Targeted mutagenesis of flavonoid biosynthesis pathway genes reveals functional divergence in seed coat colour, oil content and fatty acid composition in Brassica napus L.

Yellow-seed is widely accepted as a good-quality trait in Brassica crops. Previous studies have shown that the flavonoid biosynthesis pathway is essential for the development of seed colour, but its function in Brassica napus, an important oil crop, is poorly understood. To systematically explore the gene functions of the flavonoid biosynthesis pathway in rapeseed, several representative TRANSPARENT TESTA (TT) genes, including three structural genes (BnaTT7, BnaTT18, BnaTT10), two regulatory genes (BnaTT1, BnaTT2) and a transporter (BnaTT12), were selected for targeted mutation by CRISPR/Cas9 in the present study. Seed coat colour, lignin content, seed quality and yield-related traits were investigated in these Bnatt mutants together with Bnatt8 generated previously. These Bnatt mutants produced seeds with an elevated seed oil content and decreased pigment and lignin accumulation in the seed coat without any serious defects in the yield-related traits. In addition, the fatty acid (FA) composition was also altered to different degrees, i.e., decreased oleic acid and increased linoleic acid and α-linolenic acid, in all Bnatt mutants except Bnatt18. Furthermore, gene expression analysis revealed that most of BnaTT mutations resulted in the down-regulation of key genes related to flavonoid and lignin synthesis, and the up-regulation of key genes related to lipid synthesis and oil body formation, which may contribute to the phenotype. Collectively, our study generated valuable resources for breeding programs, and more importantly demonstrated the functional divergence and overlap of flavonoid biosynthesis pathway genes in seed coat colour, oil content and FA composition of rapeseed.

Optical effects of graphene addition on adhesives for orthodontic lingual retainers.

The objective of this study was to determine the effects on the colour of adding increasing concentrations of graphene to orthodontic fixed retainer adhesives and to evaluate changes in optical transmission during light curing and the resultant degree of conversion. Two different types of adhesives commonly used for fixed retainers were investigated: A packable composite (Transbond) and a flowable composite (Transbond Supreme). Graphene was added to the adhesives in three different concentrations (0.01, 0.05, and 0.1 wt%). Adhesives without graphene addition were set as control groups. A Minolta colourimeter was used to measure the colour and translucency parameters. Irradiance transmitted during curing was quantified using MARC Light Collector. Fourier-transform infrared spectroscopy was used to record degree of conversion. Data were statistically analysed with the Student's t-test and one-way ANOVA with Tukey's tests (α = 0.05). The findings showed that incorporating graphene darkened the adhesive colour significantly and reduced translucency. As the graphene concentration reached 0.1 wt%, samples became opaque; yet, no adverse effect on degree of conversion was observed. The addition of graphene reduces optical transmission of lingual retainer adhesives; the effect increases with graphene concentration.

Evaluation of Long-term colour resistance of composite materials used in aligner treatments: A comparative study.

AIM: The aim of this study is to evaluate the discolouration resistance of attachments made of composites having different physical properties, filler ratios and viscosity through the simulated environment and conditions. MATERIALS AND METHODS: Seventy-two extracted human teeth were aligned to simulate upper and lower dental arches. The attachments were prepared according to the guides determined by ClearCorrect. Three different composite groups were used for attachments preparation: Aligner Connect, G-Aenial Universal Injectable, and Tetric Prime and Tetric Evoflow combination. Dental models and aligners were kept in artificial saliva throughout the experiment of 96 weeks. The aligners were also subjected to 2308 thermal cycles and insertion and removing procedures 840 times for each period of 12 weeks. Afterwards, the models were kept in coffee and red wine solutions. Colour measurements were made with Vita Easy Shade 4.0 at 12th, 24th, 48th and 96th simulated weeks. RESULTS: No significant difference in discolouration was observed during thermal cycle application of 12th and 24th week experimental periods. In the later periods, discolouration was observed in the composite materials, and G-Aenial Universal Injectable was less coloured than the other samples. The composite samples were more coloured in proportion to their residence time. The G-Aenial Universal Injectable was more affected by wine solution, and Tetric Prime and Tetric Evoflow combination were more affected by coffee solution. CONCLUSIONS: Viscosity, resin matrix content and nature of inorganic filler particles of the composite materials significantly affect the colour changing properties of them due to the long-term ageing and exposure to colouring agents.

Effects of different primers and colouring solutions on orthodontic bonding: shear bond strength and colour change.

OBJECTIVES: This in vitro study evaluated the effect of different colouring solutions and primer systems used in the bonding of brackets on enamel colour change and bond strength. MATERIALS AND METHODS: 120 premolar teeth were divided into four main groups; brackets were bonded with 37% orthophosphoric acid + Transbond XT Primer in Group 1, 3 M Single Bond Universal in Group 2, Transbond Plus SEP in Group 3, and G-Premio Bond in Group 4. Each group was divided into three subgroups, and the teeth were placed in a cup containing coffee and tea mixture, in a cup containing cola and in distilled water. A bond strength test was applied to all teeth. Colour measurements of all teeth were performed at 2 different times: before bonding and after the bond strength test. RESULTS: The average bond strength of the 37% orthophosphoric acid group was higher than that of the other groups. The effect of primer and solution groups on colour change was statistically significant (p = 0.001 and p = 0.023, respectively). CONCLUSIONS: In this study, the bond strength was clinically sufficient in all primer groups. The highest colour change was observed when the tea-coffee solution and Transbond Plus SEP primer were used. CLINICAL RELEVANCE: This study has identified enamel discoloration and bond strength from different colouring solutions and primer systems used for bonding braces, which can be used to inform clinicians and patients to achieve better treatment results.

Study on the Association between anterior tooth Colour Preference based on the FAHP and individual factors.

BACKGROUND: The relationship between tooth colour and individual satisfaction in oral aesthetics has long been a topic of interest. In this study, we utilized the fuzzy analytic hierarchy process (FAHP) to investigate the impacts of sex and age on tooth colour preference. The findings of this study should provide a scientific basis for oral aesthetic practice. METHODS: In the current study, a random selection method was employed, and a survey was completed by 120 patients. To obtain tooth colour data, standard tooth colour charts were used. Smile photos were taken as template images using a single-lens reflex camera. The FAHP was utilized to conduct a weight analysis of tooth colour preferences among patients of different sexes and age groups. RESULTS: There were significant differences in tooth colour preference based on sex and age. Men tend to prefer the B1 colour, while women may prioritize the aesthetic effects of other colours. Additionally, as patients age, their preferences for tooth colour become more diverse. These findings offer valuable insights for oral aesthetics practitioners, enabling them to better address the aesthetic needs of patients across different sexes and ages. This knowledge can aid in the development of more personalized treatment plans that align with patients' expectations. CONCLUSION: In this study, we utilized scientific analysis methods to quantify the popularity of different tooth colours among various groups of people. By doing so, we established a scientific foundation for clinical practice. The findings of this study offer valuable insights for oral aesthetic research, enhancing our understanding of tooth colour. Additionally, these findings have practical applications in the field of oral medicine, potentially improving patients' quality of life and overall oral health.

Explaining the colour of natural healthy gingiva.

To examine the differences between natural gingival colour in men and women. To determine the degree of predictability of changes in the gingival colour coordinates recorded for healthy gingiva, according to age, long-term medication, frequency of toothbrushing, and smoking habits. The CIELAB colour coordinates were recorded using a spectrophotometer for 360 Caucasian adult participants (aged 18-92 years), in three zones of the healthy attached gingiva of the maxillary central incisor. Regression models were created for each zone and each sex, taking the L*, a* and b* coordinates as dependent variables and age, frequency of toothbrushing, smoking habits (0-non-smoker; 1-smoker) and whether participants were taking long-term medication (0-no; 1-yes) as independent variables. The statistical analysis was conducted with SPSS version 26.0, using multiple regression models. Statistically significant differences between men and women were found only for colour coordinate b*, in all three zones. The only colour coordinate on which the predictor variables had a significant effect was the L* coordinate. In men, age and long-term medication had the greatest effect as predictors (maximum R2 = 0.149). In women, frequency of toothbrushing was the strongest predictor in the predictive models (maximum R2 = 0.099). The colour of gingiva in men contained a larger amount of blue, given that significantly lower values for colour coordinate b* were recorded in men than women, although this difference lacked clinical implications. For both sexes, the regression models produced had a modest predictive capacity. The L* coordinate was the dependent variable that showed the greatest predictability.

Reliability between the two-colour chewing gum and the gummy-jelly tests used for the assessment of masticatory performance.

OBJECTIVE: This study aimed to evaluate the reliability of two methods used to assess masticatory performance and attempt to correlate them to achieve interchangeability between the methods. METHODS: Twelve healthy dentate volunteers (men = 6, women = 6; mean age = 28.3 ± 4.1) with no known dental or medical pathologies were requested to participate in this study. Each participant completed three masticatory performance assessments, including two two-colour mixing-ability tests using chewing-gums (CG: gum#1 and gum#2) and the gummy-jelly (GJ) test. For each method, participants created five samples each (total = 15 measurements per participant, gum#1 = 5, gum#2 = 5, GJ = 5). For the gum#1 and gum#2 methods, the predetermined chewing cycles were fixed at 10, 15, 20, 25 and 30 cycles, and for the GJ method, the time duration was fixed at 10, 15, 20, 25 and 30 s. The parameter measures were submitted to Z-score transformation, and Bland-Altman plots were generated to graphically compare the differences between two techniques against their means. Additionally, mountain plot was used to assess the cumulative distribution of measurement error between the methods. RESULTS: A total of 180 measurements were recorded. There were significant correlations between the number of chewing cycles/chewing time and masticatory performance using the gum#1 (r = -.753; p < .001), gum#2 (r = -.838; p < .001) and GJ (r = .730). When all tests were considered together for each method, significant correlations were found (p < .001). A descriptive range of mean values aiming to produce reference value ranges for predictive purposes was achieved considering the interchangeably among the methods [CG = GJ (VoH-mg = dL): 10 cycle = 10 s: 0.329 = 110; 15 cycles = 15 s: 0.177 = 164; 20 cycles = 20 s: 0.130 = 205; 25 cycles = 25 s: 0.086 = 200; 30 cycles = 30 s: 0.077 = 267]. CONCLUSION: The strong correlations and high consistency between the two masticatory performance methods found in this study conclude that the two assessment methods are reliable and interchangeable. Further evaluations are warranted to arrive at a conversion formula for translation of the results between the two methods.

Do mouthwashes affect the optical properties of resin cement?

OBJECTIVES: The objective of this study was to evaluate the effect of mouthwashes on the optical properties of resin cement. MATERIALS AND METHODS: One hundred and 60 resin cement discs (6x2mm) were produced from 4 different brands of resin cement (Panavia V5, Estecem II, RelyX Veneer, NX3) with the help of a Teflon mould. The discs were divided into 4 subgroups, 1 of which served as the control group, to be immersed in mouthwashes after measuring the initial L, a, and b values on white and black backgrounds. Colour measurements were repeated after the 1st and 7th days. The collected data were used to calculate the ∆E00 value to measure colour stability, the translucency parameter (TP00), and the contrast ratio parameter (CR) to compare translucency change. Data were statistically analysed using mixed-design analysis of ANOVA and the Bonferroni-Dunn test. Repeated measures ANOVA was used for dependent results (α = 0.05). RESULTS: On the ∆E00, TP00, and CR parameters; the joint effect of resin groups, mouthwash groups, and measurement times were found to be statistically significant. The ∆E00 (colour difference) parameter; the joint effect of resin groups, mouthwash groups, and measurement times was found to be statistically significant. The TP00; the joint effect of resin groups, mouthwash groups, and measurement times were found to be statistically significant. The CR parameter; the joint effect of resin groups, mouthwash groups, and measurement times was found to be statistically significant. In the Estecem II (Tokuyama) group, the means of Listerine Cool Mint (Johnson & Johnson) was above acceptable limits in both time periods. In the Panavia V5 (Kuraray Noritake) group, the color change was above acceptable limits in all time periods and in all mouthwash groups. Among the resin materials used, Estecem II (Tokuyama) shows the most color change. Listerine Cool Mint (Johnson & Johnson) caused more color change than other mouthwashes at all times. CONCLUSIONS: Within the limitations of this study; the colour stability and translucency value of resin cement depend on both the resin cement content and the mouthwash. Long-term use of mouthwash may adversely affect the optical properties of the resin cement. CLINICAL RELEVANCE: Clinicians should take into account the fact that mouthwash use and the composition of the resin cement employed will have an impact on the colour of laminate veneers.

Quantitative examination of factors influencing the colour reproduction ability of lithium disilicate glass-ceramics.

BACKGROUND: Effects of ceramic translucency, layer thickness, and substrate colour on the shade of lithium disilicate glass-ceramic restorations proved to be significant in several studies, however, quantitative, numerical results on the relationship between the colour difference and these parameters are still lacking. The purpose of this in vitro study was to quantitatively determine how the colour reproduction ability of a lithium disilicate glass-ceramic is affected by its translucency, layer thickness, and substrate colour. METHODS: Ceramic samples were prepared from A2 shade IPS e.max CAD blocks with high and low translucencies (HT and LT) in a thickness range of 0.5-2.5 mm (+/- 0.05 mm). Layered samples were acquired utilizing composite substrates in 9 shades; transparent try-in paste was used. The spectral reflectance of the specimens was assessed under D65 standard illumination with a Konica Minolta CM-3720d spectrophotometer. The CIEDE2000 colour difference (ΔE00) between two samples was analysed using perceptibility and acceptability thresholds set at 50:50%. Statistical analysis involved linear regression analysis and the Kruskal-Wallis test. RESULTS: An increase in the thickness of 0.5 mm reduced the ΔE00 of the HT samples to 72.8%, and that of the T samples to 71.1% (p < 0.0001). 7 substrates with HT and LT specimens had significantly different results from the mean (p < 0.05). A thickness of 0.5 mm is not sufficient to achieve an acceptable result at any level of translucency, while the low translucency ceramic at a thickness of 1.5 mm gave acceptable results, except for severely discoloured substrates (ND8 and ND9). CONCLUSIONS: The colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined.

Evaluation of colour change, marginal adaptation, fracture strength, and failure type in maxillary and mandibular premolar zirconia endo-crowns.

OBJECTIVES: The objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE*), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs). METHODOLOGY: A total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2-4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE* was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant. RESULTS: The ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 µm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 µm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height. CONCLUSION: The recorded ΔE* values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.

Resin infiltration for white spot lesions: An in vitro experimental trial.

OBJECTIVE: To evaluate the aesthetic outcome by varying the duration allowed for infiltrant penetration when treating white spot lesions with resin infiltration. DESIGN: An in vitro, experimental randomised study. METHODS: Artificially created white spot lesions (WSLs) were induced on 100 extracted anterior teeth (T1). Teeth were divided into enamel and dentine groups depending on the extent of the lesion and then randomly assigned into different treatment protocol groups: penetration times of 3, 6 and 9 min. Resin infiltration treatment was applied according to the treatment protocol assigned (T2). Samples were thermocycled for 10,000 cycles (1 clinical year) (T3). The samples from the 3-min enamel and dentine groups were then randomly assigned into either a repeat treatment or no additional treatment group (T4). Samples were then thermocycled for an additional 10,000 cycles (T5). Spectrophotometric analysis was measured colour change (ΔE) for all groups. RESULTS: Mean ΔE values equal to or greater than the critical value (3.7) indicate a detectable clinical difference in colour of the treated WSL when compared to before WSL formation. Mean ΔE values, for the enamel groups, were slightly above or significantly below the critical value, and for the dentine groups, were significantly above the critical value. Mean ΔE values within the enamel and dentine groups both demonstrated a downward trend with increasing time allowed for resin infiltrant penetration (P < 0.05). No significant mean ΔE difference (P = 0.53) was found between groups that received a single or repeat treatment. After the first thermocycling event, no significant difference in colour change was observed in all groups except for the deep dentine lesion treated for 3 min. There was a significant difference in colour change for all groups except the enamel group that received a single treatment following thermocycling after a single or repeat treatment. CONCLUSION: Increasing the resin infiltrant penetration time to at least 9 min is advised as the most optimised treatment protocol. Resin infiltration treatment should be done only once to treat a particular white spot lesion as subsequent treatment for the same lesion results in marginal colour improvement. The colour improvement of WSLs resulting from the resin infiltration treatment can be expected to last for at least 1 year. Resin infiltration treatment of shallow lesions with a single and optimised infiltration technique can be expected to last an additional year.

Post-treatment of matured landfill leachate: Synthesis and evaluation of chitosan biomaterial based derivatives as adsorbents.

Matured landfill leachate is complex in nature, hence, a single conventional treatment unit is insufficient to remove the contaminants of the leachate to achieve the discharge standards. Furthermore, high levels of organic matter, colour compounds, and iron-based materials form a dark black/brown colour in leachate which is not removed by the biological treatment units. Hence, an Anoxic-Oxic Membrane Bioreactor coupled with a tertiary adsorption unit composed of crosslinked-protonated chitosan was tested for effective removal of the colour of the permeate. Several operational parameters such a pH, contact time, and adsorbent dosage on the adsorptive removal of colour were quantified using sorption-desorption experiments. Furthermore, the biosorbent was characterized using FTIR, SEM, XRD, BET-specific surface area, and pHZPC. Response Surface analysis confirmed the optimization of operational parameters conducted through traditional batch experiments. Langmuir isotherm model fitted with equilibrium data (R2 = 0.979) indicating a monolayer homogeneous adsorption. Kinetic data followed the Pseudo-Second-Order model (R2 = 0.9861), showing that the adsorbent material has abundant active sites. The percentage removal values show that the colour removal increases with time of contact and dosage of adsorbent, but removal is mainly influenced by the solution pH levels. The experimental results manifested a colour removal efficiency of 96 ± 3.8% obtained at optimum conditions (pH = 2, adsorbent dosage = 20 g/L, contact time = 48 h) along with an adsorption capacity of 123.8 Pt-Co/g suggesting that the studied adsorbent can be used as an environmentally friendly biosorbent in a tertiary unit for colour removal in a treatment system which is used to treat matured landfill leachate.

Subjective and objective evaluation of masticatory function in patients with bimaxillary implant-supported prostheses.

BACKGROUND: People perform poorly in masticatory function tests despite well-functioning prostheses. However, it is unclear whether there is an agreement between subjective and objective measures of mastication. OBJECTIVES: To investigate the association between subjective and objective measures of masticatory function in patients with bimaxillary implant-supported prostheses. MATERIALS AND METHODS: An experimental group (n = 25, age = 70.6 ± 7.5 years, eight women) with bimaxillary implant-supported fixed prostheses and a control group (n = 25, age = 69.0 ± 5.3, 13 women) with natural dentition were recruited. The participants in the experimental group were included if they had been using the prosthesis for at least a year and had no obvious complaints with their prostheses. The control group was people with natural dentition and without any prostheses or complaints related to the masticatory system. The masticatory function was evaluated objectively with food comminution and mixing ability tests, and subjectively with jaw function limitation scale (JLFS) and oral health impact profile (OHIP). RESULTS: The experimental group performed poorly in both objective tests (p < .001). However, there was no significant differences between the two groups in total JFLS (p = .114) and OHIP (p = .312) scores. Though, there were certain positive correlations between the food comminution test and JFLS subdomains in the control group, and a positive correlation between food comminution test and specific subdomains of OHIP in the experimental group indicating poor correlation between the subjective and objective measures. CONCLUSION: Although patients with implant prostheses show poor masticatory performance, there is no agreement in the objective and subjective measures of mastication.

Complete Desorption of Hybrid Nanoclays Composed of Hydrotalcite and Disperse Dye.

Clays are considered great nanoadsorbents for many materials, including textile dyes. The use of these materials for cleaning textile wastewater is well known; however, it is not at all common to find applications for the hybrid materials formed from the clay and dye. In this work, a dye-loaded clay material was used to make new dye baths and colour a polyester textile substrate. The same hybrid could be used several times as it did not use all the adsorbed dye in a single dyeing. The hybrid obtained from hydrotalcite (nanoclay) and the dispersed red 1 dye was analysed by measuring the colour obtained, carrying out an X-ray diffraction analysis that provided information after each desorption-dyeing process, and using infrared spectroscopy to analyse the specific bands of each characteristic group. Both analyses showed that the amount of dye present in the hybrid decreases. Thermogravimetry (TGA), surface area and porosity measurements (BET), and X-ray photoelectron spectroscopy (XPS) tests were conducted. Chemical stability was assessed by subjecting the hybrid to the actions of different reagents. In addition, colour fastness tests were carried out after dyeing and washing the polyester test tubes to check for the correct fixing of the dye to the fibre. These fastness results showed that the dyeing was carried out correctly and as if it was a conventional dyeing process.

Inflammatory parameters and color alterations of dental bleaching in patients wearing fixed orthodontic appliance: a randomized clinical trial.

BACKGROUND: Many orthodontic patients request dental bleaching during orthodontic treatment to achieve a faster aesthetic resolution, however, no attention has been paid to the inflammatory processes that can occur when both therapies are indicated together. So, this clinical trial evaluated the inflammatory parameters and color alterations associated with dental bleaching in patients wearing a fixed orthodontic appliance. METHODS: Thirty individuals aged between 18 and 40 years were equally and randomly allocated into three groups: FOA (fixed orthodontic appliance), BLE (dental bleaching), and FOA + BLE (fixed orthodontic appliance + dental bleaching). The orthodontic appliances and the bleaching procedures were performed in the maxillary premolars and molars. For dental bleaching a 35% hydrogen peroxide was used. The gingival crevicular fluid (GCF) and nitric oxide (NO-) levels were evaluated at different time-points. Color evaluation was performed using an Easyshade spectrophotometer at baseline (FOA, FOA + BLE, BLE), one month after (FOA + BLE) and 21 days after appliance removing (FOA + BLE and FOA groups), in each tooth bleached. The ANOVA and Tukey's tests, with a significance level of 5%, were used for statistical analysis. RESULTS: The GCF volume in the FOA + BLE and FOA groups significantly increased at the time points evaluated (p < 0.001); however, this did not occur in the BLE group (p > 0.05). On the other hand, NO- levels significantly decreased during dental bleaching with or without fixed orthodontic appliances (FOA + BLE and BLE groups; p < 0.05), while no significant changes were observed in the FOA group (p > 0.05). Significant changes in color were observed in the FOA + BLE and BLE groups compared to in the FOA group (p < 0.01). However, the presence of fixed orthodontic appliance (FOA + BLE) negatively affected the bleaching efficacy compared to BLE group (p < 0.01). CONCLUSIONS: Dental bleaching did not increase the inflammatory parameters in patients wearing fixed orthodontic appliance. However, in the presence of orthodontic appliances, the bleaching efficacy was lower than that of bleaching teeth without orthodontic appliances. TRIAL REGISTRATION: RBR-3sqsh8 (first trial registration: 09/07/2018).

Effect of Vegetable Juices on Properties of Two Resin Composites Used for Dental Caries Management.

Background and Objectives: Resin composites represent a class of materials widely used in restorative dentistry due to patient demands for better aesthetics. Colour changes in composite resins can occur due to intrinsic and extrinsic factors. Beverages, such as vegetable juices, can be some of these extrinsic factors. The purpose of this study was to investigate the colour stability and modification of microhardness of two resin composites before and after immersion in different vegetable juices. Materials and Methods: The colour of two resin composite materials (Gradia Direct Anterior-shade A2 and Valux Plus-shade A2) was measured before and after immersion in four different solutions: distilled water (as control), beetroot, carrot, and tomato juice. Colour values (L *, a *, b *) were measured over a white background with a colorimeter, using the CIE L *a *b * system. Colour change values were calculated after 1, 3, 5, and 7 days of immersion. Microhardness measurements were taken before and after seven days immersion in test media. Repeated measures analysis of variance (ANOVA) and independent t-tests were applied for statistical analysis. Results: All vegetable juices produced statistically different discolouration after immersion for 7 days (p < 0.05). Tomato juice produced the most discolouration for the Gradia Direct specimens, whereas beetroot juice and carrot juice produced the most discolouration for the Valux Plus specimens. Microhardness of the materials immersed for 7 days in vegetable juices was reduced compared to the ones immersed in distilled water. Conclusions: Vegetable juices, immersion time, and dental resin composites are significant factors that may affect colour stability and microhardness of composite resins.

Comparison of Different Digital Color Measurement Methods on Maxillary Anterior and Canine Teeth: A Clinical Observational Study.

PURPOSE: This clinical observational study aimed to determine the reproducibility of digital color measurement methods of different front teeth. METHODS: Color determination was performed using two spectrophotometric systems (Easyshade Advance; ES and Shadepilot; SP) and digital photography using a camera with ring flash and gray card with subsequent evaluation using computer software (DP; Adobe Photoshop). In 50 patients, at two time points, a digital color determination was performed on maxillary central incisors (MCI) and maxillary canines (MC) by a calibrated examiner. Outcome parameters were: color difference ΔE based on CIE L*a*b* values and VITA color match given by spectrophotometers. RESULTS: SP showed significantly lower median ΔE values (⟨1.2) than ES (⟨3.5) and DP (⟨4.4), while no significant differences were found between ES and DP. For all methods, both ΔE values and VITA color showed lower reliability regarding MC compared with MCI. The ΔE examination of subareas revealed significant differences in MCI for all devices and in MC only for SP. When comparing VITA color stability, SP showed a significantly higher color match than ES (81% and 57%, respectively). CONCLUSIONS: Digital color determination methods tested in the current study provided reliable results. However, there are significant differences between the devices used and the teeth examined.

Assessment of colour modifications in two different composite resins induced by the influence of chlorhexidine mouthwashes and gels, with and without anti-staining properties: An in vitro study.

OBJECTIVES: Chlorhexidine (CHX)-based products are the most effective chemical agents used in plaque control and oral disinfection. One of their side effects is tooth and restoration staining. For this reason, CHX products with anti-discolouration systems (ADS) have been developed. The aim of this in vitro study was to compare different CHX-based products (gel and mouthwash) with or without ADS in composite colour modification. METHODS: Two hundred specimens were created, 100 of which were made of packable composite and 100 of flowable composite. After 24 h, colour coordinates (L*, a*, b*, C*, h°) were recorded using a spectrophotometer (T0). Then, all samples were subjected to a CHX/tea staining model and immersed in human saliva for 2 min. Composite specimens were divided in 10 groups (N = 20). Control groups (PC, FC) were soaked in distilled water and test groups (PG, PGads, FG, FGads, PM, PMads, FM and FMads) were immersed in CHX-based solutions or brushed with CHX gel. Then the cycle was repeated 6 times, and colour differences (ΔEab and ΔE00 ) were finally calculated. RESULTS: Through flowable composites, FC and FG showed the highest colour differences, respectively ΔEab = 3.48 ± 1.0, ΔE00 = 2.24 ± 0.6 and ΔEab = 2.95 ± 1.3, ΔE00 = 1.53 ± 0.6. In the composite groups instead, PM and PMads showed the highest colour differences, respectively ΔEab = 2.78 ± 1.3, ΔE00 = 1.94 ± 0.8 and ΔEab = 2.71 ± 1.4, ΔE00 = 1.84 ± 0.9. CONCLUSIONS: CHX-containing products are able to cause stains on restorative composite materials. Discolouration is more likely to occur in flowable composites than packable composites, and ADS-containing products cause fewer pigmentations than CHX products without ADS. Packable composites showed more staining after mouthwash treatment, whereas flowable composites underwent higher discolouration after treatment with gels.

Parallelized label-free monitoring of cell adhesion on extracellular matrix proteins measured by single colour reflectometry.

The understanding of the initial cell adhesion to biomaterials is crucial for the survival of implants. The manifold possibilities to tailor an implant surface and the diverse requirements for different implant applications necessitate a timesaving and highly parallelized analytical methodology. Due to its intrinsic advantages (label-free, time-resolved, robust against temperature fluctuations, and particularly the multiplexing possibilities), single colour reflectometry (SCORE) is used for the first time to investigate cell adhesion to different extracellular matrix protein-coated surfaces. The excellent correlation between the novel SCORE technology and well-established reference methods proves that the results obtained by using this direct optical method are able to reflect the cell binding processes at the transducer surface. Additionally, the high time resolution of SCORE revealed the differences in the adhesion behaviour of the cells on the different extracellular matrix protein-coated glass slides during the initial adsorption phase and during the spreading of the cells on the surfaces. Therefore, we conclude that SCORE is a perfectly suited methodology for studying the entire cell adsorption process, including morphological changes, and shows great potential for other cell-based sensing applications.

The influence of thin as compared to thick peri-implant soft tissues on aesthetic outcomes: A systematic review and meta-analysis.

OBJECTIVES: In systematically healthy patients with an implant-supported fixed restoration (P), what is the influence of thin (E) as compared to thick (C) peri-implant soft tissues on aesthetic outcomes (O)? METHODS: Following an a priori protocol, a literature search of six databases was conducted up to August 2020 to identify prospective/retrospective clinical studies on healthy patients with an implant-supported fixed reconstruction. Measurement of the buccal soft tissue thickness and an aesthetic outcome was a prerequisite, and sites presenting with a buccal soft tissue thickness of <2 mm or shimmering of a periodontal probe were categorized as a thin phenotype. After study selection, data extraction, and risk of bias assessment, random-effects meta-analysis of Mean Differences (MD) or Odds Ratios (OR) with their corresponding 95% Confidence Intervals (CI) were conducted, followed by sensitivity analyses and assessment of the quality of evidence. RESULTS: Thirty-four unique studies reporting on 1508 patients with 1606 sites were included (9 randomized controlled trials, one controlled trial, 10 prospective cohort studies, 8 cross-sectional studies, and 6 retrospective cohort studies). The mean difference of the pink aesthetic score (PES) after the follow-up was not significantly different between thin (<2.0 mm) or thick soft tissues (≥2.0 mm) or phenotypes (12 studies; MD = 0.15; [95% CI = -0.24, 0.53]; p = .46). PES changes during the follow-up, however, were significantly in favour of thick soft tissues (≥2.0 mm) or phenotypes (p = .05). An increased mean mucosal thickness was associated with an increased papilla index (5 studies; MD = 0.5; [95% CI = 0.1, 0.3]; p = .002) and an increase in papilla presence (5 studies; OR = 1.6; [95% CI = 1.0, 2.3]; p = .03). Thin soft tissues were associated with more recession, -0.62 mm (4 studies; [95% CI = -1.06, -0.18]; p = .006). Patient-reported outcome measures (patient satisfaction) were in favour of thick soft tissues -2.33 (6 studies; [95% CI = -4.70, 0.04]; p = .05). However, the quality of evidence was very low in all instances due to the inclusion of non-randomized studies, high risk of bias and residual confounding. CONCLUSION: Within the limitations of the present study (weak study designs and various soft tissue measurements or time-points), it can be concluded that increased soft tissue thickness at implant sites was associated with more favourable aesthetic outcomes.