Prevalence of internal inflammatory root resorption

Clinical Research

Prevalence of Internal Inflammatory Root Resorption
Cornel Gabor, DDS, Esther Tam, DDS, Ya Shen, DDS, PhD, and Markus Haapasalo, DDS, PhD
Abstract
Introduction: Internal inflammatory root resorption is regarded as rare because it is only occasionally detected in clinical or radiographic examination of teeth. However, inflammation is supposedly an important etiologic factor ofinternal resorption. Therefore, we tested the hypothesis that there is no difference in the presence of internal resorption between teeth with vital, healthy pulp and teeth with a history of pulp inflammation. Methods: Thirty teeth with no previous root canal treatment that were to be sequentially extracted from adult patients were diagnosed for their pulpal status (ie, healthy, pulpitis, ornecrosis). After extraction, the teeth were split buccolingually, and both halves were exposed to 6% sodium hypochlorite for 10 minutes under constant shaking to remove all organic debris covering the root canal walls. The specimens were washed in water and prepared for scanning electron microscopy to examine the root canals for the presence of internal resorption. Results: The null hypothesis of thisstudy was rejected. None of the 9 teeth with healthy pulps revealed signs of internal resorption. Four of the 8 teeth with pulpitis (50%) and 10 of the 13 teeth with necrotic pulps (77%) had internal resorption (P < .01). The average number of resorptive lesions in the affected necrotic teeth was 2.4, whereas in teeth with pulpitis and internal resorption, the average number of lesions was 1.25.The amount of resorption was always 1 mm. Most lesions (15) were detected in the middle third of the root, followed by the apical third (13). Only 1 internal resorptive lesion was detected in the coronal third of the root canal. Conclusions: Internal resorption was a frequent finding in teeth with pulp inflammation or necrosis. (J Endod 2012;38:24–27)

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nternal inflammatory root resorptiondestroys dental hard tissue by odontoclast activity (1, 2). Internal resorption starts inside the root canal and requires at least partially vital pulp tissue. If the resorption is not detected and remains untreated, it can potentially grow larger and eventually perforate the root from inside. When internal resorption is detected early enough, the treatment is usually successful, and the long-termprognosis of the affected tooth is good. Only when a significant amount of tooth structure has been destroyed and/or the resorption is close to the marginal bone (coronal third of the root) will weakening of the tooth have a negative impact on the prognosis of the treatment. Internal root resorption is regarded as rare, but the frequency of internal resorption is not well known. Many of the publishedarticles on internal resorption are case reports (3, 4), with an emphasis on the treatment of the resorption. In some studies, the occurrence of internal resorption has been estimated to be between 0.01% and 1% (1). Thoma (5) reported internal root resorption in 1 out of 1,000 teeth. However, Cabrini et al (6) detected internal resorption by histological examination in 8 out of 28 teeth (28%) 49 to320 days after calcium hydroxide pulpotomy. In another study of 33 autotransplanted maxillary canines, 17 (55%) developed internal resorption during the follow-up time of 6 years (7). The results of these studies point to inflammation as an important factor in the etiology of internal resorption. Inflammation was also reported as the primary cause of internal resorption in the classic animalstudies by Wedenberg and Lindskog (8–10), who exposed pulps of monkey teeth to Freund’s adjuvant (inflammation) or to Freund’s adjuvant and oral bacteria (inflammation + infection). A histological and scanning electron microscopic study on resorption in teeth with apical granulomas and cysts showed that apical resorption was a common finding and that intracanal resorption was also often found (11). The...