Direct radiation-induced effects on dental hard tissue

Abstract

BackgroundRadiation caries is a complication of radiotherapy characterized by enamel erosion and dentin exposure. The mechanisms of characteristic radiation caries formation are not well-understood. The aim of this study was to evaluate the direct radiation-induced effects on dental hard tissue and investigate their role in the formation of radiation caries.MethodsSixty non-carious third molars were divided into three groups (n = 20), which would be exposed to 0 Gy, 30 Gy, and 60 Gy radiation, respectively. After radiation, microhardness and elastic modulus were measured at four depths by means of a Vickers microhardness tester and atomic force microscopy (AFM). The microstructure was observed by scanning electron microscopy (SEM). X-ray diffraction and Raman microspectroscopy were used to determine crystal properties and protein/mineral (2931/960 cm− 1) ratios.ResultsA statistically significant decrease in microhardness and elastic modulus values 50 μm from the dentino-enamel junction (DEJ) in enamel was revealed in the 30-Gy and 60-Gy groups. With the increasing dose, destruction of interprismatic substance and fissures at the DEJ-adjacent region were found. A greater reduction of crystallinity was revealed in enamel compared with dentin. Raman spectroscopic analysis showed a slight increase of the protein/mineral ratio for enamel following accumulated radiation, while the protein/mineral ratio for dentin was decreased.ConclusionsRadiation could directly alter the mechanical properties, micro-morphology, crystal properties, and chemical composition of dental hard tissue. The early destruction of DEJ-adjacent enamel, combined with decreased crystallinity of enamel under radiation exposure, may be related to the formation of characteristic radiation caries.

Morphology, Volume, and Density Characteristics of the Parotid Glands before and after Chemoradiation Therapy in Patients with Head and Neck Tumors

“…e radiation dose, the localization of the tumor, and the sensitivity of the normal tissue next to the tumor are all factors affecting the severity of adverse effects to RT [5]. RT may cause xerostomia, dysphagia, mandibular osteoradionecrosis, trismus, hearing loss, and radiation caries [5,9].…”

The effect of different doses of radiation on the morphogical, mechanical and chemical properties of the primary and permanent teeth—an in vitro study

“…Lu et al 12 and Gonçalves et al 4 determined a decrease in the enamel microhardness close to the DEJ region, while de Siqueria et al 10 determined rst a decrease and then an increase. As for the dentin, while Gonçalves et al 4 found a decrease in the microhardness close to the DEJ region after radiation, de Siqueria et al 10 rst found a decrease and then an increase.…”

“…4,10 Because of the increasing amount of organic structure in the DEJ region, this region was stated to be affected more by radiotherapy than the other regions. 4,10,12,14 It was reported that the enamel and dentin hardness values increased depending on the point of the measurement, and the hardness value when moved away from the DEJ region. 25 In our study, the measurements were made from the enamel and dentin regions 50 µm away from the DEJ region.…”

“…The Vickers hardness probe in the form of a diamond pyramid in the microhardness tester was applied to the tooth under a load of 25 g for 10 s in enamel and 10 g for 15 s in dentin. 12,13,19 A Vickers measurement was performed from three different points of the enamel and dentin ( Figure 1): Surface enamel (50µm inner part of the enamel external surface), middle enamel (middle of the enamel), deep enamel (50µm away from the DEJ), surface dentin (50 µm away from the DEJ), middle dentin (middle of the dentin), deep dentin (50 µm away from the pulp chamber). The average of all three Vickers hardness values obtained from the enamel and dentin was recorded as the overall hardness value of enamel and dentin.…”

“…4,[10][11][12][13][14][15] However, the number of studies on how teeth structure changeswith radiotherapy is insu cient nowadays, and there is still no consensus in studies. 4,[10][11][12][13][15][16][17] It is important to study the effect of radiation on teeth. So, more effective strategies will be developed to prevent radiation caries and achieve better results in these patients' oral health.…”