OBJECTIVES: To evaluate, in vitro, the effects of ionizing radiation on the mechanical and micro-morphological properties of enamel and dentin of permanent teeth. METHODS: Enamel and dentin microhardness (n=12 hemi-sections) was evaluated at three depths (superficial, middle and deep) prior to (control) and after every 10Gy radiation dose up to a cumulative dose of 60Gy by means of longitudinal microhardness. Data were analyzed using two-way analysis of variance and Tukey's test at a significance level of 5%. Enamel and dentin morphology was assessed by scanning electron microscopy (SEM) for semi-quantitative analysis (n=8 hemi-sections). Data were analyzed using Kruskal-Wallis and Dunn's or Fisher exact tests at a significance level of 5%. RESULTS: The application of ionizing radiation did not change the overall enamel microhardness, although an increase in superficial enamel microhardness was observed. The micro-morphological analysis of enamel revealed that irradiation did not influence rod structure but interprismatic structure became more evident. Dentin microhardness decreased after 10, 20, 30, 50 and 60Gy cumulative doses (p<0.05) compared with non-irradiated dentin, mainly in the middle portion of the tissue. The micro-morphological analysis revealed fissures in the dentin structure, obliterated dentinal tubules and fragmentation of collagen fibers after 30 and 60Gy cumulative doses. CONCLUSIONS: Although ionizing radiation did not affect the enamel microhardness of permanent teeth as a whole, an increase in superficial enamel microhardness was observed. Dentin microhardness decreased after almost all radiation doses compared with the control, with the greatest reduction of microhardness in the middle depth region. The morphological alterations on enamel and dentin structures increased with the increase of the radiation dose, with a more evident interprismatic portion, presence of fissures and obliterated dentinal tubules, and progressive fragmentation of the collagen fibers. CLINICAL SIGNIFICANCE: This study shows that irradiation affects microhardness and micro-morphology of enamel and dentin of permanent teeth. The effects of gamma irradiation on dental substrate might contribute to increased risk of radiation tooth decay associated with salivary changes, microbiota shift and high soft and carbohydrate-rich food intake.
OBJECTIVES: To evaluate, in vitro, the effects of ionizing radiation on the mechanical and micro-morphological properties of enamel and dentin of permanent teeth. METHODS: Enamel and dentin microhardness (n=12 hemi-sections) was evaluated at three depths (superficial, middle and deep) prior to (control) and after every 10Gy radiation dose up to a cumulative dose of 60Gy by means of longitudinal microhardness. Data were analyzed using two-way analysis of variance and Tukey's test at a significance level of 5%. Enamel and dentin morphology was assessed by scanning electron microscopy (SEM) for semi-quantitative analysis (n=8 hemi-sections). Data were analyzed using Kruskal-Wallis and Dunn's or Fisher exact tests at a significance level of 5%. RESULTS: The application of ionizing radiation did not change the overall enamel microhardness, although an increase in superficial enamel microhardness was observed. The micro-morphological analysis of enamel revealed that irradiation did not influence rod structure but interprismatic structure became more evident. Dentin microhardness decreased after 10, 20, 30, 50 and 60Gy cumulative doses (p<0.05) compared with non-irradiated dentin, mainly in the middle portion of the tissue. The micro-morphological analysis revealed fissures in the dentin structure, obliterated dentinal tubules and fragmentation of collagen fibers after 30 and 60Gy cumulative doses. CONCLUSIONS: Although ionizing radiation did not affect the enamel microhardness of permanent teeth as a whole, an increase in superficial enamel microhardness was observed. Dentin microhardness decreased after almost all radiation doses compared with the control, with the greatest reduction of microhardness in the middle depth region. The morphological alterations on enamel and dentin structures increased with the increase of the radiation dose, with a more evident interprismatic portion, presence of fissures and obliterated dentinal tubules, and progressive fragmentation of the collagen fibers. CLINICAL SIGNIFICANCE: This study shows that irradiation affects microhardness and micro-morphology of enamel and dentin of permanent teeth. The effects of gamma irradiation on dental substrate might contribute to increased risk of radiation tooth decay associated with salivary changes, microbiota shift and high soft and carbohydrate-rich food intake.
Authors: Marilia Mattar de Amoêdo Campos Velo; Ana Laura Herrera Farha; Paulo Sérgio da Silva Santos; Aymée Shiota; Simone Zuquerato Sansavino; Ana Tarsila Souza; Heitor Marques Honório; Linda Wang Journal: Clin Oral Investig Date: 2018-02-11 Impact factor: 3.573
Authors: Elza Maria de Sá Ferreira; Luis Eduardo Silva Soares; Héliton Spíndola Antunes; Sofia Takeda Uemura; Patrícia da Silva Barbosa; Hélio Augusto Salmon; Giselle Rodrigues de Sant'Anna Journal: Clin Oral Investig Date: 2015-12-22 Impact factor: 3.573
Authors: R Seyedmahmoud; Y Wang; G Thiagarajan; J P Gorski; R Reed Edwards; J D McGuire; M P Walker Journal: Clin Oral Investig Date: 2017-11-18 Impact factor: 3.573
Authors: Juliana Arid; Regina Guenka Palma-Dibb; Harley Francisco de Oliveira; Paulo Nelson-Filho; Fabricio Kitazono de Carvalho; Lea Assed Bezerra da Silva; Talitha de Siqueira Mellara; Raquel Assed Bezerra da Silva; Juliana Jendiroba Faraoni; Alexandra Mussolino de Queiroz Journal: Support Care Cancer Date: 2019-04-24 Impact factor: 3.603