KEYSTONE Prehma Round Carbide Burs . 4 HP (Handpiece). Ideal for initial entry, excavating

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Manufacturer item # 05-51448  ·  USDD item # 446324  ·  Variant 5

Shank3/32" HP (Handpiece) — lab bench use

MaterialTungsten Carbide

Cut actionCuts (does not polish)

Use environmentLaboratory — straight HP handpiece

SterilizationAutoclavable (Carbide tools)

OverviewWhy You'll Love ItSpecsHow to UseCompareOrder

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Overview

KEYSTONE 3/32" HP-shank tungsten Carbide Burs are the workhorse cutting tools of the dental Laboratory bench. The 3/32" (2.35 mm) shank is the universal standard for lab straight handpieces and bench-mount handpieces used to trim, shape, and reduce denture acrylic, base metals, gold and silver alloys, and chrome-cobalt partial frameworks. Tungsten Carbide cuts cleanly and predictably through these materials at the working speeds typical of lab handpieces, with significantly longer tool life than high-speed steel.

HP-shank means handpiece — these are lab Burs intended for the bench, not for direct intraoral chair-side reduction. (Chair-side intraoral high-speed reduction uses FG friction-grip Burs; chair-side slow-speed uses RA latch Burs. HP Burs belong on the lab side of the operatory wall.)

• Universal 3/32" (2.35 mm) HP shank. Fits every lab straight handpiece and bench-mount handpiece on the market.
• Tungsten Carbide cutting edges. Six to twelve times the tool life of high-speed steel; cuts cleanly under continuous load.
• Wide head-shape selection. Round, cone, cylinder, flame, taper, pear and bud shapes for every lab geometry — trimming, contouring, hollow-grinding.
• Plain-cut, cross-cut, and diamond-cut flute geometries. Plain cut for smooth finish; cross-cut and diamond-cut for fast bulk reduction.
• Autoclavable. Withstands standard steam-autoclave sterilization cycles, so the same bur can be used across multiple cases.

Technical specifications

Material & regulatory

KEYSTONE HP-shank tungsten Carbide Burs are Laboratory tools intended for use by dental technicians on bench-mount and straight handpieces. They are not classified as intra-oral medical devices and are not intended for direct chair-side reduction of natural tooth structure. Manufactured by KEYSTONE Industries.

How to use

Recommended use. Mount the bur fully into the lab straight handpiece chuck (3/32" / 2.35 mm collet). Operate at the speed recommended for the material being cut — typically 10,000–25,000 RPM for acrylic, slower for chrome-cobalt and gold. Use light pressure; Carbide cuts on its own and does not benefit from heavy hand-loading.

Caution. Tungsten Carbide is a hard, brittle material — Burs are designed to cut, not pry. Side-loading or prying with a Carbide bur can fracture the cutting edges or snap the shank. Discard Burs with chipped or rounded edges.

What Carbide should NOT be used on: glass-ceramic restorations (e.g. lithium disilicate, zirconia, feldspathic porcelain) — use diamond Burs for those. Carbide is also not appropriate for finishing natural enamel or dentine intraorally — chair-side enamel work is done with FG diamonds or FG Carbide finishing Burs on a high-speed handpiece, not HP shank.

Compare with cross-brand alternatives

Looking for alternatives? Here are equivalent products from other manufacturers carried by USDD, serving the same clinical or Laboratory purpose. The KEYSTONE Industries row is highlighted at the top.

Order this 3/32" HP Carbide bur

Available now from US Dental Depot. Request a custom quote for volume orders or speak with a product specialist for compatibility questions and clinical guidance.