The effect of immersion in beverages and dental bleaching agents on the surface roughness of resin composites

Introduction: Composite materials may be exposed to chemicals in food and beverages in the oral cavity, which can lead to changes in surface roughness. The aim of this in vitro study was to evaluate the surface roughness of two restorative materials after exposure to coffee and green tea followed by a dental bleaching procedure. Methods: For nanofilled composite and microhybrid composite, 15 samples each were fabricated. Five specimens from each composite were stored in instant coffee and green tea for 4 h a day. After 30 days of immersion, specimens received dental at-home bleaching, using 16% carbamide peroxide (CP), for 7 h a day. The control group was stored in deionized water for 30 days. Surface roughness was determined by profilometry 24 h after polymerization, after 30 days of immersion, and after bleaching. The data were analyzed using a t-test for paired samples and mixed analysis of variance, at a 0.05 significance level. Results: Neither beverages nor CP treatment significantly altered the surface roughness of the composites. There was no difference between the tested composite materials regarding roughness. Conclusion: Surface roughness of the microhybrid and nanohybrid composites was not modified by coffee, green tea, and subsequent whitening treatment

Color Stability Assessment of Light and Self-Cured Composites Following Accelerated Aging

Svrha istraživanja bila je izmjeriti i usporediti unutarnju stabilnost boje triju svjetlosnopolimerizirajućih materijala i jednoga kemijski stvrdnjavajućeg nakon njihova ubrzanog starenja. Materijali i metode: Testovi za stabilnost boja obavljeni su na svjetlosnopolimerizirajućim kompozitima – nanopunjenju Filtek Supreme XT (3M ESPE), nanohibridu Tetric Evo Ceram (Ivoclar Vivadent) i mikrohibridu Herculite XRV (Kerr) te na samopolimerizirajućem kompozitu Bisfil II (Bisco). Svi uzorci bili su uronjeni u destiliranu vodu (37°C) i držani u tamnoj posudi 24 sata. Nakon toga podijeljeni su u tri skupine. Postupak ubrzanog starenja proveden je prema dvama protokolima – u vodenoj kupelji na 60°C i prema ISO-u 7491. Uzorci iz kontrolne skupine držani su u destiliranoj vodi 30 dana na temperaturi od 37°C. Razlike u boji – ΔE, računale su se iz koordinata CIE L*a*b* izmjerenih spektrofotometrom nasuprot bijeloj pozadini prije postupka starenja uzoraka i poslije njega. Razina osjetljivosti boje postavljena je na 1, a prihvatljivi šum na 3,5. Statistička analiza obavljena je uparenim t-testom i ANOVA-om (p≤0,05). Rezultati: Svi ispitani materijali pokazali su klinički neprihvatljive promjene boje nakon ubrzanog starenja u vodenoj kupelji, a fotostarenjem nastala je vidljiva promjena boje kod svih svjetlosnopolimerizirajućih kompozita. Nanokompozitni materijali značajno su promijenili boju i u kontrolnoj skupini. Zaključak: Unutarnja stabilnost boje testiranih materijala ovisi o uvjetima starenja i vrsti dentalnog kompozita. Kemijski stvrdnjavajući kompoziti pokazali su tijekom fotostarenja bolju stabilnost.Objectives: Measure and compare internal color stability of three light-cured composites and one chemically bonded material after their accelerated aging. Materials and Methods: Color stability tests included nano-filled Filtek Supreme XT (3M ESPE), nano-hybrid Tetric Evo Ceram (Ivoclar Vivadent), microhybrid Herculite XRV (Kerr) of light cured and Bisfil II (Bisco) of self cured composites. All samples were immersed in distilled water of 37°C and kept in a dark chamber during 24 hours. Thereafter they were divided into three groups. Accelerated aging was performed in accordance with the two different protocols, i.e. water bath at 60°C and ISO 7491. Control group specimens were stored in distilled water at 37°C for 30 days. Color differences, ΔE were calculated from CIE L*a*b* coordinates measured with spectrophotometer against white backing before and after aging of samples. The color perceptibility threshold was set at 1.7 and acceptability threshold at 3.5. Statistical tests carried out on the groups included paired t-test and ANOVA (p≤0.05). Results: All tested materials showed clinically unacceptable color changes after accelerated aging in water bath, whereas photoaging induced perceptible color change in all light-cured composites. Nano-engineered composites significantly changed their color also in the control group. Conclusions: Internal color stability of tested materials depends on aging conditions and type of dental composite. Chemically-cured material showed better color stability by photo aging

Stabilnost boje dentalnih kompozita nakon uranjanja u napitke i postupaka izbjeljivanja

Objectives: The study aimed to compare the color stability of two different light-cured composites after immersion in three liquids and the effectiveness of 16% carbamide peroxide (CP) in removing the discoloration. Material and methods: Color stability of a microhybrid (Z250, 3M ESPE) and nanocomposite (Z550, 3M ESPE) was evaluated after immersion in instant coffee, tea, Coca-Cola, and deionized water as a control group (n=5). Samples were kept in liquids for four hours daily at 37°C for 30 days. Furthermore, 16% CP was applied for the following 14 days, simulating night whitening. A digital spectrophotometer was used for color measurement based on the CIEL*a*b* color coordinates. The color changes (∆E) were measured at baseline, after immersion in the beverages, and also after the teeth whitening procedure. Mixed and factorial ANOVA followed by Bonferroni’s posthoc test were used for statistical evaluation (p≤0.05). Results: Tested resin composites showed a color change over the acceptability threshold (ΔE*> 3.48) after immersion in coffee and tea. Nanocomposite reported a significant increase in discoloration in coffee after 30 days (p 3,48) poslije uranjanja u kavu i čaj. Nanokompozit je znatno povećao promjenu boje u kavi poslije 30 dana (p < 0,05). Boja obaju materijala značajno se promijenila (p < 0,05) duž svih triju L*a*b* osi u kavi i čaju u tamniju, žutu i crvenu. Izbjeljivanje 16-postotnim CP-om bilo je učinkovito u uklanjanju vanjske diskoloracije u oba ispitivana kompozitna materijala. Zaključak: Kava i čaj prouzročili su klinički uočljive promjene boje u ispitanim dentalnim kompozitima s kumulativnim učincima. Izbjeljivanje je učinkovita metoda za uklanjanje diskoloracije s površine kompozitnih nadomjestaka