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高齢者の歯根破折象牙質の急性脆化の結果
Root fractures in seniors: Consequences of acute embrittlement of dentin.
PMID: 32958308 DOI: 10.1016/j.dental.2020.08.008.
抄録
象牙質は加齢に伴って微細構造が不可逆的に変化し、管腔にミネラルが徐々に充填されていく。歯科硬化症として知られているこのプロセスは、根尖部から始まり、冠状に進行し、象牙質の破壊に対する抵抗力の低下と関連している。
Dentin undergoes irreversible changes in microstructure with aging that involve gradual filling of the tubule lumens with mineral. Known as dental sclerosis, this process begins at the root apex, progresses coronally, and is associated with a degradation in the resistance to fracture of dentin.
目的:
i) 特に歯根内での歯間象牙質の加齢に伴う経年変化、およびii) バイタル歯と無歯（つまり非バイタル歯）の間での経年劣化の違いを明らかにすること。
OBJECTIVE: To determine i) age-related changes of intertubular dentin with aging, particularly within the root, and ii) the differences in age-related degradation between vital and pulpless (i.e. non-vital) teeth.
方法:
若年者と老年者の歯の歯間象牙質と歯周象牙質を対象に，走査型ナノスコピック動的力学解析(nanoDMA)を行った．歯根管治療を受けた歯（非治療歯）と修復物のない歯（非治療歯）について、複素数、損失係数、保存係数、およびタンデルタパラメータを評価した。
METHODS: We performed nanoscopic dynamic mechanical analysis (nanoDMA) in scanning mode on the intertubular and peritubular dentin of teeth from young and old adults. The complex, loss and storage moduli, as well as the tan delta parameter were evaluated for teeth with no restorations and teeth with root canal treatment (non-vital).
結果:
歯根間象牙質の動的弾性率には加齢に伴う有意な変化が見られたが，その変化は歯根の先端3分の1で最も大きかった．歯根間象牙質の貯蔵弾性率（変形に対する純粋な弾性抵抗力を定量化したもの）は、若い歯よりも古い歯とそうでない歯の両方で、根の長さ全体にわたって有意に（p < 0.0005）大きかった。しかし，粘性変形の相対的な能力を定量化するtanδパラメータは，これら2群で有意に低かった（p < 0.005）．
RESULTS: There were significant changes in the dynamic moduli of intertubular dentin with age, which were most substantial in the apical third of the root. The storage modulus of the intertubular dentin, which quantifies the purely elastic resistance to deformation, was significantly (p < 0.0005) larger for both the old vital and non-vital teeth than that of the young teeth, over the entire root length. However, the tan delta parameter, which quantifies the relative capacity for viscous deformation, was significantly lower in these two groups (p < 0.005).
重要性:
ラディキュラー象牙質は加齢に伴って脆化し、粘性変形能力が低下します。劣化の程度は先端3分の1が最も大きい。歯髄を除去すると、老化の進行が促進されたり、劣化の程度が複雑になったりするようです。
SIGNIFICANCE: Radicular dentin undergoes an embrittlement with aging, involving reduced capacity for viscous deformation. The extent of degradation is largest in the apical third. Removal of the pulp appears to accelerate the aging process or compound the extent of degradation.
Copyright © 2020 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.