Common CDT coding questions

During the last 30 years, I have received hundreds of emails asking questions related to CDT code selection for procedures performed by hygienists. Here are some of the more common ones.

Question: How do I handle it when my office manager asks me to change a D4346 (scaling in presence of generalized moderate or severe gingival inflammation—full mouth, after oral evaluation) to D1110 (prophylaxis-adult) because the patient’s insurance doesn’t cover D4346? 

Response: Arrange a meeting with your office manager to discuss your concerns regarding this. Explain why you selected this procedure by showing her the nomenclature and descriptor for D4346 (p. 35 in CDT 2026) and how the patient’s oral condition was medically necessary to treat her condition. 

The removal of plaque, calculus, and stains from supra- and subgingival tooth surfaces when there is generalized moderate or severe gingival inflammation in the absence of periodontitis. It is indicated for patients who have swollen, inflamed gingiva, generalized suprabony pockets, and moderate to severe bleeding on probing.  

D4346 is a therapeutic procedure; D1110 is a preventive procedure, usually reserved for patients who present with healthy conditions and/or slight, localized gingival bleeding. 

Question: For children, I only code D1120 if they have primary or mixed dentition. I do not take age into account. The lead hygienist at my office says up to 13 years, code D1120, mostly because of insurance. There are multiple doctors, and each one is credentialed with different insurance companies. I’m not going to memorize each insurance carriers’ plans because each has different age restrictions for payment. Help! 

Response: Ever since CDT 2 (1995-2000) was created, there has never been an age attached to D1110 or D1120. They have always been dentition-specific—either primary, transitional, or permanent. Insurance carriers are the ones who insert various forms of “cost containment features” (what I call it!) to limit reimbursement. 

As a licensed health-care provider, you need to select the procedure code based on the descriptor. D1110-adult includes transitional or permanent dentition, and D1120-child includes transitional or primary dentition. (see p. 13, CDT 2026 for complete descriptors)). 

The ADA Code of Ethics states that the dentist has a duty to communicate truthfully. A dentist who incorrectly describes on a third -party claim form a dental procedure in order to receive a greater payment or reimbursement or incorrectly makes a noncovered procedure appear to be a covered procedure on such a claim form is engaged in making an unethical, false, or misleading representation to such third party. To submit by age due to insurance carrier restrictions could be considered a fraudulent act.  

Question: What would you recommend in the case when a patient is a stable periodontal patient and has been maintained on D4910, but her dental insurance will no longer cover the benefit due to SRPs being completed over six years ago?  

Response: Explain to the patient that their dental plan includes cost containment features that prohibit payment of certain procedures that are necessary for your treatment. However, your office will attempt to recover some reimbursement by submitting their claim asking to consider an alternative benefit for a prophylaxis. This can be done in Box 35 on the dental claim form: “If benefits unavailable or exhausted for D4910, please consider an alternate benefit for D1110.”  

Question: My office manager uses the code D0191 when we have periodontal patients that aren’t due for an exam. What are the specifics of this code? 

Response: D0191 assessment of a patient (p. 5, CDT 2026) is considered a “prediagnostic service” with the descriptor outlining what is to be done during that appointment. 

It is a limited clinical inspection that is performed to identify possible signs of oral or systemic disease, malformation, or injury, and the potential need for referral for diagnosis and treatment. 

It seems that it could apply in this situation since we all know hygienists perform some kind of assessment before they put a sharp instrument into the patient’s mouth. It would seem you are evaluating additional signs of oral or systemic disease and need referral for diagnosis and treatment if the condition has not improved. 

Question: My office is suddenly wanting to add D1330 (oral hygiene instruction) to all dental hygiene visits. I thought that the use of this code is used when you are spending an extended amount of time on special circumstances. From what I remember or understood, the D1110 code includes our typical OHI. My concern is that this should be a selective code and not be used for all appointments. I don’t want to run into fraud issues or scenarios due to incorrect usage.  

Response: There is no descriptor for this code limiting it for use when extensive OHI is required. I always suggest including this for every patient if you discuss anything to do with OHI, at no charge.  

But if you spend additional time providing instruction such as initial oral hygiene education prior to ortho treatment or cleaning around newly placed implants, then I would charge a fee for D1330. 

Question: An insurance carrier denied a D4910 (periodontal maintenance) reimbursement because the perio charting wasn’t done within the last six months. Our office documents complete perio chartings annually. Is this becoming industry standard? 

Response: It sounds like this insurance carrier is adding to their “plan limitations” for radiographic procedures. I have not heard of this limitation, but carriers can create anything they want when it comes to required documentation.  

Regarding this patient, I would have them ask the carrier where in their contract this requirement is stated, especially the date this became a requirement. I would also ask them the rationale for requiring this. I have found some carriers make decisions midyear and “forget” to notify their subscribers. If you were not notified in a timely manner, they should not be able to withhold reimbursement. 

Editor's note: The article appeared in the April/May 2026 print edition of RDH magazine. Dental hygienists in North America are eligible for a complimentary print subscription. Sign up here.