Can Juvederm Ultra Plus or a thicker lip filler with Russian technique fix a top lip that curls inwards when I smile? (photo)

I have been performing nonsurgical lip flips, as well as the Russian Technique for lip volume for quite a few years with very gratifying results.
However, at least from the photo provided, it would appear that the longer-lasting results you are seeking can be achieved with the combined use of a Botox Lip Lift AND the use of a low viscosity, cohesive, malleable HA Filler injected along the vermilion border of the upper lip. to better define and accentuate the vermilion. The combination of the Botox and filler tends to synergistically have considerably more long-lasting, durable results.
You would be wise to consult with a board certified cosmetic dermatologist injection expert and best of luck.

When you smile, the orbicularis oris muscle can contract inward, pulling the upper lip in the way you described. Being young and having braces might actually accentuate this muscular response. In your situation, I recommend a straightforward approach without surgery.
Neuromodulators are typically the first option, though they don’t last very long. I suggest combining this with a vertical lip filler technique using Restylane Kysse. This filler can mimic some effects of neuromodulators and, when combined with a lip flip using toxin, can extend the duration of the desired outcome.
Most of my patients return every 8 months for mild touch-ups, often just with the toxin, to maintain their results.
Remember: keep it simple.