Fluorescence intensities of composite resins on photo images.

Recording fluorescence using flash photography, may help reduce time of capture and apply effectively in clinical practice. To test methods for visualizing composite resins fluorescence by direct digital photography. Sixty-four specimen discs (1.5 × 10 mm) were prepared from 8 different composite resin brands. Their CIELAB color coordinates (L*, a*, b*) and fluorescence were measured using a portable colorimeter and a fluorescence spectrophotometer. The mean of three measurements was recorded and then specimens were photographed by a DSLR camera with two different filters (365 nm and 405 nm) mounted on a commercial macro flash. RGB values of all specimens on the photographs were measured by using Photoshop software and converted to CIELab. Data were then analyzed using Kruskal-Wallis and Dunn's multiple comparisons tests. Correlation and regression analyses were also used to relate fluorescence and color parameters on the photographs at α = 0.05. Fluorescence and color data indicated significant differences among the materials (p < 0.05). L* a* and b* color coordinates from both photographs were highly correlated to fluorescence intensities found by the reference method (r365 - 0.95, r405 - 0.94), while regression analysis indicated a strong linear relationship (R2365 - 0.88, R2405 - 0.89). The study showed that filtered flash photography either by the use of a 365 nm or a 405 nm band pass filter can directly visualize fluorescence of composite resin materials and differences in fluorescence between them.

Evaluation of the Effect of Different Surface Treatments on Luting CAD/CAM Composite Resin Overlay Workpieces.

PURPOSE: To evaluate the effect of different surface treatments on luting CAD/CAM composite resin workpieces. MATERIALS AND METHODS: One-hundred eight (108) composite CAD/CAM block sections (Lava Ultimate) 3 mm in thickness were polished up to 4000 grit and then randomly assigned to 6 experimental groups according to the applied surface treatment (no treatment, sodium bicarbonate [NaHCO3], glycine, alumina [Al2O3], CoJet, and SilJet). After standardized sandblasting procedures, 2 block sections from each group were randomly chosen for the qualitative SEM evaluation of the sandblasted surfaces. The remaining 96 CAD/CAM block sections were luted in pairs using a bonding agent (Single Bond) and a restorative composite resin (Filtek Ultimate). Specimens were aged for 2 weeks in 37°C water with 3000 thermal cycles (5°C/55°C), the microtensile test was performed (n = 30), and the values were statistically analyzed with ANOVA and Tukey's HSD post-hoc test (p = 0.05). RESULTS: The qualitative SEM evaluation of the sandblasted surfaces showed that sodium bicarbonate and glycine had almost no conditioning effect on the CAD/CAM composite resin. In contrast, aluminum oxide, CoJet, and SilJet had a profound conditioning effect on the CAD/CAM composite resin. No treatment, sodium bicarbonate, and glycine specimens were debonded after thermal stressing (0 MPa), while aluminum oxide, CoJet, and SilJet showed high microtensile values (Al2O3: 104.45 ± 18.76 MPa; CoJet: 105.55 ± 11.88 MPa; SilJet: 105.02 ± 20.84 MPa), which were not statistically significantly different from each other. CONCLUSION: Aluminum oxide-based sandblasting powders are the best choice for the surface treatment of CAD/ CAM workpieces.

Marginal adaptation of large adhesive class IV composite restorations before and after artificial aging.

PURPOSE: To test the marginal adaptation of Class IV restorations made of different composite materials designed for anterior use. MATERIALS AND METHODS: Forty-two extracted caries-free human maxillary central incisors were randomly divided into 7 experimental groups - one per composite tested - for which Class IV cavities were prepared. The microfilled composite materials tested (SolidBond/Durafill [D/SB], Syntac classic/Heliomolar [H/SC], Scotchbond1/ Experiment127 [EXI/SB1], Optibond FL/Point 4 [P4/OBFL], Prime&Bond NT/Esthet-X [EX/PBNT], ART Bond/ Miris [MIR/ART], SE Bond/Clearfil ST [CLE/SE-B]) were inserted in two increments after polymerization of their respective adhesive systems. While under simulated dentinal fluid pressure, specimens were submitted to cyclic incisal stress (1,200,000 cycles, maximum load 49 N) and thermal loading (3000 cycles). Both after polishing and after thermomechanical loading, impressions were made of the surface of each restoration, and epoxy replicas were prepared for the marginal adaptation evaluation using SEM. RESULTS: Perfect margins before loading in enamel ranged from 49.9% (EXI/SB1) to 98.2% (MIR/ART) and after loading from 25.3% (EXI/SB1) to 91.9% (MIR/ART). For margins located in dentin, perfect margins ranged from 16.8% (EXI/SB1) to 100% (CLE/SE-B) before loading and from 4.6% (EXI/SB1) to 67.1% (CLE/SE-B) after loading. CONCLUSION: The poor results obtained in this in-vitro test with the microfilled composites suggest avoiding their use in large Class IV restorations with margins in dentin.

Is the glass half empty or half full? A novel "philosophical" approach to the "mystery" of the so-called ferrule effect.

The prognosis of endodontically treated teeth has traditionally been associated with the presence of the so-called ferrule effect that is generally related with the presence of a minimum of 1-2 mm of sound tooth structure at the cervical area of parallel axial walls that totally encircle the tooth. Even though all of these factors are well desired, one should question if their absence should condemn a tooth and compel extraction as the only logical treatment plan option. For this reason an hypothesis is being formed that associates the aforementioned factors not with the presence of the so-called ferrule effect, but rather with the resistance form of the preparation that is being provided by the sound tooth structure at the cervical area of the tooth. When the desired resistance form is provided by sound tooth structure of endodontically treated teeth, then less lateral forces are being transferred to the post & core and subsequently to the root of the teeth, thus minimizing the chances of decementation of the post & core or worst fracture of the root. Even more important, if this hypothesis may be further entertained, then even when the so-called ferrule effect is not present, the teeth may not be extracted, but alternative strategies for post & core restorations may be investigated, such a more flexible carbon- or glass-fiber posts & core build ups made from flowable resin composite that may accommodate for the increased lateral forced exerted to the post & core complex during function.

A Novel Method of Capturing Fluorescence in Clinical Dentistry.

OBJECTIVES: A fully integrated esthetic restoration should emit levels of fluorescence similar to that of natural dentition. Also, dental practitioners should be able to monitor this property in their routine clinical setting. The aim of this study was to investigate the efficacy of a removable filter for a macro flash illumination set-up required for the digital photographic recording of the fluorescence emission of human teeth and dental restorations. METHODS: The traditional fluorescence capturing method in clinical dentistry, using continuous lighting, was compared with the proposed flash lighting method. A digital single-lens reflex Canon 550D camera with a Canon 100-mm macro lens and a commercially available standard Canon MT-24EX twin light macro flash were used in this study. A custom-fabricated plastic o-ring was fixed with silicone to the original flash framework, which received a removable fluorescence filter composed of two 365-nm ultraviolet (UV) glass filters on both sides, covering the flash lamps. The original protective plastic diffusers in front of the flash lamps were replaced with clear plastic to release the full excitation wavelength range of the xenon flash lamps. No additional filter was placed in front of the lens. RESULTS: The results showed that using the proposed custom-made flash/filter illumination source, f-numbers between 16 through 22, a shutter speed of 1/60, and ISO 800 or 1600 sensitivity settings attained satisfactory fluorescent digital images. Results were comparable to those accomplished using a traditional photographic technique, without the need for a dark room, extended exposure times, and time-consuming set-ups. CONCLUSION: A contemporary photographic technique was demonstrated using macro flash UV-A 365-nm illumination that allowed fluorescent digital photograph acquisition under standard dental office conditions. Fluorescence documentation using a quick, straightforward procedure can take place during the restorative session to help increase the success rate of dental restorations.

Marginal adaptation after aging of a self-etching adhesive containing an antibacterial monomer.

PURPOSE: To evaluate the marginal adaptation of mixed Class V cavities restored with Clearfil Protect Bond (Kuraray), Clearfil SE Bond (Kuraray), and two experimental combinations of both marketed adhesives, after fatigue and water storage. MATERIALS AND METHODS: Four groups (Clearfil Protect Bond, Clearfil SE Bond, Exp. 1 and Exp. 2) of Class V cavities were restored with a microhybrid restorative composite (Clearfil APX, Kuraray). The marginal quality of these restorations was quantified by evaluation of gold-coated epoxy replicas with scanning electron microscopy before loading, after loading, and after a 12-month period of water storage. Data from marginal adaptation along the total margin length, on enamel, and on dentin were analyzed with the Wilcoxon signed rank test for differences within a group and with Kruskal-Wallis in order to assess the differences between groups. The Bonferroni test was used for post-hoc comparisons, and the confidence level was set to 95%. RESULTS: The mean percentages (+/-SD) of "continuous margin" of the total marginal length ranged from 79.5% (+/-13.3) to 62.2% (+/-10.4) and from 70% (+/-11) to 61% (+/-15.1) after loading and after storage, respectively. No significant differences could be detected amongthe different groups. However, the marginal adaptation of Clearfil Protect Bond remained the most stable of all materials tested, as no significant differences were detected between the percentages of continuous margins before loading, after loading, or after storage. CONCLUSIONS: The use of an antibacterial adhesive system was as effective as the conventional two-step self-etching adhesive in the marginal adaptation of Class V restorations.

Marginal and internal adaptation of bulk-filled Class I and Cuspal coverage direct resin composite restorations.

This in vitro study compared the marginal and internal adaptation of bulk-filled Class I and cuspal coverage direct resin composite restorations filled with different types of adhesive restorative systems and different thicknesses of bonding agent. Seventy-two intact, caries-free, freshly extracted human molars were randomly divided into 12 groups of six teeth each, according to the type of cavity (Class I [I] or Cuspal Coverage [C]), adhesive restorative system (SE Bond/Clearfil AP-X [SE] or Prime&Bond NT/Spectrum TPH [PB]) and thickness of bonding agent (normal or thick layer) in Class I restorations. Standardized Class I and Cuspal coverage cavities with enamel outer margins were prepared and restored with the corresponding type and thickness of bonding agent and respective resin composite. The resin composite was placed and polymerized in one increment (bulk filling). Dentinal fluid was simulated using 1:3 diluted horse serum and fed into the pulp chamber both during restoration and stressing. In six of the 12 groups, the restorations were subjected to 1.2 million mechanical occlusal cycles (maximum force 49 N; frequency 1.7Hz) and 3,000 simultaneous thermal cycles (5-50-5 degrees C). Marginal adaptation before and after mechanical and thermal stressing was assessed by using the replica technique and quantitative evaluation under SEM at 200x magnification. The teeth were dissected in a mesio-distal direction with a slow rotating diamond disc under water cooling, and the internal adaptation was also assessed by using the replica technique under the conditions described. Statistical evaluation of the continuous margin at the external and internal interface was performed with one-way analysis of variance (ANOVA) and Tukey's Studentized Range (HSD) test (p = 0.05). Even though Cuspal coverage restorations (SE- C: 96.89 +/- 1.83 and PB- C: 97.15 +/- 2.93) exhibited statistically significantly better external adaptation than Class I restorations (SE- I: 63.95 +/- 12.82 and PB- I 64.74 +/- 14.62) before stressing, there was no statistically significant difference after mechanical and thermal stressing (SE- C: 76.35 +/- 18.53 and PB- C: 76.02 +/- 12.49 SE- I: 54.67 +/- 10.82 and PB- I: 59.94 +/- 15.20). After stressing, SE Bond Cuspal coverage restorations (SE- C: 96,72 +/- 3,26) exhibited superior internal adaptation compared to SE Bond Class I restorations (SE- I: 57.83 +/- 12.91). No difference was observed in internal adaptation between Prime&Bond NT Cuspal coverage and Class I restorations (PB- C:36.46 +/- 21.82, PB- I: 38.71 +/- 6.76). In Class I restorations, the increased thickness in bonding did not improve the marginal and internal adaptation either before or after stressing. Bulk-filled direct resin composite Cuspal coverage restorations exhibited marginal adaptation similar to bulk-filled direct resin composite Class I restorations. The internal adaptation of Cuspal coverage SE Bond/Clearfil AP-X restorations was superior to all the other groups tested.

Digital Photographic Procedure for Comprehensive Two-Dimensional Tooth Shade Analysis.

Current commercially available restorative materials vary in their esthetic properties, depending on brand and shade. Variations are related not only to basic color parameters such as hue, chroma, and value, but also to other important properties that affect the overall esthetic restorative outcome, such as opalescence, fluorescence, translucency, and metamerism. Fluorescence and bluish opalescence, though associated with the ingredients and chemical composition of the material, may be controlled and refined by a proper layering technique if that pretreatment analysis has been performed with the aid of appropriate photographic techniques. Digital cameras and dental photography have long been imperative tools for clinicians in their daily practice. Traditionally, digital photography has been used for recordkeeping, documentation, presentation, and informing patients of their oral status before and after treatment. Today, evolved techniques facilitate clinicians' ability to compare the esthetic properties of restorative materials with those of natural teeth for delivery of natural-looking restorations. Moreover, documentation obtained before and after restoration may be used for more comprehensive information for the patient.

Degree of remaining C=C bonds, polymerization shrinkage and stresses of dual-cured core build-up resin composites.

This study measured the degree of remaining C=C bonds (RDB), linear polymerization shrinkage (LPS) and polymerization stresses (PS) of dual-cured resin composite build-up materials using a variety of light exposure scenarios. Four commercially available materials were used: Bis-Core, FluoroCore, Build-it! and Permalute. The RDB was measured using FTIR spectroscopy, and custom-made devices were used to measure LPS and PS values. Data were obtained using three different modes of photoactivation: NLC (No Light-Curing); ILC (Immediate Light-Curing, where 60 second light-curing was applied at the start of the observation period); and DLC (Delayed Light-Curing, where 60-second light-curing was applied 10 minutes from the start of the observation period). Statistical evaluation of the data at the end of the 13-minute observation period was performed with two-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) Test (p=0.05) and simple linear regression. Differences in the development of LPS and PS during the 13 minutes were studied using mathematical calculus. Bis-Core presented the highest RDB and Permalute the lowest when ILC was applied, while no differences were found between Build-it! and FluoroCore and NLC and DLC increased RDB for FluoroCore and Permalute compared to ILC; whereas, no differences were noted for Build-it! and Bis-Core. Using DLC, a decrease in RDB was found only for Build-it! FluoroCore and Permalute exhibited a reduction in LPS and PS using NLC relative to ILC. No differences in LPS and PS values were detected for the materials Bis-Core and Build-it! when subjected to NLC or DLC, compared to ILC. Simple linear regression showed that only the two polymerization shrinkage properties studied were highly correlated (LPS-PS r2=0.85). The RDB rate was not correlated with either polymerization shrinkage properties (RDB-LPS r2=0.40; RDB-PS r2=0.57). A study of the evolution of the real-time curves of percentage values of LPS and PS showed that these properties evolved in a similar exponential mode and that, most often, there was a delay in the development of PS.

Polymerization shrinkage of flowable resin-based restorative materials.

This study measured the linear polymerization displacement and polymerization forces induced by polymerization shrinkage of a series of flowable resin-based restorative materials. The materials tested were 22 flowable resin-based restorative materials (Admira Flow, Aelite Flow, Aeliteflow LV, Aria, Crystal Essence, Definite Flow, Dyract Flow, Filtek Flow, FloRestore, Flow-it, Flow-Line, Freedom, Glacier, OmegaFlo, PermaFlo, Photo SC, Revolution 2, Star Flow, Synergy Flow, Tetric Flow, Ultraseal XT and Wave). Measurements for linear polymerization displacement and polymerization forces were performed using custom made measuring devices. Polymerization of the test materials was carried out for 60 seconds by means of a light curing unit, and each property was measured for 180 seconds from the start of curing in eight specimens for each material. Statistical evaluation of the data was performed with one-way analysis of variance (ANOVA), Tukey's Studentized Range (HSD) test (p=0.05) and simple linear regression. A wide range of values was recorded for linear polymerization displacement (26.61 to 80.74 microns) and polymerization forces (3.23 to 7.48 kilograms). Statistically significant differences among materials were found for both properties studied. Very few materials (Freedom, Glacier, and Photo SC) presented low values of linear polymerization displacement and polymerization forces (similar to hybrid resin composites), while the majority of materials presented very high values in both properties studied. Study of the shrinkage kinetics revealed the exponential growth process of both properties. The polymerization forces development exhibited a few seconds delay over linear polymerization displacement. Simple linear regression showed that the two polymerization shrinkage properties that were studied were not highly correlated (r2=0.59).

Immediate dentin sealing of onlay preparations: thickness of pre-cured Dentin Bonding Agent and effect of surface cleaning.

This study evaluated the thickness of Dentin Bonding Agent (DBA) used for "immediate dentin sealing" of onlay preparations prior to final impression making for indirect restorations. In addition, the amount of DBA that is removed when the adhesive surface is cleaned with polishing or air abrasion prior to final cementation was evaluated. For this purpose, a standardized onlay preparation was prepared in 12 extracted molars, and either OptiBond FL (Kerr) or Syntac Classic (Vivadent) was applied to half of the teeth and cured in the absence of oxygen (air blocking). Each tooth was bisected in a bucco-lingual direction into two sections, and the thickness of the DBA was measured under SEM on gold sputtered epoxy resin replicas at 11 positions. The DBA layer of each half tooth was treated with either air abrasion or polishing. The thickness of the DBAs was then re-measured on the replicas at the same positions. The results were statistically analyzed with non-parametric statistics (Mann-Whitney U test and Kruskal-Wallis test) at a confidence level of 95% (p=0.05). The film thickness of the DBA was not uniform across the adhesive interface (121.13 +/- 107.64 microm), and a great range of values was recorded (0 to 500 microm). Statistically significant differences (p<0.05) were noted, which were both material (OptiBond FL or Syntac Classic) and position (1 to 11) dependent. Syntac Classic presented a higher thickness of DBA (142.34 +/- 125.10 microm) than OptiBond FL (87.99 +/- 73.76 microm). The higher film thickness of both DBAs was at the deepest part of the isthmus (the most concave part of the preparation), while the lowest was at the line angles of the dentinal crest (the most convex part of the preparation). OptiBond FL presented a more uniform thickness around the dentinal crest of preparation; Syntac Classic pooled at the lower parts of the preparation. The amount of DBA that was removed with air abrasion or polishing was not uniform (11.94 +/- 16.46 microm), and a great range of values was recorded (0 to 145 microm). No statistically significant differences (p<0.05) were found either between different DBAs (OptiBond FL or Syntac Classic) or between different treatments (air abrasion or polishing). As far as the effect of different treatments at different positions, polishing removed more DBA from the top of the dentinal crest, but the difference was not statistically significant. Air abrasion removed less DBA from the corners of the dentinal crest (Positions 4 and 6) than the outer buccal part of the preparation (Positions 1 and 2). Neither air abrasion nor polishing removed the entire layer thickness of the DBA in the majority of the cases.

Marginal integrity of pit and fissure sealants. Qualitative and quantitative evaluation of the marginal adaptation before and after in vitro thermal and mechanical stressing.

This research quantitatively evaluated the marginal adaptation of pit and fissure sealants. The occlusal surfaces of 48 intact, caries-free human molars were cleaned with an air-abrasion unit. The teeth were then randomly divided into eight groups of six teeth each according to the type of enamel conditioning, sealant material applied and curing unit used. After applying either 40% phosphoric acid gel (K-etch, Kuraray Co) or a self-etching primer adhesive system (Clearfil SE Bond, Kuraray Co), sealant materials of two viscosities were applied (Teethmate F-1 and Protect-Liner-F, Kuraray Co) and cured with halogen (Optilux 500, Demetron) or plasma arc (Apollo-95E, Dental & Medical Diagnostic Systems, Ltd) curing units. The marginal adaptation of the pit and fissure sealant restorations was evaluated by using a computer-assisted quantitative margin analysis in a scanning electron microscope (SEM) on epoxy replicas before and after thermal and mechanical stressing of the teeth. The results were statistically analyzed with one-way analysis of variance (ANOVA) at a confidence level of 95% (p=0.05). A post-hoc Tukey HSD-test was used for multiple pairwise comparisons between groups. The null hypothesis was that there was no statistically significant difference between the groups that were tested in this study. The statistically significant differences between groups were more pronounced after loading. In most cases, the self-etching adhesive system (SE Bond) proved as effective as phosphoric acid etching (K-etch). The low viscosity sealant material (Teethmate F-1), in most cases, exhibited better marginal adaptation than the high viscosity material (Protect-Liner F). The high viscosity material performed equally well only when used in combination with the self-etching primer adhesive system as an intermediate layer. The halogen curing unit (Optilux 500) led to better marginal adaptation than the plasma arc curing unit (Apollo 95E), especially after thermal and mechanical stressing.

Linear displacement and force induced by polymerization shrinkage of resin-based restorative materials.

PURPOSE: To measure the linear displacement and force induced by polymerization shrinkage of a series of resin-based restorative materials. METHODS: The materials tested were 10 ultrafine midway-filled resin-based composites, mainly used in anterior restorations (Brilliant Dentin, Brilliant Enamel, Charisma F, Pertac II Aplitip, Prodigy, Resulcin, Sculpt-it, Synergy Duo, Tetric and Z100), 11 ultrafine compact-filled composites, suggested by the manufacturers as "amalgam substitutes" for posterior restorations (Alert, Ariston pHc, Definite, EXI-119, EXI-120, Nulite F, Prodigy Condensed, Prodigy High Viscosity, Solotaire, Surefil and Synergy Compact), and six polyacid-modified composites (Compoglass, Dyract, Dyract AP, Elan, F2000 and Hytac Aplitip), also known as compomers. Each property was measured for 180 seconds from the start of curing with the help of custom made devices in eight specimens for each material. Statistical evaluation of the data was performed with one-way ANOVA, Tukey's Studentized Range (HSD) Test (P= 0.05) and simple linear regression. RESULTS: Statistically significant differences among groups and among composites were found for both of the properties that were studied. The ultrafine compact-filled composites (amalgam substitutes) exhibited the least linear displacement, followed by the polyacid-modified composites (compomers) and the ultrafine midway-filled composites, with statistically significant differences among all groups. The groups followed the same order in the polymerization force, with only the compomer-amalgam substitute comparison not being statistically significantly different. The simple linear regression showed that the two studied properties were also highly correlated (r=0.89).

A minimally invasive treatment of severe dental fluorosis.

This article describes a minimally invasive technique to treat a severe case of enamel fluorosis using microabrasion to eliminate the hypermineralized, white-colored, superficial enamel layer, followed by home bleaching treatment and chairside re-creation of superficial enamel microstructure. The proposed technique may improve the esthetics of fluorotic teeth without requiring other restorative procedures. Microabrasion followed by home bleaching may be an interesting alternative for the restorative treatment of teeth affected by fluorosis.

Resin composite shrinkage and marginal adaptation with different pulse-delay light curing protocols.

The aims of this study were, first, to measure shrinkage induced by different methods of pulse-delay light curing and, second, to verify their influence on the marginal adaptation of class V restorations in enamel and dentin. Eight groups, comprising seven groups (n = 6) with different pulse-delay parameters and a control group, were compared for dynamic linear displacement and force by using a fine hybrid composite. Based on these results, the pulse-delay curing procedure with the lowest shrinkage force was chosen and tested against the control group with respect to marginal adaptation in class V restorations (n = 8) before and after simultaneous thermal and mechanical loading. Statistically significant differences between groups were found for both shrinkage properties tested, with one pulse-delay group giving the lowest overall shrinkage values. However, the percentages of 'continuous margin' of this group, and of the control before and after loading, were not significantly different in dentin, whereas a significantly lower percentage of 'continuous margin' was detected in the pulse-delay group in enamel after loading.

Effect of different high-palladium metal-ceramic alloys on the color of opaque and dentin porcelain.

STATEMENT OF PROBLEM: The color of dental porcelain depends on the type of metal substrate. Little research has been done to document the effects of different types of high-palladium alloys on the color of dental porcelain. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different high-palladium alloys on the resulting color of dentin porcelain, as well as on that of opaque porcelain after simulated dentin and glazing firing cycles. MATERIAL AND METHODS: Three Pd-Cu-Ga alloys, Spartan Plus (S), Liberty (B), and Freedom Plus (F), and 5 Pd-Ga alloys, Legacy (L), IS 85 (I), Protocol (P), Legacy XT (X), and Jelenko No.1 (N), were examined. A Pd-Ag alloy, Super Star (T), was included for comparison to the high-palladium alloys, and the Au-Pd alloy, Olympia (O), served as the control. Six cast discs (16 x 1 mm) were prepared from each of the alloys. Shade B1 opaque porcelain (Vita-Omega) was applied at a final thickness of 0.1 mm. After 2 opaque porcelain firing cycles, the surfaces were airborne-particle abraded, and the specimens were divided into 2 groups. In the first group, 0.9 mm of B1 dentin porcelain was applied. The other group of specimens with only opaque porcelain underwent the same dentin porcelain and glazing firing cycles. Color differences (DeltaE) were determined with a colorimeter between the control and each experimental group, after the second opaque porcelain, second dentin porcelain, and glazing firing cycles. One-way analysis of variance and Dunnett's multiple range test were performed on the DeltaE data (alpha=.05). RESULTS: After the application of dentin porcelain, the 3 Pd-Cu-Ga alloys showed significantly different (P<.05) DeltaE values (S=2.3 +/- 0.5, B=1.4 +/- 0.3, and F=1.3 +/- 0.7) than the control group. After the glazing cycle of this group, the 3 Pd-Cu-Ga alloys and the Pd-Ag alloy exhibited significantly different (P<.05) DeltaE values (S=2.8 +/- 0.8, B=2.2 +/- 0.3, F=1.9 +/- 1.0, and T=1.4 +/- 0.5) than the control group. After the simulated dentin porcelain firing cycles, the specimens with only opaque porcelain exhibited significantly different (P<.05) DeltaE values (S=5.2 +/- 1.4, B=5.4 +/- 0.6, and F=3.9 +/- 0.2) than the control group. The color difference between the 3 Pd-Cu-Ga alloys with only opaque porcelain and the control group increased more after the simulated glazing cycle (S=6.6 +/- 1.5, B=6.3 +/- 0.5, and F=4.6 +/- 0.1). The observed color differences between the Pd-Ga alloys and the control group were not statistically significant at any point. CONCLUSIONS: The Pd-Cu-Ga alloys with only opaque porcelain, after the simulated dentin porcelain and glazing firing cycles, exhibited clinically unacceptable color differences. The application of dentin porcelain to the Pd-Cu-Ga alloys resulted in clinically acceptable color differences. The application of dentin porcelain to the Pd-Ag alloy, after the glazing firing cycle, resulted in clinically acceptable color differences (approximately 2.8 to 3.7 DeltaE CIELAB units). The Pd-Ag alloy specimens with only opaque porcelain did not exhibit significant color differences from the control group, whereas significant color differences from the control group after the dentin porcelain and glazing firing cycles were still clinically acceptable.