Disorders of Dental Hard Tissues Induced by Radioiodine-131 (I-131) Therapy Used in Differentiated Thyroid Cancer: An In Vitro Study

Abstract

This study aimed to evaluate, in vitro, the effects of I-131 on enamel and dentin in healthy human incisive permanent maxillary teeth. Our in vitro model analogue with the in vivo conditions of differentiated thyroid carcinoma patients treated with I-131, consisted in a solution of I-131 dissolved in artificial saliva. A total of 48 teeth were divided into eight groups (n = 6): control, irradiation groups at 3, 6, 12, 24, 36, 48, and 192 h, respectively. At the end of radiation exposure, radioiodine activity of specimens was assessed. Fine microstructure, nanostructure, surface roughness, and hidroxyapatite (HAP) crystallite diameter were investigated by atomic force microscopy (AFM) to both enamel and dentin structures. There is a constant increase of radioactivity in dental structures at 3, 6, 12, 24 h, due to progressive retention and I-131 migration, with a maximum at 36 h. Enamel showed notable alterations, which was correlated with the increase of the treatment time. A relevant visible distance between the HAP prisms was observed after 24 h. The surface suffered a loss in its compact structure. I-131 acts in the same way on HAP crystallites in dentin as in those in enamel. It was noticed that their morpho-dimensional changes occurred only after 12 h of treatment. Radioiodine-131 determines degradation of enamel and dentin by starting from the alteration of the crystalline network of HAP prisms, transforming them from compact materials into an agglomeration of rocky submicron structures.

The Side Effects of Therapeutic Radioiodine-131 on the Structure of Enamel and Dentin in Permanent Human Teeth

“…The influence of radioiodine therapy on the periodontal structures depends on the health condition of the oral soft tissues, prior to the initiation of radiation therapy, but also on the dose of radioiodine prescribed for each specific case [ 17 ]. Periodontal defects or mixed endodontic-periodontal disorders can occur after radioiodine therapy [ 17 ]. Gingival inflammation or hemorrhages are also cited among the undesired side effects of I-131 treatment.…”

“…For radioiodine-131 irradiation, we used an in-vitro protocol that simulates the procedure for radioiodine therapy performed for patients with differentiated thyroid carcinomas (DTC) [ 17 ]. The amount of radioiodine activity was calculated to be similar to that administered in the ablation therapies of DTC.…”

Radioiodine-131 Therapy Used for Differentiated Thyroid Cancer Can Impair Titanium Dental Implants: An In Vitro Analysis

“…For this study, ethics committee approval was not necessary. Our in vitro model analogue with the in vivo conditions of thyroid cancer patients treated with radioiodine-131 consisted in a solution of 592 MBq (16 mCi) I-131 dissolved in 50 mL of artificial saliva [14,17]. This experimental model was already tested in other in vitro publications by the authors [14,17].…”

“…Our in vitro model analogue with the in vivo conditions of thyroid cancer patients treated with radioiodine-131 consisted in a solution of 592 MBq (16 mCi) I-131 dissolved in 50 mL of artificial saliva [14,17]. This experimental model was already tested in other in vitro publications by the authors [14,17]. In the prepared solution, titanium implants (n = 24) were introduced and were then taken out at 6, 12, 24, 48, 192 and 384 hours post-irradiation [16].…”

Oral Microbiome, Oral Health and Systemic Health: A Multidirectional Link

“…Recent studies, for instance, have reported a correlation between oral microbiome impairments and an increased risk of pancreatic and liver diseases, with the presence of oral pathogens, predominantly P. gingivalis , in the diseased organ [ 16 ]. Furthermore, cancer therapies, including chemotherapy, head and neck radiation therapy, or thyroid cancer radioiodine therapy, can damage dental tissues and alter the oral microbiome [ 17 , 18 , 19 , 20 ]. In this perspective, innovative strategies for fine tuning the oral microbiome, counteracting dysbiosis, may help in preventing the disease and the complications of therapies.…”