Can Fillers Be Used to Straighten the Dip in Nose Profile?

The area you are describing on your profile is known as a "supra-tip dip" or a depression just above your nasal tip. The answer is that it can be filled with a hyaluronic acid filler (Juvederm, Restylane) or with calcium hydroxylapatite (Radiesse). I would prefer to use Radiesse because it lasts longer (about a year) than hyaluronic acid fillers. If you are considering a Rhinoplasty in the future, be aware that Radiesse can lead to a greater degree of fibrosis (scar tissue) and make the procedure more complex.

In the hands of advanced physician injectors, fillers such as hyaluronic acid (e.g. Restylane, Juvederm) or Radiesse would be a fantastic options to address nose enhancement or contour deformity.

Fillers are a great way to improve the contour of the dorsum (the bridge) in just the way you suggest. For noses, I almost always suggest starting with a temporary and easily reversible filler such as Juvederm so that the patient can try it on, so to speak. If a patient likes those results, then Artefill is a nice way to make it permanent.
Silikon-1000 is not something I use (unlike Artefill, Silikon-1000 has no cosmetic approval by the FDA), but other physicians report excellent results with it, too.
Because of the permanent nature of fillers like Artefill and Silikon-1000, I suggest that patients see a doctor who also performs surgical rhinoplasty, since such specialists are often more experienced in assessing nasal aesthetics and determining what can and can't be done safely with fillers.
All the best,
--DCP