If you shop off-exchange, pediatric dental is required. If you purchase an off-exchange plan, the carrier must be “reasonably assured” that you have exchange-certified pediatric dental coverage in place in order to sell you a policy without pediatric dental.
If you have no children under age 19 on your application and you’re shopping off-exchange, you may be able to purchase a zero-premium “adult pediatric” dental plan. You wouldn’t pay anything for the policy, but since it only covers children, it wouldn’t provide any dental coverage for adults on the plan.
If you do have children under 19 on your application and you’re shopping off-exchange, you are not allowed to opt out of pediatric dental coverage. You must either purchase pediatric dental coverage (embedded with your plan or as a supplemental policy) or attest to the fact that you already have it from another carrier.