Why is it necessary to pre-authorize certain treatments?

As you are entitled to a deductible from the sum insured per procedure in case of major treatments, in first place it is beneficial for you to get to know which services and to what extent are subject to reimbursement. With this information, you can either 1) negotiate the price of the treatment with your dentist, or b) find an alternative dental clinic that is willing to offer a better price. Both you and the insurer will benefit from one or the other.