Background

The objectives were, establishment of diamond coating using Chemical Vapor Deposition (CVD) on tungsten carbide burs and, assessment of diamond film adherence at 250,000 rpm after cavity preparations on teeth.

Methods

Hot Filament CVD (HFCVD) was used to deposit a thin diamond film on tungsten carbide burs using 1–1.5% methane in excess hydrogen at 1800–2200 °C and 2700 - 6700 Pa pressure. Consistent and repeated film deposition of Microcrystalline diamond (MCD) and Nano crystalline diamond (NCD) could be achieved. Raman spectrometry and scanning electron microscopy (SEM) were used to confirm diamond deposition.

Adherence of the films was checked after cavity preparations on human teeth at speeds of ~250,000 rpm, and flank wear was determined using SEM.

Results

SEM images confirmed presence of microcrystalline and nanocrystalline forms. MCD had a 3–7 μm cubo-octahedral crystal formation. NCD was seen as 25–50 nm cuboidal facets in columnar formation. Raman spectrometry corroborated these findings. SEM of NCD showed no loss of diamond film or blunting of blades after three cavity preparations followed by a maximum loss of 33 μm after nine repeated cavity preparations. MCD showed partial loss of diamond film after third cavity with a maximum loss of 91 μm after nine repeated cavities.

Conclusion

Successful deposition of uniform diamond coating on tungsten carbide burs that remain adherent even at high rotational speeds was achieved and NCD coating adhered better compared to MCD.

Practical implication

The newly developed dental bur which combines the cutting action of bladed instruments and the hardness of diamond and provides a new area of clinical application.

中文翻译：

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用于高速空气涡轮机头的化学气相沉积金刚石牙钻

背景

目的是在碳化钨钻头上使用化学气相沉积（CVD）建立金刚石涂层，并在牙齿上准备腔后评估在250,000 rpm下金刚石膜的附着力。

方法

热丝CVD（HFCVD）用于在1800-2200°C和2700-6700 Pa的压力下，在过量氢气中使用1-1.5％的甲烷，在碳化钨钻头上沉积金刚石薄膜。可以实现微晶金刚石（MCD）和纳米晶金刚石（NCD）的一致且重复的膜沉积。拉曼光谱法和扫描电子显微镜（SEM）用于确认金刚石沉积。

在以〜250,000 rpm的速度在人牙齿上准备腔后，检查薄膜的附着力，并使用SEM确定侧面磨损。

结果

SEM图像证实了微晶和纳米晶形式的存在。MCD具有3–7μm的立方八面体晶体形成。NCD被视为柱状形成中的25–50 nm长方体小平面。拉曼光谱法证实了这些发现。NCD的SEM显示，经过三次腔准备后，金刚石膜没有损失或叶片变钝，经过九次重复腔准备后，最大损失为33μm。MCD在第三个腔后显示出金刚石膜的部分损失，在九个重复腔后最大损失为91μm。

结论

在均匀的碳化钨钻头上成功沉积了均匀的金刚石涂层，即使在高转速下也保持附着力，并且与MCD相比，NCD涂层的附着力更好。

实际意义

新开发的牙钻结合了刃具的切割作用和金刚石的硬度，为临床应用提供了新的领域。