Abstract
Background Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure. This study evaluated the effect of different solutions on the dentin chemical composition and collagen structure of irradiated dentin. Material and Methods Sixty maxillary canines were distributed in 2 groups (n=30): non-irradiated and irradiated (radiotherapy: X-rays of 6 MV in 30 cycles of 2 Gy to 60 Gy). The teeth were sectioned, sanded, and polished to obtain 3x3x2 mm fragments, which were redistributed in 3 subgroups (n=10) according to the treatment employed: chlorhexidine 2% (CL), chitosan 0.2% (QT), and 0.5 M carbodiimide (EDC). The samples were analyzed in FTIR at time zero (T0-control) and after 1 (T1), 3 (T3), and 5 (T5) minutes of immersion in the tested solutions. The data for the areas of the carbonate (C), amide I (AI) bands, and the ratio between the areas of the amide III/proline and hydroxyproline (AIII/PH) bands were analyzed using ANOVA and Tukey test (α=5%). Results QT showed lower C values at T1, T3, and T5 (P<0.0001), presenting lower values when compared to CL and EDC subgroups (P<0.05). AI values at T3 and T5 were higher than T0-control and T1, independently of the radiotherapy and dentin treatment factors (P<0.05). At T0-control, the AIII/PH ratio was lower in the irradiated group (P<0.05), whereas the EDC treatment at T1, T3, and T5 and QT at T3 and T5 increased these values (P<0.05), making them similar to non-irradiated subgroups (P>0.05). Conclusions Radiotherapy changes the secondary structure of collagen, and EDC was able to restore collagen integrity after 1 minute of immersion, without changing dentin inorganic composition. Key words:Radiotherapy, collagen, dentin, FTIR, chemical composition.
Highlights
Radiotherapy is used for treatment of head and neck cancer and can be used as primary therapy, as adjunctive to surgical treatment and chemotherapy, or as palliative treatment in the final and inoperable stages of the disease, the treatment mode being determined by tumor type, stage, and locality [1,2]
Radiotherapy changes the secondary structure of collagen, and EDC was able to restore collagen integrity after 1 minute of immersion, without changing dentin inorganic composition
Radiation therapy consists of high energy ionizing radiation that interacts with the cells generating electrons that ionize the medium and lead to the rupture of the deoxyribonucleic acid (DNA) chains and water hydrolysis, promoting the inhibition of cell division in addition to the production of free radicals that result in the destruction of neoplastic tissues [3]
Summary
Radiotherapy is used for treatment of head and neck cancer and can be used as primary therapy, as adjunctive to surgical treatment and chemotherapy, or as palliative treatment in the final and inoperable stages of the disease, the treatment mode being determined by tumor type, stage, and locality [1,2]. Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure [5], such as changes in the dentin chemical composition [6], besides changes in the peptide chains, dehydration of the collagen fibers [7], and increased expression of metalloproteinases (MMPS) [8]. These alterations may interfere with tooth-restoration interaction, reducing the bond strength of adhesive systems [9] and increasing the susceptibility to failure of the restorations [10]. At T0-control, the AIII/PH ratio was lower in the irradiated group (P
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