I had a plan with simply health, think it was about £25 per month just for dental, it was a conscious choice as i needed a lot of work, bad experience when i was young, didnt go to dentist for about 10 years.
Got 100% cash back for maintenance such as cleaning, check up an xray and 50% cash back for treatment such as filling, crowns and bridges. Implants not covered though as they are classed as cosmetic.
The beauty of it was i could go to what ever public or private dentist i wanted. So i could find one i was happy with.
Got a ton of work done, 2 root canal, a single tooth crown, 3 tooth bridge, lots of filling, it still worked out a bit more expensive than NHS, the dentist i settled on charged £80-100 for a filing, and £380 for a crown (i got 50% of that back) but it was a private dentist who was really understanding of my psychological issues with dentists, and used cutting edge filling and bridging materials /technology. You can't tell my crown and bridge from a natural tooth it's that good, ive seen some really bad crowns in my time, they colour matched it, and even sent some back to the lab to be re - engineered when they weren't happy with the fit/colour. At no extra cost.
I had major psychological issues, but by the end i was happily having my dentist do 2 fillings and a crown in one long session.
In the end the insurance company cancelled my policy as id claimed the limit, but that was ok as i had got the work done and im very happy with the results.
Another bonus of going private is no waiting, i think about 2 weeks for any work was about standard.