Hello Aspirant. You mentioned you come from OBC-NCL category and that you expect to score 340 out of 720 in NEET UG 2021. Based on your marks, your overall percentile ends up around 82.51 - 83.01 and your AIR may end up somewhere around 265081 - 305231 considering difficulty of the paper to be moderate.

Based on previous years' cutoff data, it is less likely for you to get admission to MBBS at any Government medical colleges or Private medical colleges (under Government Quota) in Tamil Nadu, even though you have good chances to opt for BDS at few Government Dental colleges and Private Dental colleges (under GQ) in Tamil Nadu such as:

1. Adhiparasakthi Dental College and Hospital, Melmaruvathur
2. Asan Memorial Dental College and Hospital, Chengalpattu, Kancheepuram
3. Best Dental Science College, Madurai
4. J.K.K. Natraja Dental College and Hospital, Namakal District
5. Karpaga Vinayaka Institute of Dental Sciences, Kancheepuram
6. Madha Dental College and Hospital, Chennai
7. Priyadharshini Dental College and Hospital, Thiruvallur
8. Rajas Dental College and Hospital, Tirunelveli

and few more...

Now, if you ask about All India Counselling, then please note, you have less chance to opt for MBBS from any Government or Private Medical Colleges via 15% AIQ although you may get chance to grab a seat for BDS at few Private Dental colleges under Government Quota.

Nevertheless, I suggest you to participate at State Counselling sessions instead of All India Counselling to get comparatively better options.

To know more about NEET UG overall Cutoff trends, follow this article:

https://medicine.careers360.com/articles/neet-cut-off

To know your admission chances in medical/dental colleges with NEET Score, to get a personalized report with Top MBBS & B.D.S Colleges and to check course & counselling wise cut-offs of NEET for various state quotas, caste groups etc., I encourage you to use NEET UG 2021 College Predictor:

https://medicine.careers360.com/neet-college-predictor?utm_source=qna&utm_medium=neet_rp

I hope you find this information helpful.

Thank you and all the very best!