熱サイクルを受けたクラスVコンポジット修復物の marginal microleakage に対する選択した脱感作剤の影響：in vitro 研究

The influence of a selected desensitizer on marginal microleakage of a class V composite restoration subjected to thermocycles: an in vitro study.

抄録

序論:

象牙質知覚過敏症は、痛みを伴う臨床症状である。象牙質知覚過敏症の発生頻度は8～57％であり，対象となるグループや調査方法によって異なる．推奨される減感作剤は，その作用機序や効果が異なる。私たちは、効果を向上させると同時に、例えば基材として、術後の過敏症対策、辺縁部のマイクロリークの低減など、より幅広い使用を可能にする解決策を模索しています。本研究の目的は，ハイドロキシアパタイトカルシウムで象牙質細管を閉塞する選択された脱感作剤が，サーモサイクルにかけられたクラスVコンポジット修復物の辺縁マイクロリーク形成に及ぼす影響を評価することである．

INTRODUCTION: Dentin hypersensitivity is a painful clinical condition. The frequency of its occurrence varies from 8 to 57%, depending on tested group and different methods of investigations. Recommended desensitizing agents have different mechanism of action and effectiveness. We are still looking for solutions that will improve their effectiveness and simultaneously allow for wider use of e.g. as a base material, counteracting postoperative hypersensitivity, reducing marginal microleakage. The aim of the study was to assess the effect of a selected desensitizing agent occluding dentin tubules with calcium hydroxyapatite on marginal microleakage formation of a class V composite restorations subjected to thermocycles.

材料と方法:

臼歯部と小臼歯部の40症例を2つのグループに分けて研究を行った。両群とも標準的な窩洞を作製した。研究群（SG）では，ボンディング剤を塗布する前に，Teethmate Desensitizer（f. Kuraray, Noritake Dental Inc.対照群（Control group - CG）では，OptiBond All-in-one（f. Kerr, Bioggio, Switzerland）ボンディング剤を使用し，Gradia Direct（f. GC Europe N.V., Leuven, Belgium）を用いて窩洞を充填した．生理食塩水で保存した後、歯を600回のサーモサイクルにかけ、受動的な色素浸透テストを行い、充填部分の歯をその長軸に沿って切断した。光顕微鏡で拡大してマイクロリーケージの値を測定し，限界マイクロリーケージ率（M）を数えた。テストの結果は，STATISTICA 12.0 (StatSoft, USA)を用いて統計的に分析した．

MATERIALS AND METHODS: In study it was used 40 molars and premolars, which were alternately assigned into two groups. In both groups standardized cavities were prepared. In the study group (study group - SG) before application of bonding agent Teethmate Desensitizer (f. Kuraray, Noritake Dental Inc., Okayama, Japan) was used. In the control group (control group - CG) OptiBond All-in-one (f. Kerr, Bioggio, Switzerland) bonding agent was used and cavities were filled using composite material Gradia Direct (f. GC Europe N.V., Leuven, Belgium). After storage in saline, teeth were subjected to 600 thermocycles, passive dye penetration test was done, teeth were cut in the area of filling, according to its long axis. Under light microscope magnification value of microleakage was measured and marginal microleakage rate (M) was counted. The results of the tests were statistically analyzed using the package STATISTICA 12.0 (StatSoft, USA).

結果:

SG群のMの平均値は0.46（最小0.05、最大0.76、SD 0.226）、CG群は0.22（最小0、最大0.74、SD 0.235）であった。M値の違いは、統計的に有意であった（p＝0.0094）。

RESULTS: The average value of M for the SG group was 0.46 (min 0.05, max 0.76, SD 0.226) and for CG was 0.22 (min 0, max 0.74, SD 0.235). The differences between M values were statistically significant (p = 0.0094).

結論:

ボンディングシステムの保持部位の数が減ると，実験条件でのマイクロリークの形成が容易になり，コンポジット材の歯の硬組織への接着度が低下する。

CONCLUSION: A reduction in the number of retention sites for the bonding system, facilitates the formation of microleakage in the experimental conditions and reduces the degree of adhesion of the composite material to the hard tissues of the tooth.