Good luck with it and let us know what happens. Don't forget about CareCredit as well... they are a very good option for stuff like this.
I had CareCredit with a $2,800 limit. I only used it 1x for an annual visit for my dog to keep the card active. Synchrony canceled it, Chevron, and Mattress Firm all within 3 weeks even though I never was late on any payments, never asked for a CLI, nada.
The only thing I can figure is that when I maxed out a couple of cards to pay for my Mom's funeral, they saw me as high risk and shut everything down. CareCredit and Chevron has $0 balances. I'm taking my time on paying Mattress Firm just because I opted to pay the creditors that kept my accounts open during that time.
During this same time, CFNA (Firestone) gave me an unrequested CLI from $1600 to $2400. I did try to open a CareCredit again a couple of weeks ago and was immediately declined with the only reason being that I had a Synchrony account before. C'est la vie...
Well I hope you come up with a viable solution and are able to get your dental work done. It really is a gamechanger when it comes to self-esteem.