Round Carbide Burs RA

RA Round Burs for Slow-Speed Contra-Angle Handpieces

These RA round burs are latch-type round carbide burs made for slow-speed contra-angle handpieces. The 2.35 mm RA latch shank locks into the handpiece head, and the 6-blade tungsten carbide head gives smooth, controlled cutting for caries excavation and access work. Choose from RA1/4 through RA8 (ISO 005 to 023), the RA330, or the surgical long-neck RAOS versions. Each pack contains 5 burs.

Why Use a Latch-Type Round Bur?

A slow-speed contra-angle gives more tactile feedback than a high-speed handpiece, which is why a slow speed round bur is a common choice for removing soft decay, entering the pulp chamber and refining a preparation. The latch shank holds the bur securely in the contra-angle head while you work.

Clinical Uses

• Slow-speed caries excavation and removal of soft, decayed dentin
• Entering the pulp chamber and refining endodontic access
• Opening and refining cavity preparations
• Restorative work in pediatric patients
• RAOS long neck: bone removal and tooth sectioning in oral surgery, where extra reach is needed

RA vs FG Round Burs

• RA (right angle, latch type): 2.35 mm shank with a latch groove, for slow-speed contra-angles. Lower speed and more control - preferred for deep caries and fine access work.
• FG (friction grip): 1.6 mm smooth shank held by friction in a high-speed handpiece. Faster cutting for enamel entry and cavity outlines.
• HP (straight handpiece): a longer, straight shank for straight handpieces - not interchangeable with RA.

An RA bur will not fit an FG handpiece, and the reverse is also true - check your handpiece head before ordering.

RA Round Bur Size Guide

RA sizes follow standard US round bur numbering. The ISO number gives the head diameter in tenths of a millimeter.

• RA1/4 – ISO 005, about 0.5 mm head
• RA1/2 – ISO 006, about 0.6 mm head
• RA1 – ISO 008, about 0.8 mm head
• RA2 – ISO 010, about 1.0 mm head
• RA3 – ISO 012, about 1.2 mm head
• RA4 – ISO 014, about 1.4 mm head
• RA5 – ISO 016, about 1.6 mm head
• RA6 – ISO 018, about 1.8 mm head
• RA7 – ISO 021, about 2.1 mm head
• RA8 – ISO 023, about 2.3 mm head
• RA330 – pear-shaped carbide bur on an RA shank
• RA2OS, RA3OS, RA4OS, RA6OS, RA8OS – surgical long-neck versions of sizes 2, 3, 4, 6 and 8

Choosing an RA Round Bur Size

• RA1/4 to RA1: pinpoint access, small pits and fine detail
• RA2 to RA4: pulp chamber entry, pulp horns and small to medium lesions
• RA5 to RA8: larger carious lesions and wide pulp chambers
• RAOS: surgical bone work and tooth sectioning

How to Use a Latch Round Bur

• Insert the shank fully and close the latch so the bur cannot slip or wobble.
• Run at the speed recommended by the handpiece and bur manufacturer.
• Use light pressure and short, sweeping strokes; let the blades cut.
• For caries excavation, work from the periphery of the lesion toward the pulp.
• For surgical RAOS use, irrigate copiously following your surgical protocol.

Cleaning, Sterilization and Bur Life

Before each use, pre-soak the burs in a disinfectant suitable for carbide, clean ultrasonically in a bur holder, rinse, dry, pouch and autoclave. Avoid cold sterilizing solutions and hydrogen peroxide, which can degrade tungsten carbide. Inspect every bur and discard it if the blades are chipped or dull, the shank is bent, or you see corrosion.

Common Mistakes That Shorten Bur Life

• Pressing hard instead of letting the bur cut
• Leaving the latch partly open or using a worn handpiece head
• Continuing with a dull bur, which raises heat and vibration

Specifications

• Shank: RA latch type, 2.35 mm (RAOS: longer surgical neck)
• Handpiece: slow-speed contra-angle with a latch-type head
• Material: one-piece tungsten carbide
• Blades: 6
• Head shape: round (RA330: pear)
• Pack size: 5 burs per pack
• Origin: made in Israel

Need FG Round Burs Too?

If you also use a high-speed handpiece, our round carbide burs in FG, RA and surgical long-neck shanks bring all three shank types together on one page. For fissure, pear and finishing shapes, browse our carbide burs collection.