Dentistry graduate going to Japan for research (MEXT) – Can I work as a dentist? Part-time options? No Japanese yet.

I’m a dentistry graduate and I may be going to Japan as a MEXT research student. My academic background is in dental medicine, and I’m licensed in my home country.
I have a few questions and I would really appreciate insights from anyone who has been in a similar situation:
Has anyone here gone to Japan for research studies (especially in dentistry or medicine) and managed to work clinically as a dentist?
Is there any possibility to work under supervision?
Is there a temporary or special license for foreign-trained dentists?
Or is passing the full Japanese national dental exam the only way?
Regarding paid work in general:
As a MEXT research student, is it realistically possible to work part-time?
I understand there is a 28-hour/week limit with permission, but how strict is this in practice?
Does online income (e.g., social media or remote work) fall into a grey area?
How realistic is it to find any kind of part-time job if you do NOT speak Japanese yet?
Is basic English enough for certain jobs?
How long does it usually take to reach a functional Japanese level for work?
For those in dentistry/medical research in Japan:
Is the research experience worth it long-term if you don’t practice clinically there?
Does it strengthen your CV internationally?
Would you recommend focusing purely on research instead of trying to work on the side?
Emotionally and practically — how difficult is the adjustment if you arrive without Japanese language skills?
Any honest advice, personal experiences, or warnings would mean a lot.
Thank you in advance 🙏

by Calm-Arm4230