which course have large scope in future bams or bds
Both the courses you have mentioned are really good. I would say if you wish to go for any of the course then you need to have some perspective regarding it.
If you want to be a clinical practioner like MBBS doctor but only for dental illness, you can become a surgeon and perform operations in dentistry, you can prescribe medicine then going for the course of BDS will give you this exposures.
Now if you want to develop medicines from plants and want to be involved more in research or in production houses of ayurvedic medicines then going for the course of BAMS can be a great option for you. BAMS don't provide you exposure to being a surgeon and it don't have that much of a scope for private clinics.
For more information regarding the BAMS consider the link below:
https://www.careers360.com/courses/bams-bachelor-of-ayurvedic-medicine-and-surgery
For more information regarding BDS consider the link below:
https://www.careers360.com/courses/bds-bachelor-of-dental-surgery
I hope this helps. Wish you a great eve!