Vita Zahnfabrik Research Articles

Clinical justification of the effectiveness of the use of digital devices for determining the color of the tooth

BACKGROUND: The procedure for determining the color of teeth can be carried out visually using colors or special devices, or both methods at the same time. The visual definition of shades using popular instrumental techniques, although ubiquitous, is nevertheless very subjective. The hardware method for determining the color of teeth consists in an objective computer analysis of the image obtained under ideal optical conditions. Ambient light should not affect the color detection results obtained by spectrophotometers and colorimeters. The main advantage of the hardware method of determining the color of teeth is the elimination of subjectivity. The world scientific literature describes many studies comparing the quality of color determination by hardware and visual methods. However, these data differ, and the conclusions are not unambiguous in the choice of a particular method, therefore, the clinical effectiveness of digital technologies for determining the color of teeth, as well as the scientific justification of their use, is an urgent problem of modern dentistry.
 AIM: To evaluate the accuracy of determining the color of teeth with digital dental devices in comparison with the visual assessment of color by an expert group.
 MATERIAL AND METHODS: In order to achieve this goal and form the design of the study, we analyzed the sources of scientific literature. The information search was carried out in the scientific electronic databases eLibrary, Scopus, PubMed in the period from 2002 to 2020, according to the keywords of the query: methods for determining the color of teeth, comparison of methods for determining the color of teeth, hardware methods for determining the color of teeth. The results of the study of special literature on this topic have identified the most accurate and frequently used methods for determining color in practical healthcare. Of the visual methods, preference is given to determining the color of teeth using the colors VITA Toothguide 3D-Master (VITA Zahnfabrik, Germany) and VITA Classical (VITA Zahnfabrik, Germany). Of the devices, among spectrophatometers, most authors prefer VITA Easyshade (VITA Zahnfabrik, Germany) and Spectro Shade (Micro High Technologies, Italy), among hybrid devices (intraoral scanners) 3Shape TRIOS (3Shape, Denmark). The evaluation of the accuracy of determining the color of teeth by digital dental devices was carried out on 20 natural right medial central incisors of 20 patients in a dental office. The effectiveness of these devices was determined in comparison with the teeth color indicators determined by the expert group. For each pair of the studied methods, Cohens kappa was determined a statistical coefficient for determining the mutual reliability of appraisers. When calculating Cohens mouthguard, the results of color determination for each third of the tooth surface were compared separately by compiling multi-field tables. Statistical processing was carried out in Excel 2016.
 RESULTS: According to the interpretation intervals of Cohens kappa values, mutual reliability of evaluators is defined as excellent at values from 0.75 to 1.0, good from 0.6 to 0.74, acceptable and bad from 0.4 to 0.59 and less than 0.4, respectively. The Spectra Shade device showed excellent consistency with experts in determining the color of the tooth in all three parts of the surface. Vita Easyshade V showed less consistency with the expert assessment, but its level is interpreted as good. The color detection data using the 3Shape Trios digital scanner did not agree well with the opinion of experts. The devices showed consistency between themselves in the range from acceptable to good, while mutual reliability in the Spectra Shade - Vita Easyshade V pair turned out to be better than others.
 CONCLUSION: Taking into account the fact that the accuracy of the devices does not depend on the factors to which a person is exposed, such as subjectivity, illumination, time of day, eye fatigue, the color of nearby teeth, etc., it is advisable to use the Spectra Shade and Vita Easyshade V devices in clinical practice to increase the objectivity of color determination and improve patient satisfaction with dental treatment.

Spectrophotometric examination of the optical properties of lithium-silicate glass-ceramics with different substrates

Creating esthetic, natural-looking crowns and fixed partial dentures (FPD) is highly affected by the experience of the dental technician even today. The aim of this in vitro study is to examine the optical properties of glass-ceramics of different translucency and thickness, combined with try-in pastes and substrates of different shades. Glass-ceramic specimens were produced of VITA Suprinity (VITA Zahnfabrik) zirconia-reinforced lithium-silicate ceramic, shade A1 T (low translucency) and HT (high translucency), in 0.5 mm; 1.0 mm; 1.5 mm; 2.0 mm; 2.5 mm thickness. Nine types of substrates (cobalt-chromium alloy, copper alloy, zirconia, and six shades of VITA Simulate Material) and three shades of Variolink Esthetic try-in pastes (Ivoclar Vivadent) were used to make 270 different combinations of layered specimens. PerkinElmer® LAMBDA 1050 UV/Vis/NIR Spectrophotometer was used in this study. The device measures the reflectance spectrum by which the L*a*b* and ΔE values can be calculated based on the CIEDE2000 formula. ΔE value indicates the color difference between two colors. Averages were compared to the reference specimen. ΔE values of layered specimens have been decreasing by the thickening of the lithium-silicate ceramic. The highest ΔE values were measured beside metal and zirconia substrates. The effect of different try-in pastes was below the perceptibility threshold (ΔE 0.8). ΔE of the reference substrate was zero, proving the precision of the measurement. The optical properties of lithium-silicate glass-ceramic specimens are significantly affected by the shade of the substrate, the thickness, and translucency of the ceramic; however, the effect of try-in paste shades is not significant.

Effect of erosive media on microhardness and fracture toughness of CAD-CAM dental materials

BackgroundErosive acids might create surface flaws and deteriorate the mechanical properties of CAD-CAM materials. This invitro study aimed to investigate the effect of simulated gastric HCl and extrinsic erosive acids on surface microhardness and fracture toughness of CAD-CAM materials.Methods400 bar-shaped specimens (17×4×2 mm3) were prepared from 4 different CAD-CAM dental materials (n = 100/group); monolithic zirconia (Ceramill Zolid HT+, Amanngirbach, Austria), lithium disilicate ceramic (IPS e.max CAD, Ivoclar Vivadent, Liechtenstein), nanohybrid resin composite (Grandio Blocs, VOCO) and polymer-infiltrated glass network (Vita Enamic, VITA Zahnfabrik). Specimens from each material type were further subdivided into 5 groups (n = 20) according to the erosive media applied (simulated gastric HCl, white wine, Coca-Cola®, orange juice, and artificial saliva that served as a control). Specimens were immersed for 24 h in an incubator at 37 ℃, then ultrasonically cleaned in distilled water and air-dried. Half of the specimens were tested for Vickers microhardness (VHN) at parameters of 500 gf for 10 s, while the rest of the specimens underwent 3-point flexure till fracture. Fractured surfaces were examined under a scanning electron microscope (SEM) for fracture toughness (KIC) calculation using the quantitative fractographic analysis method. Data collected were statistically analyzed using two-way analysis of variance (α = 0.05) after verification of data normality and homogeneity of variances.ResultsErosive media created surface flaws that lowered the surface microhardness of the material and initiated the fracture pattern under different loads according to material type. The material type was a more predominant factor than erosive media that affected either the microhardness or the fracture toughness of CAD-CAM dental materials. The highest VHN and KIC values were found among Ceramill Zolid HT+ groups followed by IPS e.max CAD and Grandio Blocs regardless of the erosive media employed. Erosive media significantly reduced the VHN and KIC in Vita Enamic specimens compared to the rest of the material types.ConclusionAll CAD-CAM materials used, except Vita Enamic, showed high resistance against the erosive acids indicating higher longevity of the material in patients frequently exposed to either extrinsic or intrinsic acid.

Color stability of hybrid ceramics exposed to beverages in different combinations

BackgroundThe aim of this study is to evaluate the color stability of hybrid ceramics stored in different combinations of beverages that are routinely consumed.MethodsThe specimens were prepared with resin nano-ceramic (Lava Ultimate, 3M Espe, USA) and hybrid ceramic (Vita Enamic, Vita Zahnfabrik, Germany). The specimens were aged in a thermocycler machine for 10,000 cycles. They were stored in different combinations of beverages (water, tea, coke, coffee, red wine, pomegranate juice, and turnip juice) for 12 + 12 h. Surface roughness measurements were performed using a profilometer. The specimen colors were measured using a spectrophotometer. The color values (L-a-b) of the specimens and mean surface roughness values (Ra) were recorded at the end of the 1st (D1), 7th (D7), 14th (D14) and 28th (D28) d.ResultsWhen the solution groups were examined, significant color changes were observed in the Lava coffee-tea, Enamic coffee-tea, Lava coffee-wine, and Enamic coffee-wine groups compared with the other groups (p < 0.01). Except for the samples in the Lava coffee-wine 28th day (D28) and Enamic coffee-wine 28th day (D28) groups, more color changes were observed in the Lava samples than in the Enamic samples across all groups and periods.ConclusionGreater color changes (except for the samples stored in coffee-wine) were observed in the Lava samples than in the Enamic samples across all groups and periods. It was observed that the coffee-tea and coffee-wine beverage combinations produced the greatest color change in hybrid ceramics within the limitations of this study.

Accelerated artificial aging and color stability in resin-based cements.

The aim of this study was to determine color change after accelerated artificial ageing (AAA) of different composite cements that are used with veneers. Five cylindrical test specimens, 15 mm in diameter and 2 mm thick, were made from a single layer of each of the following: RelyX Veneer 3M ESPE (RX), Paracore White Coltene (PC), Solocem White Opaque Coltene (SO), Resin Duo Cement Densell (DC), Panavia V5 Paste Kuraray Noritake (PA) and Panavia F2.0 Kuraray Noritake (PF) (30 specimens altogether). The specimens were light cured following manufacturers' instructions using a Coltolux LED (Coltene) unit. Initial color was determined using an Easyshade - Vita Zahnfabrik Spectrophotometer. Then, the specimens were subjected to AAA for two weeks (336 hours) with cycles of 4 hours of UV light at 60 °C and 4 hours of vapor condensation at 50 °C, successively, after which color was recorded again. Color change was determined for each specimen according to the differenceinshadeon the Vita scale before and after AAA. Results were analyzed using Kruskal Wallis test. Mean and standard deviation for each group were: RX 8.40 (1.52); PC 8.60 (3.13); SO 6.40 (3.51); DC 10.00 (0.00); PA 7.60 (3.29); PF 2.00 (0.00). The Kruskal Wallis test showed significant difference for material (p<0.05), and comparison of means showed difference between Panavia F2.0 and the other materials. A table providing equivalence between the Vita Classic and CIELAB scales was used to transfer the recorded colors to the CIELAB scale, and the color difference ΔE was calculated for each group, where ΔL, Δa and Δb are the differences in the L, a and b values before and after the AAA. The mean and standard deviation were analyzed statistically by the ANOVA test and Tukey's test. Mean and standard deviation for each group were: RX 14.94 (2.02); PC 14.51 (4.02); SO 12.08 (4.53); DC 16.31 (0.00); PA 10.9 (3.38); PF 7.24 (0.00). The ANOVA test showed significantdifferenceformaterial (p<0.05). Tukey's test showed two groups (PF-DC, RX, PA). Under the experimental conditions of this study, it can be concluded that accelerated ageing significantly affects the color stability of the resin based cements tested.

Effect of ocular dominance, clinical experience, and sex on the accuracy of shade selection.

The study aimed to evaluate the influence of ocular dominance, clinical experience, and sex on the accuracy of visual color matching. A total of 104 selected participants consisting of dental students and dental practitioners were allocated into two groups based on their clinical experience of using visual shade matching tabs for the selection of tooth shade. Both the inexperienced (IXP), as well as experienced participants (EXP), were then asked to correctly match the shades of five tabs (A2, A3.5, B1, C2, and D3) of a commonly used visual shade guide (Vitapan Classical shade guide, VITA Zahnfabrik) that were kept constant throughout the study. The participants documented the shade of those tabs using another set of shade guide using the right eye (left eye covered), left eye (right eye covered), as well as both eyes. Test for ocular dominance was performed using the Dolman method. The results were statistically analyzed using the chi-square test with a level of significance set at < .05. The percentage of correct shade matching with the monocular dominant vision (53%) was significantly better as compared to the monocular non-dominant vision (12%) (P < .001) or binocular vision (44%) (P < .05). Sex had an influence in shade selection (P = .031). However, clinical experience was an insignificant aspect in shade matching (P = .078). Knowing the clinician's dominant eye can be clinically relevant, as it can influence the accuracy of shade selection, irrespective of sex and clinical experience.

Lithium disilicate and zirconia reinforced lithium silicate glass-ceramics for CAD/CAM dental restorations: biocompatibility, mechanical and microstructural properties after crystallization

ObjectivesThe objective of this study was to define the impact of heating rate on the crystal growth, the mechanical properties, and the biocompatibility of three different kinds of CAD/CAM glass-ceramics treated with a conventional furnace. MethodsLithium disilicate (IPS EMax-CAD, Ivoclar Vivadent) (LS2) and two zirconia reinforced lithium silicate (ZLS) ceramics (Vita Suprinity PC, VITA Zahnfabrik; Celtra Duo, Dentsply Sirona) (ZLSS; ZLSC) were used. The mechanical properties and the crystal growth were evaluated on 42 specimens (n = 14 per group). The thermal treatments recommended by the manufacturers were carried out. All groups were tested for fracture toughness (Ft) and Vickers hardness (Hv). Scanning electron microscope (SEM) images were taken after a slight surface etching with hydrofluoric acid solution (1% for 20 s). Differential Thermal Analysis (DTA) was performed and cellular adhesion with human periodontal ligament stem cells (hPDLSCs) culture was qualitatively assayed. Data were analyzed with Repeated Measurements ANOVA and ANOVA followed by Tukey post hoc test. ResultsThe crystals’ mean size (±SD) after heat treatment was 1650.0 (±340.0) nm for LS2, 854.5 (±155.0) nm for ZLSS and 759.9 (±118.4) nm for ZLSC (p < 0.05 among the groups). As consequence of crystallization, the Hv was 6.1 ± 0.3 GPa for LS2, 7.6 ± 0.7 GPa for ZLSS and 7.1 ± 0.5 GPa for ZLSC (p < 0.05 for LS2 vs ZLSS and ZLSC), while the Ft was 2.2 ± 0.1 MPa m1/2 for LS2, 4.7 ± 0.8 MPa m1/2 for ZLSS and 3.8 ± 0.6 MPa m1/2 for ZLSC (p < 0.05 among the groups). The DTA curves showed a crystallization process for LS2, ZLSS and ZLSC at a temperature range 810–840 °C. The amount of adherent hPDLSCs was superior on LS2 than on ZLS. ConclusionsAll the CAD/CAM materials can be properly crystallized if heat treated following the manufacturers’ instructions. The crystallization process highly depends on temperature. ZLS glass ceramics show significantly inferior crystals dimensions and higher fracture toughness and Vickers hardness than LS2 ceramic. hPDLSCs cultured on LS2 have a superior adhesion than those cultured on ZLS. Clinical significanceThe value of this study relies on the demonstration that a proper heat-treatment of CAD/CAM lithium disilicate and ZLS glass ceramics generates products that are suitable for clinical use . The differences highlightable in mechanical properties and biocompatibility behavior do not affect their successful clinical application.

Effect of stain brand and shade on color stability of stains applied on a CAD-CAM feldspathic ceramic

The aim of this study was to investigate the effect of stain brand and color on color stability of stains on a CAD-CAM ceramic after aging. Specimens (15 × 8 × 1.5mm) were fabricated from A2-shade ceramic blocks (Mark II; Vita Zahnfabrik) (N = 120). Specimens were divided into two groups (n = 10) to be stained with six different stains (yellow, orange, blue, gray, violet, and brown) from two manufacturers (GC initial spectrum (GC) and IPS e.max Ceram (IPS)). Aging was performed for 5h at 134°C. Color coordinates before and after aging were measured to calculate color differences (ΔE00). Kubelka-Munk absorption (K) and scattering coefficients (S) of stains were compared with those of A2 shade tab. Two-way ANOVA was used to analyze the ΔE00 values and Tamhane T2 was used to analyze the K and S coefficients (alpha = 0.05). A significant interaction was found between stain color and brand (p < 0.001). Color changes with IPS stains were higher than those with GC stains except for brown. The highest color difference was with orange stain of IPS (p < 0.001). Absorption and scattering coefficients of different stains on CAD-CAM ceramic were different from those of A2 shade tab except for brown stain (p < 0.001). Tested stains on CAD-CAM ceramic had varying color changes after aging. Color of gray, violet and brown of both stains was stable. Yellow, orange, and blue GC stains were more color stable compared with IPS. Absorption and scattering coefficients of stains in different colors varied.

Evaluation of Microshear Bond Strength of Four Different CAD-CAM Polymer-Infiltrated Ceramic Materials after Thermocycling.

To evaluate the bond strength of three monolithic hybrid ceramics/resin nanoceramics and a zirconia-reinforced lithium silicate to resin cement after thermocycling. Using four materials, including Vita Enamic (VITA Zahnfabrik), Lava Ultimate (3M ESPE), Crystal Ultra (Digital Dental), and Vita Suprinity (VITA Zahnfabrik), 64 specimens were prepared with dimensions of 4 mm × 3 mm × 1.5 mm. Vita Suprinity samples were sintered at 840°C for 8 min. After polishing and cleaning all the samples in each group (n = 16), they were subjected to their recommended surface treatment: 10% hydrofluoric acid for Vita Enamic (60s) and Vita Suprinity (20s); air abrasion of Lava Ultimate and Crystal Ultra with 50 u Al2 O3 particles. Then, tygon tubes were filled with dual cure resin cement (Panavia F2.0), cured and then subjected to thermal cycling (2000 cycles; 5-55°C). The microshear bond strength was measured using microtensile testing machine. The data were analyzed using Welch and Games-Howell tests (α = 0.05). The mode of failure was also evaluated using a stereomicroscope. The highest and the lowest mean microshear bond strength belonged to the Crystal Ultra (7.71 ± 1.54 MPa) and Vita Suprinity (4.73 ± 1.87 MPa) groups, respectively. The differences between groups were significant and Crystal Ultra had higher bond strength in comparison to all three materials (p < 0.05). Hybrid ceramics showed higher bond strength to resin cements in comparison to resin nanoceramics and zirconia-reinforced lithium silicate materials.

Color difference between the vita classical shade guide and composite veneers using the dual-layer technique.

BackgroundThe purpose of this in vitro study was to evaluate the color difference between the Vita Classical Shade Guide and composite veneers using the dual-layer technique. Material and MethodsThirty samples were fabricated using a custom-made mold (Easy Layering Shade Guide Kit, 3M) using two resin composites: Filtek Supreme Ultra (3M); and Estelite Omega (Tokuyama) (n=3). The composite veneers were made by layering the different enamel and body or dentin shades from each composite. The color measurements were taken using a spectrophotometer (Vita Easyshade V®, Vita Zahnfabrik). The ΔE00 between the Vita Classical Shade Guide (Vita Zahnfabrik) and the composite veneers were calculated using the CIEDE2000 formula. ResultsFor the composite veneers using Filtek Supreme Ultra, the best match for A1 Vita shade was achieved layering either EA1 with DA2 or DA3; EA2 with DA1 or DA2 (ΔE00= 1.53 ~ 1.96 ± 0.4). For A2 Vita shade the best match would be EA3 with DA3 or EA3 with DA2 (ΔE00= 1.40 ~ 1.85 ± 0.1); or for A3 Vita shade the best match would be EA3 with DA2 2.50±(0.6). For the composite veneers using Estelite Omega, the were no best match for neither A1, A2 or A3 Vita shade (ΔE00> 2.5). ConclusionsThe combination of enamel and dentin shades from Filtek Supreme Ultra provided acceptable color match for A1, A2 and A3 shades from the Vita Shade Guide, while Estelite Omega did not provide acceptable color match for any of the Vita Shade Guide standard shades tested. Key words:Color, color matching, optical properties, resin composite, layering.

65 - Evaluating Boron-Doped Soda Lime Glass for Finishing Dental Zirconias

Even though monolithic restorations can be produced from dental zirconias, glaze and stains applications are routine procedures for a natural appearance result. Thus, this study evaluated the use of boron-doped soda lime glass as an alternative for finishing zirconia restorations. Disc-shaped samples of second and third generations zirconia were prepared: 3Y-TZP (ZPex, Tosoh) and 5Y-PSZ (Zpex Smile, Tosoh) (ISO 6872, diameter: 12 mm; thickness: 1.2 mm). The samples were polished with SiC #1200 sandpaper, sintered at 1550 C for 2 hours (Sirona inFire HTC speed) and randomly divided into 4 groups: 3Y-TZP with comercial glaze (3Y-G); 5Y-PSZ comercial glaze (5Y-G); 3Y-TZP with boro-doped soda-lime glass (3Y-SL) and 5Y-PSZ with boron-doped soda lime glass (5Y-SL). Then, glaze layer (Vita Akz 25, VITA Zahnfabrik, Germany) was mixed with the manufacturer building liquid, applied over the zirconia discs with a brush and fired at 950 C for 20 min. The boron-doped soda lime glass powder was mixed with propylene glycol, applied with a brush and fired at 1200 C for 20 min. The samples were subjected to surface roughness analysis in a contact profilometer for average (Ra) and ten-point-mean roughness (Rz) assessment. The biaxial flexural strength (MPa) was measured in a universal testing machine with a loading speed using the piston-on-three-ball method. The strength and roughness values (MPa) were analyzed by two-way ANOVA (α= 0.05). The glaze application led to slightly lower Ra values when applied over the 5Y-PSZ when compared to the other groups: 3Y-G (Ra-0.011; Rz-0.083), 3Y-SL(Ra-0.011; Rz-0.076), 5Y-G (Ra-0.008; Rz-0.054), 5Y-SL (Ra-0.011; Rz-0.076). However, no statistical difference was observed in Rz (p>0.05). The highest flexural strength values were observed for 3Y-TZP samples. The statistical analysis showed significant differences as follows: 3Y-SL (1026.99 MPa 130.04) > 3Y-G (818.401 MPa 89.63) > 5Y-SL (762.91 MPa 123.30) > 5Y-G (620.87 MPa 50.38). Although roughness values were similar among the experimental groups, boron-doped soda lime glass was able to improve flexural strength of both 3Y-TZP and 5Y-PSZ when compared to commercial glaze.

Spectrophotometric comparison of two porcelain systems, VMK master and VM13 with the VITA 3D-master shade guide (An in vitro study)

Accurate shade matching of metal-ceramic restorations with natural teeth is one of the most challenging aspects of dental restorations and esthetic dentistry. The aim of this study was to evaluate of the color parameters of two types of porcelain systems VMK Master and VM13 porcelain with VITA 3D-master shade guide. In this in vitro study a total of 56 metal discs (10 mm diameter and 2 mm thickness) were fabricated. Each of the disks was veneered with porcelain (Vita Zahnfabrik, Bad Sackingen, Germany) of the VITA shade. The discs were randomly divided into four groups (2M2 and 3M2 from VM13, 2M2 and 3M2 from VMK master) of 14 (n = 14). The spectrophotometer was used for taking color measurements based on the numerical color data of the CIELAB color system. Data analysis was performed by t-test (P < 0.05). Comparison of color parameters in different porcelain showed that the type of porcelain caused a significant difference in color parameters (L, a, and b) (P < 0.05). The degree of translucency (L*) or glaze of VMK porcelains was higher than VM13, but the parameters a* and b* were higher in VM13 porcelains than VMK (P < 0.05). Furthermore, the color difference of two porcelain in 2M2 (1.63 ± 0.84) and 3M2 (1.71 ± 0.96) shades was within the acceptable clinical limit. Considering the total color difference (ΔE), there were no significant differences between the ΔE values produced by any of shades (P > 0.05). In the present study, the spectrophotometric analysis revealed that the porcelain shade type causes a change in the color parameters, but the color difference between two porcelains VMK and VM13 is within the acceptable range of clinical color. Therefore, both porcelain systems with 2M2 and 3M2 shades are suitable for enhancing the results of restorative dentistry.

Management of Post Orthodontic White Spot Lesions Using Resin Infiltration and CPP-ACP Materials- A Clinical Study

The purpose of this present study was to assess and compare the effectiveness and durability of topical application of remineralizing agent Casein Phospho Peptide (CPP-ACP, Toothmousse, GC corporation, Germany, Europe) and Resin infiltration (ICON, DMG, Hamburg, Germany) in the management of post orthodontic white spot lesions. A Randomized Control clinical trial was conducted among 60 children who had undergone fixed orthodontic therapy presented with white spot lesions (WSLs) on maxillary or mandibular anteriors after debonding. Identification of WSLs was done with International Caries Detection and Assessment System (ICDAS II) criteria. The clinical photographs recorded were used to measure the size of lesion. The color assessment of the lesion and sound adjacent enamel was recorded by using spectrophotometer (Vita-Easy shade 4.0, VITA Zahnfabrik, Germany). Area of the lesion was calculated using Digimizer software (Digimizer, MedCalc Software, Belgium). The selected samples were randomly allocated into two groups: Group I- Resin infiltration- Icon, DMG, Germany, (n=30) and Group II- Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP)-GC Toothmousse, GC Corporation, Germany, (n=30). The WSLs were evaluated immediately following resin infiltration, and in CPP-ACP group after 1 month. In both the groups lesions were evaluated at 1, 3, 6 and 12 months. There was significant reduction in lesion area, and improvement in color of white spot lesions with both of the treatment modalities. Both the resin infiltration and CPP-ACP have desired and durable esthetic improvement in terms of reduction in the area as well as color of post orthodontic white spot lesions.

Color change, tooth sensitivity, aesthetic self-perceptions and quality of life after at-home dental bleaching

Objective: The aim of this study was to determine the color change, tooth sensitivity, aesthetic self-perceptionand quality of life after at-home dental bleaching. Material and Methods: Dental examination was performedand the initial color of the upper right incisor was recorded using a spectrophotometer (Easyshade Compact,Vita Zahnfabrik) and CIELab parameters. Individual vinyl trays were delivered to the patients (n=37) who wereinstructed to use the carbamide peroxide 16% (Total Blanc Home C16%, DFL) for 2 hours daily for 2 weeks.One-week after the end of treatment, measurements were repeated to calculate color (Eab, E00) and whitenessindex (WID) variations. Oral Health Impact Profile (OHIP) and Psychosocial Impact of Dental AestheticsQuestionnaire (PIDAQ) questionnaires were applied before and 30 days after treatment. Tooth sensitivity wasby checked by visual analogue scale (VAS). Spearnan’s correlation tests were used to verify the possible relationbetween color change parameters and sensitivity. The Wilcoxon test was applied for results obtained by OHIP andPIDAQ questionnaires. Results: Significant color change was observed after 14 days, regardless of the consideredparameter. There was no significant correlation between sensitivity and color change. The dental self-confidencedomain increased after bleaching (p = 0.029) and the psychological impact decreased (p = 0.001). Conclusion:At-home dental bleaching was effective on the overall whitening and the color change was not related to toothsensitivity. The bleaching treatment had a positive impact on the quality of life, reducing psychological discomfortand improving dental self-confidence and aesthetic self-perception. KEYWORDSAesthetics; Quality of life; Tooth whitening.

58 - Experimental Silver-Infiltrated Glass on Biofilm Formation in Monolithic Zirconia

The aim of this study was to evaluate the effect of different coating applications of experimental glass with silver particles on surface properties, biofilm formation and inhibition of microbial adhesion to yttria-stabilized tetragonal zirconia (Y-TZP). 105 YZ T zirconia samples (VITA Zahnfabrik, Germany) with dimensions of 5.0 ×5.0 ×2.0 mm were divided into 7 groups: Polished YZ (P), Glazed YZ (G), YZ with infiltration glass (INF), YZ + 4% Ag (Ag4), YZ + 5% Ag (Ag5), YZ with glass + 4% silver (IAg4) and YZ with glass + 5% silver (IAg5). The experimental infiltration glass was made from silicic acid, which was obtained when sodium meta silicate (Na 2 SiO 3 5H 2 O) passed through aqueous solution (10% m / m) and an ion exchange resin (IR120 - Rohm and Haas). The glass with was obtained through a similar protocol, which was then followed by the addition of silver nitrate (AgNO 3 ) and silicon (SiO 2 ), aluminum (Al 2 O 3 ), calcium (CaO), sodium (Na 2 O), and potassium (K 2 O) oxides. The product upon completion comprised 5% AgNO 3 , 65% SiO 2 , 1.1% Al 2 O 3 , 0.59% K 2 O, 14.54% Na 2 O, 8.93% CaO and 3.41% MgO. Specimens were submitted to the following tests: surface roughness, colony-forming unit count (CFU) of Candida albicans, Streptococcus mutans and Streptococcus sanguinis, and Scanning Electron Microscopy (SEM). The different coating exhibited notable differences, both in relation to surface roughness, and bacterial and fungal adhesion. Regarding surface roughness, the Ag5 and IAg5 had a rougher profile when compared to the other groups, that were smoother and statistically similar to each other. However, in the CFU tests of Candida albicans and Streptococcus mutans groups P, G, and INF showed higher adherence of microorganisms, while all silver groups had less biofilm adherence, being statistically similar to each other. In the SEM it was possible to observe that all the groups of glass with silver (Ag4, IAg4, Ag5 and IAg5) presented silver particles anchored to the zirconia-glass system. The application of silver coating made the surface of the monolithic Vita HT zirconia resistant to the tested oral pathogens, causing inhibition of bacterial growth in the nearby surrounding region and also preventing the formation of biofilm on the ceramic surface.

Mechanical Properties of Bisacryl-, Composite-, and Ceramic-resin Restorative Materials.

Resin-based materials used in restorative dentistry are introduced at a fast pace with limited knowledge about their properties. Comparing properties of these materials from different restorative categories is lacking but can help the clinician in material selection. This study aimed to compare mechanical properties and wear resistance of bis-acryl-, composite-, and ceramic-resin restorative materials. Bisacryl-resin (Bis-R, LuxaCrown, DMG), composite-resin (Com-R, Filtek Supreme Ultra, 3M Oral Care), and ceramic-resin (Cer-R, Enamic, VITA Zahnfabrik) specimens were prepared for mechanical tests: fracture toughness (FT) with and without initial thermomechanical loading using a mastication simulator, flexural strength (FS), and flexural modulus (FM), compressive strength (CS), and volumetric wear loss measurement. The datasets for FT and wear resistance were each analyzed using two-way ANOVA followed by pairwise comparisons or Tukey testing as appropriate. The datasets for FS, FM, and CS were analyzed using one-way ANOVA followed by the Tukey test. Analysis of FS, FM, and CS showed significant differences between materials, with all pairwise comparisons between materials showing significance. Analysis of FT resulted in a significant interaction between the material and treatment, with analysis of wear loss showing a significant interaction between the material and the number of cycles. Cer-R demonstrated superior FT, CS, and wear resistance compared to Bis-R and Comp-R materials. Fracture toughness of Bis-R increased after thermomechanical loading.

MODERN TECHNOLOGIES FOR THE MANUFACTURE OF GLASS-CERAMIC DENTAL PROSTHESES

The relevance of the problem of improving the quality of life and protecting human health in the context of the successful development of the modern society was presented. A literary review of well-known modern technologies for the design and manufacture of dental prostheses was carried out, as well as the leading domestic and foreign companies that were engaged in this were given. The history of the development of materials for obtaining clinical restorations (crowns, inlays, onlays, etc.) was considered and the main directions of the development of innovative ceramic materials for dental prosthetics were outlined. Based on the analysis of the properties of various types of materials for dental prosthetics, the prospects of using glass-ceramic materials in the development of dental prostheses have been substantiated. The chemical compositions of lithium silicate glasses for the synthesis of the glass matrix have been developed and the technological parameters for the production of glass-ceramic dental prostheses have been selected (Тgl. melting = 1350–1400 °С, Тheat treatment = 600–650 °С). Preliminary heat treatment before the formation of products ensures the formation of the required number of the nucleus of crystalline phase and the prerequisites for creating a volume crystallized structure under conditions of short-term heat treatment. The glass-ceramic prosthesis with a formed interpenetrating sitallized structure was obtained by the method of hot pressing with a short exposure (18-20 min). It was found that the obtained glass-ceramic material containing lithium disilicate as a crystalline phase in an amount of 40-60 vol. %, had high values of bending strength (σ = 400 MPa) and fracture toughness. The indicated mechanical properties of the developed materials, along with the approximate values of their modulus of elasticity to natural teeth, will significantly extend the service life of products under conditions of significant alternating loads that arise during the chewing cycle. A comparative assessment of the competitiveness of the developed dental prostheses based on lithium disilicate with world analogues was carried out, in particular the products of Ivoclar Vivadent and Vita Zahnfabrik, in terms of the main operational parameters. The positive effect of the introduction of domestic developed glass-ceramic dental prostheses to reduce import dependence has been determined.

Computer Engineering Complete Dentures Workflow: Systematic Techniques Review

Background: The progress in the use of computer-aided design/computer aided manufacturing (CAD/CAM) to fabricat removable prosthodontic prostheses in dental clinics has been exponential. Commercially existing CAD/CAM denture techniques grow every year with increasing benefits to dentists and patients.&#x0D; Study Design: Systematic review.&#x0D; Aims: This review assessed and evaluated the different clinical production protocols of presently accessible CAD/CAM denture systems that offer decision support for dental practitioners.&#x0D; Methodology: Data for the current object were collected by surveys from different companies manufacturing the Computer Engineering Complete Denture (CECDs). All related subjects published at the last 10 years were collected and included in this review. Techniques were arranged in alphabetical order, as follows. AvaDent Digital Dentures (Global Dental Science), Baltic Denture Creator System (Merz Dental GmbH), and Ceramill Full Denture System (Amann Girrbach AG) can manufacture denture fabrication in three visits, including a try-in step. DENTCA Digital Dentures (Whole You Nexteeth, Inc) can also perform this in three visits. The Wieland Digital Denture (Ivoclar Vivadent, Inc) can manufacture in four dental appointments. Recently developed VITA VIONIC Digital System (VITA Zahnfabrik, Bad Säckingen, Germany) can perform two-step CECD manufacturing.&#x0D; Results: Most of the systems involved subtractive manufacturing for the fabrication of their dentures and only closed systems. However, Baltic Denture System and VITA VIONIC material types are an open structure that allow users to choose among different handling protocols. It can be shared with several unclosed digital scanner, CAD software options, and milling machines.&#x0D; Conclusions: The six existing CECD fabrication systems offer many advantages. The decision on which technique to use may be contingent on the dentist’s prosthodontic expertise, patient output amount, and requirements concerning denture individualization.

Is it possible to determine the optical properties of resin composites with clinical spectrophotometers?

AbstractThe present study aimed to determine how spectrophotometer type and background blackness affect the optical evaluation of resin composites. Cylindrical specimens were built using one resin composite, provided with translucencies named Effect, Enamel, Body, and Dentin (n = 3). The CIELAB color coordinates were assessed over black and white backgrounds using a handheld spectrophotometer designed for laboratory readings (SP60, X‐Rite) and a spectrophotometer designed for clinical application (Easyshade V5, Vita Zahnfabrik). The black portion of a grayscale target (ColorChecker) and the black trap portion of the calibration reference of the spectrophotometer were used. Color differences between the devices were calculated, as well as the translucency parameter and contrast ratio. Data were analyzed by repeated‐measures ANOVA and linear regressions (α = .05). In general, Easyshade resulted in higher values for all color coordinates than the SP60, irrespective of the background. Easyshade was unable to measure the color of composite Effect over black backgrounds. For other composite translucencies, both spectrophotometers yielded similar values of translucency parameter and contrast ratio, and the blackness of the black background did not affect these results. The highest agreement for the translucency parameter and contrast ratio values was observed for the composite Dentin. High agreement was observed between the two spectrophotometers regarding the translucency parameter and contrast ratio values. However, the clinical spectrophotometer was unable to measure the color of the more translucent composite over a black background and overestimated the color coordinates.

The Effect of Different Dietary and Therapeutic Solutions on the Color Stability of Resin-Matrix Composites Used in Dentistry: An In Vitro Study.

The purpose of this study was to evaluate the color stability of aesthetic restorative resin-matrix materials after their immersion in different dietary and therapeutic solutions. Thirty disc-shaped specimens (10 × 2 mm) were prepared from three different types of resin-matrix composites used in dentistry (BE, FS, AF). The color coordinates (L*a*b*, ΔL*, Δa*, Δa*, Δb* and ΔE*) were measured using a VITA Easyshade 3D-Master (VITA Zahnfabrik, Bad Säckingen, Germany) before and after the immersion of the specimens in coffee, red wine, Coca-Cola®, Eludril Care®, and distilled water solutions for 40 h. The color change (ΔE*) was calculated and analyzed by the Kolmogorov -Smirnov test and the Kruskal -Wallis multiple-comparison test. All the restorative materials showed significant color (ΔE*) changes after their exposure to red wine, followed by coffee and Coca-Cola®; however, one nanohybrid resin-matrix composite showed a high color stability in such colored test solutions. The chemical composition and content of the organic matrix played a key role in the color stability of the resin-matrix composites. Clinicians should advise their patients about the chemical interaction between dietary substances and different resin-matrix composites.