ラマン顕微鏡とKnoop微小硬さを用いたカリウス象牙質の化学機械的特性評価

Chemo-mechanical characterization of carious dentine using Raman microscopy and Knoop microhardness.

• M Alturki
• G Koller
• U Almhöjd
• A Banerjee

抄録

歯牙齲蝕病変の臨床的な手術管理の目的の一つは，感染性の高い構造的に変性した歯質組織を選択的に除去しつつ，長期的な機械的強度を確保するために深部の修復可能な患部や無傷の健康な組織を保持することである．本研究では，ラマン分光法とKnoop微小硬さ試験を用いて，カリウス病変の深さの違いによる化学官能基と微小硬さの相関を調べた．帰無仮説として，ラマンピーク比（アミドI：リン酸塩）と等価なKnoop微小硬さ測定値との間には相関がないことを検討した．抜歯したばかりの人間の永久歯10本を切片化し，高分解能ラマン顕微鏡を用いて調べた．アミドIバンドとリン酸塩バンドの吸光度比を病変部の深さまでの139のスキャンポイントから計算し，139個のKnoop微小硬さの凹みと相関させた．その結果，カリウス象牙質病変内でのピーク比と等価なKnoop硬度との間には高い相関関係（<0.01）があることが示された．本研究では，ラマン分光法は，侵襲的で機械的なKnoop硬さ試験に代わる非侵襲的な分析技術として，ピーク比を用いてカリウス象牙質層の硬さを識別する研究に利用できると結論づけた．

One of the aims in the clinical operative management of dental carious lesions is to remove selectively the highly infected and structurally denatured dentine tissue, while retaining the deeper, repairable affected and intact, healthy tissues for long-term mechanical strength. The present study examined the correlation of chemical functional groups and the microhardness through the different depths of a carious lesion using Raman spectroscopy and Knoop microhardness testing. The null hypothesis investigated was that there was no correlation between Raman peak ratios (amide I : phosphate ) and equivalent Knoop microhardness measurements. Ten freshly extracted human permanent teeth with carious dentine lesions were sectioned and examined using high-resolution Raman microscopy. The ratio of absorbency at the amide I and phosphate bands were calculated from 139 scan points through the depth of the lesions and correlated with 139 juxtaposed Knoop microhardness indentations. The results indicated a high correlation ( < 0.01) between the peak ratio and the equivalent Knoop hardness within carious dentine lesions. This study concluded that Raman spectroscopy can be used as a non-invasive analytical technology for studies to discriminate the hardness of carious dentine layers using the peak ratio as an alternative to the invasive, mechanical Knoop hardness test.

© 2020 The Authors.