Melatonin-doped polymeric nanoparticles induce high crystalline apatite formation in root dentin

Manuel Toledano-Osorio; Fátima S Aguilera; Esther Muñoz-Soto; Estrella Osorio; Manuel Toledano; Germaine Escames; Antonio L Medina-Castillo; María T Osorio; Modesto T López-López; Marta Vallecillo-Rivas; Raquel Osorio

doi:10.1016/j.dental.2021.09.001

Melatonin-doped polymeric nanoparticles induce high crystalline apatite formation in root dentin

Dent Mater. 2021 Nov;37(11):1698-1713. doi: 10.1016/j.dental.2021.09.001. Epub 2021 Sep 17.

Affiliations

¹ University of Granada, Department of Stomatology, Colegio Máximo de Cartuja s/n, Granada 18071, Spain.
² University of Granada, Department of Stomatology, Colegio Máximo de Cartuja s/n, Granada 18071, Spain. Electronic address: toledano@ugr.es.
³ Faculty of Medicine, Department of Physiology, Biomedical Research Center, CIBERFES, Ibs. San Cecilio University Hospital, University of Granada, Granada, Spain.
⁴ University of Granada, NanoMyP, Spin-Off Enterprise, Edificio BIC-Granada, Av. Innovación 1, 18016, Armilla, Granada, Spain.
⁵ Independent Research Scholar, Granada, Spain.
⁶ University of Granada, Faculty of Science, Applied Physics Department, Av. Fuente Nueva s/n, 18071 Granada, Spain.

PMID: 34544591
DOI: 10.1016/j.dental.2021.09.001

Abstract

Objective: To investigate the effect of novel polymeric nanoparticles (NPs) doped with melatonin (ML) on nano-hardness, crystallinity and ultrastructure of the formed hydroxyapatite after endodontic treatment.

Methods: Undoped-NPs and ML-doped NPs (ML-NPs) were tested at radicular dentin, after 24 h and 6 m. A control group without NPs was included. Radicular cervical and apical dentin surfaces were studied by nano-hardness measurements, X-ray diffraction and transmission electron microscopy. Mean and standard deviation were analyzed by ANOVA and Student-Newman-Keuls multiple comparisons (p < 0.05).

Results: Cervical dentin treated with undoped NPs maintained its nano-hardness values after 6 m of storage being [24 h: 0.29 (0.01); 6 m: 0.30 (0.02) GPa], but it decreased at apical dentin [24 h: 0.36 (0.01); 6 m: 0.28 (0.02) GPa]. When ML-NPs were used, nano-hardness was similar over time [24h: 0.31 (0.02); 6 m: 0.28 (0.03) GPa], at apical dentin. Root dentin treated with ML-NPs produced, in general, high crystallinity of new minerals and thicker crystals than those produced in the rest of the groups. After 6 m, crystals became organized in randomly oriented polyhedral, square polygonal block-like apatite or drop-like apatite polycrystalline lattices when ML-NPs were used. Undoped NPs generated poor crystallinity, with preferred orientation of small crystallite and increased microstrain.

Significance: New polycrystalline formations encountered in dentin treated with ML-NPs may produce structural dentin stability and high mechanical performance at the root. The decrease of mechanical properties over time in dentin treated without NPs indicates scarce remineralization potential, dentin demineralization and further potential degradation. The amorphous stage may provide high hydroxyapatite solubility and remineralizing activity.

Keywords: Apatite; Dentin; Hardness; Melatonin; Polymeric nanoparticles; Remineralization; Transmission electron microscopy; X-ray diffraction.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Apatites
Dentin
Humans
Melatonin*
Nanoparticles*
Polymers

Substances

Apatites
Polymers
Melatonin