The tax-deductible dental expenses you can claim on your tax return depend on your AGI and total medical and dental expenses for the tax year. You can only deduct total health expenses, including dental costs, beyond the threshold of 7.5% of your AGI for the tax year. Costs for future care beyond the current tax year are typically not deductible.The tax-deductible dental expenses you can claim on your tax return depend on your AGI and total medical and dental expenses for the tax year. You can only deduct total health expenses, including dental costs, beyond the threshold of 7.5% of your AGI for the tax year. Costs for future care beyond the current tax year are typically not deductible.