Spectrophotometric evaluation of the optical influence of core build-up composites on all-ceramic materials

ObjectivesTo evaluate the optical influence of core build-up composites on the resultant color of ceramic–composite combinations, and analyze the color difference of ceramic–composite combinations to Vita Lumin shade guide with the same nominal shade.MethodsThirty ceramic specimens, with a standardized thickness, were made from three all-ceramic materials (Empress2, In-Ceram, Vita Mark 2). Nominal shades A1 and A3 of the Vita Lumin shade guide were selected. Fifty disc-shaped composite specimens were fabricated using ten colors of core build-up composites. The combinations of ceramic and resin specimens were used to simulate the all-ceramic restorations. The colors of the combinations and A1/A3 shade tabs were measured with a spectrophotometer. The results were converted to CIE L^*a^*b^* and CIE L^*C^*H^* values, then color differences (ΔE) and translucency parameters (TP) were calculated for each combination and ceramic material. Mean ΔE values were analyzed with three-way ANOVA and Turkey's multiple comparison tests were used to evaluate the within-group effect of the shades of the composites. The corrections between the ΔEs and TPs were evaluated using a linear analysis.ResultsColor differences were significantly influenced by the composite shade, ceramic system, and ceramic shade (P < 0.001). Mean color differences were 7.023, 8.290, and 6.347 for In-Ceram, Empress2 and Mark2 system, respectively. ΔE values were significantly associated with the TP values.SignificanceThe color of underlying core composite has a significantly influence on the resultant color of an all-ceramic restoration. The use of the Vita Lumin shade guide does not accurately achieve the intended color duplication.     

Curing potential and color stability of different resin-based luting materials

PurposeTo determine the curing potential and color stability of resin-based luting materials for aesthetic restorations.Material and MethodsFour resin-based luting agents were tested: traditional dual-activated resin cement (RelyX ARC, ARC), amine-free dual-activated resin cement (RelyX Ultimate, ULT), light-activated resin cement (RelyX Veneer, VEN), and pre-heated restorative resin composite (Filtek Supreme, PHC). Degree of C = C conversion was determined by infrared spectroscopy (n = 3) with direct light exposure or with interposition of 1.5-mm-thick ceramic (e.max Press HT) between the luting material and light. The curing potential considered the ratio between these two scenarios. Color difference (n = 6) was determined by CIELAB (ΔE_ab) and CIEDE2000 (ΔE₀₀) methods, by spectrophotometer measurements made 24 h after photoactivation and 90 days after storage in water. Data was submitted to ANOVA and Tukey’s test (α = 0.05).ResultsThe luting agents affected both conversion and color stability. With ceramic, ARC produced the highest conversion among the tested groups (75 ± 1%) and the pre-heated composite (PHC) the lowest one (51 ± 3%), but the curing potential was similar for all materials. ULT produced lower ΔE_ab than ARC. PHC presented the lowest color difference when considered both CIELAB and CIE2000 methods (ΔE_ab 2.1 ± 0.4; ΔE₀₀ 1.6 ± 0.2).SignificanceAll luting strategies presented high curing potential. Amine-free dual-activated material was able to reduce color difference than that formulated with the amine component. Pre-heated composite produced the least color variation after storage.     

Optical influence of the type of illuminant,substrates and thickness of ceramic materials

ObjectivesThe present study is an instrumental evaluation of the optical influence of the type of illuminant, substrate and different thickness on the color of dental ceramics.MethodsThirty ceramic disks were prepared from IPS-Empress and IPS-Empress2 in three different thicknesses (1.5, 2.0 and 2.5 mm). Disks made of composite resin; silver–palladium alloy and gold were used as substrates. The disks with a 1.5 mm thickness were placed on a neutral gray photographic paper and measured with a spectrophotometer under three illuminants: daylight (D65), incandescent light (A) and fluorescent light (F6). All ceramic disks were combined with the substrate disks and a spectrophotometer was used to measure the coordinates of lightness (L*) and chromaticity (a* and b*). Two-way ANOVA (p < 0.05) was used to analyze the combinations of ceramics, substrates and illuminants tested considering the coordinates of lightness (L*) and chromaticity (a* and b*), and also differences of color (ΔE), lightness (ΔL*), chromaticity values (Δa* and Δb*).ResultsFor the illuminants tested, the results present significant differences for coordinates of chromaticity a* and b*, suggesting a metamerism effect. In combination with the substrates, the results present statistical differences in all the tested conditions, especially where there is no ceramic substructure.SignificanceThe presence of discolored tooth remnants or metallic posts and cores can interfere with the desired aesthetic result, based on the selection of color aided by a single luminous source. Thus, the substrate color effect, thickness of the ceramic materials and type of illuminant are important factors to be considered during the clinical application of the ceramic systems.     

Influence of pigments and opacifiers on color stability of silicone maxillofacial elastomer

ObjectivesTo determine the effects of opacifiers and silicone pigments on the color stability of silicone A-2000 maxillofacial prosthetic elastomers subjected to artificial aging.MethodsSeventy-five groups (n = 5) were made by various combinations (5%, 10%, and 15%) of four dry earth opacifiers (Georgia kaolin, Gk; calcined kaolin, Ck; Artskin white, Aw; titanium white dry pigment, Td); and 1 silicone pigment white (Sw) with one of 5 silicone pigments (no pigment (control), red (Pr), yellow (Py), burnt sienna (Po), and a mixture of Pr + Py + Po). A reflection spectrophotometer was used for color measurements. Color differences (ΔE*) between baseline and after an energy exposure of 450 kJ/m² in an artificial aging chamber were calculated. A ΔE* = 3.0 was used as 50:50% acceptability threshold in result interpretation, while ΔE* = 1.1 was used as 50:50% perceptibility threshold. Means were compared by Fisher's PLSD intervals at the 0.05 level of significance. Color differences after aging were subjected to three-way analysis of variance.ResultsYellow ochre mixed with all opacifiers at all intervals had increased ΔE* values significantly from 0.7–2.1 up to 3.8–10.3. When mixed groups were considered, at 5%, Gk exhibited the smallest color changes, followed by Td < Aw = Sw < Ck, respectively. At 10%, Aw < Td < Gk < Sw = Ck. At 15%, Td < Aw < Gk = Sw < Ck (< indicates p < 0.0001 and = indicates p > 0.05). The smallest color differences, observed for opacifier groups, were recorded for Gk at 5%, and Td and Aw at 10% and 15%. Overall, 15% Td exhibited the smallest, whereas 5% Ck exhibited the most pronounced color change after artificial aging. All ΔE* values were below the 50:50% acceptability threshold, indicating acceptable color stability. Color differences for 10% and 15% of Aw and Td were below 50:50% perceptibility thresholds, indicating excellent color stability.ConclusionSilicone pigments mixed with 10% and 15% Artskin white and titanium white dry pigment opacifiers protected silicone A-2000 from color degradation over time. Yellow silicone pigment significantly affected color stability of all opacifiers especially silicone pigment white and calcined kaolin.     

Effects of duration of whitening strip treatment on tooth color: A randomized,placebo-controlled clinical trial

ObjectivesA randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate efficacy and safety of 6% hydrogen peroxide whitening strip used twice daily over an extended, 6-week period.MethodsAfter informed consent, 40 eligible adults were randomly assigned to 6% hydrogen peroxide whitening strips (Crest Whitestrips, The Procter & Gamble Company, USA) or placebo strips without peroxide. Treatment was twice daily for 30 min, and response was evaluated biweekly after initial (Week 2) and extended (Weeks 4 and 6) use. Tooth color was measured under standardized lighting conditions using digital image analysis, and safety was assessed from clinical examination and interview. Whitening was measured using data derived from digital images taken at baseline compared to post-treatment, with outcomes reported using the CIELAB color notation system. Analysis of variance and covariance were used to assess initial response, and repeated measures regression analysis was used to model color change during sustained use.ResultsForty subjects (25–58 years old) started the study. At baseline, L* ranged from 68.0 to 76.8, a* ranged from 8.0 to 11.8, and b* ranged from 16.4 to 23.1. Groups differed significantly (p < 0.001) on all color parameters at Week 2 and thereafter, favoring the 6% hydrogen peroxide strips. Week 2 adjusted means ± SE were ?2.1 ± 0.2 for Δb* and 1.9 ± 0.2 for ΔL* for the peroxide group compared to ?0.3 ± 0.2 for Δb* and 0.4 ± 0.2 for the placebo group. With sustained use (Weeks 2–6), the slope for the peroxide strip was estimated as ?0.3 for Δb* and +0.2 for ΔL* per week, with both slopes differing significantly from zero (p < 0.0001), while slopes for the placebo strip were not significant (p = 0.22) and nearly zero. Treatment was generally well tolerated, with adverse events confined to symptoms only.ConclusionsTwice-daily use of 6% hydrogen peroxide whitening strips resulted in teeth becoming lighter and less yellow versus baseline and placebo during initial 2-week use, with no evidence of placebo response during sustained (Weeks 2–6) use.     

Effect of denture cleansers on physical properties of heat-polymerized acrylic resin

PurposeThis study aimed to measure the color change, surface roughness and flexural strength of heat-polymerized acrylic resin after its immersion in denture cleansers, simulating a 180-day use.MethodsThirty disk-shaped (15 mm × 4 mm) and 30 rectangular samples (65 mm × 10 mm × 3.3 mm) were prepared from heat-polymerized acrylic resin and immersed in Corega Tabs, Bony Plus, and distilled water. Color measurements (ΔE) were determined by a portable colorimeter. A surface analyzer was used to measure the roughness before and after immersion (ΔRa). The flexural strength (S) was measured using a 3-point bending test. The ΔE values were submitted to statistical analysis by the Kruskal–Wallis test, followed by Dunn's Multiple Comparisons test. The ΔRa and S values were submitted to statistical analysis by ANOVA, followed by a Student–Newman–Keuls test (α = .05).ResultsThe color changes were significantly higher for the Corega Tabs than for the control group. The mean ΔE values quantified by the National Bureau of Standards (NBS) were classified as Trace (0.0–0.5). The Bony Plus group had significantly higher surface roughness than the other groups. Corega Tabs and Bony Plus groups presented lower flexural strength than the control group.ConclusionsAlthough the color changes after the immersion in denture cleansers were clinically insignificant, the Corega Tabs group showed higher color differences. The Bony Plus group showed significantly increased surface roughness. Both effervescent tablets Corega Tabs and Bony Plus significantly diminished the flexural strength of the acrylic resin.     

Color changes of polyetheretherketone (PEEK) and polyoxymethelene (POM) denture resins on single and combined staining/cleansing action by CIELab and CIEDE2000 formulas

PurposeThe purpose of study was to investigate the long-term effect of staining and/or cleansing solutions on the color stability of two non-metal removable partial denture materials.MethodsOne hundred disks (25×3 mm) of polyoxymethylene (POM) and polyetheretherketone (PEEK) were immersed in water, wine, coffee, cleanser and combo bath, simulating normal daily use. Color parameters in the CIELAB system was measured every 30 cycles up to 240 using a contact colorimeter and color differences estimated using ΔE_ab and ΔE₀₀ formulas. Two-way repeated measures ANOVAs and regression analyses were performed at α = 0.05.ResultsRegression analysis indicated a strong R² between color changes and number of cycles, for both materials. Tests of within-subjects effects for the ΔE_ab revealed significant differences among cycles and between the materials in the wine and coffee baths (p < 0.001). Significant materialXcycles interactions were also recorded with all staining baths. ΔE₀₀ values were lower than ΔE_ab up to 63.6%. Tests within and between-subjects effects for the ΔE₀₀ gave similar but not the same with ΔE_ab results.ConclusionsΔE₀₀ found to correlate well with ΔE_ab. Long term exposure of both materials showed a progressive discoloration in all except control baths. POM discolored more than PEEK in coffee, and combo baths but not in cleanser. Discoloration was smaller in combo bath (where a cleanser was also used) indicating the effectiveness of a cleanser to prevent long term discoloration of both materials.     

Color stability of silorane-based composites submitted to accelerated artificial ageing--an in situ study

ObjectivesTo assess the in situ color stability, surface and the tooth/restoration interface degradation of a silorane-based composite (P90, 3M ESPE) after accelerated artificial ageing (AAA), in comparison with other dimethacrylate monomer-based composites (Z250/Z350, 3M ESPE and Esthet-X, Dentsply).MethodsClass V cavities (25 mm² × 2 mm deep) were prepared in 48 bovine incisors, which were randomly allocated into 4 groups of 12 specimens each, according to the type of restorative material used. After polishing, 10 specimens were submitted to initial color readings (Easyshade, Vita) and 2 to analysis by scanning electronic microscopy (SEM). Afterwards, the teeth were submitted to AAA for 384 h, which corresponds to 1 year of clinical use, after which new color readings and microscopic images were obtained. The values obtained for the color analysis were submitted to statistical analysis (1-way ANOVA, Tukey, p < 0.05).ResultsWith regard to color stability, it was verified that all the composites showed color alteration above the clinically acceptable levels (ΔE ≥ 3.3), and that the silorane-based composite showed higher ΔE (18.6), with a statistically significant difference in comparison with the other composites (p < 0.05). The SEM images showed small alterations for the dimethacrylate-based composites after AAA and extensive degradation for the silorane-based composite with a rupture at the interface between the matrix/particle.ConclusionIt may be concluded that the silorane-based composite underwent greater alteration with regard to color stability and greater surface and tooth/restoration interface degradation after AAA.     

Color and contrast ratio of resin composites for whitened teeth

ObjectivesThe purpose of this study was to determine the optical properties, color and contrast ratio (CR) of commercially available resin composites marketed for the restoration of whitened teeth.MethodsTwenty-six resin composites designed for restoration of whitened teeth and four shade B1 (control) were evaluated. Five resin composite disks (d = 12 mm, h = 1.54 mm) were fabricated for each shade of composite and were stored in water at 37 °C for at least 24 h. A colorimeter was used to measure specimen color over both white and black backgrounds. CIELAB and CIExyY color spaces were used. The CIELAB color notation system provides values for L*a*b*. The CIExyY system provides lightness and chromaticity values, where Y represents lightness and xy chromaticity. The contrast ratio (CR) was assessed using, CIE xyY, of the specimens against black (Yb) and white (Yw) backgrounds, with CR = Yb/Yw. The data for L*, a*, b* and CR were analyzed by one-way ANOVA, Tukey's test, and the correlation L* and CR was analyzed by Pearson correlation test (α = 0.05).ResultsSignificantly different L*, a*, b* values and CR were observed. Premise XL2 had the highest L* and CR values and Vit-l-escence PS had the lowest. Vit-l-escence PS had the highest a* value and Point 4XL2 had the lowest, Premise XL1 had the highest b* value and Supreme WB the lowest. The L* and CR correlation was positive and statistically significant.ConclusionsComposites designated for whitened teeth have different levels of color and contrast ratio. Awareness of the optical properties of the composites allows the operator to choose the appropriate materials to mimic the remaining tooth structure.     

Influence of TiO2 nanoparticles on the optical properties of resin composites

ObjectivesTo determine the influence of titanium dioxide (TiO₂) nanoparticle addition on the opalescence, color, translucency and fluorescence of experimental resin composites.MethodsA light curing resin matrix was made by mixing 60 wt.% Bis-GMA and 40 wt.% TEGDMA. Silane coated glass filler (mean particle size: 1.55 μm) was added in the ratio of 50 wt.% of the resin composites. A fluorescent whitening agent was also added (0.05 wt.%). TiO₂ nanoparticles (<40 nm) were added with the concentrations of 0, 0.1, 0.25 and 0.5 wt.%. Reflected and transmitted colors of 1 and 2 mm thick specimens were measured relative to the illuminant D65 with reflection spectrophotometers. Opalescence parameter (OP), color difference (ΔE*_ab), translucency parameter (TP), fluorescence parameter (FL), and fluorescence and opalescence spectra were calculated.ResultsFor the 1 mm thick specimens measured with 3 mm × 8 mm rectangular aperture, when the concentration of TiO₂ increased from 0% to 0.5%, OP increased from 2.4 to 18.0, TP decreased from 35.4 to 13.1, and fluorescence spectra remained unchanged. Color difference between these specimens was in the range of 3.4–6.6 ΔE*_ab units. OP values were significantly influenced by the thickness of the specimens and the configuration of the spectrophotometers (p < 0.05).SignificanceAddition of TiO₂ nanoparticles significantly increased the opalescence of resin composites while leaving the fluorescence spectra unchanged; however, it significantly decreased the translucency and also changed the color (p < 0.05). Resin composites with 0.1–0.25% TiO₂ nanoparticle would simulate the opalescence of human enamel.     

Influence of photoinitiator system and nanofiller size on the optical properties and cure efficiency of model composites

ObjectiveTo establish the relationship between photoinitiator system and nanofiller size on the optical properties and cure efficiency of model composites.MethodsModel composites based on BisGMA/TEGDMA (60:40 mol%) were loaded with 40 wt% of 7 nm or 16 nm-sized filler particles. One of the following photoinitiator systems was added: camphorquinone (CQ) associated with an amine (EDMAB), monoacylphosphine oxide (TPO), or bysacylphosphine oxide (BAPO). The optical properties of disk-shaped specimens were measured 24 h after curing and repeated after storage in water for 90 days and coffee for 15 days. A large spectrum LED unit (Bluephase G2, Ivoclar Vivadent) was used for photoactivation. CIE L*a*b* parameters, color difference (ΔE), and translucency parameter (TP) were calculated. Knoop hardness readings were taken at top and bottom composite surfaces. Cure efficiency was determined by bottom/top hardness ratio. Data were statistically analyzed at α = 0.05 significance level.ResultsComposites formulated with 16 nm particles had higher CIE L* than those with 7 nm particles in all storage conditions. BAPO-based composites generally had lower CIE a* than the other composites. The group TPO + 16 nm before storage and all groups with 16 nm-sized particles after storage had lower CIE b* (i.e. lower degree of yellowing) than the other groups. TPO-based materials had higher color stability. The cure efficiency was not significantly affected by photoinitiator system or particle size. CQ + 7 nm had the lowest and BAPO + 16 nm the highest hardness values.SignificanceCombination of photoinitiator system and filler particle size might affect the optical properties of composites, with low influence on cure efficiency.     

Effect of changes in sintering parameters on monolithic translucent zirconia

ObjectivesAim of this study was to evaluate the effect of different sintering parameters on color reproduction, translucency and biaxial flexural strength of monolithic zirconia.MethodsTranslucent zirconia discs having 15 mm diameter, 1 mm thickness, and shade A3 were milled and divided according to the sintering temperatures (1460 °C, 1530 °C, and 1600 °C) into three groups (n = 30). Each group was later divided into three subgroups (n = 10) according to the sintering holding time (1, 2, and 4 h). Easyshade spectrophotometer (Vita, Bad Säckingen, Germany) was used to obtain the ΔE between the specimens and the shade A3. Mean ΔE values below 3.0 were considered “clinically imperceptible”, ΔE values between 3.0 and 5.0 were considered “clinically acceptable” and ΔE values above 5.0 were considered “clinically unacceptable”. Contrast ratio (CR) was obtained after comparing the reflectance of light through the specimens over black and white background. Biaxial flexural strength was tested using the piston-on-three balls technique in a universal testing machine.ResultsMean ΔE results ranged from 4.4 to 2.2. Statistically significant decrease in the Delta E was observed as the sintering time and temperature increased. CR decreased from 0.75 to 0.68 as the sintering time and temperature increased. No significant change in the biaxial flexural strength was observed.SignificanceSintering zirconia using long cycles and high temperatures will result in reduction of ΔE and CR. Biaxial flexural strength is not affected by changes in the evaluated sintering parameters.     

Influence of implant scanbody material,position and operator on the accuracy of digital impression for complete-arch: A randomized in vitro trial

PurposeTo evaluate the influence of implant scanbody (ISB) material, position and operator on the accuracy of a confocal microscopy intraoral scanning (IOS) for complete-arch implant impression.MethodsAn edentulous maxillary model with 6 internal hexagonal connection analogues was scanned with an extraoral optical scanner to achieve a reference file. Three ISBs made of different materials (polyetheretherketone (Pk), titanium (T) and Pk with a titanium base (Pkt)) were scanned with IOS by 3 operators. The resulting 45 test files were aligned to the reference file with a best fit algorithm. Linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Absolute values of the linear discrepancies were summed up to obtain a global measure of linear absolute error (ΔASS). Influence of ISB material, position and operator was statistically assessed using the mixed general linear model.ResultsAt multivariate analysis, whenΔASS was considered as response variable, it was identified a significant influence of material (p < 0.0001) and position (p = 0.0009) while no significant operator effect was detected.When ΔANGLE was considered as response variable, material and position significantly influenced the expected ΔANGLE (p = 0.0232 and p < 0.0001) and no operator effect was identified.ConclusionsThe investigated IOS for complete-arch digital impression was influenced by the ISB material with peek reporting the best results on both linear and angular measurements followed by titanium, peek-titanium resulting as the less accurate. Implant angulation affected significantly the linear deviations while implant position the angular deviations. Operator did not show any significant effect on the IOS accuracy.     

Effect of the shades of background substructures on the overall color of zirconia-based all-ceramic crowns

PURPOSE

The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown.

MATERIALS AND METHODS

Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core build-up. The color measurements of all-ceramic crowns were made before try-in, before and after cementation. A repeated measure ANOVA was used for a statistical analysis of a color change of all-ceramic crowns at α=.05. Twenty four zirconia specimens, with different core thicknesses (0.4-1 mm) were also prepared to obtain the contrast ratio of zirconia materials after veneering.

RESULTS

L^*, a^*, and b^* values of all-ceramic crowns cemented either on a metal cast post and core or on a prefabricated post did not show significant changes (P>.05). However, the slight color changes of zirconia crowns were detected and represented by ΔE^*_ab values, ranging from 1.2 to 3.1. The contrast ratios of zirconia specimens were 0.92-0.95 after veneering.

CONCLUSION

No significant differences were observed between the L^*, a^*, and b^* values of zirconia crowns cemented either on a metal cast post and core or a prefabricated post and composite core. However, the color of a background substructure could affect the overall color of posterior zirconia restorations with clinically recommended core thickness according to ΔE^*_ab values.     

Opalescence of bleached teeth

ObjectivesTo evaluate the influence of tooth bleaching on the opalescence properties of enamel.MethodsColor of 38 specimens was determined by colorimetric analysis before and after bleaching in the reflectance and transmittance modes. The results were described as CIELab color coordinates. The Opalescent Parameter (OP) was calculated as the difference in yellow–blue color coordinate (CIE Δb*) and red–green color coordinate (CIE Δa*) between the reflected and transmitted colors.ResultsMean OP value of the specimens was 18.9 (±1.6) before bleaching and 16.1 (±1.0) after bleaching.ConclusionsBleaching decreases the OP of the specimens (p > 0.001). OP decrease was correlated with differences in b* color coordinate in the transmittance mode.     

The effect of surface defects in early caries assessment using quantitative light-induced fluorescence (QLF) and micro-digital-photography (MDP)

ObjectivesThe purpose of this study was to consider the impact of surface defects on quantitative light-induced fluorescence (QLF) and micro-digital-photography (MDP) measures, in relationship to lesion depth.MethodsSimulated enamel carious lesions were developed on 45 extracted human teeth. Images of each tooth were captured with both QLF and MDP. The teeth were sectioned and lesion depth was measured with polarized light microscopy (PLM). Pearson correlations were computed using data from the 27 lesions which did not have surface loss, and then separately based upon the 18 lesions which did display surface loss. MDP variables ΔR and ΔX measure reflected light, whereas QLF variables ΔF and ΔQ measure fluorescence.ResultsA strong correlation was identified between lesion depth and ΔF (r = ?0.765, p < 0.0001), and ΔQ (r = ?0.827, p < 0.0001) on intact lesions while a weak but suggestive, although non-significant, correlation was identified between average lesion depth and ΔR (r = 0.369, p = 0.059) and ΔX (r = 0.595, p = 0.0011). However, the corresponding correlation was not statistically significant, when lesions with surface loss were considered for QLF and MDP measures.ConclusionsQLF measures ΔF and ΔQ were strongly correlated with lesion depth in lab-simulated lesions with no surface loss, but not among lesions with surface defects. The two MDP-associated measures, ΔR and ΔX, could not be said to differ significantly when lesions with and without surface defects were compared with lesion depth. Because intact lesions can be remineralized, accurate assessment of their status is imperative for caries treatment.Clinical significanceDental caries is still widely prevalent today. We now know that with early stage detection, remineralization can be accomplished. Being able to identify dental caries in its reversible stage (before physical surface loss) is paramount for the clinician to be able to treat the disease non-invasively.     

Color change of some aesthetic dental materials: Effect of immersion solutions and finishing of their surfaces

ObjectivesThe purpose of this research was to evaluate the color change of five aesthetic dental materials, before and after immersion in distilled water and blue food color solution for 7 and 21 days, and to study the effect of finishing the surfaces on any color change.MethodsDisc shaped samples of five types of light curing composite (A2) (n = 10 samples/composite) were prepared and all samples were light-cured with a Plasma Arc light cure unit for ten seconds. One side of each sample disc was finished and polished with a Super-Snap system all samples. After 24 h, color measurements of each sample were conducted using a digital spectrophotometer. Five sample discs from each composite group were immersed in 30 ml of food color solution for 7 and 21 days, while the remaining five sample discs were immersed in 30 ml of distilled water as a control. Color measurements were repeated for all samples at 7 and 21 days after immersion. The color changes were statistically analyzed using t-tests within the same group. A result was considered statistically significant at α = 0.05.ResultsThe color differences (ΔE) ranged from 0.4 to 4.66 and statistically significant differences on the finished and unfinished surfaces were observed after immersion in the food color solution for 7 days. No significant differences were found in any group after immersion in the food color solution for 21 days. The Tetric EvoCeram and Arabesk groups showed less color differences after 7 and 21 days than other composites.ConclusionFinished composite surfaces showed less coloration than unfinished surfaces after 7 days, but all surfaces (finished and unfinished) were highly colored for all composite types after 21 days.     

Promotion of enamel caries remineralization by an amelogenin-derived peptide in a rat model

ObjectiveAn amelogenin-derived peptide has been shown to promote remineralization of demineralized enamel in an in vitro model of initial caries induced by pH cycling. The present study examines whether the peptide exerts similar effects within the complex oral environment in vivo.DesignSpecific pathogen-free Sprague-Dawley rats (n = 36) were infected with Streptococcus mutans, given ad libitum access to Diet 2000 and drinking water supplemented with sucrose (10%, w/v), and then randomly divided into three groups treated with 25 μM peptide solution, 1 g/L NaF or deionized water. Molar teeth were swabbed twice daily with the respective solutions for 24 days. Then animals were killed, their jaws were removed and caries lesions were analyzed using the quantitative light-induced fluorescence-digital (QLF-D) technique to measure changes in mineral content. To verify QLF-D results, caries were scored for lesion depth and size using the Keyes method, and analyzed using polarized light microscopy (PLM).ResultsMineral gain was significantly higher in teeth treated with peptide or NaF than in teeth treated with water (p < 0.05), based on the QLF-D results (ΔF and ΔQ). Incidence of smooth-surface and sulcal caries based on Keyes scores was similar in rats treated with peptide or NaF, and significantly lower in these groups than in rats treated with water (p < 0.05). Lesions on teeth treated with peptide or NaF were shallower, based on PLM. No significant differences were observed between molar enamel caries treated with peptide or NaF.ConclusionsThis amelogenin-derived peptide can promote remineralization in a rat caries model, indicating strong potential for clinical use.