This development of a dental diagnostic terminology is timely given the expanding presence of electronic health records (EHR) in dentistry, which medicine is capitalizing upon. For example, through the analysis of International Classification of Diseases (ICD) codes entered into the EHR, researchers were able to identify an association between myocardial infarction and the COX-2 inhibitors rofecoxib and celecoxib.3The dental profession’s ability to conduct similar studies is critically impeded by the lack of a standardized dental diagnostic terminology. In medicine, a number of standard terminologies have been developed to facilitate data exchange among individuals and systems because no single terminology has satisfied all needs for all users. In addition to the ICD, other widely used terminologies include Diagnosis-Related Groups (DRGs), developed for the purpose of Medicare prospective payment; International Classification of Primary Care (ICPC), a classification of about 1,400 diagnostic concepts that are partially mapped to ICD-9; Current Procedural Terminology (CPT), used for billing and reimbursement; and the Diagnostic and Statistical Manual of Mental Disorders (DSM), providing definitions of psychiatric disorders and specific diagnostic criteria.
In contrast, while there have been previous efforts to standardize dental diagnostic terms, they have not achieved widespread acceptance, and they have fallen short in their comprehensiveness or availability. Early on, it was noted that terms for oral diseases within the ICD terminology were insufficiently precise and not consolidated within the ICD volume. Consequently, the ICD-DA (application of the ICD to Dentistry and Stomatology) was added at the time of the eighth revision of the ICD in 1965.4 Nevertheless, recent articles have highlighted the inadequacy of the existing ICD terminology as it pertains to oral diagnosis documentation.5 In the United States, organized dentistry has become increasingly involved in the movement to codify diagnostic terms. Since the early 1990s, the American Dental Association (ADA) has led the creation of SNODENT, the Systematized Nomenclature for Dentistry. Where ICD is a terminology, SNODENT is an ontology. The distinction between the two is that a terminology is a set of terms representing the concepts within a particular field, while an ontology represents the relationships between these concepts. SNODENT is comprised of diagnoses, signs, symptoms, and complaints6 and currently includes over 6,000 terms. However, unlike its available medical counterparts (SNOMED and ICD-9), SNODENT has not yet been finalized and is not available for use by general practitioners or dental schools. To address the critical need, some groups have independently generated dental diagnostic terminologies.7,8 However, there is no supporting literature on whether they have served their purpose well,9 and among these, only the Toronto codes have been systematically evaluated.1 In 1998, the University of California, San Francisco (UCSF) created Z codes based upon the Toronto codes10 and the existing ICD version. In 2007 Creighton University made further modifications to these Z codes.
