US No. 7 Bur – Busch Round Carbide & Steel, Made in Germany

The US No. 7 is the American number for a round bur with a 2.1 mm head (ISO size 021): a spherical head that cuts on every surface, so it excavates, opens and shapes in any direction. Busch & Co. manufactures it in Germany as Busch No. 1 021 and Busch No. 1S 021 (plus 2 further variants below). Every US No. 7 on this page is a genuine Busch instrument and ships from our US warehouse.

Which US No. 7 Do You Need?

FG (friction grip, 1.6 mm shank, high-speed handpiece). RA (latch, 2.35 mm shank, contra-angle). HP (2.35 mm shank, straight handpiece). RA-L (latch, 26 mm surgical length). See the Busch Bur Size Chart for head and shank dimensions.

Clinical Uses of the US No. 7

• Caries excavation: removing softened dentin from the cavity floor and walls with light, sweeping strokes.
• Access: initial penetration of enamel and the first opening of a cavity or endodontic access.
• Retention and shaping: undercuts and retention grooves where a rounded form is wanted, and smoothing rounded internal line angles.
• Laboratory work: the HP and steel versions hollow out, relieve and adjust acrylic, plaster and wax in the straight handpiece.

At 2.1 mm the No. 7 is a large head for gross excavation, prosthetic and laboratory reduction.

The 7S is Busch’s fast-cutting version (green ring); the 7SX adds the SX-cut geometry that cuts fast with noticeably less vibration (green ring, gold-plated neck); the 7SXM puts the same SX-cut on an extra-slender neck for a clear view of the working area in minimally invasive excavation.

Speed and Technique

In the high-speed handpiece use the FG versions with water spray and a light touch; the RA versions belong in the slow-speed contra-angle for caries removal, where lower speed gives better tactile feedback; HP versions run in the straight handpiece for laboratory work. Maximum recommended speeds for every Busch shape are in our Dental Bur Speed Chart, and reprocessing steps in the Bur Sterilization Guide.

Made in Germany by Busch & Co.

Busch & Co. has manufactured rotary instruments in Engelskirchen, Germany since 1905. Every instrument on this page is a genuine Busch product, precision-ground on a concentric shank under ISO-certified quality management and guaranteed to arrive free of manufacturing defects under our Busch arrival guarantee.

FAQ

What is the Busch number for a US 7 bur? Busch No. 1 021 in carbide (FG/RA/HP); Busch No. 1 021 in steel (HP). The 7S is Busch 1S 021; the 7SX is Busch 1SX 021; the 7SXM is Busch 1SXM 021.

What size is a No. 7 bur? The No. 7 has a 2.1 mm head diameter (ISO size 021) on a round bur head, ISO shape 001 (ball).

What do the letters after No. 7 mean? The 7S is Busch’s fast-cutting version (green ring); the 7SX adds the SX-cut geometry that cuts fast with noticeably less vibration (green ring, gold-plated neck); the 7SXM puts the same SX-cut on an extra-slender neck for a clear view of the working area in minimally invasive excavation.

Carbide or steel? Tungsten carbide for enamel, dentin, composite and amalgam in the clinic; the steel No. 7 is the economical choice for acrylics, plaster and other soft materials in the laboratory.

Are Busch No. 7 burs reusable? Yes. Carbide and steel burs are cleaned, disinfected and sterilized between patients and replaced when they dull; the Bur Sterilization Guide gives the validated steps.

Related resources: US Bur Number Finder · Bur Comparison Chart · Speed Chart · Bur Glossary · Nearby sizes: US No. 5, US No. 6, US No. 8, US No. 9