Effect of radiotherapy on the chemical composition of root dentin. Issue 1 (15th December 2018) - Campi, Lívia Bueno
Abstract: Background: The radiotherapy can directly affect the bond strength of the adhesive materials, interfering in the prognosis of restorative treatments, which may be caused by chemical changes in dentin structure. Methods: Twenty inferior homologues premolars were distributed in 2 groups (in vitro study) ( n = 10): nonirradiated and irradiated. The specimens were submitted to the analysis of phosphate (ν1 PO4 3− ;ν2 PO4 3− ;ν4 PO4 3− ), carbonate (ν3 CO3 2− ), amide I, CH2, amide III, and amide I/III ratio by confocal Raman spectroscopy. Data were submitted to statistical analysis (T test, P < .05). Results: In intracanal dentin, the irradiated group had lower ν4 PO4 3− values (1.23 ± 0.06) compared to nonirradiated group (1.40 ± 0.18) ( P < .05), with no difference for ν1 PO4 3− and ν2 PO4 3 peaks ( P > .05). The irradiated (1.56 ± 0.06) had lower carbonate, amide III (1.05 ± 0.19), and amide I/III ratio values (0.19 ± 0.06) compared to nonirradiated group (1.42 ± 0.10, 1.28 ± 0.24, and 0.31 ± 0.10, respectively) ( P < .05). For medium dentin irradiated group (1.30 ± 0.12) had lower phosphate values compared to nonirradiated group (1.48 ± 0.22) ( P < .05). In cementum, there was no statistical difference between the groups. Conclusion: The radiotherapy was able to cause changes in ν4 PO4 3−, carbonate, and amide III peaks of root dentin.