Greetings dear aspirant

As you are from OBC category and having Karnataka domicile,  please follow the link below to know previous year's cutoffs category wise for both All india quota and State quota. https://medicine.careers360.com/articles/neet-cutoff-karnataka

The cutoffs are variable depending several factors every year.

Now, according to your marks 300 even though having category, you have very less chance in govt. dental college but can secure seat in semi government or private dental colleges. Because, the cut off even for obc category is about 350+

Please follow this college predictor tool  to know about the colleges you have a chance

https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer

Hope this helps!!

All the best for your future career