Reversible Pulp Damage after Spontaneous Pain

Objective: pulps with the history of spontaneous pain have been shown clinically to be preserved with vitality using LSTR 3 Mix-MP therapy (IADR: 2000), even though spontaneous pain has been considered a clinical sign of “irreversible” pulpitis and an indication for removal of pulps (pulpectomy or pulpotomy). In this study, human third molars with pulpitis were examined patho-histologically how the pulp tissue had been damaged after spontaneous pain, especially on odontoblasts and nerves. Methods: Under informed consent, 25 teeth were extracted because of lack of antagonists and scanned with Micro-CT, and then processed for thin-sections and immunohistochemistry (nestin as the marker of differentiated odontoblasts and PGP 9.5 as the marker of nerve fibers). Results: Micro-CT revealed that in all cases carious lesions were extended to the pulps. Patho-histologically, extensive inflammation of pulps at crown portion was observed in 16 cases. Slight inflammation located only beneath the exposed areas was in 9 cases. In 10 cases, limited empty spaces (depth: less than 1.1 mm) where the pulps were necrotic, were observed at areas of exposed-pulp. Immunoreactivities of nestin and PGP 9.5 revealed positive in all cases. These results may suggest that inflammation is not fatal even after experiences of spontaneous pain. In addition, functions of odontoblasts and nerves are most likely preserved rather well even in cases with spontaneous pain, and such teeth with pulpitis can be preserved by LSTR 3 Mix-MP therapy without surgical pulp removal, such as pulpectomy. However, prolonged pulp exposures seemed to cause extended pulp necrosis. Conclusion: Pulp damages even with the history of spontaneous pain were not fatal in all the cases examined, suggesting that it may be worth re-considering for the treatment of cases of “irreversible” pulpitis.