who earns more a dentist or a scientist , and what is more struggling in india

Hii

There is nothing like to compare for salaries. The earnings depends upon how well you are setteled in your professional field. Sometimes,  we can see a dentist earning a lots of money  if he is good doctor and is running hospital in bigger city. But when he is in small city or not good, it may even hard to earn 1k rupees daily.

A scientist is more prestigious post than dentist.  Generally a scientist are working government of India in different organizations like-DRDO, ISRO, ICMR, CSIR, etc.. They have fixed pay band and increase with experience and promotion.

So, there is nothing like to compare between two professions.  You should persue what you like.

All the best