Abstract
HEAD AND NECK CANCER, CAVITY
Considering the side effects in the oral cavity and dental structures of
radiotherapy (RDT) for head and neck cancer, this study aimed to evaluate the
effects of RDT on the root dentin concerning the obliteration of dentinal
tubules, the inorganic composition of intra-radicular dentin, and the integrity
of collagen fibers. Thirty human canines were selected from a biobank and
randomly divided into two groups (n=15). The samples were sectioned
buccolingually, and a hemisection was used for structural analysis by scanning
electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS).
Low-vacuum SEM images were obtained at 2000-x magnification to observe the
obliteration of the dentinal tubules. Moreover, compositional evaluation was
performed using EDS. After RDT, the SEM and EDS analyses were repeated using the
same methodology. RDT was applied fractionally at 2 Gy per day, 5 days per week,
for 7 weeks, resulting in a total dose of 70 Gy. The collagen integrity of the
irradiated and non-irradiated samples was analyzed using Masson’s trichrome and
picrosirius red staining polarization microscopy. Samples subjected to RDT
exhibited dentinal tubule obliteration (p < 0.001); low integrity of type I
and III collagen fibers (p < 0.05); compositional reduction of calcium (p =
0.012), phosphorus (p = 0.001), and magnesium (p < 0.001); an increased Ca/P
ratio (p < 0.001). RDT affects the structure of dentinal tubules, the
inorganic composition of intra-radicular dentin, and the collagen fiber
integrity in the root dentin, which may interfere with the effectiveness and
durability of dental procedures.