Velo Marilia Mattar de Amoêdo Campos, Farha Ana Laura Herrera, da Silva Santos Paulo Sérgio, Shiota Aymée, Sansavino Simone Zuquerato, Souza Ana Tarsila, Honório Heitor Marques, Wang Linda
Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Al. Dr Octávio Pinheiro Brisolla 9-75 Vila Universitária, Bauru, SP, CEP: 17012-901, Brazil.
Department of Surgery, Stomatology, Pathology and Radiology, Bauru School of Dentistry, University of São Paulo, Al. Dr Octávio Pinheiro Brisolla 9-75 Vila Universitária, Bauru, SP, CEP: 17012-901, Brazil.
Clin Oral Investig. 2018 Nov;22(8):2871-2878. doi: 10.1007/s00784-018-2373-6. Epub 2018 Feb 11.
Post-radiation dental lesions affect mainly the cervical area of the tooth. Until now, there are quite few evidences regarding the effects of radiation exposure on root dentin breakdown. To better understand this effect, we used human root dentin specimens obtained from third molars from similarly aged individuals.
Twenty specimens were analyzed by the surface hardness (SH), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) to evaluate the baseline properties of their root dentin. Other six human teeth were prepared and analyzed by scanning electron microscopy (SEM). Then the specimens were randomly distributed between two groups (n = 13 per group) and irradiated with a total dose of 55 or 70 Gy in a linear accelerator. The percentage of EDX and surface hardness loss (%SHL) were determined based on measurements before and after irradiation. The specimens were also analyzed after irradiation by SEM and XRD. The Ca/P weight ratio was calculated.
Based on SEM analysis, radiation exposure induced dehydration of the dentin. The Ca/P weight ratio decreased (p = 0.0045). The %SHL of specimens irradiated with 70 Gy was higher than that of the 55-Gy group (p < 0.05), although even the lower dose induced root dentin breakdown.
Overall, we can state that radiation exposure changes the composition and structure of human root dentin, which detrimentally affect its hardness.
The changes reported herein might influence the selection of the dental materials and will bring new knowledge in this field to prevent radiation-related caries in root dentin.
放射后牙齿病变主要影响牙齿的颈部区域。到目前为止，关于辐射暴露对牙根牙本质破坏影响的证据相当少。为了更好地理解这种影响，我们使用了从年龄相仿个体的第三磨牙获取的人牙根牙本质标本。
通过表面硬度（SH）、能量色散X射线光谱法（EDX）和X射线衍射（XRD）对20个标本进行分析，以评估其牙根牙本质的基线特性。另外制备并通过扫描电子显微镜（SEM）分析了6颗人牙。然后将标本随机分为两组（每组n = 13），并在直线加速器中接受55或70 Gy的总剂量照射。根据照射前后的测量结果确定EDX和表面硬度损失百分比（%SHL）。照射后还通过SEM和XRD对标本进行分析。计算钙/磷重量比。
基于SEM分析，辐射暴露导致牙本质脱水。钙/磷重量比降低（p = 0.0045）。接受70 Gy照射的标本的%SHL高于55 Gy组（p < 0.05），尽管较低剂量也会导致牙根牙本质破坏。
总体而言，我们可以说辐射暴露会改变人牙根牙本质的组成和结构，从而对其硬度产生不利影响。
本文报道的这些变化可能会影响牙科材料的选择，并将为该领域带来新知识，以预防牙根牙本质中的放射性龋齿。
