A Short Case Study: Tooth No. 30—Cyst or Granuloma?

Rico D. Short, DMD


I hope you’re doing well and being safe during this unprecedented time. I wanted to share a very interesting case with you.

A patient came in with pain on tooth No. 30. It had a previous root canal performed. The pre-op radiograph showed inadequate cleaning, shaping, and obturation (Figure 1). In addition, there was a large lesion on the distal root and a smaller one on the mesial root (Figure 2). This prompted some questions.

Q: Is it a cyst or a granuloma?

A: The only way to really find out is to do a biopsy preoperatively.

Q: Can cysts heal after root canal therapy?

A: Yes and no. Pocket or bay cysts will heal after root canal therapy, but not true cysts, which have to be surgically removed.

Q: If the lesion is large, is it a cyst?

A: No. The size of the lesion can’t specify its etiology.

Q: How often are cysts found in previously treated teeth?

A: Only about 20% of the time.

Figure 2. There was a large lesion on the distal root and a smaller lesion on the mesial root. Figure 3. Endodontic treatment required two visits with calcium hydroxide for two weeks.
Figure 4. Six months later, there was nice healing on both roots.

I performed endodontic retreatment in two visits using calcium hydroxide for two weeks (Figure 3). I obturated the canals with warm vertical compaction with Kerr Pulp Canal Sealer EWT. A six-month recall showed very nice healing on both roots (Figure 4).

The lesion on the distal will take a little longer due to its large size. Studies show that it can take up to eight years before the bone completely repairs.

This was not a cyst. It was a granuloma. I hope you learned something today!

Dr. Short attended the Medical College of Georgia School of Dentistry to attain a DMD degree in 1999. In 2002, he earned his post-doctorate degree in endodontics from Nova Southeastern University and then became a Diplomate of the American Board of Endodontics in 2009. Dr. Short is an expert consultant in endodontics to the Georgia Board of Dentistry, author, speaker, and assistant clinical professor at the Dental College of Georgia in Augusta. His private practice, Apex Endodontics PC, is located in Smryna, Ga. He can be reached at dr.short@yahoo.com.

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