Usually yes, and there is a reason for it: we do not pay damages for pain and suffering, but treatment costs actually incurred. That is why we reimburse after the treatment, as soon as we have the invoice and the surgical report of the correction. Most clinics for their part insist on payment in advance.
If the clinic exceptionally waives this, we settle directly with them. And if your health insurer reclaims money, we settle that directly with the insurer on request.
What you can have in advance is certainty: with the cost estimate you know in writing, before the treatment, what will be covered.