Impact of Different LED Units, Tip Distance and Time of Light Exposure on Microhardness of Resin-Based Composite for Posterior Teeth

ORIGINAL ARTICLE
Timur V. Melkumyan, Surayo Sh. Sheraliava, Elena Ju. Mendosa, Zurab S. Khabadze, Maria K. Makeeva, Shahnoza K. Musoshayhova, Angela D. Dadamova, Shukhrat M. Shakirov, Azad A. Mukhamedov, Furkat M. Tojinazarov, Nurmukhammad E. Iskandarov

 
For citation: Melkumyan TV, Sheraliava SSh, Mendosa EYu, Khabadze ZS, Makeeva MK, Musoshayhova ShK, Dadamova AD, Shakirov ShM, Mukhamedov AA, Tojinazarov FM, Iskandarov NE. Impact of Different LED Units, Tip Distance and Time of Light Exposure on Microhardness of Resin-Based Composite for Posterior Teeth. International Journal of Biomedicine. 2024;14(4):700-703. doi:10.21103/Article14(4)_OA27
 
Originally published December 5, 2024
 

Abstract: 

Background: The aim of this in vitro study was to reveal in a time-dependent manner the effect of received irradiance produced by different light-emitting-diode (LED) lamps on the surface microhardness of composite material used in the restoration of posterior teeth.
Methods and Results: A single nanofilled resin composite, Estelite Posterior (Toquyama Dental Corp, Japan) shade PA3, was used to perform this in vitro study. Ninety cylindrical filling samples were made with the help of plastic ring molds and plates to obtain flat surfaces. The mean diameter and height of prepared specimens were 5.5±0.05mm and 2.5±0.1mm, respectively. For the polymerization of the composite, two different types of light-curing units (LCU) were selected for this study: Valo X (Ultradent Products, Inc., USA) operated in a “standard” mode, and Bluephase 20i (Ivoclar Vivadent, Liechtenstein) ran in a “high” mode. Photoactivation was done with the light tips fixed parallel to the surface of the filling material and above it at a distance level of 1 mm, 4 mm, and 8 mm. The radiant power (mW) of each LCU was registered in a PL-MW2000 Optical power meter (Beijing Perfectlight Technology Co., Ltd., China).
A total of 18 groups, with five filling samples in each, were formed and processed. Upon the completion of light treatment, by the ISO-4049 protocol, each specimen was immersed in water and stored at 37°C for 24 hours in a lightproof container. After this period, samples were washed and tested for the hardness of top surfaces using a “ПMT-3” Vickers hardness tester.
The means of light intensities of two LCUs in the study were significantly different at 4 mm and 8 mm tip distances in 1.26 and 2 times, respectively. Analysis of hardness values did not reveal significant differences in the light-curing efficacy of two LED lamps. The differences in VHN values were obvious among the 10- and 40-second time exposure groups when the photoactivation was carried out at an 8mm tip distance.
Conclusion: The effective polymerization of composite restorations with poor accessibility is still a matter of time, not the power of LCU.

Keywords: 
light-curing unit • light intensity • resin composite • surface hardness
References: 
  1. Milosevic A, Burnside G. The survival of direct composite restorations in the management of severe tooth wear including attrition and erosion: A prospective 8-year study. J Dent. 2016 Jan;44:13-9. doi: 10.1016/j.jdent.2015.10.015. Epub 2015 Nov 2. PMID: 26542166.
  2. Melkumyan TV, Dadamova AD, Sheralieva SSh, Kamilov NKh, Daurova FYu. Treatment of Class II Caries Lesions with Application of Packable and Conventional Resin Composites: Clinical and Experimental Study. International Journal of Biomedicine.2020;10(1):66-69. doi: 10.21103/Article10(1)_OA11
  3. Galvão MR, Caldas SG, Bagnato VS, de Souza Rastelli AN, de Andrade MF. Evaluation of degree of conversion and hardness of dental composites photo-activated with different light guide tips. Eur J Dent. 2013 Jan;7(1):86-93. PMID: 23407620; PMCID: PMC3571515.
  4. Sato T, Matsuyama Y, Fujiwara T, Tagami J. Pulp survival after composite resin restoration of caries lesions in adults. J Oral Sci. 2020 Dec 23;63(1):27-30. doi: 10.2334/josnusd.19-0534. Epub 2020 Oct 3. PMID: 33012762.
  5. Shimokawa CA, Carneiro PM, Lobo TR, Arana-Chavez VE, Youssef MN, Turbino ML. Five second photoactivation? A microhardness and marginal adaptation in vitro study in composite resin restorations. Int Dent J. 2016 Oct;66(5):257-63. doi: 10.1111/idj.12227. Epub 2016 Apr 8. PMID: 27061395; PMCID: PMC9376633.
  6. Melkumyan TV, Sheraliava SSh, Mendosa EYu, Khabadze ZS, Makeeva MK, Kamilov NKh, Musoshayhova ShK, Dadamova AD, Shakirov ShM, Mukhamedov AA. Effect of Preheating on Mechanical Properties of Different Commercially Available Dental Resin Composites. International Journal of Biomedicine.2023;13(4):317-322. doi: 10.21103/Article13(4)_OA14
  7. Lima RBW, Troconis CCM, Moreno MBP, Murillo-Gómez F, De Goes MF. Depth of cure of bulk fill resin composites: A systematic review. J Esthet Restor Dent. 2018 Nov;30(6):492-501. doi: 10.1111/jerd.12394. Epub 2018 Oct 29. PMID: 30375146.
  8. Shortall AC, Palin WM, Jacquot B, Pelissier B. Advances in light-curing units: four generations of LED lights and clinical implications for optimizing their use: Part 2. From present to future. Dent Update. 2012 Jan-Feb;39(1):13-7, 20-2. doi: 10.12968/denu.2012.39.1.13. PMID: 22720376.
  9. Motlhake D, Mthethwa SR, Sekati EM. Bacterial contamination of curing light guides: prevalence and students' knowledge and awareness of measures to maintain sterility. South African Dental Journal. 2023;78(7):353-358.  doi: 10.17159/sadj.v78i07.16425
  10. Soares CJ, Braga SSL, Ribeiro MTH, Price RB. Effect of infection control barriers on the light output from a multi-peak light curing unit. J Dent. 2020 Dec;103:103503. doi: 10.1016/j.jdent.2020.103503. Epub 2020 Oct 19. PMID: 33091553; PMCID: PMC7569381

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Received October 28, 2024.
Accepted November 28, 2024.
©2024 International Medical Research and Development Corporation.