Knoop microhardness, surface roughness, and cytotoxicity analysis of arginine-modified experimental orthodontic resins: An in vitro study

Pérola Costa Bitencourt Santos; Analia Gabriella Borges Ferraz Facury; Lenita Marangoni Lopes; Mário Alexandre Coelho Sinhoreti; Daniel Navarro da Rocha; Lourenço Correr-Sobrinho; Ana Rosa Costa; José Guilherme Neves

doi:10.1016/j.ortho.2025.101014

Knoop microhardness, surface roughness, and cytotoxicity analysis of arginine-modified experimental orthodontic resins: An in vitro study

Int Orthod. 2025 May 8;23(4):101014. doi: 10.1016/j.ortho.2025.101014. Online ahead of print.

Authors

Pérola Costa Bitencourt Santos¹, Analia Gabriella Borges Ferraz Facury², Lenita Marangoni Lopes¹, Mário Alexandre Coelho Sinhoreti², Daniel Navarro da Rocha³, Lourenço Correr-Sobrinho², Ana Rosa Costa⁴, José Guilherme Neves⁵

Affiliations

¹ Herminio Ometto Foundation, Araras Dental School, Araras, SP, Brazil.
² Department of Restorative Dentistry, Dental Materials Area, Piracicaba Dental School, State University of Campinas, FOP - UNICAMP, Piracicaba, SP, Brazil.
³ Department of Materials Engineering-SE/8, Military Institute of Engineering, Rio de Janeiro, Brazil.
⁴ Herminio Ometto Foundation, Araras Dental School, Araras, SP, Brazil; Department of Restorative Dentistry, Dental Materials Area, Piracicaba Dental School, State University of Campinas, FOP - UNICAMP, Piracicaba, SP, Brazil.
⁵ Department of Restorative Dentistry, Dental Materials Area, Piracicaba Dental School, State University of Campinas, FOP - UNICAMP, Piracicaba, SP, Brazil. Electronic address: nevesjoseguilherme@gmail.com.

PMID: 40344701
DOI: 10.1016/j.ortho.2025.101014

Abstract

Aim: The study aimed to evaluate the impact of incorporating 2.5%, 5%, and 7% arginine on the hardness, roughness, and cytotoxicity of 3M™ Transbond™ XT.

Material and methods: A total of 48 samples were divided into four groups (n=12): G1 - commercial resin 3M™ Transbond™ XT (TXT); G2 - TXT+2.5% arginine; G3 - TXT+5% arginine; and G4 - TXT+7% arginine. The hardness analysis was performed by a microhardness tester. The measurements of roughness were performed by a surface roughness measuring instrument. The surface morphology analysis was analyzed by digital images obtained with a scanning electron microscope (SEM). For the in vitro cytotoxicity test, dental pulp mesenchymal cells underwent a cell viability reduction assay. For statistical analysis, ANOVA (one-way/two-way) was used, followed by Tukey's test post hoc (P<0.05).

Results: There was a reduction in the hardness of experimental resins compared to 3M™ Transbond™ XT commercial resin (P < 0.05). There was no difference between concentrations of 2.5% and 5%, but there was the largest reduction in resin with 7% arginine (P < 0.05). Surface roughness analysis showed there was no statistical difference between the samples (P ≥ 0.05). SEM also did not demonstrate changes in the surface roughness of the resins. All groups exhibited good cell viability at each timepoint. After 48h, an increase was observed for groups contaning arginine (P < 0.05).

Conclusion: Surface hardness was modified with when arginine incorporation - to the Transbond™ XT resin formulation. No differences were observed for surface roughness. Due to the initial cytotoxicity of the resins, precautions regarding satisfactory photopolymerization and the distance of application in relation to the gingival tissues must be adopted.

Keywords: Arginine; Cell tracking; Dental bonding; Hardness; Orthodontics; Surface properties.