Acid resistance enhancement of human tooth enamel surface by Nd:YAG laser and incorporating silver nanoparticles: in vitro study

  • Walid K. HamoudiEmail author
  • Raid A. Ismail
  • Zinah S. Shakir
  • Amera Alkaisi
Original Article



This work was devoted to assess the use of Nd:YAG laser with and without nanosilver particles to enhance tooth resistance of dental enamel against carries.


Forty-eight tooth samples were randomly divided into three main groups and received different treatments. Samples of group 1 were illuminated by a single pulse at different laser fluences, while those of group 2 received different number of laser pulses at fixed laser fluence, and finally the samples of group 3 received laser and colloidal silver nanoparticle treatments at different conditions. The samples were subjected to Vickers microhardness test, atomic force microscopy analysis, scanning electron microscopy observation, energy dispersive spectroscopy investigation, and demineralization and re-mineralization tests.


Due to fast laser heating and quenching, a significant microhardness increase in the treated dental enamel samples was seen. This resulted in an improvement in the enamel resistance against acids because of the decrease in hydroxyapatite lattice stress and the reduction in enamel solubility. The addition of silver nanoparticles to the laser-treated enamel surface helped stabilize the granules of the enamel surface tissue under the effect of laser irradiation. The demineralization of laser-treated samples showed higher Ca/P ratios than control group, indicating a higher resistance against acids.


The combined laser illumination and the addition of silver nanoparticles lowered the tooth abrasion degree and increased tooth resistance to decay. The demineralized samples of all laser-treated samples had higher Ca/P ratios compared to the demineralized control sample. Laser energy has modified the Ca/P mineral ratio and forms steadier and lesser acid soluble compositions.


Dental enamel Nd:YAG laser Silver nanoparticles Demineralization rate Tooth decay reduction 


Funding information

The authors received financial support from the University of Technology, Department of Applied Sciences.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

The authors declare that all work presented in this paper was in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.


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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Walid K. Hamoudi
    • 1
    Email author
  • Raid A. Ismail
    • 1
  • Zinah S. Shakir
    • 1
  • Amera Alkaisi
    • 2
  1. 1.Department of Applied SciencesUniversity of TechnologyBaghdadIraq
  2. 2.Department of DentistryAl-Farabi University CollegeBaghdadIraq

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