Farah Abdul_Razzak Mahmood Al_Bazaz - Lecturer. B.D. S, M.Sc, Ph.D. Dentistry Department, Al-Rafidain University College, Baghdad, Iraq
Nada Jafer MH. Radhi - B.D.S., M.Sc., Ph.D. Assist. Prof., Dentistry Department, Baghdad University, Collage of Dentistry, Head of Pedodontic and Preventive, Baghdad, Iraq
Kadhim A. Hubeatir - B.S.C., M.Sc., Ph.D., Assist. Prof., Laser and Optoelectronic Engineering Department, University of Technology, Baghdad, Iraq
Maha Waleed Alghazali - Assist. Lecturer, B.D.S, MS.c. Dentistry Department, Al-Rafidain University College, Baghdad, Iraq

Lasers have been tested with positive findings for the suppression of incipient caries, and many theories have been offered for this phenomenon. Nevertheless, early caries lesion prevention and biomimetic treatment are still difficulties despite massive efforts to promote dental hygiene. Nanoparticles' exceptional qualities make them a promising biomaterial for a variety of medical and dental uses. There are a lot of exciting and promising uses for nanotechnology in the field of tissue repair and replacement, especially in dental mineralized tissues, thanks to the growing interest in this area. This research aimed to examine how certain nanoparticles and CO۲ laser radiation affected the microhardness of enamel. In order to conduct the microhardness test, ۸۰ first premolars from the maxilla were randomly split into eight groups, one control group and seven study groups, each containing ten teeth. Each tooth’s buccal (cheeky) side was standardized to have a circular window placed there, measuring ۶ mm in diameter. The exposure period was ۵ seconds in continuous wave (CW) mode, and the laser power was calculated to be ۰.۸۵ W using a unique equation. The concentration of the hydroxyapatite nanoparticles solution employed was ۱۰%, whereas the concentration of the iron oxide nanoparticles solution was ۱۲.۵%. In this study, we evaluated the effects of certain agents on the microhardness of enamel before and after inducing a caries lesion by pH cycling techniques. Hardness variation was determined for each sample using a tailored equation. After demineralization, enamel microhardness values were found to be significantly lower across the board compared to healthy teeth’ microhardness values. This was the case across all groups. After treatment with certain agents, there was a marked increase in enamel microhardness values for all groups, with a statistically highly significant difference (p<۰.۰۰۱). The groups treated with laser followed by hydroxyl apatite nanoparticles (HANPs) and those treated with laser followed by iron oxide nanoparticles (IONPs) saw the greatest increases in their microhardness values. Treatment of teeth samples with laser followed by iron oxide nanoparticles (IONPs) induced the greatest change in enamel microhardness, while treatment of teeth samples with IONPs resulted in the lowest change in enamel microhardness compared to all of the other agents. As a potential preventative intervention against dental cavities, enamel treatment with CO۲ laser, hydroxyapatite, and iron oxide nanoparticles might be examined.

Laser, Hydroxyapatite nanoparticles, Iron Oxide Nanoparticles, enamel microhardness