Please read the following from the HCA: 

Attention Dental Providers:

The Health Care Authority (HCA) revised the Oral Health Connections Pilot Project Billing Guide, published July 1, 2019, to change the frequency of periodontal maintenance (CDT code D4910) from 12 months to 90 days after the completion of scaling and root planing. This change aligns with WAC 182-535-1270.

To view the revised Oral Health Connections Pilot Project Billing Guide, see HCA's Billing guides and fee schedules webpage. Scan down and select Dental Program.