Which Joint Classification System Should I Use?

When I present Advanced Occlusion, several common questions arise during each session. One is, “Which TMJ classification system should be used in clinical practice?” As with many other things in dentistry, the answer is, “It depends.”

Please take a look at the photo below. Some people will see the beautiful Japanese art, some will notice the wood in the antique buffet, and some will notice the glass of red wine.

The thought process is similar to TMJ classifications. The three most common joint classification systems are the Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD)¹, the Wilkes Classification System², and the Piper Classification system³. Each system offers valuable information and a logical way to classify joints. However, choosing a joint classification system will depend on the focus of the practice.

An Overview of the Three Major TMJ Classification Systems

The Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) was published in 1992. It’s based on Axis I physical assessment and an Axis II psychosocial status and pain-related disability. The American Academy of Orofacial Pain has been influential in the 2014 updated publication of the RDC/TMD. This system emphasizes pain and can be effective in an orofacial pain practice.

The Wilkes Classification System uses five stages (early, early/intermediate, intermediate, intermediate/late, late) to describe TMJs. Each stage is described from a clinical, radiological, and surgical perspective. Many oral surgeons have adopted this system, and it can be effective in an oral surgery practice.

The Piper Classification system also uses five stages to describe TMJs. Piper Stage 1 joints are normal. Piper Stage 2 joints have laxity at the lateral pole. Piper Stage 3A joints have a reducing disk displacement at the lateral pole. Piper Stage 3B joints have a non-reducing disk displacement at the lateral pole. Piper Stage 4A joints have a reducing disk displacement at the medial pole. Piper Stage 4B joints have a non-reducing disk displacement at the medial pole. Piper Stage 5A joints are perforated and typically painful. Piper Stage 5B joints are perforated and typically adapted.

The Piper Classification is designed for the restorative dentist to assess risk factors related to growth and development, occlusal instability, and pain. Disk coverage at the medial pole is vital for growth and development, occlusal stability, and load distribution. Piper Stage 1-3B joints have disk coverage at the medial pole and, as a result, have lower risk factors for incomplete growth, occlusal instability, or pain. Conversely, Piper Stage 4A-5B joints lack disk coverage at the medial pole and have higher risk factors for incomplete growth, occlusal instability, or pain.

Why the Piper Classification Stands Out

The Piper Classification System is unique in its ability to differentiate between lateral and medial pole structural changes. Its ability to recognize higher-risk patients (Piper 4A/4B/5A/5B) increases the confidence of restorative dentists and specialists when developing a treatment plan. This increased confidence leads to increased case acceptance. For this reason, the Piper Classification system is widely used by restorative dentists and their interdisciplinary teams.

So, which classification system is best for your practice? It depends on the focus of your practice. The RDC/TMD system may be best for you if you have an orofacial pain practice. You may use the Wilkes system if you have a TMJ surgical practice. If you are a restorative dentist or a specialist in an interdisciplinary team, the Piper system will be best for your practice.

References

1. Piper, M., & MD, D. (2020). Temporomandibular joint imaging. In Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dental Medicine (pp. 582-697). IGI Global.
2. Schiffman, E., Ohrbach, R., Truelove, E., Look, J., Anderson, G., Goulet, J. P., … & Dworkin, S. F. (2014). Diagnostic criteria for temporomandibular disorders (DC/TMD) for clinical and research applications: recommendations of the International RDC/TMD Consortium Network and Orofacial Pain Special Interest Group. Journal of Oral & Facial Pain and Headache, 28(1), 6.
3. Wilkes, C. H. (1989). Internal derangements of the temporomandibular joint: pathological variations. Archives of Otolaryngology–Head & Neck Surgery, 115(4), 469-477.