Study of Dental Cutting with Tungsten Carbide Burs Covered with HFCVD Diamond of Different Thickness
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Study of Dental Cutting with Tungsten Carbide Burs Covered with HFCVD Diamond of Different Thickness F. Maass, E. Rojas Departamento de Física, Universidad de Antofagasta, Av. Angamos 601, Antofagasta, Chile. Email: [email protected]
ABSTRACT This study describes the covering process of dental burs with CVD diamond and the quality of its cut during dental procedure proving, at the same time, its advantages in comparison to regular dental burs. Ten equals burs made of tungsten carbide (WC) were covered with CVD diamond trough Hot Filament Chemical Vapor Deposition technique (HFCVD), varying thickness and temperature of deposit, leaving constant the rest of the deposit parameters like pressure (50 mbar) and gas flow (H2 and CH4). Dental cuts were comparing in a standard cutting device. The burs as well as the cuts were analyzed trough Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDX), what allow obtaining accurate measures of cuts and covering is chemical components. The quality and stress of the grown diamond was characterized by Raman analysis. Keywords: CVD, nucleation, Raman, SEM, diamond.
INTRODUCTION Usually, WC dental burs are used to cut tender tissue like dentine and cavity. However, burs can soon be damaged if get in contact with enamel due to its mineral and thick composition. Likewise, diamonds stones use to open enamel get soon damaged, suffering saturation of its surface by dentine, losing its cut capacity. Conventional diamond stones also lose its matrix particles during the process, becoming a less accurate instrument. Besides, being low dense and having a not fully homogeneous distribution, burs are excessively vibrating, get an uneven surface and lose diamonds faster [1,2,3]. In this study, active peaks of WC burs (SSWhite FG-57) has been covered with polycrystalline diamond trough Hot Filament Chemical Vapor Deposition technique (HFCVD)[8], determining that cut efficiency of burs do not change with CVD diamond covering; this is due to the characteristics of its mass, which is homogeneous and thin (20 µm), keeping the wedge action cut principle[5]. The kinetic friction coefficient of CVD diamond is like Teflon, and has a high thermal conduciveness coefficient, five times higher than cooper, making heat flow faster to the drain, keeping the surface with low temperatures. This has the advantage to allow innocuous cuts in order to maintain pulp vitality, also keeping down the damage to the teeth.
Mater. Res. Soc. Symp. Proc. Vol. 1275 © Materials Research Society
EXPERIMENTAL Ten WC burs were covered with polycrystalline diamond trough HFCVD technique. Deposit parameters of variation were time of deposit and temperature of deposit, while the rest were constant, like pressure (50 mbar) and H and CH4 gas (1% proportion of CH4 in H2). Five different thicknesses were covered (1 µm, 5 µm, 13 µm, 15 µm y 20 µm) with 2 temperatures of 700 y 800 ºC each one. Before each deposit, every bur was treated following a two-steps procedure, including an ultrasonic bath, and chemical att
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