Hello Mr.Manoharan Nair, 

The top ranked government and private colleges in Kerala, Tamil Nadu and Karnataka are as follows:

Kerala:

1. Government dental college

2. KMCT dental college

3. University of Calicut 

Tamil Nadu:

1. Madha dental collge and hospital

2. Tamil Nadu government dental college

3. The Tamil Nadu Dr.M.G.R medical university 

Karnataka:

1. AL-Badar rural dental college and hospital 

2. Governemnet dental college and research institute - GDRI 

3. KGF college of dental sciences and hospitals - KGFCDS

4. Navodaya dental college and hospital 

5. Sri Sidhartha academy of higher education 

Hope the above provided information helped you!