Reitemeier Bernd, Reitemeier Gottfried, Schmidt Annette, Schaal Wolfgang, Blochberger Peter, Lehmann Dietmar, Herrmann Thomas
Department of Prosthodontic Dentistry, Medical Faculty Carl Gustav Carus, Technical University of Dresden, Dresden, Germany.
J Prosthet Dent. 2002 Mar;87(3):323-7. doi: 10.1067/mpr.2002.122506.
For some patients, radiation treatment is a part of tumor therapy in the head and neck area before and/or after surgery. The oral cavity and teeth are thereby frequently exposed to high doses of radiation. In this situation, electronic backscatter from dental materials may damage the surrounding soft tissue.
This study determined the degree of absorption and the backscatter effect of therapeutic radiation used in the presence of 4 different dental materials. The efficacy of a protective stent also was investigated.
The influence of 4 dental materials (a high-gold alloy, pure titanium, amalgam, and a synthetic material) on radiation dose distribution was tested on 2 test models that simulated the presence of teeth. An alanine dosimeter was used to make measurements with and without the presence of a protective stent. To verify the results, one of the test models was compared to a computer simulation.
Backscatter effects on the surface of dental materials caused an increase of up to 170% of the radiation dose measured without the materials. The rate of overdose increased with the atomic number of the dental material. The extent of the backscatter effect was a maximum of 4 mm.
The considerable overdose of 170% found in this study suggests that soft tissue surrounding dental restorations should be protected from radiation. The backscatter results indicate that soft tissue could be effectively shielded with a 3-mm synthetic stent.
对于一些患者而言，放射治疗是头颈部肿瘤手术前和/或后的治疗组成部分。口腔和牙齿因此经常暴露于高剂量辐射。在这种情况下，牙科材料的电子反向散射可能会损伤周围软组织。
本研究确定了4种不同牙科材料存在时治疗性辐射的吸收程度和反向散射效应。还研究了一种保护性支架的效果。
在2个模拟牙齿存在情况的测试模型上，测试了4种牙科材料（一种高金合金、纯钛、汞合金和一种合成材料）对辐射剂量分布的影响。使用丙氨酸剂量计在有和没有保护性支架的情况下进行测量。为验证结果，将其中一个测试模型与计算机模拟进行比较。
牙科材料表面的反向散射效应导致测量的辐射剂量比没有材料时增加了高达170%。过量剂量率随牙科材料的原子序数增加而增加。反向散射效应的范围最大为4毫米。
本研究中发现的高达170%的显著过量剂量表明，牙科修复体周围的软组织应受到辐射防护。反向散射结果表明，使用3毫米的合成支架可以有效屏蔽软组织。
