初期の天然う蝕病巣における定量的なレーザー蛍光と光路長に及ぼす乾燥の影響について

The influence of drying on quantitative laser fluorescence and optical pathlengths in incipient natural caries lesions.

抄録

14個の天然う蝕病巣における乾燥の影響を，定量的光誘起蛍光および光路長分光法を用いて検討した．結果は，病巣表面の臨床的判断および病巣のマイクロラジオグラフィ的特徴と比較した．相対蛍光と平均光路長は乾燥時間の経過とともに減少し，その減少時間は35.5分から1分未満であった．深さとミネラルの減少は，平均パスレングスの変化と相関し（それぞれr = -0.79/-0.60），蛍光の変化とはあまり相関しなかった（r 約 = 0.3）。相対蛍光の乾燥過程の減衰時間は、病変部と表層部の水の拡散に基づく理論モデルとよく相関したが、減衰時間が大きい場合のみであった。臨床的判断は，表面層の特性や平均パスレングスの変化とは関連しないが，相対蛍光の変化とは弱い関連性があった。結論として，(i)蛍光効果は，象牙質およびエナメル象牙質接合部からの蛍光が病変部で遮蔽されることに起因する，(ii)病変部での水の蒸発は，表面層の浸透性が低い大きな病変部でのみ拡散法則に適合する，(iii)蒸発プロセスは，表面の浸透性が低い場合（約0.1 vol% microm(-1)）にのみ表面層によって制御される，とした。

Drying effects in 14 natural lesions were studied with quantitative light-induced fluorescence and optical pathlength spectroscopy. Results were compared with clinical judgments of the lesion surface and microradiographical characterizations of the lesions. Relative fluorescence and average pathlength decreased as a function of drying time with a decay time ranging from 35.5 to <1 min. Depth and mineral loss correlated with average pathlength total changes (r = -0.79/-0.60, respectively) and poorly with total fluorescence changes (r approximately = 0.3). The decay time of the drying process for the relative fluorescence correlated well with a theoretical model based on water diffusion in lesion and surface layer, but only for large decay times. Clinical judgments could not be related to the surface layer properties or the changes in the average pathlength, but were weakly related to the changes in the relative fluorescence. We conclude that (i) fluorescence effects are mostly due to the screening by the lesion of the fluorescence from the dentin and enamel-dentin junction; (ii) water evaporation in lesions conforms to the diffusion laws only in large lesions with low surface layer penetrability; (iii) the evaporation process is controlled by the surface layer only for small surface penetrabilities (approximately 0.1 vol% microm(-1)).