The Department of Pediatric Dentistry, Orthodontics, and Preventive Dentistry at the College of Dentistry, University of Mosul, held a doctoral dissertation defense on Thursday, August 27, 2026, for the dissertation entitled:

“Effect of Chitosan-Coated Cocos nucifera Endosperm Extract as a Remineralizing and Antimicrobial Agent: An In Vitro Study”

The dissertation was submitted by doctoral student Tasneem Zuhair Saeed Al-Wattar.

The study aimed to prepare and evaluate Cocos nucifera endosperm extract prepared using sodium dodecyl sulfate-assisted extraction and coated with chitosan nanoparticles (COE-CHNPs), as a promising biomaterial for supporting tooth enamel remineralization and combating Streptococcus mutans. The study also evaluated the antibacterial effect of cold atmospheric plasma, both alone and in combination with the nanocomposite formulation.

The ionic gelation method was employed to prepare the chitosan nanoparticles and encapsulate the extract. The prepared materials were characterized using elemental, spectroscopic, and microscopic analyses, in addition to X-ray diffraction (XRD). Cytotoxicity was evaluated using the MTT assay, while the minimum inhibitory concentration (MIC) was determined using the broth microdilution method. Antibiofilm activity was assessed using the crystal violet assay against four strains of S. mutans. Bacterial plate counting was used to evaluate the effect of plasma, while enamel surfaces were examined using atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) after the samples were allocated into eight groups.

The results demonstrated that the extract contained minerals, phenolic compounds, and flavonoids, with spectroscopic changes occurring following the coating process and the formation of nanoparticles with a granular morphology. The COE-CHNPs maintained cell viability above 80% and recorded the lowest minimum inhibitory concentration compared with the other materials. The free extract achieved the highest percentage of biofilm inhibition, whereas the COE-CHNPs exhibited moderate activity. Plasma also contributed to reducing bacterial colony counts, with the greatest reduction observed when it was combined with COE-CHNPs.

Enamel demineralization resulted in increased surface roughness and porosity, accompanied by a reduction in its mineral content. In contrast, both the COE-CHNPs and plasma combined with COE-CHNPs groups improved calcium and phosphorus values. EDX analysis showed a more uniform distribution of calcium and phosphorus in the COE-CHNPs group, while XRD analysis revealed a more pronounced apatite-related crystalline pattern following treatment with COE-CHNPs.

The study concluded that COE-CHNPs represent a promising natural nanomaterial for supporting tooth enamel remineralization and combating S. mutans. Cold atmospheric plasma also enhances the reduction of bacterial growth when combined with the nanocomposite formulation. However, the study recommended further research addressing pH cycling, multispecies biofilms, and clinical simulation before the material can be adopted for clinical applications.

The dissertation defense committee was chaired by Professor Dr. Fadhil Abdullah Kareem, with Distinguished Professor Dr. Raya Jasim Mohammed, Professor Dr. Emad Farhan Ali, Assistant Professor Dr. Neam Riyadh Saleem, and Assistant Professor Dr. Mustafa Muad Hamid serving as members. Professor Dr. Maha Jamal Abbas supervised the dissertation and also served as a member of the defense committee.

At the conclusion of the defense, the dissertation was accepted after the required amendments were made.