Untitled 1 Volume 16 2017 e17077 Original Article a Department of Dental Materials and Prosthodontics, Araçatuba Dental School, UNESP – Univ Estadual Paulista, Araçatuba School of Dentistry, Araçatuba, São Paulo, Brazil. b Department of Restorative Dentistry, Araçatuba Dental School, UNESP – Univ Estadual Paulista, Araçatuba, São Paulo, Brazil c Department of Dental Materials and Prosthodontics, University of São Paulo – USP, Ribeirão Preto, São Paulo, Brazil. d Department of Operative Dentistry, Bauru Dental School – University of São Paulo – USP, Bauru, São Paulo, Brazil. Surface roughness, gloss and color change of different composites after exposure to ultimate challenges Cleidiel Aparecido Araujo Lemosa, Silvio José Maurob, André Luiz Fraga Brisob, Fernanda de Carvalho Panzeri Pires de Souzac, Maria Fidela de Lima Navarrod, Ticiane Cestari Fagundesb Correspondence: Profa. Ticiane Cestari Fagundes; Departamento de Materiais Odontológicos e Prótese; Faculdade de Odontologia de Araçatuba, UNESP - José Bonifácio, 1193, Araçatuba, SP, Brasil / CEP - 16015-050 Telephone: +55 18 3636-3253 / Fax: +55 18 3636-3253 E-mail: ticiane@foa.unesp.br Received: July 23, 2017 Accepted: September 20, 2017 Aim: The study aimed to investigate the effect of the association of chemical and mechanical degradation on the surface VSYKLRIWW��KPSWW�ERH�GSPSV�SJ�RERS�ERH�QMGVSƼPPIH�GSQTSWMXIW�� Method: Disc-shaped specimens (n=10) were prepared for three nanocomposites (Filtek Z350XT, IPS Empress Direct, Charisma (MEQSRH � ERH� XLVII� QMGVSƼPPIH� GSQTSWMXIW� �)WXIPMXI� ·� 5YMGO�� (YVEƼPP�:7��6IREQIP ��%JXIV�TSPMWLMRK��FEWIPMRI�WYVJEGI�VSYKLRIWW�� gloss and color measurements were obtained. Specimens were submitted subsequently to the following challenges: chemical for 1 week (Hydrochloric acid, Coca-Cola and Red Wine) and mechanical (Toothbrushing). Surface roughness and gloss data were analyzed by Kruskal-Wallis followed by Dunn’s test. Color difference (') � [EW� EREP]^IH� F]� SRI�[E]� %23:%� ERH� 8YOI]� test. Results: The initial data were compared with those after challenges using the Wilcoxon test (p<0.05). All composites WLS[IH� E� WMKRMƼGERX� MRGVIEWI� �T ���� � SJ� WYVJEGI� VSYKLRIWW�� EJXIV�SZIVWXVIWW��*MPXIO�>����<8�ERH�6IREQIP�LEH�XLI�PS[IWX�ƼREP� surface roughness values and roughness increase (p<0.05). The GSQTEVEXMZI�EREP]WMW�VIZIEPIH�XLEX�)WXIPMXI�·�5YMGO�ERH�6IREQIP� HMH�RSX�WMKRMƼGERXP]�GLERKI�XLI�KPSWW�EJXIV�GLEPPIRKIW��T!����� �� Filtek Z350 XT and IPS Empress Direct had higher color variations, after the challenges than the other resins (p<0.05). Conclusion:�'LIQMGEP�ERH�QIGLERMGEP�GLEPPIRKIW�MRƽYIRGI�SR� GLEVEGXIVMWXMGW�SJ�EPP�GSQTSWMXIW��I\GITX�JSV�KPSWW�SR�)WXIPMXI�·� 5YMGO�ERH�6IREQIP�GSQTSWMXIW�� Keywords: Dental Resin; Physical properties; Immersion; Toothbrushing. http://dx.doi.org/10.20396/bjos.v16i0.8651057 2 Lemos et al. INTRODUCTION Changes in surface roughness, gloss, and color can compromise the longev- ity and the clinical success of restorations1. The composites undergo the action of intrinsic factors due to the physicochemical reactions in the inner portions of the restorative material, and also suffer the action from extrinsic factors, such as acidic substances that degrade organic matrix, exposing the material to coloring agents present in foods and beverages2,3, and abrasive substances, for example, from the brushing process4��MRƽYIRGMRK�XLI�GSQTSWMXI�GLEVEGXIVMWXMGW��WYGL�EW�WYV- face roughness5 and gloss. Surface roughness has been recognized as high clinical relevance parameter that contributes to dental plaque accumulation6. It is known that composite roughness MW�MRƽYIRGIH�F]�XLI�WM^I��HMWXVMFYXMSR�ERH�ZSPYQI�SJ�XLI�ƼPPIV�GSRXIRX�TVIWIRX�MR�XLI� restorative material. Furthermore, the increase of roughness is correlated with the characteristics of gloss and color of the composites restoration because of the possi- FMPMX]�SJ�E�PS[IV�PMKLX�VIƽIGXERGI�ERH�LMKLIV�VIXIRXMSR�SJ�TMKQIRXW1. It has been observed that the better the polish obtained at the end of the composite restoration, the greater the scattering of light inside the material and consequently this can result in a gloss increase7. In a condition that is necessary to produce highly aesthetic restorations, the gloss has an important role, since it needs to reproduce the optical properties of the enamel surface, making the restorations imperceptible to the human eye8. The visible differences in color between teeth and esthetic materials are the major cause of patient discontentment with restorative treatments9. In this context, to obtain a composites restoration that reproduce colors of the tooth structure is considered a GLEPPIRKI��QEMRP]�MR�ERXIVMSV�XIIXL�[LIVI�WPMKLX�GSPSV�GLERKIW�SZIV�XMQI�GER�MRƽYIRGI� patient compliance9. 8LI�QMGVSƼPPIH�GSQTSWMXIW�LEZI�LMKL�WYVJEGI�WQSSXLRIWW�FYX�TVIWIRX�PS[�QIGLERM- cal strength in comparison with universal composites and therefore can be indicated as surface resins for anterior teeth4��8LI�EHZIRX�SJ�XLI�RERSXIGLRSPSK]�ƼIPH�LEW�PIH� to the development of nanocomposites with smoothness characteristics similar to XLSWI�SJ�QMGVSƼPPIH�VIWMRW��ERH�EPWS�[MXL�LMKL�QIGLERMGEP�WXVIRKXL4. In vitro stud- MIW�LEZI�EREP]^IH�XLI�TIVJSVQERGI�SJ�XLIWI�X]TIW�SJ�GSQTSWMXIW�[MXL�XLI�MRƽYIRGI� of toothbrushing and chemical degradation separately1-3,8,10. Thus, it is important to note that in the oral cavity, there is the interaction of these mechanical and chemical challenges4,5. However, there is a lack of studies evaluating the effects of chemicals immersions in association with toothbrushing. The objective of this study was to evaluate the surface roughness, gloss and color GLERKIW�SJ�RERSGSQTSWMXIW�ERH�QMGVSƼPPIH�VIWMRW�EJXIV�XLI�EWWSGMEXMSR�SJ�GLIQMGEP� and mechanical challenges. The null hypotheses tested were: 1) there is no difference before and after challenges for composites when surface roughness and gloss were IZEPYEXIH�� �XLI�WM^I�ERH�ƼPPIVW�SJ�GSQTSWMXIW�HS�RSX�MRƽYIRGI�XLI�WYVJEGI�VSYKLRIWW�� gloss and color change after chemical and mechanical challenges. 3 Lemos et al. MATERIAL AND METHODS Specimen Preparation The composites used in this experiment are shown in Table 1. Sixty disc-shaped spec- imens (5.0 mm diameter and 1.5 mm height) for each composites (n=10) were built YT�YWMRK�E�8IƽSR�VMRK�QEXVM\��%JXIV�XLI�QEXVM\�[EW�ƼPPIH��XLI�QEXIVMEP�[EW�GSZIVIH� with a polyester strip and a glass slab. The specimens were then light-activated in the upper and lower surfaces for 40 seconds each, using a LED light-curing unit (Ultraled, Dabi Atlante, Ribeirão Preto, SP, Brazil, irradiance of 500 mW/cm2, monitored by a radi- ometer (model 100; Kerr, Danbury, CT, USA). After 24 hours in water storage at 37ºC, all specimens were sequentially polished (Aropol E, Arotec Ind. Com. SA, Cotia, SP, Brazil) with the silicon carbide papers: 320-, 600-, 800- and 1200-grit. Uniform pres- sure and application time of 120 seconds were standardized, under constant water irrigation. The direction of polishing was from left to right and the rotation rate was set as 10.000 rpm. Between each silicon carbide paper and at the end of polishing proce- dures the specimens were cleaned in an ultrasonic bath (Cristófoli, Campo Mourão, 46��&VEWMP �[MXL�HMWXMPPIH�[EXIV�JSV���QMRYXIW��8LI�ƼREP�TSPMWLMRK�[EW�QEHI�YWMRK�E� Diamond Flex felt disks (FGM, Joinville, SC, Brazil) associated with polishing paste (Enamelize, Cosmedent Inc., Chicago, IL, USA) manually, to better simulate clinical procedures. After polishing, the specimens were stored in relative humidity at 37°C for 24 hours before the initial readings of surface roughness, gloss and color. Table 1. Characteristics of composites materials analyzed in this study. Composite resins Manufacturer Classification Mean filler size and composition Weight (%) Organic Matrix Batch # Estelite Σ Quick Tokuyama Dental Co. Tokyo, Japan Submicron filled Spherical silica-zirconia filler 0.1-0.3 Pm 71 Bis-GMA, TEG-DMA E536 Durafill VS Heraus Kulzer, Hanau, Germany Microfilled Prepolymerized Silica: 10-20 Pm Sílica: 0.02-2 Pm 40 UDMA 010218 Renamel Cosmedent Inc., Chicago, IL, USA Microfilled Pyrogenic silicic acid filler 0.02-0.04 Pm 59 Bis-GMA Bis-EMA 104819J Filtek Z350XT 3M/ESPE, St. Paul, MN, USA Nanofilled Zircônia and silica clusters:0.6-1.4 Pm Sílica: 5-20 nm 55 Bis-GMA Bis-EMA TEG-DMA UDMA 1210900268 IPS Empress Direct Ivoclar Vivadent, Schaan, Liechtenstein Nanohybrid Barium alumina fluorosilicate glass, barium glass filler, mixed oxide,copolymer 0.04–3 Pm 52-59 Bis-GMA TEG-DMA UDMA N21727 Charisma Diamond Heraus Kulzer, Hanau, Germany Nanohybrid Barium, aluminium, fluoride glass 5-20000 nm 64 TCD-DI-HEA UDMA 010041 4 Lemos et al. Surface Roughness Measurements 8LVII�IUYMHMWXERX�VIEHMRKW�SJ�WYVJEGI�VSYKLRIWW��6E �[EW�VIKMWXIVIH��4VSƼPSQIXIV�� SJ-401, Mitutoyo, Kanagawa, Japan) that represents the arithmetic mean of peaks and valleys of surface roughness on the specimens. The measurement was per- formed in each specimen individually, and the needle was positioned on the specimen surface and moved at a constant speed of 0.05 mm/s, using a cut-off of 0.25 mm. Three readings were performed on each surface specimen in equidistant positions in approximately 120°11. The average of these three measurements was calculated as roughness value of the specimen. Surface Gloss Measurements 8LI�WYVJEGI�KPSWW�[EW�QIEWYVIH�EX�E���{�ERKPI�SJ�MRGMHIRGI�ERH�VIƽIGXMSR�YWMRK�E�GEP- ibrated glossmeter (Microgloss, BYK Gardner, Geretsried, Germany). The instrument QIEWYVIW�XLI�MRXIRWMX]�SJ�E�VIƽIGXIH�PMKLX�FIEQ�EJXIV�WXVMOMRK�XLI�WYVJEGI�ERH�GSQ- pares it to a reference value. The device has a measuring window of 2 mm x 2 mm, SZIV�[LMGL�XLI�WTIGMQIR�MW�TPEGIH�ERH�XLIR�GSZIVIH�[MXL�E�ƼPQ�GSRXEMRIV�XS�EZSMH� external light exposure during the measurement. The average of three measurements was recorded for each specimen. Color analysis Baseline color was measured according to the CIELab (Commission Internationale HI� -ƅ)GPEMVEKI � GSPSV� W]WXIQ� YWMRK� E� VIƽIGXMSR� WTIGXVSTLSXSQIXIV� �9:������� 7LM- madzu, Kyoto Japan) over a black background and standard illuminant D65. The CIELab color space graph is a 3-D color measurement: L refers to the lightness coordinate, and its value ranges from 0 for perfect black to 100 for perfect white; “a” and “b” are chromaticity coordinates on the green–red (a = green; +a = red) and blue–yellow (b = blue; +b = yellow) axes11,12. Color change was calculated between the color before challenges (baseline) and after challenges, measured by the formula: ²)�!��?²0�A���?²E�A���?²F�A2)½ 11. Chemical and mechanical challenge After initial readings, the specimens were submitted to chemical challenge by immer- sion of the samples individually into 10 ml of hydrochloric acid (pH 1.6, HCl 0.01mol/l, Apothicário, Araçatuba, Brazil) simulating the action of acid from the gastric juice, 10 ml of Coca Cola (pH 2.5, Coca Cola Company, Spaipa S.A., Marília, SP, Brazil) in order to sim- ulate the action of the acid from soft drinks, and 10 ml of red wine (pH 3.4, Concha y Toro Cabernet Sauvignon, Santiago, Chile). The samples were individually stored in sealed tubes for one week in each acid solution at 37°C13,14. Between each acidic challenge, the samples were washed and immersed in 10 ml of distilled water for 24 hours at 37°C. 7TIGMQIRW�[IVI�MRHMZMHYEPP]�WYFNIGXIH�XS��������QIGLERMGEP�FVYWLMRK�G]GPIW��1):���3HIQI� Biotechnology, Joaçaba, SC, Brazil) performed with toothbrushes (one for each specimen, Colgate Classic Clean, Colgate, Palmolive Co. Osasco, SP, Brazil) and toothpaste (Colgate Total 12, Colgate Palmolive, Kolynos Division of Brazil Ltd, Osasco, SP, Brazil) diluted in dis- tilled water (ratio 1:2 by weight). After brushing, the specimens were rinsed with distilled 5 Lemos et al. water for 2 minutes and submitted to ultrasonic bath for 10 minutes with distilled water to remove the abrasive particles from the toothpaste. The specimens were maintained in VIPEXMZI�LYQMHMX]�EX���q'�JSV����LSYVW�FIJSVI�ƼREP�VIEHMRKW�SJ�WYVJEGI�VSYKLRIWW��KPSWW�ERH� color, under the same conditions previously stated. Color changes ('E) were calculated by the formula: ')�!�?�'0� 2 + ('E� 2 + ('F� 2A1/2. All analyses were blinded to the resins. Scanning Electronic Microscopy (SEM) Analysis SEM analysis was not performed initially because same specimens were used in all experimental procedures. Two specimens of each material were mounted on alumi- num stubs, sputter-coated with gold (Balzers SCD-050 sputter coater, OC Oerlikon 'SVTSVEXMSR�%+��4JʞƾOSR��7[MX^IVPERH �ERH�WYFQMXXIH�XS�7)1�EREP]WMW��)ZS�07���� 'EVP�>IMWW��3FIVOSGLIR���+IVQER] �EX�����\�QEKRMƼGEXMSR� Statistical Analysis The assumptions of equality of variances and normal distribution of data were checked using the Shapiro–Wilk test, once the homogeneity was not achieved, data of surface roughness and gloss were analyzed with nonparametric tests, Kruskal-Wallis followed by Dunn’s test. However, the normal range was observed JSV�XLI�GSPSV�GLERKI��MR�[LMGL�XLI�QIERW�[IVI�IZEPYEXIH�F]�ER�%23:%�ERH�8YOI]ƅW� multiple comparisons. Wilcoxon test was applied for surface roughness and gloss analysis considering two-time evaluation (before and after challenges). Spearman test was used to check the correlation between the surface roughness and gloss TEVEQIXIVW��7XEXMWXMGEP�XIWXMRK�[EW�TIVJSVQIH�YWMRK�7477�:IVWMSR�����-&1�7477� Statistics for Windows, Armonk, NY, USA). A p-value less than 0.05 was considered WXEXMWXMGEPP]�WMKRMƼGERX� RESULTS Data of surface roughness are shown in Figure 1. Charisma Diamond had the high- IWX�MRMXMEP�WYVJEGI�VSYKLRIWW�ZEPYI��[MXL�E�WMKRMƼGERX�HMJJIVIRGI�JSV�EPP�VIWMRW��I\GITX� JSV�)WXIPMXI�·�5YMGO��T!����� ��%JXIV�GLEPPIRKIW��'LEVMWQE�(MEQSRH�ERH�(YVEƼPP�:7� showed the highest values of surface roughness (Fig. 2B and F). All composites WLS[IH�E�WMKRMƼGERX�MRGVIEWI�MR�EQSYRX�SJ�WYVJEGI�VSYKLRIWW�EJXIV�XLI�EWWSGMEXMSR� of challenges. Filtek Z350 XT and Renamel had the lower Ra values when compared to other composites, as shown in Fig. 2C and D. The initial analysis of the gloss revealed that the IPS Empress Direct and Cha- risma Diamond had the highest and lowest gloss values, respectively, with statis- tical difference for the other composites (p<0.05). After association of the chal- PIRKIW�� MX� [EW� JSYRH� XLEX� XLI� QMGVSƼPPIH� VIWMRW� LEH� XLI� PS[IWX� KPSWW� VIHYGXMSR� ZEPYIW��*MK���%��&�ERH�' ��8LI�GSQTEVEXMZI�EREP]WMW�VIZIEPIH�XLEX�)WXIPMXI�·�5YMGO� ERH�6IREQIP�HMH�RSX�WLS[�WXEXMWXMGEPP]�WMKRMƼGERX�GLERKI�SJ�KPSWW�EJXIV�GLEPPIRKIW� (p=0.185). These values can be seen in Figure 3. The Spearman correlation test showed positive correlation between surface roughness and gloss for the initial analysis (p=0.0198; Coef. 0.8827), however, there was no correlation after the chal- lenges (p=0.1107; Coef. 0.7143). 6 Lemos et al. Su rf ac e ro ug hn es s (R a) Roughness of composites before and after challenges Estelite Σ Quick Before BC/a AB/a AB/a A/a A/a C/a CD/b DE/b AB/b A/b BC/b E/b After 0.18 0.15 0.12 0.09 0.06 0.03 0 Durafill VS Renamel Filtek Z350XT IPS Empress Direct Charisma Diamond Figure 1. Box plots of surface roughness values (Ra: Pm) of resin composites before and after the challenges. Different uppercase letters represent statistical significance among composites (p<0.05). Different lowercase letters indicate statistical significance before and after challenges (p<0.05). A B C D E F EHT = 20.00Kv WD = 13.0 mm Signal A = SE1 Photo No. = 2262 Date = 15 Sep 2014 Time: 14:07:37 FEIS - UNESP Mag = 5.00 K X EHT = 20.00Kv WD = 18.0 mm Signal A = SE1 Photo No. = 2233 Date = 15 Sep 2014 Time: 11:48:03 FEIS - UNESP Mag = 5.00 K X EHT = 20.00Kv WD = 17.5 mm Signal A = SE1 Photo No. = 2221 Date = 15 Sep 2014 Time: 11:38:51 FEIS - UNESP Mag = 5.00 K X EHT = 20.00Kv WD = 18.0 mm Signal A = SE1 Photo No. = 2237 Date = 15 Sep 2014 Time: 11:50:52 FEIS - UNESP Mag = 5.00 K X EHT = 20.00Kv WD = 14.5 mm Signal A = SE1 Photo No. = 2212 Date = 15 Sep 2014 Time: 11:17:12 FEIS - UNESP Mag = 5.00 K X EHT = 20.00Kv WD = 13.0 mm Signal A = SE1 Photo No. = 2274 Date = 15 Sep 2014 Time: 14:17:44 FEIS - UNESP Mag = 5.00 K X 2µ 2µ 2µ 2µ 2µ 2µ Figure 2. Representative scanning electron micrographs of composites after submission challenges. (A) Estelite Σ Quick, (B) Durafill VS, (C) Renamel, (D) Filtek Z350 XT, (E) IPS Empress Direct, and (F) Charisma Diamond. Note different patterns of corroded resin matrix provided by the association of chemical and mechanical challenges. Original magnification 5000X. G lo ss u ni t ( G U ) Gloss of composite before and after challenges Estelite Σ Quick Before B/a B/a B/a B/a A/a C/a AB/b B/b A/a B/b B/b C/b After 5 10 15 20 25 30 35 40 45 0 Durafill VS Renamel Filtek Z350XT IPS Empress Direct Charisma Diamond Figure 3. Box plots of gloss (GU unit) of resin composites before and after challenges. Different uppercase letters represent statistical significance among composites (p<0.05). Different lowercase letters indicate statistical significance before and after challenges (p<0.05). 7 Lemos et al. Regarding color changes, after challenges it was found that Filtek Z350 XT and IPS Empress Direct had higher color variations than the other resins (p<0.05) (Table 2). DISCUSSION In vitro�WXYHMIW�LEZI�EREP]^IH�WITEVEXIP]�XLI�MRƽYIRGI�SJ�GLIQMGEP�GLEPPIRKIW2,14,15 and toothbrushing7,8,10 on surface changes of resin composites. However, it is well known that the degradation of materials in the oral environment is a complex pro- cess, which involves mechanical and chemical mechanisms5,15,16. Thus, challenges were not performed separately in this present study to predict the performance of composites after ultimate challenge. The characteristics of surface roughness, gloss and color are considered important properties for the clinical success of restorative materials1. The chemical challenges tested in this study used acidic solutions and dyes, sim- YPEXMRK�XLI� MRƽYIRGI�SJ� MRXVMRWMG�ERH�I\XVMRWMG�JEGXSVW� MR�VIWXSVEXMZI�QEXIVMEPW17,18. The mechanical challenge was performed by brushing process that, over time, has caused wear on the resin surface, especially in the organic matrix promoting the inorganic particles display, and increasing the surface roughness of the compos- ites4,7,10. Twenty thousand brush cycles were used since it is considered superior to 3 years in vivo19. 8LI�ƼVWX�RYPP�L]TSXLIWMW�IZEPYEXIH�[EW�VINIGXIH��%PP�SJ�XLI�XIWXIH�GSQTSWMXIW�WLS[IH� statistically Ra surfaces after challenges. These results corroborate with previous studies that found the increase in surface roughness after chemical challenge2 and mechanical challenges2,4,7,10. 6IKEVHMRK�XLI�KPSWW��SRP]�X[S�QMGVSƼPPIH�GSQTSWMXIW�WXYHMIH�HMH�RSX�WLS[�WXEXMW- tical difference after the proposed challenges. Lee et al.20 observed that Renamel showed lowest change in gloss when compared with other composites studied, when a progressive number of toothbrushing cycles were applied, as it was observed in the present study. Renamel also presented the best values of gloss when different ƼRMWLMRK�ERH�TSPMWLMRK�TVSGIHYVIW�[IVI�WXYHMIH21. It is noteworthy that this resin showed the lowest value of gloss loss among all analyzed resins, changing only 1% of the initial gloss after exposure to ultimate challenge proposed in this present study (Fig. 1C). Table 2. Comparisons of color change among different materials, 'L*, 'a*, 'b* e 'E. Composite resins ΔL* Δa* Δb* ΔE Estelite Σ Quick 0.69 0.72 -1.17 1.80 (0.42) B Durafill VS -1.08 0.26 -0.85 1.50 (0.66) B Renamel -0.24 -0.16 1.59 1.70 (0.46) B Filtek Z350 XT -2.08 0.94 -0.80 2.80 (1.08) A IPS Empress Direct 1.63 2.40 1.70 3.54 (0.80) A Charisma Diamond 1.31 0.55 0.17 1.65 (0.74) B Means followed by the same letters in columns are not statistically different for the ANOVA and Tukey test at p>0.05. 8 Lemos et al. 8LI� PEGO� SJ� HMJJIVIRGI� MR� KPSWW� EJXIV� XLI� GLEPPIRKIW� JSV� FSXL� )WXIPMXI� ·� 5YMGO� ERH� 6IREQIP�GER�FI�NYWXMƼIH�F]�XLI�WLETI�ERH�WM^I�SJ�ƼPPIVW20��7MRGI�)WXIPMXI�·�5YMGO�YWIW� WTLIVMGEP�ƼPPIVW��XLIWI�TEVXMGPIW�EVI�EFPI�XS�VIƽIGX�QSVI�PMKLX�XLER�MVVIKYPEV�SRIW20. Although Renamel have irregular shapes, the predominance of particles were of one micron or less22. However, there is no consensus regarding the change of gloss, since large loss of gloss was observed after performing challenges when various types of composites were evaluated7. Therefore, it seemed that change in gloss was primarily MRƽYIRGIH�F]�XLI�GLEVEGXIVMWXMGW�SJ�XLI�GSQTSWMXIW��RSX�F]�EQSYRX�SJ�[IEV20. When comparing the composites in relation to the characteristics evaluated, the sec- ond null hypothesis was also rejected. The highest Ra values for the Charisma Dia- mond resin were found before and after challenges. This composite resin, despite its nanometric particles, present large particle (Fig. 1F) size in the range 0.005-20Pm, [LMGL�QE]�MRƽYIRGI�JSV�PEVKIV�WYVJEGI�VSYKLRIWW�ZEPYIW�EJXIV�XLI�HIKVEHEXMSR�SJ�XLI� organic matrix, as also observed in a previous study23. The lowest value was found for ƼREP�WYVJEGI�VSYKLRIWW�ERH�MRGVIEWIH�WYVJEGI�VSYKLRIWW�SJ�XLI�RERSƼPPIH�*MPXIO�>���� XT. This can be explained by the greater resistance to chemical and mechanical wear found by this resin, due to less exposure of the organic matrix, favored by the pres- ence of nanoclusters in its composition, which can be observed in Fig. D2. Renamel exhibited similar surface roughness to the Filtek Z350 XT, probably due to its small average particle size (Fig. 1C)22. Higher values of roughness are unacceptable, since it favors the accumulation of bacteria and consequently greater risk of carious lesion ERH�KMRKMZEP�MRƽEQQEXMSR7. In this study, it was observed that after the challenge pro- posed, all composites presented surface roughness lower than the 0.2Pm (Ra), which is considered clinically acceptable6. Gloss values, they vary according to the incidence of light on surface resin; the lack SJ�VIƽIGXMSR�WLS[W�ZEPYIW���+9��[LMPI�E�KPEWW�WYVJEGI�[MXL�E�LMKL�VIJVEGXMZI�MRHI\�LEW� about 100 GU21. To avoid changes in the refractive index of the samples, they were EREP]^IH�HV]��TVIZIRXMRK�XLI�JSVQEXMSR�SJ�[EXIV�ƼPQ��[LMGL�[SYPH�EPXIV�XLI�FVMKLXRIWW� SJ�XLI�VIƽIGXMSR�ZEPYI24. In the present study, the nanohybrid IPS Empress Direct showed the highest initial val- ues of gloss, as seen in a previous study, after performing the polishing25. Takahashi, et al.10�VITSVXIH�XLEX�XLI�VIWMR�-47�)QTVIWW�(MVIGX�GPEWWMƼIH�JSV�IREQIP��GSRXEMR�ƼRI�FEV- MYQ�KPEWW�ƼPPIVW��[LMGL�QE]�JEZSVEFPI�LMKL�WYVJEGI�PYWXIV��'LEVMWQE�(MEQSRH�VIWMR�WXE- tistically had the lowest brightness values, probably due to its particular feature regard- MRK�MRWIVXMSR�SJ�PEVKIV�TEVXMGPIW�ERH�E�KVIEX�[IMKLX�SJ�ƼPPIV���� ��*YVXLIVQSVI��'LEVMWQE� Diamond present a distinct monomer called TCD-DI-HEA instead of Bis-GMA and this could also have contributed for this result. It is known that Bis-GMA presents a high resistance to degradation from effects of immersion media by the fact that bis-acryl resin composite materials contain bifunctional acrylatto provide increase d mechanical strength and resistance to weakening in the presence of solvents26,27. In this context, the cross-link nature of the resin matrix, and the solvent sorption YTXEOI�QE]�MRƽYIRGI�QSVI�HMVIGXP]�XLI�TSP]QIVƅW�HIKVEHEXMSR�VEXI3. Toothbrushing after the immersion on food-simulating media resulted in the removal of part of the SVKERMG�QEXVM\�EVSYRH�XLI�PSSWIR�ƼPPIVW5,26. However, the effect of toothbrushing in the composites resins depends on different factors, such as the type of toothpaste, type 9 Lemos et al. and shape of the brush bristles, the proportion of deionized-water solution as well as speed and weight applied during simulation process26. After association of challenges, the highest gloss values were observed for the micro- ƼPPIH�VIWMR�6IREQIP�JSPPS[IH�F]�)WXIPMXI�·�5YMGO��%PXLSYKL��XLI�VIWMR�)WXIPMXI�·�5YMGO� TVIWIRX�LMKL�VSYKLRIWW�ZEPYIW��*MK���% ��8LMW�ƼRHMRK�QE]�MRHMGEXI�XLEX�WTLIVMGEP�ƼPPIVW� facilitate the abrasive media sliding from the surface of the specimen, instead of the ƼPPIVW�FIMRK�VIQSZIH�F]�XLI�EFVEWMZI�QIHME��I\TPEMRMRK�[L]�XLMW�QEXIVMEP�VIXEMRW�MXW� gloss after mechanical abrasion20��8LIR��KPSWW�MW�RSX�MRƽYIRGIH�SRP]�F]�XLI�WYVJEGI� roughness, but also by other factors such as difference in the refractive indices of the VIWMR�QEXVM\�ERH�XLI�ƼPPIVW20. These factors may explain the existing initial correlation between the parameters sur- face roughness and gloss, since there is greater homogeneity of values in polished surfaces7,20��-QQIHMEXIP]�EJXIV�ƼRMWLMRK�ERH�TSPMWLMRK�TVSGIHYVIW�MW�TSWWMFPI�XS�PIZIP� the organic and inorganic phase by the regularly wear of rotary cutting instruments. However, when the samples are subjected to experimental challenges, such action MW�WIPIGXMZI�ERH�QE]�LEZI�MRƽYIRGI�MR�XLI�SVKERMG�TLEWI�ERH�MR�XLI�HMJJIVIRX�X]TIW�SJ� ƼPPIVW15. This explains the lack of correlation between surface roughness and gloss EJXIV�XLI�GLEPPIRKIW��[LMGL�QE]�GEYWI�E�HIKVII�SJ�VERHSQ�VIƽIGXMSR�XS�XLI�I\XIRX�XLEX� there is loss of surface polishing26. Regarding color results, despite all the composites are marketed as A2, differences were SFWIVZIH�FIX[IIR�XLI�GSQTSWMXIW�XIWXIH�EJXIV�XLI�GLEPPIRKIW��8LI�RERSƼPPIH�*MPXIO�>���� XT and IPS Empress Direct showed greater variation in color when compared to the oth- ers. Filtek Z350 XT resin, despite having nanoparticles in its composition, showed higher WSVTXMSR�GETEGMX]�XLER�XLI�QMGVSL]FVMH�ERH�QMGVSƼPPIH�VIWMRW17��8LMW�JEGXSV�QE]�LEZI�MRƽY- enced to reduce the color stability, favoring the absorption of the dyes that are in Coke and wine. The nanohybrid IPS Empress Direct presents small particles of barium, com- promising the strength of the material4,10 and increasing the possibility of incorporation of color pigments27��3XLIV�JEGXSVW�XLEX�QE]�MRƽYIRGI�JSV�XLI�GSPSV�GLERKI�EVI�XLI�EQSYRX� SJ�TLSXSMRMXMEXSVW�EKIRXW��ƼPPIVW�ERH�TMKQIRXW�EKIRXW�MRGSVTSVEXIH�F]�QERYJEGXYVIVW28. However, it is important to remember that these differences in color changes only become clinically noticeable when 'E value is higher than 3.312. According to the pres- ent study, IPS Empress Direct was the only resin in that category, since other com- posites showed good color stability after chemical degradation and brushing. Ren et al.18 also reported that a nanocomposite (Filtek Supreme Ultra) showed more color change than TPH and Renamel after the stain challenges and after brushings. An in vitro study cannot represent all the conditions and interactions acting on the restorative material in the oral cavity, since cycles of acid challenge and toothbrush- ing occurs in patients. In this sense, randomized clinical trials are required in order to EWWIWW�XLIWI�TEVEQIXIVW��ERH�IWTIGMEPP]�XLI�MRƽYIRGI�SJ�XLIWI�SR�XLI�UYEPMX]�SJ�PMJI� of the patient, as it interferes directly with the patient’s self-esteem. Therefore, infor- mation obtained with this present study should prove valuable for clinicians to make decisions in selecting the best materials for aesthetic restorations for their patients. However, none of studied composites had the best performance for all analysis per- formed in this study. 10 Lemos et al. 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