Abstract
This study tested the hypothesis that head and neck radiotherapy (HNRT) impacts the immunoexpression of type I collagen, bone sialoprotein (BSP) and bone morphogenetic protein 4 (BMP4), thereby leading to micromorphological changes in the dentin-pulp complex (DPC), and promoting the onset and progression of radiation caries (RC). Twenty-two demineralized sections of carious teeth (a group of 11 irradiated teeth and a control group of 11 non-irradiated teeth) extracted from 19 head and neck cancer patients were analyzed by conventional optical microscopy and immunohistochemistry to investigate the micromorphology (cellular layer hierarchy, blood vessels, odontoblasts, fibroblasts, extracellular matrix, calcification, necrosis, reactionary dentin formation, and chronic inflammation), and the patterns of staining/immunolocalization of type I collagen, BSP and BMP4 in the dental pulp of irradiated and control samples. No significant differences attributable to the direct impact of radiotherapy were detected in DPC micromorphology between the groups. In addition, the patterns of immunohistochemical staining and immunolocalization of the proteins studied did not differ between the irradiated and the control samples for type I collagen, BSP or BMP4. This study rejected the hypothesis that HNRT directly damages dentition by changing the organic components and the microstructure of the DPC, ultimately leading to RC.
Highlights
Radiotherapy is one of the main treatment choices for head and neck cancer
Bone morphogenetic protein 4 (BMP4) – a growth factor related to tooth development – and type I collagen seem to be found in the dental pulp, and may be related to the formation of the dentin matrix.[16,17]
Regarding bone morphogenetic protein 4 (BMP4), this protein may be expressed by odontoblasts and at the region near the predentin, suggesting that it plays an important role in dentin matrix formation.[16,17]
Summary
Radiotherapy is one of the main treatment choices for head and neck cancer. considered highly effective, head and neck radiotherapy (HNRT) causes several acute and chronic toxicities that affect nontargeted tissues, such as oral mucositis, hyposalivation, recurrent oral infections, trismus, radiation caries (RC), and osteoradionecrosis, among other disorders.[1,2]RC is a chronic side effect that affects approximately 29% of the patients who undergo HNRT, with a 37% increased risk of developing RC withinBraz. Head and neck radiotherapy (HNRT) causes several acute and chronic toxicities that affect nontargeted tissues, such as oral mucositis, hyposalivation, recurrent oral infections, trismus, radiation caries (RC), and osteoradionecrosis, among other disorders.[1,2]. RC is a chronic side effect that affects approximately 29% of the patients who undergo HNRT, with a 37% increased risk of developing RC within. Generalized infection in the oral microenvironment in advanced cases frequently requires dental extractions, increases the risk for developing osteoradionecrosis, and has a negative impact on the quality of life of cancer survivors.[5,6] Atypical clinical progression patterns and lack of symptomatology associated with RC encourage research and investigation into its etiology and pathogenesis. Even though RC is commonly attributed to the indirect effects of radiotherapy, such as mucositis and hyposalivation,[7,8] in vitro studies have suggested that the direct effects of HNRT on mineralized tooth structures might be a significant causal factor for RC.[9,10]
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