Effect of Gamma Radiation and Endodontic Treatment on Mechanical Properties of Human and Bovine Root Dentin

Abstract

This study evaluated the effect of gamma radiation and endodontic treatment on the microhardness and flexural strength of human and bovine root dentin. Forty singlerooted human teeth and forty bovine incisor teeth were collected, cleaned and stored in distilled water at 4 °C. The human and bovine teeth were divided into 4 groups (n=10) resulting from the combination of two study factors: first, regarding the endodontic treatment in 2 levels: with or without endodontic treatment; and second, radiotherapy in two levels: with or without radiotherapy by 60 Gy of Co-60 gamma radiation fractioned into 2 Gy daily doses five days per week. Each tooth was longitudinally sectioned in two parts; one-half was used for the three-point bending test and the other for the Knoop hardness test (KHN). Data were analyzed by 3-way ANOVA and Tukey HSD test (α=0.05). No significant difference was found for flexural strength values. The human dentin had significantly higher KHN than the bovine. The endodontic treatment and radiotherapy resulted in significantly lower KHN irrespective of tooth origin. The results indicated that the radiotherapy had deleterious effects on the microhardness of human and bovine dentin and this effect is increased by the interaction with endodontic therapy. The endodontic treatment adds additional negative effect on the mechanical properties of radiated tooth dentin; the restorative protocols should be designed taking into account this effect. E f f e c t o f G a m m a R a d i a t i o n a n d E n d o d o n t i c T r e a t m e n t o n M e c h a n i c a l P r o p e r t i e s o f

Effect of radiotherapy on the chemical composition of root dentin

“…This imbalance is related to the lower degree of mineralization and higher density of tubules in the intracanal root dentin region, which also justifies the nonalteration of carbonate in the middle root dentin region. In addition, the literature evidences the reduction of dentin microhardness after radiotherapy …”

Tratamento Endodôntico em Pacientes Submetidos a Radioterapia: Revisão de Literatura

“…Pacientes com tumores de cabeça e pescoço sob tratamento radioterápico podem apresentar alguns distúrbios orais e a complicação mais evidente para a dentição é a cárie induzida por radiação, no entanto, o efeito adicional causado pela terapia endodôntica realizada em dentes irradiados permanecia desconhecido. Pacientes com dentes obturados que requerem Research, Society and Development, v. 10, n. 7, e1010716127, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i7.16127 radioterapia podem ter mais alterações nas propriedades mecânicas do substrato da dentina radicular (Novais et al, 2016) Em um estudo de Kataoka, S. H. et al em 2012, pacientes foram avaliados em diversas fases durante um tratamento de irradiação na região de orofaringe. Estes foram submetidos ao teste de sensibilidade pulpar ao frio no início e no final do tratamento, sendo que todos responderam ao teste de forma positiva no início do tratamento.…”

Apical Displacement and Residual Root Canal Filling with Single-Cone After Post Space Preparation: A Micro-CT Analysis

“…However, this technique should be avoided in oval root canals, being better indicated for round canals (18), justifying the tooth type selected for this study. The use of bovine teeth does not invalidate the study model, since these have often been used in laboratory studies in endodontics (19). Bovine teeth have morphological similarity with human tooth and the used of these teeth do not require approval of the ethics committee.…”