Abstract
Aim: The literature has not yet reported investigations about the effect of laser photobiomodulation (LPBM) over the cytotoxicity of drugs for endodontic treatments. Thus, the aim of this study was to evaluate, in vitro, the effect of the association between LPBM and intracanal medications on fibroblasts viability in different exposure times. Methods: Calcium hydroxide (Ca(OH)2) and iodoform (IO) were used pure or associated to LPBM. Eluates of medications were prepared and placed in contact with the cells in three different periods: 24h, 48h and 72h. Laser irradiation (emitting radiation λ 660nm, power density of 10mW, energy density of 3 J/cm²) has been performed in two sessions within a six hour interval, for 12s per well. After each experimental time, the colorimetric assay (MTT) has been performed. Statistical analysis was applied for Mann-Whitney test with 5% α error admitted test. Results: At 24h, the use of LPBM did not increase cell viability while after 72h cell proliferation was stimulated in the group without medications. LPBM application did not increase cell viability in Ca(OH)2 group and IO at any tested time. Ca(OH)2 cytotoxicity at 24h was higher than iodoform, while at 72h not difference was observed. Therefore, after 72 hours was no statistical difference between the IO and Ca(OH)2 groups. Conclusion: LPBM was able to increase cell viability in 72h in the group without medication, although no improvement was observed in the other groups. Thus, LPBM was not able to reduce the cytotoxic effects of the materials on fibroblasts in vitro.
Highlights
Decontamination of the root canal system is the critical step to achieve success in endodontics, being performed through effective chemical-mechanical preparation[1,2,3]
laser photobiomodulation (LPBM) is the term applied to describe the wide range of laser applications with low-energy densities and based on photochemical mechanisms where the energy is transferred to the intracellular mitochondrial chromophores and respiratory chain components[12,14]
After 72hs LPBM group demonstrated the best results for cell viability maintenance, it has been observed exclusively in the group without medication (p < 0,05)
Summary
Decontamination of the root canal system is the critical step to achieve success in endodontics, being performed through effective chemical-mechanical preparation[1,2,3]. Decontaminant pastes, as calcium hydroxide – Ca(OH)2 – and iodoform – IO – are essential to combat the microorganisms resisting of root canal system[5] These medications should be biocompatible, not carcinogenic, and/or genotoxic to periradicular tissue since they remain in contact with the periodontium[6]. Products of materials degradation in contact with existing cells in periradicular tissue can result in chemical irritation and inflammation, with a huge variety of chemical inflammatory mediators, which in high levels can cause tissue destruction and delay on healing process[7,8,9] These medications should present the ability to induce repair in the injured area without interfering with osteogenesis and cementogenesis[9,10,11]. LPBM can induce cell’s metabolic changes through a series of cascading reactions through photochemical and photoelectric with primary and secondary effects on exposed tissue to laser irradiation[12]
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