You will not have to pay taxes on your dental care.
In addition, your intervention could be tax deductible.

You will not have to pay taxes on our dental services
No tax (GST and QST) applies for the services of a dentist. For example, dental services rendered to individuals by dentists who are licensed or otherwise licensed to practice are exempt.

Your dental care could also be tax deductible
In Quebec, as in Canada, a tax credit may be applied for the portion of medical expenses that have not been reimbursed by an insurer. Dental expenses are part of the medical expenses and are therefore eligible for such tax credits, thus reducing the actual amount to pay for the care you received. Consult your financial advisor or accountant to find out if you can include the cost of your care on your tax return.