Are 'free at the point of delivery' health services more or less likely to foster preventative medicine than privatised medical services?

'Drill & fill' dentistry is not as effective against tooth decay
as treatment that focuses on preventing tooth decay, say
researchers at University of Dundee

What Doctors Don't Tell You printed magazine has recently had an apt name change to Get Well magazine for newsagent shelves, and an article from wddty.com highlights for me one of the perils of privatised 'medical services'.
https://www.wddty.com/news/2019/12/standard-drill-and-fill-not-the-best-way-to-tackle-tooth-decay.html

A study by of 3-to-7-year olds by researchers at University of Dundee showed that avoidance of tooth-rotting sugary substances is the best treatment for tooth decay. That, of course, involves responsible parenting and avoidance of what critics have dubbed 'Big Soda'. Eg, https://cspinet.org/new/201303191.html
Title: Soda Industry's "Selfish Giving": [Center for Science in the Public Interest] Report Tells How Big Soda's "Philanthropy" Buys Friends, Sliences Critics, and Sweetens Profits.

It also strikes me that dentistry has been one of the main branches of our National Health Service has been far from 'free at the point of delivery' for many years and the underfunding of public services such as sports provision increase the influence of 'Big Soda' on society.

Advertising revenue from 'Big Soda' is also likely to quell the willingness of a lot of MainStream Media from publicising this piece of dentistry research.

But as the NHS has been largely privatised now and is likely to become a terminal case in the event of trade deals with the USA post-Brexit, I believe that the question needs to be asked, "Are 'free at the point of delivery' health services more or less likely to foster preventative medicine than privatised medical services?"