キュレットの研磨とスケーリングによる摩耗と破壊

Wear and fracture of curettes due to sharpening and scaling processes.

抄録

目的:

新品のGracey社製キュレットの研ぎ出しとスケーリングによる摩耗を調べ、破損までの使用回数を記録する。

OBJECTIVES: To examine the wear occurring in a group of new Gracey curettes due to the sharpening and scaling processes and record the number of service cycles before breakage.

研究方法:

本研究では，592本のGracey curettesを対象とし，研磨とスケーリングのサイクルを行った。各工程の前後に，刃の三次元的な測定と作用端の状態を記録した。

METHODS: This study included 592 working ends of Gracey curettes that were subjected to cycles of sharpening and scaling. Three-dimensional measurements of the blades and the status of the working ends were recorded before and after each process.

結果:

使用回数の増加に伴い，刃の三次元的な寸法は減少した。今回の研究では184個のワーキングエンドが破損したが，そのうち38.59%が#11/12 Gracey curettesであり，#7/8 Gracey curettesはわずか8.15%であった。Gracey curettesの破断に要した平均サイクル数は14.34であった。Cox回帰分析の結果、生存サイクルに影響を与える因子は、使用前のチップ幅とグレイスキュレットの種類であった。また，器具の摩耗の約半分は，研磨工程で生じていた。4種類のGracey curettesの中では、#11/12 Gracey curettesが最も多くのシャープニング摩耗を示し、全摩耗の50％以上を占めた。

RESULTS: With an increase in the number of usage cycles, the three-dimensional measurements of the blades decreased. During this study, 184 working ends were broken, of which 38.59% were of #11/12 Gracey curettes, and only 8.15% were of #7/8 Gracey curettes. The average number of cycles required for the fracture of Gracey curettes was 14.34. Cox regression analyses showed that the factors influencing the survival cycles were the tip width before usage and the type of Gracey curette. Moreover, the sharpening process was responsible for approximately half of the total instrument wear. Among the four types of Gracey curettes, the #11/12 Gracey curettes showed the greatest amount of sharpening wear, accounting for >50% of the total wear.

結論:

Gracey curettesの寿命はその種類によって異なり、#11/12 Gracey curettesは破損しやすく、#7/8 Gracey curettesは長い寿命を持つ傾向があることがわかった。また，キュレットの摩耗には，研磨工程が大きく関与していた。

CONCLUSIONS: The service life of Gracey curettes varies according to their types; the #11/12 Gracey curettes are more susceptible to breakage, while #7/8 Gracey curettes tend to have a long service life. Furthermore, the sharpening process was responsible for a considerable amount of curette wear.