - Counter Whitening Products on the Microhardness,Surface Roughness,Color and Shear Bond Strength of Enamel

ObjectiveThe purpose of this in vitro study was to evaluate the effects of four over-the-counter (OTC) whitening products on the microhardness, surface roughness, color, shear bond strength (SBS) and surface charecteristics of human enamel compared with a product used for dentist-supervised home whitening.Materials and methodsSeventy eight enamel specimens allocated into 6 groups (n=13): 1-Opalescence PF 10% (OP) dentist prescribed home whitening product, 2-Opalescence Go prefilled tray (PT), 3-Opalescence Whitening Toothpaste (WT), 4-Listerine Healthy White whitening mouth rinse (WMR), 5-Cavex Bite&White whitening pen (WP) and 6- no treatment (Con). The microhardness (VHN), surface roughness (Ra) and color of the specimens were measured (T₀). The specimens were then subjected to whitening protocols for 14 days (T₁.) followed by artificial saliva storage for 14 days (T₂). The measurements were repeated at T₁ and T₂. The SBS test was done after the application of 35% phosphoric acid (Scotchbond Universal Etchant), followed by a universal adhesive (G-Premio Bond) and a micro hybrid/universal resin composite (Essentia) into a Teflon tube attached to the enamel surface (p<0.05). Surface morphologies of the enamel surfaces were examined by SEM. p value was set at 0.05ResultsApplication of OP, PT and WP decrased the microhardness of enamel specimens (p<0.05) whereas, no significant changes were seen in the microhardness of enamel specimens treated with WT and WMR (p>0.05). Ra values of enamel specimens increased with the application of OP, PT and WT (p<0.05); whereas no changes were observed after the applications of WMR and WP (p>0.05). OP, PT, WMR, and WP changed the color of the enamel(p<0.05). There were not any significant differences among the SBSs groups, apart from OP applied enamel specimens. OP showed the least SBS values (p=0.001). SEM observations revealed smooth enamel surfaces.ConclusionsThe whitening products affected the microhardness, surface roughness, color of enamel differently. Only OP decreased the SBS of the enamel.     

Comparison of the color stability of ten new-generation composites: An in vitro study

Objectives. The aim of this in vitro study was to evaluate the color stability of modern light-cured composites when subjected to various physico-chemical and staining conditions. Methods. Ten brands were evaluated including hybrids, microfine hybrids and microfilled composites. Some universal shade samples underwent only staining tests, while others were subjected to one of the following experimental conditions: thermocycling, postcuring, polishing or a 1 wk immersion in saline, prior to staining. The coloring solutions used for the staining tests were: coffee, E 110 food dye, vinegar and erythrosin. A colorimetric evaluation according to the CIE L*a*b* system was performed after experimental periods of 1 and 3 wk. Results. Erythrosin caused the greatest color change for the composites tested. A reduced susceptibility to staining was observed where surfaces had been polished. Low water sorption, a high filler-resin ratio, reduced particle size and hardness, and an optimal filler-matrix coupling system were related to improved composite resistance to discoloration. Significance. Resistance of modern composites to discolorations still depends on their structure and manipulation.     

美白牙膏去除人离体牙咖啡及茶渍效果的比较研究

目的研究一种含过氧化物的美白牙膏对咖啡及茶渍色素去除的效果及差异。 方法选择2018年9月至2019年5月北京大学口腔医院综合科因正畸需要新鲜拔除的完整人双尖牙20颗，采用随机数字表法分为2组（咖啡溶液浸泡组与红茶溶液浸泡组），每组10颗。美白牙膏配制为牙膏溶液，使用200 g压力，100次/分钟频率，140次作为1个刷牙周期（相当于刷牙1周），连续刷牙8周。应用Crystaleye分光光度比色仪进行颜色测定。表面颜色测定选取的时间点为：基线、染色后及每个刷牙周期后。计算染色后及每个刷牙周期后与基线值之间，国际照明委员会（CIE）颜色的明度值之差ΔL_0-8*。各个样本染色后及每个刷牙周期后颜色与基线颜色之间的色差用ΔE_0-8表示，各组不同测量点组内差异应用配对t检验进行统计分析。各组组间差异应用ANOVA方差分析进行统计，P<0.05为差异有统计学意义。 结果咖啡溶液浸泡组及红茶溶液浸泡组，随着美白牙膏刷牙时间的延长，ΔE值较染色后逐渐降低。但直至美白牙膏刷牙第8周，仍无法恢复到基线水平。咖啡溶液浸泡组美白牙膏刷牙第1周起，牙齿颜色变化ΔE₁（5.2 ± 1.4）较染色后ΔE₀（6.1 ± 1.3）差异有统计学意义（t= 9.1，P<0.001）。红茶溶液浸泡组美白牙膏刷牙第4周起，牙齿颜色变化ΔE₄（5.6 ± 1.5）较染色后ΔE₀（6.4 ± 1.1）差异有统计学意义（t= 2.7，P= 0.025）。咖啡溶液浸泡组及红茶溶液浸泡组，离体牙样本明度值较基线值明显降低，从美白牙膏刷牙第1周起，ΔL₁*（-4.3 ± 0.9；-4.2 ± 1.0）较染色后ΔL₀*（-5.3 ± 0.9；-6.1 ± 1.2）差异有统计学意义（t_ΔL1*=-9.4，P_ΔL1*<0.001；t_ΔL0*=-12.1，P_ΔL0*<0.001）。 结论美白牙膏能够在一定程度上去除咖啡及红茶造成的牙面着色。其改善效果与使用时间成正相关。对于不同着色类型，美白牙膏去除外源性色素的效果不尽相同。     

Effect of ageing and immersion in different beverages on properties of denture lining materials

Objectives

To evaluate the color stability and hardness of two denture liners obtained by direct and indirect techniques, after thermal cycling and immersion in beverages that can cause staining of teeth.

Material and Methods

Seventy disc-shaped specimens (18 x 3 mm) processed by direct (DT) and indirect techniques (IT) were made from elite soft (n=35) and Kooliner (n=35) denture liners. For each material and technique, 10 specimens were subjected to thermal cycling (3,000 cycles) and 25 specimens were stored in water, coffee, tea, soda and red wine for 36 days. The values of color change, Shore A hardness (elite soft) and Knoop hardness (Kooliner) were obtained. The data were subjected to ANOVA, Tukey’s multiple-comparison test, and Kruskal-Wallis test (P<0.05).

Results

The thermal cycling promoted a decrease on hardness of Kooliner regardless of the technique used (Initial: 9.09±1.61; Thermal cycling: 7.77±1.47) and promoted an increase in the hardness in the DT for elite Soft (Initial: 40.63±1.07; Thermal cycling: 43.53±1.03); hardness of Kooliner (DT: 8.76±0.95; IT: 7.70±1.62) and elite Soft (DT: 42.75±1.54; IT=39.30±2.31) from the DT suffered an increase after the immersion in the beverages. The thermal cycling promoted color change only for Kooliner in the IT. Immersion in the beverages did not promote color change for elite in both techniques. The control group of the DT of Kooliner showed a significant color change. Wine and coffee produced the greatest color change in the DT only for elite Soft when compared to the other beverages.

Conclusion

The three variation factors promoted alteration on hardness and color of the tested denture lining materials.     

Color stability of visible light-cured, hard direct denture reliners: an in vitro investigation.

PURPOSE: Previous studies have disclosed the unsatisfactory color stability of autopolymerizing, hard direct denture reliners (HDDR). The present study investigated the color stability of the newly introduced visible light-cured and dual-cured HDDRs. MATERIALS AND METHODS: Five HDDRs were evaluated after 1 hour, 1 day, 7 days, and 30 days of immersion in coffee, tea, and water. Color measurements were obtained with a tristimulus colorimeter, and color differences (delta E*) were calculated. RESULTS: After 30 days of immersion one visible light-cured material exhibited the highest delta E* value (17.8). The other materials showed acceptable color stability in water and coffee. However, tea strongly affected their color. CONCLUSION: Reliners, staining solutions, and immersion time are significant factors that affect color stability. After 7 days of immersion, all of the materials showed perceptible color differences. Tea exhibited higher staining capacity than coffee.     

Influence of acid-etched splinting methods on discoloration of dental enamel in four media: an in vitro study

The aim of this in vitro study was to assess the staining of enamel in relation to fixation of luxated teeth. Color changes induced by chlorhexidine, red wine. tea, and coffee were detected with a Minolta Chroma Meter (CR-121) after extracted teeth were treated to simulate construction of dental splinting. L*a*b* color readings were made before and after 7 days of incubation in the above-mentioned media in teeth treated 1) by acid-etching, 2) by acid-etching followed by resin, 3) by resin and composite, 4) by Triad Gel. and 5) by Protemp. L* is an indicator of black (0) and white (100). The a* values relate to the red (+100) -green (−100) color axes, and the b* values to the yellow (+100) and blue (−100) axes. Untreated teeth served as controls. One-way analysis of variance of mean L* values revealed no statistically significant differences in treatment. Discoloration was observed in all teeth, including the control ones. However, Protemp yielded the largest changes in mean L* values. Analysis of variance of mean L* values revealed statistically significant differences between incubation liquids because no increase in staining of enamel was noted after 7 days' incubation in chlorhexidine. Red wine increased the mean L* values more than coffee or tea. Changes in a*b* readings were toward red (+a*) after incubation in red wine, except in the case of teeth treated with resin. The color of all such teeth changed more toward yellow (+b*), because the resin used was yellow. No statistically significant difference was noted between the three pastes used for polishing. None of the pastes restored the enamel to the same color as before incubation.     

着色介质及表面粗糙度对热固化基托树脂着色的影响

目的:研究4种着色介质对不同表面粗糙度的热固化基托树脂的表面着色状况。方法:制作64个热固化基托树脂试件,随机分成4组,不同组试件的测试面打磨出不同的粗糙度等级,用表面粗糙度轮廓仪测量其表面粗糙度参数Ra并记录,然后将每组试件分别浸泡于蒸馏水(对照)、咖啡、茶和陈醋中,用分光光度比色仪测量试件浸泡前及浸泡4周后的颜色,得到L*、a*、b*值,计算浸泡前后的色差△E,采用统计学方法,分析热固化基托树脂着色与上述因素的关系。结果:除对照组外,咖啡组和茶组试件的色差值△E均增大(P<0.05),且咖啡组的△E大于茶组(P<0.05),陈醋组的△E无明显改变(P>0.05);同一浸泡液中不同表面粗糙度的试件的△E值差异有显著性(P<0.05),表面粗糙度越大,△E越大。结论:外源性色素能引起基托树脂的着色,并且树脂表面越粗糙,着色越明显。