Which Joint Classification System Should I Use?

When I present “Demystifying Occlusion” with my fellow faculty members Drs. Frank Spear and Gregg Kinzer, several commons questions arise during each session. One is, “which TMJ classification system should be used in clinical practice?” As with so many other things in dentistry, the answer is: “it depends.”

Look at the photo below. Some people will see the beautiful Japanese art. Some people will notice the wood in the antique buffet. Some people will notice the glass of red wine.

The thought process is similar with 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 of these systems offers valuable information and a logical way to classify joints. But choosing a joint classification system will depend upon the focus of the practice.

The Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) was published in 1992. It is 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 of these stages are 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 used five stages to describe TMJs. Piper Stage 1 are normal joints. Piper Stage 2 are joints with laxity at the lateral pole. Piper Stage 3A are joints with a reducing disk displacement at the lateral pole. Piper Stage 3B joints are joints with a non-reducing disk displacement at the lateral pole. Piper Stage 4A are joints with a reducing disk displacement at the medial pole. Piper Stage 4B joints are joints with a non-reducing disk displacement at the medial pole. Piper Stage 5A joint 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.

The Piper Classification System is unique in its ability to differentiate between structural changes at the lateral and medial pole. The ability to recognize the higher risk patients (Piper 4A/4B/5A/5B) increases the confidence of restorative dentists and specialists when developing a treatment plan. The increased confidence leads to an 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. If you have an orofacial pain practice, the RDC/TMD system may be best for you. If you have a TMJ surgical practice, you may use the Wilkes system. If you are a restorative dentist or a specialist in an interdisciplinary team, the Piper system will be best for your practice.

References

1. Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD) Schiffman, Eric et al. Journal of Oral & Facial Pain and Headache 2014, 28:1: 6-27.
2. Wilkes CH. Internal Derangements of the TM Joint. Arch Otolaryngol Neck Surg. 1989. 469-77.
3. Piper, DMD MD, Mark. Handbook of Research on Clinical Applications of Computerized Occlusal Analysis in Dent Med IGI Global, 2020. 582-697.