I almost always read in the news/press that dentists recommend to brush teeth two times a day for 2-3 minutes.
This drives me crazy, because it does not make sense; The point for dental health is to systematical clean every surface of your teeth twice a day (and use inter-dental brushes/floss once a day). For me, brushing my teeth takes around 6 minutes, if I hurry up. For someone faster it might be possible in 1 minute.
So, why do dentists always give the 2-3 minutes recommendation?
The National Institute of Health has a ton of public-paid studies. Did you even bother to search it before making your astounding claim? https://www.nih.gov
Just one search for
nih brush timeshows several studies. Let me just link the top two...https://pubmed.ncbi.nlm.nih.gov/19723429/ -> "This study was undertaken to measure plaque removal during untutored brushing over timed periods between 30 and 180 seconds with"
https://pubmed.ncbi.nlm.nih.gov/16355646/ -> "This review shows that there is consensus in the literature that (meticulous) tooth brushing once per day is sufficient to maintain oral health and to prevent caries and periodontal diseases. Tooth brushing is also regarded as an important vehicle for application of anti-caries agents, such as fluorides. However, most patients are not able to achieve sufficient plaque removal by performing oral hygiene measures at home. Therefore, tooth brushing twice daily is recommended by most of the dentists in order to improve plaque control."
OP poses one question with two parts. The first study answers the time (2-3 minutes) part. The second link answers the other part (twice daily).
Is there any way to actually see those articles? All that's given is an abstract, and the articles don't appear to be linked.
https://kagi.com/search?q=pubmed+download+full+text
-> https://www.nlm.nih.gov/oet/ed/pubmed/quicktours/fulltext/index.html
It looks like the two articles I linked don't have free sources available. You might also search for the co-authors of the studies -- for example the first author in the first study has other citations https://pubmed.ncbi.nlm.nih.gov/?term=Creeth+JE&filter=simsearch2.ffrft with full text available. You could download those, obtain the author's contact information, and send a request for a copy of the one you want. Just be nice about it :) If that doesn't work then maybe you have a friend with a "subscription" to download such things... from school or work or... something.