Color and Translucency Variation of a One-Shaded Resin-Based Composite after Repeated Heating Cycles and Staining.

(1) Background: This study aimed to determine the effect of repeated pre-polymerization heating on the color and translucency of a one-shaded resin-based composite and to evaluate whether the heating cycles affect its color stability. (2) Methods: Fifty-six samples of 1-mm thickness were fabricated from Omnichroma (OM) after applying different heating cycles (for one, five, and ten times at 45 °C) before polymerization (n = 14/group) and afterwards were stained with a yellow dye solution. CIE L*, a*, b*, C*, h° coordinates were recorded, and color differences, whiteness, and translucency were calculated, before and after staining. (3) Results: Heating cycles significantly influenced the color coordinates, WID00, and TP00 of OM being higher after one heating cycle and decreasing as the number of heating cycles increased. The color coordinates, WID, and TP00 after staining significantly differed for each group. The color and whiteness differences calculated after staining exceeded the acceptability thresholds for all groups. The color and whiteness variations after staining were clinically unacceptable. (4) Conclusions: Repeated pre-polymerization heating induces a clinically acceptable color and translucency change to OM. Although the color changes resulting after staining are clinically unacceptable, increasing the number of heating cycles up to ten times slightly reduces the color differences.

The use of digital dental photography in an Eastern European country.

Aims: To assess the use of digital photography in dentistry and its relation with the professional experience of the dental practitioners in Romania. Methods: An anonymous questionnaire including eight questions was distributed online to collect information on the use of dental photography. Results: 84.84% of the respondents were using a photographic equipment in their clinical practice. Regarding the type of photographic equipment used, 51.79% of the participants indicated DSLR cameras, 44.05% smartphones, 2.38% compact cameras and 1.78% other devices for taking clinical images. There was a significant association (p<0.05) between the experience of the practitioners and the use of dental photography, type of equipment and protocol used. Conclusions: Respondents with more than 10 years of experience were more likely to use digital photography in their practice than those with less experience. Most of the digital photography users with more than 10 years of experience were taking images with a DSLR Camera (65.52%) followed by 31.04% smartphone users. Conversely, 56.42% of the clinical photography users with less than 5 years of experience mainly preferred a smartphone device and 41.02% a DSLR Camera.

Masking Ability of Monolithic and Layered Zirconia Crowns on Discolored Substrates.

There is scarce information on the colorimetric behavior of monolithic and layered zirconia crowns in combination with various abutment colors. This study evaluated the masking ability on discolored substrates of monolithic and layered zirconia crowns. Anterior crowns were fabricated using 3Y-TZP zirconia and layering ceramic and divided into three groups: monolithic (ML), bi-layer (BL), and tri-layer (TL). The crowns were placed over eleven substrates (ND1-ND9, zirconia, metal), and CIE L*, a*, b*, C*, and h° color coordinates were measured in the cervical, middle, and incisal areas with a spectrophotometer. Masking ability was calculated using the color difference formula, and values were interpreted according to the perceptibility and acceptability thresholds. Data were analyzed statistically (α = 0.001). The L* coordinate was not significantly different between BL and TL crowns, regardless of the measurement area or substrate (p ≥ 0.001). In the middle area, the L* coordinate of the ML group was statistically different from the BL and TL groups only for zirconia and metal substrates, while in the incisal area, only for ND7 and metal substrates. The a* coordinate was significantly different between the ML and layered crowns for all measurement areas and substrates (except zirconia). The b* and C* coordinates differed significantly between the groups only in the cervical area (p < 0.001). The ML crown had better masking ability than the BL and TL crowns. However, the color differences for ML crowns were below the acceptability threshold for ND2, ND3, and ND7 substrates in the cervical and middle areas and below perceptibility threshold only for the incisal area. The lowest masking ability of the crowns was found for ND9 and metal substrates in all measurement areas.

Influence of manufacturing technique on the color of zirconia restorations: Monolithic versus layered crowns.

OBJECTIVES: The study aimed to compare the color of monolithic and layered zirconia crowns fabricated using different brands in the cervical, middle, and incisal areas. MATERIALS AND METHODS: A total of 45 crowns were fabricated from three brands (Katana, Nacera, Cercon) using three methods (monolithic = ML (n=5), cut-back + enamel = BL (n=5), cut-back + dentin + enamel = TL (n=5)). CIE L*, a* b*, C*, h° color coordinates were recorded with a dental spectrophotometer in cervical, middle, and incisal areas. Color differences between manufacturing techniques, tooth areas, and brands were calculated using the CIEDE2000(1:1:1) formula, and the values were compared to the perceptibility (PT00 ) and acceptability thresholds (AT00 ). Comparisons between color coordinates were analyzed statistically (Kruskal-Wallis and Mann-Whitney U tests, p < 0.001). RESULTS: Significant differences were found between CIE L*, a*, b*, C*, h° coordinates of the zirconia crowns (p < 0.001), generally. The lowest color differences were obtained between BL and TL crowns in cervical and middle areas. Color differences between cervical and middle areas were mostly below PT00 . An acceptable color difference was found between Katana and Cercon crowns. CONCLUSIONS: The manufacturing technique and the brand influenced the color of zirconia crowns. Also, the color of the crowns varied from cervical to incisal. CLINICAL SIGNIFICANCE: Reproducing the optical properties of teeth with ceramic crowns might be challenging, given the differences in the internal configuration of the enamel and dentine, as well as their complex behavior when interacting with light. When deciding whether to fabricate a monolithic crown in translucent zirconia or improve its appearance by layering with more translucent glass-ceramic, the clinicians and dental technicians must be aware of these procedures' effect on the final color of the restorations.

Factors Involved in the Perception of Enamel Dyschromic Lesions-A Questionnaire-Based Study.

Dyschromic lesions (DLs) of tooth enamel are common disorders, with multiple etiologies and various clinical forms, that raise public health concerns. This study aimed to determine the factors that influence the perception of DLs and to assess the perceived need for dental treatment in various clinical cases. A paper-based questionnaire with attached images of frontal teeth exhibiting different DLs was distributed to patients, dental students, and dentists. A total of 383 volunteers participated in this study, and their answers were statistically described and analyzed. This study found that in cases with multiple, well-demarcated areas of opacities associated with diffuse opacities on neighboring teeth, most respondents noticed and reported only the most severe lesions, disregarding the minor ones. The contrast of the lesion with the color of the substrate influenced the overall perception and a significant correlation between these two variables was found. However, the color of the DLs did not significantly impact the overall perception of the lesions. A higher overall perception of DLs was significantly correlated with a favorable opinion regarding the need for treatment. Furthermore, gender and medical background were significantly associated with the overall perception of DLs.

Evaluation of smartphone dental photography in aesthetic analysis.

Aims To investigate the influence of the system used for digital photography upon the aesthetic analysis in dental medicine.Materials and methods The aesthetic parameters were evaluated on photographs taken with different systems: two DSLR camera set-ups (DSLR + ring flash and DSLR + twin flash) and a smartphone-based system using a five-point Likert scale questionnaire.Results Generally, the DSLR camera + twin flash photographic method performed the best with an overall average score of 4.3, receiving the highest scores for eight statements included in the questionnaire, followed by the smartphone-based system with an average score of 4.04 (the highest values for three statements) and DSLR camera + ring flash with an average score of 3.92 (the highest values for four statements). The scores recorded for the images taken with the DSLR camera + twin flash, DSLR camera + ring flash and smartphone-based system were significantly different for each statement (p <0.05).Conclusions When analysing the characteristics of the dental arches and of individual teeth, images taken with the DSLR camera and twin flash photographic method received the best evaluation, while for the examination of the dentofacial relations and the gingival characteristics, the images obtained with the DSLR camera and ring flash setting, respectively, with the smartphone-based system were considered optimal.

Water Sorption and Solubility of Flowable Giomers.

The objective of this study is the characterization of a novel experimental flowable giomer (G) regarding water sorption, water solubility, and the microstructural characteristics, in comparison to three commercial giomers: Beautifil flow Plus X F00 (B-F00), Beautifil flow F02 (B-F02) and Beautifil flow Plus X F03 (B-F03), Shofu, Kyoto, Japan. Methods: Water sorption/solubility was performed by weighing the specimens before and after water immersion for 1, 2, 3, 14, 21 and 30 days. Data analysis was carried out with the software Origin2019b Graphing & Analysis using the ANOVA test and the Tukey test for post hoc comparison of the groups of materials. The microstructural analyses were done with a scanning electron microscope (SEM) and an atomic force microscope (AFM). The results showed significant differences between the tested materials (p < 0.05). For sorption, the Tukey test indicated differences between all four sample groups, except between B-F02 and B-F03, which exhibited no differences in any of the investigation days. The Tukey test also showed significant differences regarding solubility between all sample groups in the 30-day interval. SEM images and roughness showed that after 30 days of immersion in water, the experimental giomer G had the roughest surface.

Optical properties and masking capacity of flowable giomers.

BACKGROUND AND AIMS: To assess the color, translucency and masking properties of novel flowable giomers. METHODS: Three flowable giomers were used for the fabrication of 1-mm thick samples (n=126) in three different consistencies (Beautifil flow Plus X F00; Beautifil flow F02; Beautifil flow Plus X F03, Shofu Dental Corporation, Japan) and two shades (VITA Classical shade A2 and A3). The relative spectral reflectance was recorded over white, black, C3 (VITA Classical shade C3 simulating a severe tooth discoloration), and a tested-sample colored background. Lightness (L*), and color coordinates a* and b*, Relative Translucency parameter (RTP00) and masking capacity of C3 background were calculated; differences in color and translucency were compared with thresholds for perceptibility and acceptability (PT and AT). Statistical analyses used significance tests for paired samples. RESULTS: All tested materials displayed increased values of L*: for A2 F00=86.16(±0.86), F02=86.39(±0.63), F03=86.40(±0.63); for A3: F00=84.24(±0.58), F02=83.34(±0.3), F03=84.19(±0.4), as well as of RTP: for A2 F00=30.34(±0.88), F02=31.37(±0.94), F03=31.11(±1.15), for A3 F00=29.64(±1.64), F02=30.79(±1.02), F03=30.1(±1.26). For A2 samples, the masking capacity was significantly different for all materials, whilst for A3 there were differences only between F00-F03 and F02-F03. CONCLUSIONS: The tested flowable giomers proved high values of lightness and translucency. The color differences between the materials with the same designation and different consistencies were below the perceptibility threshold in most cases. In addition, the differences in relative translucency parameter ranged between the perceptibility and acceptability thresholds. However, all tested flowable giomers had an unacceptable masking capacity for a dyschromic background.

Perceptions of Dental Dyschromia by Patients and Dentist.

PURPOSE: To assess patient self-perception of overall dental appearance and of potentially localized dyschromic teeth and to compare them to the perception of the treating dentist. MATERIALS AND METHODS: A sample of 160 patients from Cluj-Napoca, Romania, answered a questionnaire regarding the self-perception of their dental appearance and of potential localized dental discolorations. The same questions were answered by their dentist, without knowing their answers, after clinical examination of each patient. Each patient and the dentist were asked to indicate a tooth with a pleasant color to be considered as reference. Color measurements of teeth indicated as dyschromic and of the reference teeth were performed using a spectrophotometer. Color differences were calculated using the ΔE00 formula. RESULTS: Tooth color was considered the most disturbing factor of their dental appearance by 41.25% of patients. Most patients (58.12%) acknowledged localized dyschromic teeth in their dental arches. Agreement between patients and dentist regarding the identification of dyschromic teeth was found in 61.87% of cases. The DE00 between the reference teeth and the teeth considered dyschromic by both patients and dentist ranged between 0.8 and 23.1. Disagreement between patients and dentist was found in 38.12% of situations. For teeth considered dyschromic only by patients, the ΔE00 ranged between 0.8 and 23.1. For teeth considered dyschromic only by the dentist, the ΔE00 ranged between 0.8 and 25. CONCLUSION: Most patients expressed concerns regarding their overall dental color and perceived themselves as having teeth with localized dyschromia. More than a third of the investigated patients had different perceptions regarding dyschromic teeth compared to their dentist. The majority of ΔE00 values calculated between dyschromic and reference teeth exceeded the perceptibility and acceptability thresholds.

Color and masking properties of translucent monolithic zirconia before and after glazing.

Purpose 1. to assess the ability of four brands of translucent monolithic zirconia with different thicknesses to mask discolored substrates; 2. to assess the influence of glazing upon their color coordinates and masking properties.Methods Sixty samples of shade A1 (0.8, 1.5, and 2.0 mm thickness) from: ZirCAD/MT, Katana/HT, Vita YZ/HT, Cercon/HT were fabricated and glazed using a standardized laboratory procedure. CIE L*a*b* parameters were recorded on composite substrates, (IPS Natural Die Material Kit) (ND1=reference; ND2, ND3, ND4, ND5=test backgrounds), before and after glazing. The color changes of zirconia samples induced by glazing were analyzed. Masking properties was calculated as the color difference between CIE L*a*b* parameters of the samples placed on reference and test substrates with CIEDE2000(1:1:1) formula. The effect of material, thickness, substrate, and glazing on the color of monolithic zirconia was analyzed with ANOVA test and the multiple comparisons were analyzed with Tukey HSD tests (α=0.05).Results After glazing, lightness L* significantly increased, while chromatic coordinates a* and b* decreased (p<0.05). Significant differences in the masking properties of the four materials (p<0.001) were found, with IPS e.max ZirCAD/MT having the lowest masking effect (p<0.001). Thickness, substrate and glazing had a significant effect on the color masking properties of monolithic zirconia (p<0.001).Conclusions Masking properties of translucent zirconia were significantly influenced by the materials, the thickness and the color of the substrate; moreover, glazing improved the masking ability for all zirconia samples.

Color matching of full ceramic versus metal-ceramic crowns - a spectrophotometric study.

BACKGROUND AND AIMS: To verify the color match of metal-ceramic and full ceramic crowns, using instrumental methods. METHODS: A number of 153 teeth (anterior and posterior teeth), in 62 patients, were restored with metal ceramic (MC, n=119), pressed-ceramic (PC, n=28), and zirconia-ceramic (ZC, n=6) full coverage crowns. The shade of a reference natural tooth was recorded instrumentally with a dental spectrophotometer (Vitaeasyshade Advance 4.0) in "single tooth measurement", which provided the base color in Vita Classic (VC) and Vita 3D Master shades (3D).For verifying the outcome of the restoration "verify restoration" mode was used, and ΔE values were recorded for both VC and 3D Master shade guides. Moreover, matching symbols were also recorded (***=good, **=fair, *=poor). Descriptive statistics was performed and data were analyzed (One-sample z-Test, α=0.05) for comparison with visual thresholds in dentistry (Perceptibility Threshold - PT=1.2 and Acceptability Threshold - AT=2.7). RESULTS: The data did not follow a normal distribution (Kolmogorov-Smirnov test, p<0.05). Recorded color difference was significantly higher than PT and AT, for all types of restorations, regardless of the coding system (p<0.05). For MC crowns in 2.52% (4.20% for 3D) of the cases the color difference was smaller than PT, in 19.32% (the same for 3D) of cases was between PT and AT, and in 78.15% (76.47% for 3D) of cases was higher than the AT. For PC crowns in 3.57% (0% for 3D) of the cases the color difference was smaller than PT, in 25% (32.14% for 3D) of cases was between PT and AT, and in 71.42% (67.85% for 3D) of cases was higher than the AT. In the case of ZC crowns none of the restorations had color difference smaller than PT, but in 16.66% of cases was between PT and AT, and in 83.33% of cases was higher than the AT, for both VC and 3D. CONCLUSION: Within the limitations of the study, a better color match was achieved in the case of pressed ceramic crowns, made of lithium disilicate. In most of the situations the color difference between the restoration and the reference tooth exceeded the perceptibility thresholds, but the matching was recorded as "fair" by the spectrophotometer.

The accuracy of dental shade matching using cross-polarization photography.

The aim of this study was to assess the influence of a polarizing filter on the accuracy of dental shade matching using digital photography. A comparison was performed using ΔEab parameters between CIE L*a*b* values obtained from digital images taken under two different conditions (with direct light and with polarized light) and the values given by the dental spectrophotometer SpectroShade Micro, which is considered to be the standard. Color differences (ΔEab) calculated between the parameters recorded with the dental spectrophotometer and polarized photography were below or at the level of the 50:50% acceptability threshold of 2.7 in 23% of the cases. Interdevice agreement found between the dental spectrophotometer and polarized photography exceeded 0.82 for all the three parameters recorded. Digital photography with polarizing filters might be a useful tool for dental shade matching.

Effect of accelerated staining and bleaching on chairside CAD/CAM materials with high and low translucency.

The aim of the study was to assess the effect of staining and bleaching on CAD/CAM materials with high (HT) and low translucency (LT or T). Samples were stored in coffee and subsequently bleached. CIELAB parameters were recorded at baseline, after coffee immersion, after bleaching. Translucency parameter (TP), whiteness index (WID) and color changes were calculated (ΔE00). Influence of staining and bleaching was analyzed with repeated-measures ANOVA and color differences between materials were analyzed with one-way ANOVA (α=0.05). Staining and bleaching significantly affected CIELAB parameters and WID for all materials (p<0.001). TP was significantly influenced by staining and bleaching for Crios and Enamic (p<0.05). Mean color differences were significantly different between materials (p<0.001). The greatest color changes due to staining were observed for Lava Ultimate while the lowest for e.max CAD. Both coffee staining and bleaching induced greater color changes for HT materials of the same brand compared to LT.

Effect of glazing on translucency, color, and surface roughness of monolithic zirconia materials.

OBJECTIVES: To assess the effect of material, thickness and glazing upon the color, translucency, and roughness of monolithic zirconia. MATERIALS AND METHODS: Sixty discs (0.8, 1.5, and 2 mm thickness) were fabricated from A1 translucent zirconia (IPS e.max ZirCAD/MT, Katana/HT, Vita YZ/HT, Cercon/HT) and glazed. Roughness (Ra) was assessed with a profilometer and color coordinates were measured with a spectrophotometer on a black, white, and tooth-shaded background before and after glazing. Relative translucency parameter (RTP), color differences (CIEDE2000) and differences in translucencies between materials, before and after glazing were calculated. RTP, Ra, color differences were statistically analyzed using ANOVA. Any significant interaction between factors was further analyzed using Tukey's HSD. RESULTS: RTP values were significantly different between materials (P < .001) and thicknesses (P < .001), with the interaction effect between material type and thickness, also significant (P < .001). However, glazing did not have a significant effect on RTP values (P = .782). Color differences resulted after glazing were significantly different between materials (P < .001), and thicknesses (P < .001) with the interaction effect also significant (P < .001). Glazing influenced roughness, Ra decreasing for all materials (P < .001). CONCLUSIONS: As a result of glazing, only color changes were statistically significant. Translucency varied among brands of precolored monolithic zirconia; the differences increased for greater thicknesses. CLINICAL SIGNIFICANCE: Glazing is an important step in the technological process of ceramic restorations; however, it can influence the final optical appearance of the restoration as color changes could be expected after the application of the glaze.

Giomers in dentistry - at the boundary between dental composites and glass-ionomers.

INTRODUCTION: From the variety of direct restorative dental materials, composite resins are considered as having the most esthetic and functional properties. The conservative preparation, esthetic results, good mechanical qualities and surface finishing properties of dental composites, combined with the protective properties of fluoride from glass-ionomers, led to a new generation of dental materials: the giomers. OBJECTIVE: The purpose is to review the available literature about the giomers, regarding the chemical composition, handling properties and esthetics, adhesion and microleakage, fluoride releasing and protection offered, clinical indications. METHOD: The search was carried out using ScienceDirect and PubMed databases with the following keywords: giomer, esthetic properties giomers and fluoride releasing giomers. A total of 232 articles were initially selected, with the following inclusion criteria: full text articles, written in English, with topics on the properties and the clinical implications of giomers. Papers presented as abstract were not included. In the next step, review articles, duplicates, and articles in other languages were removed; as a result, a total of 44 sources published between 2004 and 2017 were selected. RESULTS: The selected articles referred to the following aspects about the giomers: chemical composition (8 articles), adhesion and microleakage (10 articles), fluoride releasing and pulp protection (15 articles), clinical indications (6 articles), effects of additional treatments and dietary habits (11 articles).

Whiteness difference thresholds in dentistry.

OBJECTIVE: To determine the visual whiteness thresholds for esthetic dentistry using the whiteness index for dentistry based on CIELAB color space (WID). METHODS: A total of 60 observers (Dentists and Laypersons; n=30) from three research sites participated in the study. A psychophysical experiment based on visual assessments of simulated images of teeth on a calibrated display was performed. Images of simulated upper central incisors (SUCI) were consecutively displayed in pairs (60) and the whiteness of each SUCI pair was compared. WID was used to calculate the visual thresholds (WPT- perceptibility threshold; and WAT- acceptability threshold) with 95% confidence intervals (CI) and a Takagi-Sugeno-Kang (TSK) Fuzzy Approximation model was used as fitting procedure. Data was statistical analyzed using paired t-test (α=0.05). RESULTS: WPT and WAT were 0.72 (CI: 0.0-2.69; r2=0.52) and 2.62 (CI: 0.2-7+; r2=0.57) WID units, respectively. Significant differences (p<0.05) were found between WPT and WAT, and between dentist (WPT=0.46WID units; WAT=2.20 WID units) and layperson (WPT=0.94 WID units; WAT=2.95 WID units). SIGNIFICANCE: The visual whiteness difference thresholds determined with WID index can serve as reference values for research and manufacturing of dental materials, and for clinical practice situations such as assessing the effectiveness of bleaching treatments.

Color comparison between non-vital and vital teeth.

PURPOSE: The aim of this study was to define a color space of non-vital teeth and to compare it with the color space of matched vital teeth, recorded in the same patients. MATERIALS AND METHODS: In a group of 218 patients, with the age range from 17 to 70, the middle third of the buccal surface of 359 devitalized teeth was measured using a clinical spectrophotometer (Vita Easyshade Advance). Lightness (L*), chromatic parameters (a*, b*), chroma (C*), hue angle (h) and the closest Vita shade in Classical and 3D Master codifications were recorded. For each patient, the same data were recorded in a vital reference tooth. The measurements were performed by the same operator with the same spectrophotometer, using a standardized protocol for color evaluation. RESULTS: The color coordinates of non-vital teeth varied as follows: lightness L*: 52.83-92.93, C*: 8.23-58.90, h: 51.20-101.53, a*: -2.53-24.80, b*: 8.10-53.43. For the reference vital teeth, the ranges of color parameters were: L*: 60.90-97.16, C*: 8.43-39.23, h: 75.30-101.13, a*: -2.36-9.60, b*: 8.36-39.23. The color differences between vital and non-vital teeth depended on tooth group, but not on patient age. CONCLUSION: Non-vital teeth had a wider color space than vital ones. Non-vital teeth were darker (decreased lightness), more saturated (increased chroma), and with an increased range of the hue interval. An increased tendency towards positive values on the a* and b* axes suggested redder and yellower non-vital teeth compared to vital ones.

Evaluation of chromatic changes of a nanocomposite resin using the new whitness index.

BACKGROUND AND AIMS: To evaluate the staining effects of two brands of coffee and the bleaching efficiency of two in-office bleaching methods, upon different opacities of a commercial nanocomposite. METHODS: Twenty four specimens of each opacity, A3 Dentin, A3 Body and A3 Enamel, were fabricated from Filtek Supreme (3MEspe). The specimens were further divided into two groups (n=12) and were immersed in two coffee solutions (Bio Organic Coffee Bellarom, 100% Arabica, and Iulius Meinl Coffee), for 24 hours. Between the staining sessions, the specimens were stored in sterile water, at 37°C. Each group was further divided into three (n=4), in order to be bleached, as follows: Group 1 - Beyond 35% in office, for 4 applications of 15 minutes each, Group 2 - Zoom Day White 6% in office, for 4 applications of 15 minutes each, Group 3 - Control Group, stored in sterile water. Color values were measured with a dental spectrophotometer Vita EasyShade 4.0 and five measurements were recorded for each sample at a time. Lightness L*, color coordinates a* and b* were recorded, at baseline, after staining in coffee and after bleaching. Whiteness index (WID) of the three composite resins (A3D, A3B, A3E) in the three moments were calculated, as well as the color difference Delta E* correspondent to the staining and bleaching process. Data were analyzed using one-way repeated measures ANOVA and the WID index was calculated WID (p<0.05). Univariate analysis of variance was performed for assessing the influence of staining solution upon composite resins, as well as for testing the effect of bleaching agents. The significance level was set at α=0.05 and pairwise comparisons were adjusted by the Least Significant Difference method. RESULTS: The pairwise comparisons showed no significant difference between the effects of the two bleaching agents upon the WID, meaning that they induce almost similar color changes. The results of the univariate ANOVA test indicated a significant effect of the composite resin and the staining solution upon the WID (p<0.05). However, no significant interaction effect was found between the composite resin and the staining solution (p=0.095). There was a significant difference in the staining effect of the two coffee solutions only for A3B and A3E composite resins (p<0.05). CONCLUSIONS: The chromatic changes of the nanocomposite resin could be evaluated by the variation of the whiteness index. The staining effect induced by the two types of coffee was similar. The most effective protocol was the in-office bleaching method based on Beyond 35%.

Translucency and masking properties of two ceramic materials for heat-press technology.

OBJECTIVES: To assess the translucency of two pressable ceramics and to analyze their masking property when placed on different tooth-shaded backgrounds. MATERIALS AND METHODS: Thirty discs (1-mm thickness) were fabricated using two pressable ceramics (shade/translucency): 1M1T/HT, 1M2T/HT, 2M2T (VITA PM9), and A1LT/HT, B1LT/HT, A2LT (e.max Press). Color measurements of discs were performed with a dental spectrophotometer on tooth-colored backgrounds (A1/A2/A3/A3.5/A4), and black and white backings. The masking property was calculated as the color difference (CIEDE2000) between parameters of discs on control (A1, A2) and test backgrounds (A3, A3.5, A4). One-way ANOVA was used for assessing differences in translucency parameter (TP) between ceramics. Two-way ANOVA was used for detecting differences among groups when measured over tooth-shaded backgrounds (α = 0.05, Bonferroni correction). RESULTS: TP ranged between 14.96 (B1LT) and 25.18 (1M1HT). A significant difference in TP was found between tested ceramics (F = 949.949, P < .001). However, TP did not vary significantly between 1M1HT and 1M2HT (P > .05), 1M1T, A1HT and B1HT (P > .05), 1M2T, 2M2T, and A2HT (P > .05). A significant interaction effect of underlying background on color of ceramic discs was found (F = 107.994, P < .001). CONCLUSION: VITA PM9 demonstrated higher translucency than e.max Press ceramics. Except A1LT, all ceramic materials evaluated showed poor masking properties on A4 background. CLINICAL SIGNIFICANCE: Highly translucent ceramics should be wisely used for restoring the appearance of dental structures since background color has a large effect upon these materials. The more recently introduced pressable ceramics showed high levels of translucency.

Ultrasonographic evaluation of periodontal changes during orthodontic tooth movement - work in progress.

BACKGROUND AND AIM: Orthodontic tooth movement (OTM) is a process whereby the application of a force induces bone resorption on the pressure side and bone apposition on the tension side of the lamina dura. However, only limited data are available on the in vivo behavior of the periodontal tissues. The aim of this study was to assess the changes of periodontal tissues, induced by the orthodontic canine retraction, using 40 MHz ultrasonography. METHODS: Ultrasonographic evaluation of periodontal tissues was conducted in 5 patients with indication for orthodontic treatment. The upper first premolars were extracted bilaterally due to severe crowding, and the canines were distalized using elastomeric chain with a net force of 100 cN. Ultrasonographic scans (US scans) were performed before, during and after retraction, in three distinct areas of the canines buccal surface: mesial, middle and distal. The reference point was the bracket, which appeared hyperechoic on the US scan. Four different dimensions were obtained: D1 (depth of the sulcus), D2 (thickness of the gingiva), D3 (length of the supracrestal fibers), D4 (width of periodontal space). RESULTS: An increase of D1 was observed in all three areas of the periodontium, during orthodontic treatment. D3 was strongly correlated before and immediately after force delivery only for the mesial area (r=0.828, p<0.05). In total, 228 variables were statistically analyzed using Pearson's correlation coefficients, in order to demonstrate the relationship between periodontal findings during orthodontic tooth movement. CONCLUSION: High-resolution ultrasonography has the capability to obviate changes in periodontal ligament space and free gingiva during orthodontic tooth movement.