Influence of home bleaching regimen on microhardness and flexural strength of two contemporary composite resins – an in vitro evaluation

Year 2023, Volume: 57 Issue: 2, 90 - 95, 31.05.2023

Kalaivani Muralidasan Dattaprasad S Indumathi M Sruthipriya M Janani Balachandran Pavankumar O

https://doi.org/10.26650/eor.20231083203

Abstract

Purpose

This study was to compare and evaluate the effect of home bleaching on the microhardness and flexural strength of microhybrid and nanohybrid composite resins.

Materials and Methods

The study samples were prepared using a custom-made silicon rubber mold. For microhardness evaluation, 40 disc-shaped specimens (4mm*2mm) were prepared and divided into 4 groups: GROUP A (n=10): microhybrid (GC Solaire X, GC Corporation) control group, GROUP B (n=10) nanohybrid (Tetric N Ceram, Ivoclar Vivadent) control group, GROUP C (n=10): microhybrid bleaching group, GROUP D (n=10) nanohybrid bleaching group. For flexural strength evaluation, 40 bar shaped specimens (25mm*2mm*2mm) were prepared. They were divided into 4 groups, GROUP 1 (n=10): microhybrid control group, GROUP 2 (n=10) nanohybrid control group, GROUP 3 (n=10): microhybrid bleaching group, GROUP 4(n=10) nanohybrid bleaching group. All the control groups were placed in artificial saliva and bleaching groups were exposed to home bleaching agent for 14 days according

to manufacturer’s instructions. The microhardness and flexural strength were evaluated for the respective specimens after 14 days and the data were statistically analyzed.

Results

Home bleaching regimen decreased microhardness of both microhybrid and nanohybrid composites whereas there was no significant effect on the flexural strength. Nanohybrid composites showed greater microhardness values before and after bleaching.

Conclusion

Bleaching agents, irrespective of their concentration can decrease the microhardness of the composite resin samples, which raises a concern about replacement of these restorations due to the effects on physical and mechanical properties.

Keywords

Composite resin, Home bleach, Nanohybrid, Microhardness, Flexural strength

References

• Yap AUJ, Wattanapayungkul P. Effects of in-office tooth whiteners on hardness of tooth colored restoratives. Oper Dent. 2002 Apr;27(2):137–41.
• Polydorou O, Mönting JS, Hellwig E, Auschill TM. Effect of in-office tooth bleaching on the microhardness of six dental esthetic restorative materials. Dent Mater Off Publ Acad Dent Mater. 2007 Feb;23(2):153–8.
• Taher NM. The effect of bleaching agents on the surface hardness of toothcolored restorative materials. J Contemp Dent Pract. 2005 May 15;6(2):18-26.
• Hannig C, Duong S, Becker K, Brunner E, Kahler E, Attin T. Effect of bleaching on subsurface micro-hardness of composite and a polyacid modified composite. Dent Mater Off Publ Acad Dent Mater. 2007 Feb;23(2):198–203.
• Srinivasan K, Chitra S. Effects of Different Concentrations of Bleaching Agent on the Micro hardness of Restorative Materials- An In Vitro Study. J Res Med Dent Sci. 2015;3(3):188.
• Solomon. An in vitro evaluation of microhardness of different direct resin-based restorative materials on using 10% carbamide peroxide gel as a bleaching agent. J Oral Res Rev. 2016;8(2):59-65.
• Cullen DR, Nelson JA, Sandrik JL. Peroxide bleaches: Effect on tensile strength of composite resins. J Prosthet Dent. 1993 Mar;69(3):247–9.
• Okte Z, Villalta P, García-Godoy F, Lu H, Powers JM. Surface hardness of resin composites after staining and bleaching. Oper Dent. 2006 Oct;31(5):623–8.
• Gul P, Harorli O, Akgül N, Gundogdu M. Effect of different bleaching applications on the surface properties and staining susceptibility of dental composites. J Wuhan Univ Technol-Mater Sci Ed. 2016 Jun 1; 31:677–83.
• Effects of Two Different Bleaching Agents on the Microhardness of Composite. Pak J Med Dent. 2021Oct; 10(4):11-6.
• Alqahtani MQ. Tooth-bleaching procedures and their controversial effects: A literature review. Saudi Dent J. 2014 Apr;26(2):33–46.
• Kashima-Tanaka M, Tsujimoto Y, Kawamoto K, Senda N, Ito K, Yamazaki M. Generation of free radicals and/or active oxygen by light or laser irradiation of hydrogen peroxide or sodium hypochlorite. J Endod. 2003 Feb;29(2):141–3.
• Yu H, Li Q, Lin Y, Buchalla W, Wang Y. Influence of carbamide peroxide on the flexural strength of tooth-colored restorative materials: an in vitro study at different environmental temperatures. Oper Dent. 2010 Jun;35(3):300–7.
• Silva Costa SX, Becker AB, de Souza Rastelli AN, de Castro Monteiro Loffredo L, de Andrade MF, Bagnato VS. Effect of four bleaching regimens on color changes and microhardness of dental nanofilled composite. Int J Dent. 2009:313845.
• Kothari. Comparison and evaluation of color stability and flexural strength of various provisional restorative materials after bleaching: An in vitro study. J Int Oral Health. 2019;11(5):293-98.
• Campos I, Briso ALF, Pimenta LAF, Ambrosano G. Effects of bleaching with carbamide peroxide gels on microhardness of restoration materials. J Esthet Restor Dent. 2003;15(3):175–82.
• Yap AU. Effectiveness of polymerization in composite restoratives claiming bulk placement: impact of cavity depth and exposure time. Oper Dent. 2000 Apr;25(2):113–20.
• Firoozmand LM, Pagani C. Influence of bleaching treatment on flexural resistance of hybrid materials. Acta Odontol Latinoam AOL. 2009;22(2):75–80.
• Muralidasan K et al. Influence of In-Office and Home Bleaching Regimen on Flexural Strength of Nano-Hybrid Composite Resins: An In-Vitro Evaluation. IOSR J Dent Med Sciences. 2020;19(1):72-76.
• Feiz A, Samanian N, Davoudi A, Badrian H. Effect of different bleaching regimens on the flexural strength of hybrid composite resin. J Conserv Dent. 2016;19(2);157-60.