"Decline in NHS Dental Treatment"

I have been using an NHS dentist for many years and have been pleased with the service given. Over the last year I have seen a rapid decline a very basic service is now offered, my dentist used to employ a hygienist who gave my teeth a thorough clean and polish every 6 months this service is no longer on offer, the dentist now gives a 5 minute scrape a 5 minute check up and it's on your way. i have needed a crown replacing for 6 months, after mentioning it to my dentist he assures me it's fine and not due for replacement. I feel I need to go private in order to maintain a good standard of dental care, then feel why am I paying NI contributions. I'm in a dilemma!