There are two main TM joint classifications used today in dentistry. The Wilkes Classification system addresses concepts from a surgical perspective and has been discussed in a previous article.
The Piper Classification System1 addresses concepts from a restorative and occlusal perspective. It was developed by Mark Piper who is an oral surgeon in St. Petersburg, Florida. This system addresses structural alterations in the TM joint in three different areas.
The first area describes the soft tissues in the TM joint. The second area describes the degree and direction of diskal displacements. The third area outlines the condition of the bony structures in the TM joint.
Stage 1 - Normal diskal alignment
1. The medial and lateral collateral ligaments are intact.
2. The posterior band of the disk is located at the 1:00 posture at both poles.
3. The disk shows no medial or lateral directional herniation.
4. The bearing zone of the disk interposes between the loaded areas at both poles.
5. The retrodiskal tissues fill the space behind the condyle and the posterior band.
6. The condyle has no bony disorder.
7. The joint dimensions are stable.
Stage 2 - Intermittent Lateral Pole Disk Herniation
1. The medial collateral ligament system is intact.
2. The disk aligns at 1:00 at the medial pole.
3. The lateral collateral ligament system has laxity.
4. Disk herniation at the lateral pole is variable (1:00, 12:00, 11:00, or 10:00).
5. The lateral part of the disk aligns 1:00 most of the time.
6. The disk shows no medial or lateral directional herniation.
7. The bearing zone of the disk always interposes between the loaded medial pole.
8. The retrodiskal tissues fill the space behind the condyle and the posterior band.
9. The condyle has no bony disorder.
10. Imaging rarely shows Stage II displacements, and the diagnosis is made clinically.
11. The joint dimensions are stable.
Stage 3A - Lateral Pole Disk Herniation with Reduction
1. The medial collateral ligament system is intact.
2. The disk aligns at 1:00 at the medial pole.
3. The lateral collateral ligament system has laxity.
4. In FSCP, the disk is herniated at the lateral pole (12:00, 11:00, or 10:00).
5. The lateral pole of the condyle reduces beneath the disk during translatory movements.
6. The disk may show medial directional herniation.
7. The bearing zone of the disk interposes between the loaded medial pole in FSCP.
8. The bearing zone of the disk interposes between the loaded lateral pole in TCP.
9. The retrodiskal tissues fill the space behind the condyle and the posterior
10. The condyle has no bony degeneration.
11. The growing child may show an osteochondral growth deficiency.
12. The joint dimensions are stable unless a child patient has an osteochondral growth deficiency
Stage 3B - Lateral Pole Disk Herniation with Locking
1. The medial collateral ligament system is intact.
2. The disk aligns at 1:00 at the medial pole.
3. The lateral collateral ligament system has laxity.
4. Disk herniation in FSCP is abnormal at the lateral pole (10:00).
5. The disk is locked off the lateral pole of the condyle during translatory movements.
6. The disk may show medial directional herniation.
7. The bearing zone of the disk interposes between the loaded areas of the joint at the medial pole in FSCP.
8. The retrodiskal tissues fill the space behind the condyle and the posterior band.
9. The condyle may show lateral pole articular surface degeneration.
10. The growing child may show an osteochondral growth deficiency.
11. The joint dimensions are stable unless a child patient has an osteochondral growth deficiency.
Stage 4A - Medial Pole Disk Herniation with Reduction
1. The medial and lateral collateral ligament systems have laxity.
2. Disk alignment in centric is abnormal at the medial and lateral poles (12:00, 11:00, 10:00).
3. The degree of disk herniation is graded independently for each pole.
4. Both poles of the condyle reduce beneath the disk during translatory movements.
5. The disk may show lateral or medial directional herniation.
6. The bearing zone of the disk interposes between the loaded areas only with condylar translation.
7. The retrodiskal tissues fill the space behind the condyle and the posterior band.
The condyle may show medial or lateral pole articular surface degeneration.
9. The growing child will have an osteochondral growth deficiency.
10. The joint dimensions may not be stable.
Stage 4B - Medial Pole Disk Herniation with Locking
1. The medial and lateral collateral ligament systems have laxity.
2. Disk alignment in FSCP is abnormal at the medial and lateral poles (10:00).
3. The disk locked off the medial and lateral poles of the condyle during all movements.
4. The disk may show lateral or medial directional herniation.
5. The bearing zone of the disk does not interpose between the loaded areas with any movement.
6. The retrodiskal tissues fill the space behind the condyle and the posterior band.
7. The condyle may show medial or lateral pole articular surface degeneration.
8. The condyle may show marrow degeneration.
9. The growing child will have an osteochondral growth deficiency.
10. The joint dimensions may not be stable.
Stage 5A - Diskal Herniation with Retrodiskal Perforation and Acute Condylar Degeneration
1. The medial and lateral collateral ligament systems have laxity.
2. Disk alignment in centric is abnormal at the medial and lateral poles (10:00).
3. The disk locked off the medial and lateral poles of the condyle during all movements.
4. The disk may show lateral or medial directional herniation.
5. The bearing zone of the disk does not interpose between the loaded areas with any movement.
6. The retrodiskal tissues are perforated superior to the condyle.
7. The condyle may show medial or lateral pole articular surface degeneration.
8. The condyle may show marrow degeneration.
9. The growing child will have an osteochondral growth deficiency.
10. The condylar bony dimensions are unstable.
11. The joint dimensions are unstable.
Stage 5B - Diskal Herniation with Retrodiskal Perforation and Chronic Condylar Degeneration
1. The medial and lateral collateral ligament systems have laxity.
2. Disk alignment in centric is abnormal at the medial and lateral poles (10:00).
3. The disk is locked off the medial and lateral poles of the condyle during all movements.
4. The disk may show lateral or medial directional herniation.
5. The bearing zone of the disk does not interpose between the loaded areas with any movement.
6. The retrodiskal tissues are perforated superior to the condyle.
7. The condyle may show medial or lateral pole articular surface degeneration.
8. The condyle may show marrow degeneration.
9. The growing child will have an osteochondral growth deficiency.
10. The condylar bony dimensions are stable unless a child patient with osteochondral growth deficiency.
11. The joint dimensions are stable.
References
1. Dawson, PE, Cranham JC. The Complete Dentist Manual: The Essential Guide to Being a Complete Care Dentist St. Petersburg, Widiom 2017, 217-238.
Dr. Jim McKee, Spear Resident Faculty
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