From Public Health Scotland today:

95.4% of the Scottish population were registered with an NHS dentist as at 30 September 2022.

As at 30 September 2022, 87.2% of children were registered, compared to 87.4% on 30 September 2021.

As at 30 September 2022, 2.6 million registered patients had seen an NHS dentist within the last two years (50.4% compared to 43.1% in March 2022). Registered children were more likely than adults to have seen an NHS dentist within the last two years (65.7% compared to 47.2%).

https://www.publichealthscotland.scot/publications/dental-statistics-registration-and-participation/dental-statistics-nhs-registration-and-participation-24-january-2023/

Comparative data for England are not available, but according to the Guardian in August 2022:

Just over a third of adults (34%) accessed NHS dental care in the two years to 31 March across England. It has since climbed to 36% in the two years to June but remains well below the pre-pandemic level of 50%. Just 44.8% of children were seen in the year to the end of March, rising to 46.2% in the year to June, despite there being no restrictions on dental surgeries treating patients. That is far below the 58.7% of children seen in the last full year before the pandemic.

https://www.theguardian.com/society/2022/aug/25/england-nhs-dentists-dental-deserts-data#:~:text=Just%20over%20a%20third%20of,to%2031%20March%20across%20England.