Análise topográfica e morfológica da dentina irradiada submetida à desmineralização e remineralização: estudo in vitro

Abstract

Introduction: Radiation-related caries is an adverse effect of radiotherapy in the head and neck region, characterized by rapid progression and challenging management. Its development results from both direct and indirect effects of radiation on the oral cavity. The effectiveness of fluoride in the prevention of dental caries is well-established in the literature, due to its ability to inhibit demineralization and promote remineralization of the dental structure. Objective: To analyze the effect of demineralization and remineralization using conventional toothpaste (1,450 ppm F) on irradiated dentin, through topographic and morphological imaging. Materials and Methods: Twenty human third molars were divided into two groups (n=10): control and irradiated. The irradiated group underwent a radiotherapy protocol totaling 72 Gy. Dentin blocks (4x4x2 mm) were obtained. The samples were subjected to a demineralizing solution to induce artificial caries, followed by pH-cycling and immersion in a toothpaste slurry with 1,450 ppm fluoride. Topographic analyses using Atomic Force Microscopy (AFM) and morphological analyses using Scanning Electron Microscopy (SEM) were performed at initial (sound dentin), after demineralization, and final (after pH cycling and toothpaste immersion). Results: AFM showed that the initial control dentin had a smooth and homogeneous surface, while the irradiated dentin exhibited grooves and cavities, indicating structural alteration. After demineralization, both groups showed increased roughness and opening of the dentinal tubules. At the final stage, both groups showed greater surface roughness in a similar manner. Additionally, SEM revealed alterations in the dentin after radiotherapy. The irradiated dentin showed fragmentation and obliteration of the dentinal tubules. After demineralization, both control and irradiated dentin underwent mineral loss, represented by increased tubule diameter and loss of peritubular dentin. After pH cycling, fragments and fissures persisted in the irradiated dentin. Conclusion: Ionizing radiation alters the topography and morphology of healthy, demineralized dentin, and dentin subjected to pH cycling with immersion in conventional fluoride toothpaste. AFM and SEM methodologies are complementary, allowing for comprehensive analysis of the dentin surface.