Ceramic bearings extend life of dental handpiece

DN Staff

June 10, 1996

3 Min Read
Ceramic bearings extend life of dental handpiece

Lancaster, PA--For dentists, autoclaving or heat sterilization provides the best barrier against the transmission of communicable diseases. Unfortunately, the process takes a toll on powered instruments.

Other Applications

- Bone reamers - Plaster cast rotary saws - Turbocharger impellers

Autoclaving's high temperatures exacerbate the corrosive effects of the moisture and chemicals normally used to lubricate the bearing assemblies of such tools. It's estimated that a turbine-driven handpiece not subjected to sterilization can last a dentist 20 years with minimal repair. The same handpiece, if subjected to heat sterilization, lasts about two years with major repairs.

By substituting 1-mm-diameter silicon nitride balls for the traditional steel balls in its lube-free turbine-powered handpiece, Star Dental offers dentists a long-life, high-performance tool that withstands the rigors of autoclaving.

BEARING BALL MATERIAL PROPERTY COMPARISON

PROPERTY

NBD-200

M50

BG42/440C

Si3N4

STEEL

STEEL

STEEL

DENSITY (g/cc)

3.16

7.6

7.8

HARDNESS (Rc)

78

64

62

ELASTIC MODULUS (GPa)

320

190

200

POISSON'S RATIO

0.26

0.28

0.28

THERMAL EXPANSION COEFFICIENT (10-6/C) (RT TO 800C)

2.9

12.3

10.1

MAXIMUM USE TEMPERATURE (C)

1,000

320

260

FATIGUE LIFE, L10(Relative to M50)

100X

1X

0.5X

WEAR RESISTANCE (Relative to M50 In Fatigue Testing)

100X

1

0.5X

Supplied by Norton Advanced Ceramics, East Granby, CT, the ceramic bearing components will not surface-erode under high-speed stress. Unlike steel bearings, they maintain a low coefficient of friction, exhibit little heat buildup, reduce centrifugal loads, and minimize retainer wear. Pre-loading, moreover, keeps the bearings in constant contact with their raceways, which prevents ball skidding during startup--another source of premature wear.

Equally important, the ceramic bearings operate without lubrication. The steel bearing assemblies of high-speed dental tools, by comparison, require a continuous supply of lubricant, normally contained within the air supplied to the turbine. In the long run, such lubricated parts do not withstand steam- or chemical-vapor sterilization.

Lubrication-free operation offers a side benefit as well. Because there are no residual lubricants that might be expelled into the oral cavity, the handpiece promotes infection control.

Additional details, ceramic bearings...Contact Tony Taglialavore, Norton Advanced Ceramics, 10 Airport Park Rd., East Granby, CT 06026, (203) 653-8071.

Additional details, handpiece...Contact Star Dental, Den-tal-ez Inc., 1816 Colonial Village Lane, Lancaster, PA 17601, (717)-291-1161.

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