title -Effect of limited Cone Beam Computed Tomography on micronucleated cell count of buccal mucosa.

Rationale: Our study aims to detect and establish a correlation between mean micronucleated cell count and nuclear morphometry in exfoliated cells from affected and apparently unaffected mucosa after CBCT radiation and compare them with exfoliated cells from normal appearing mucosa of normal subjects before CBCT. This could prove beneficial in early detection of malignant conversion of buccal mucosa after CBCT and hence improve the prognosis and better treatment outcome of the patient.

RESEARCH QUESTION-what is the effect of CBCT radiations on the no. Of micronucleated cells in the buccal mucosal cells Population- Patients Planned For CBCT Intervention- None Control-None Outcome- change in number of mean micronucleated cell count before and after the CBCT exposure Time- 1 year (Jan 2020- April 2021)

Ionizing radiation is a well-known mutagen and carcinogen in the human population which has both direct and indirect effects on the tissues. It can damage the tissues through different mechanisms like breakage, cross linking of DNA strands, change or loss of the base and disruption of hydrogen bonds. These radiations cause changes in the buccal mucosa, salivary glands, dentin and enamel leading to xerostomia, mucositis and radiation related caries.

Buccal mucosal cells are under direct radiation exposure in dental radiographic techniques and act as the primary target for radiation-induced damage. Also, it has a highly proliferative epithelial cells and can be easily collected and studied. Micronuclei, an anomaly structure, originates from the chromosome fragments or whole chromosomes that lag behind at anaphase during nuclear division under physical and chemical factors. The micronucleus index has become one of the standard cytogenetic endpoints and biomarkers used in genetic toxicology in vivo or in vitro2. In healthy epithelial tissues these MNi ranges from 0.5 to 2.5 MNi /1000 cells. The studies have shown an increase in their frequency in individuals exposed to radiation or other genotoxic agents.

However, these studies observed the effect on the micronuclei at small and medium FOV, but the radiation induced damage is seen mostly at smaller FOVs which involves high resolution, thereby causing more radiation exposure.

Keeping this in mind, the aim of this study is to observe and correlate the mean micro nucleated cell count of the buccal epithelial cells with the help of PAP smear after CBCT exposure at different voxel sizes (90 and 200) at small FOV. This could prove beneficial and shed light on the cytogenetic damage and malignant conversion potential of buccal mucosa after CBCT.

Inclusion Criteria:

• systemically healthy individuals

Exclusion Criteria:

- Subjects with any other potentially malignant disorder present in the oral cavity. .

2. Subjects who are smokers and alcoholics. 3. Subjects with history of malignancy. 4. Subjects receiving dietary supplementations 5. Any subjects exposed to radiation or other carcinogens in the past one month.

- patient reporting to oral radiology for CBCT for any dental conditions