Hi Guest!

D8060- Interceptive orthodontic treatment of transitional dentition
D8070- Comprehensive orthodontic treatment of the transitional dentition
D8080- Comprehensive orthodontic treatment of the adolescent dentition
D8090- Comprehensive orthodontic treatment of the adult dentition

The codes listed above do not have a direct crosscode we are aware of, so you can either bill the "D" code on the medical claim (many insurers these days will process "D" codes when they are medically necessary services), or you can use the CPT code below and include a narrative report describing the procedure:
41899 - Unlisted procedure, dentoalveolar structures

Just to be sure you are aware, it us not extremely common for a medical insurer to cover othodontic treatment unless it is due to accidental injury/trauma. Having said that, there is now under the Affordable Care Act, coverage under medical plans for pediatric orthodontics for some diagnoses. Most medical policies i come across indicate coverage for ortho for diagnoses/conditions such as severe malocclusions, speech abnormalities, trauma, etc.
Here’s a really good guide from United Healthcare on the Pediatric Dental Essential Health Benefit in the Affordable Care Act (ACA), which includes “medically necessary orthodontia” (among other things, of course)
https://www2.cbia.com/ieb/ag/medical/zpdf/MemberBenefits/Oxford%20Pediatric%20Dental.pdf

Also, here is a link to Aetna's medical policy titled "Medically Necessary Orthodontia Related to the Pediatric Dental Essential Benefit in the Affordable Care Act (ACA):
https://www.aetna.com/health-care-professionals/clinical-policy-bulletins/dental-clinical-policy-bulletins/DCPB039.html#

Aetna even lists out the codes you might use right in the medical policy, and they are "D" codes! Here they are below:
• D8010- Limited orthodontic treatment of the primary dentition
• D8020- Limited orthodontic treatment of the transitional dentition
• D8030- Limited orthodontic treatment of the adolescent dentition
• D8040- Limited orthodontic treatment of the adult dentition
• D8050- Interceptive orthodontic treatment of the primary dentition
• D8060- Interceptive orthodontic treatment of transitional dentition
• D8070- Comprehensive orthodontic treatment of the transitional dentition
• D8080- Comprehensive orthodontic treatment of the adolescent dentition
• D8090- Comprehensive orthodontic treatment of the adult dentition


Hope this helps!