Abstract : Purpose : In Japan, the number of elderly people with many teeth has increased through the 8020 campaign. As a result, there is a growing number of dental diseases that are difficult to treat. Their causative diseases include apical root fracture and cemental tear, but external root resorption is also considered a disease that must be differentiated from other diseases. In this study, external resorption showing a characteristic morphology was observed in the root apex of a mobile molar, and is reported from the viewpoint of its microstructure.
Case : A 69-year-old male presented to our clinic with a chief complaint of a mobile mandibular right first molar. Treatment consisted of tooth extraction, and observation of the extracted tooth using micro X-ray CT and scanning electron microscopy revealed external root resorption in the mesial root.
Results and Discussion : In the distal root, there was tartar deposition all the way to the root apex, and a variety of bacteria had formed a biofilm. The shape of the root apical foramen remained and was circular, with a diameter of 0.42 mm. The mesial root had lost surrounding dentin, leaving a root canal, and microstructural observation revealed a shell-shaped resorption fossa and external root resorption of dentin. The structure of the root apical foramen was flat, at 0.12×2.13 mm, and the edges were sharp.
Conclusion : In teeth in which external resorption of the root apex has occurred, the morphology of the root apical foramen may be altered by the progression of the lesion, making treatment more difficult. Proper treatment and explanation to the patient should be carefully considered.
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