ICD-9-CM 521.5 is a billable medical code that can be used to indicate a diagnosis on a reimbursement claim, however, 521.5 should only be used for claims with a date of service on or before September 30, 2015. For claims with a date of service on or after October 1, 2015, use an equivalent ICD-10-CM code (or codes).
A regressive change of teeth characterized by excessive development of secondary cementum on the tooth surface. It may occur on any part of the root, but the apical two-thirds are most commonly affected. (Dorland, 27th ed)