Dental Bur Chart: Carbide Bur Numbers, Shapes and ISO Sizes

A dental bur chart for carbide burs connects two numbering systems. In the US each shape family has its own number range, so the number alone separates a 330 pear from a 557 straight fissure crosscut or a 701 tapered fissure crosscut. ISO 6360 gives every rotary instrument a 15-digit code whose last group is the head diameter in tenths of a millimeter: a 557 has a 1.0 mm head and the ISO size code 010.

Operative carbide burs from SS White, Kerr and Midwest have six blades, while finishing burs have 12 or 30, which cut less and leave a smoother surface. The same number often comes in friction grip, latch and straight handpiece versions, and dental carbide burs are sold in anything from surgical-length 5-packs to 100-bur clinic packs.

What Separates One Carbide Bur From Another

Five characteristics separate carbide burs that look alike in a catalog, and each shows up in the number or its letters.

• Head diameter. Within a shape family a higher number means a larger head, from 0.5 mm for the 1/4 round to 2.3 mm for the 8.
• Blade cut. Crosscut straight fissure burs take a leading 5, so the 57 becomes the 557; KaVo Kerr describes crosscuts as more efficient, also in dentin at lower speeds.
• End shape. A leading 1 marks the round-end version of a fissure bur, as in the 1557, which leaves rounded internal line angles.
• Head length. An L suffix marks a longer head at the same diameter: 5.2 mm for the 169L against 4.2 mm for the 169 in Brasseler USA's chart.
• Shank. FG shanks fit high-speed handpieces, RA latch shanks slow-speed contra-angles and HP shanks straight handpieces.

Dental Bur Chart: Carbide Shapes, US Numbers and ISO Sizes

The dental bur chart gives the main US numbers of each carbide shape, their head diameters and the ISO size codes. Diameters are those on which the Brasseler USA, Coltene (Alpen), Dentsply Sirona (Midwest) and KaVo Kerr catalogs agree, and "varies by brand" marks the exceptions.

Where Dental Bur Charts From Different Brands Disagree

Head diameters match across catalogs for most dental bur numbers. The exceptions start with the 1/2 round, 0.6 mm for Brasseler, Kerr and Midwest and 0.7 mm for Alpen. The 245 is 0.8 mm for Brasseler, Alpen and NTI and 0.9 mm for Kerr, Midwest and Meisinger, and the 556 is 0.9 mm for Brasseler, Alpen and Midwest but 0.8 mm in SS White's listings.

Inverted cones vary the most: Brasseler and Alpen list the 34, 36 and 37 at 0.8, 1.2 and 1.4 mm, Midwest's operative chart at 0.9, 1.0 and 1.2 mm, and the 33 1/2 is 0.6 or 0.7 mm depending on the brand. Head lengths differ too, so the chart leaves them out: the 169 cuts over 3.2 mm for Midwest, 4.1 mm for Alpen and 4.2 mm for Brasseler. When brands are mixed in one operatory, the diameter and length on each listing are the figures to compare.

What Do the Five Groups of an ISO Bur Number Mean?

An ISO 6360 bur number has 15 digits in five groups of three, each coding one characteristic. ISO 6360-1 sets the structure, and the later parts of the standard hold the tables.

• Material. 500 for tungsten carbide, 806 for diamond.
• Shank and overall length. 314 for standard friction grip, 313 short shank, 316 surgical length, 204 latch and 104 straight handpiece.
• Shape. A code from the tables of ISO 6360-2.
• Specific characteristics. The type of toothing for carbide burs (ISO 6360-3) and the grit of dental diamond burs.
• Nominal diameter. The largest head diameter in tenths of a millimeter.

A 557 on a standard friction grip shank therefore reads 500, 314 and 010 in the first, second and fifth groups, and the size group is what links the dental bur chart to ISO. Brasseler USA uses a shorter code on the same logic: its 556 is H31.31.009, for shape figure, shank and size.

Shank Types: FG, RA Latch and HP

Every head in the dental bur chart comes on one or more shanks, and the KaVo Kerr and Brasseler USA catalogs agree on the dimensions of the FG, RA and HP types.

• FG (friction grip), ISO 314. 1.6 mm wide and 19 mm overall, for high-speed handpieces. The short shank (FGSS, ISO 313) is 16 to 16.5 mm, and the surgical length (ISO 316), labeled FGSL, FG Surg or FGOS, is 25 mm.
• RA latch, ISO 204. 2.35 mm wide and 22 mm overall, for slow-speed contra-angles; 26 mm in surgical versions (ISO 205).
• HP (straight handpiece), ISO 104. 2.35 mm wide and 44.5 mm overall; up to 65 mm for oral surgery (ISO 105).

Not every number comes on every shank: in Brasseler's chart the 330 is made in five shank versions, latch and HP included, while the 245 comes only in FG and short shank.

Round Burs, 1/4 to 8

Round burs have the widest size range of the carbide shapes, and the series continues past the dental bur chart to the 10, at 2.7 mm. KaVo Kerr and Midwest describe them for initial entry, caries excavation, access openings and retentive features, with the smaller sizes for conservative preparations.

For excavation at slow speed, the round #4 comes on a latch shank with the same 1.4 mm head as the friction grip version.

Pear Burs and the 245

Pear burs cut converging walls with rounded internal line angles, which KaVo Kerr and Midwest describe for mechanical retention. The 245 keeps a similar outline on a longer head, 2.7 to 3.0 mm against 1.6 to 2.0 mm for the 330, and SS White, Kerr and Midwest list it as an amalgam preparation bur.

For small occlusal preparations, the 330 is the 0.8 mm pear, and the size tested in the autoclaving study discussed below.

For amalgam preparations with a flat floor, the 245 is the longer-headed alternative.

Straight Fissure Burs: 56 to 58, 556 to 558 and 1557

Straight fissure burs cut parallel walls and a flat floor to establish the outline of a preparation, and the round-end 1556 to 1558 give the same walls with rounded corners and an easier entry. Surgical-length 557 and 1557 burs are made for sectioning teeth and cutting bone.

For preparation outlines, the crosscut 557 combines a 1.0 mm head with the faster cut of notched blades.

Tapered Fissure Burs: 169 to 171 and 699 to 703

Tapered fissure burs cut the divergent walls of inlay, onlay and crown preparations, and KaVo Kerr notes that the taper helps keep full-length enamel margins on convex surfaces. The crosscut 700 to 703 also come in surgical and straight handpiece versions for sectioning teeth and bone.

For indirect restorations, the 169L adds head length without changing the 0.9 mm diameter.

Inverted Cone and End Cutting Burs

Inverted cone burs are wider at the tip than at the neck and cut undercuts and retention locks. End cutting burs carry blades only on the tip, so they flatten a floor or finish a margin without cutting the axial wall; the 957 measures 1.0 mm and the 958 1.2 mm.

Trimming and Finishing Burs: 7000 and 9000 Series

Finishing burs follow their own numbering. In the KaVo Kerr and Midwest catalogs the 7000 series has 12 blades and the 9000 series 30, so the 7406 and the 9406 are the same egg shape with a different blade count. The shapes include the egg or football, the needle 7901 for secondary anatomy and the flame 7104 to 7108, and NTI adds its own figure number, H379, to the football burs listed as 7404 to 7408.

For contouring posterior occlusal surfaces, the 7406 is the 12-blade football in the middle size.

Can Carbide Burs Be Sterilized and Reused?

Carbide burs can go through repeated autoclave cycles without a perceived loss of sharpness, but after clinical use they carry damage and debris that led the authors of a 2023 study to classify them as single-use. Spranley et al. (2011) gave five experienced operators No. 330 burs autoclaved zero, one, two, five or ten times, without telling them which was which; each bur cut through the enamel of an extracted tooth and then an occlusal preparation in a composite model. Up to ten cycles did not significantly change the ratings of initial sharpness or cutting effectiveness, although the ratings were subjective and most of the cutting was in composite.

Uchoa-Junior et al. (2023) examined 84 rotary cutting instruments, 42 carbide and 42 diamond burs, by electron microscopy and culture in a study of five cycles of clinical use and processing. Carbide burs in every group showed structural damage, bacteria were isolated from 4 instruments (9.52%) and biofilm was seen on 3 (7.14%), and the authors concluded that these instruments should be single-use, in which case the price per bur becomes a cost per procedure.

Carbide Burs and Alara: Get the Best Deals from Trusted Suppliers

Carbide burs are reordered by the pack for every operatory, and the same number is sold by many vendors at different prices. Alara compares real-time offers on the carbide burs in this dental bur chart, from SS White and NTI to Midwest, Kerr, Meisinger and Alpen, across 15+ verified vendors.

References

1. Spranley TJ, Cheramie TJ, Ireland EJ, Sergent RS, Yeadon WR, Desonier DP, Raymond WD, Hagen JL. Cutting effectiveness of carbide burs following multiple steam autoclaving cycles. Gen Dent. 2011;59(1):53-58. PMID: 21613040. DOI: not listed in PubMed
2. Uchoa-Junior FA, Barata TJE, Leao-Vasconcelos LSNO, Ribeiro EL, Tipple AFV. Biofilm on and structural damage of rotary cutting instruments after 5 cycles of clinical use and processing. J Am Dent Assoc. 2023;154(6):495-506. PMID: 37115139. DOI: 10.1016/j.adaj.2023.03.005