{"title":"US No. 40 Bur – Busch Inverted Cone Steel, Made in Germany","description":"\u003cp\u003eThe \u003cstrong\u003eUS No. 40\u003c\/strong\u003e is the American number for a inverted cone bur with a 2.1 mm head (ISO size 021): a head that widens toward the tip, so it cuts undercuts and flat floors that a round or cylinder bur cannot. Busch \u0026amp; Co. manufactures it in Germany as \u003cstrong\u003eBusch No. 2 021\u003c\/strong\u003e. Every US No. 40 on this page is a genuine Busch instrument and ships from our US warehouse.\u003c\/p\u003e\u003ch2\u003eWhich US No. 40 Do You Need?\u003c\/h2\u003e\u003cdiv style=\"overflow-x:auto;-webkit-overflow-scrolling:touch;\"\u003e\u003ctable style=\"border-collapse:collapse;font-size:14px;\"\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eUS No.\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eBusch No.\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eMaterial\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eCut\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eShank\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003eBest for\u003c\/th\u003e\n\u003cth style=\"border:1px solid #ddd;padding:6px 10px;text-align:left;background:#f6f6f6;\"\u003ePack\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\u003ctr\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003e\u003ca href=\"\/products\/inverted-cone-steel-dental-bur-hp-us-40-pack-of-6\"\u003e40\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003e2 021\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003eSteel\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003ePlain-cut\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003eHP\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003eEconomical laboratory cutting of acrylics and plaster\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ddd;padding:6px 10px;\"\u003e6\u003c\/td\u003e\n\u003c\/tr\u003e\u003c\/tbody\u003e\n\u003c\/table\u003e\u003c\/div\u003e\u003cp style=\"font-size:13px;\"\u003eHP (2.35 mm shank, straight handpiece). See the \u003ca href=\"\/pages\/busch-bur-size-chart\"\u003eBusch Bur Size Chart\u003c\/a\u003e for head and shank dimensions.\u003c\/p\u003e\u003ch2\u003eClinical Uses of the US No. 40\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eRetention form:\u003c\/strong\u003e cutting undercuts at the base of a preparation so a restoration locks in place.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlat floors:\u003c\/strong\u003e flattening the pulpal floor of Class I and Class II preparations.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClass V and access refinement:\u003c\/strong\u003e squaring the internal form of small preparations.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLaboratory work:\u003c\/strong\u003e the HP and steel versions cut retention channels and relief in acrylic and plaster.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eAt 2.1 mm the No. 40 is a large head for prosthetic and laboratory reduction.\u003c\/p\u003e\u003ch2\u003eSpeed and Technique\u003c\/h2\u003e\u003cp\u003eBecause the widest cutting edge is at the tip, work with the side of the head in short strokes rather than plunging; use water spray with the FG versions and laboratory speed for HP. Maximum recommended speeds for every Busch shape are in our \u003ca href=\"\/pages\/dental-bur-speed-chart\"\u003eDental Bur Speed Chart\u003c\/a\u003e, and reprocessing steps in the \u003ca href=\"\/pages\/dental-bur-sterilization-guide\"\u003eBur Sterilization Guide\u003c\/a\u003e.\u003c\/p\u003e\u003ch2\u003eMade in Germany by Busch \u0026amp; Co.\u003c\/h2\u003e\u003cp\u003eBusch \u0026amp; 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 \u003ca href=\"\/pages\/warranty\"\u003eBusch arrival guarantee\u003c\/a\u003e.\u003c\/p\u003e\u003cdiv style=\"text-align: center;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/files\/MadeInGermanySmall.png?v=1775134964\" alt=\"Dental Instruments, Tools, Burs, Diamonds and Polishers Made In Germany\"\u003e\u003c\/div\u003e\u003ch2\u003eFAQ\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Busch number for a US 40 bur?\u003c\/strong\u003e Busch No. 2 021 in steel (HP).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat size is a No. 40 bur?\u003c\/strong\u003e The No. 40 has a 2.1 mm head diameter (ISO size 021) on a inverted cone bur head, ISO shape 010 (inverted cone).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eAre Busch No. 40 burs reusable?\u003c\/strong\u003e Yes. Carbide and steel burs are cleaned, disinfected and sterilized between patients and replaced when they dull; the \u003ca href=\"\/pages\/dental-bur-sterilization-guide\"\u003eBur Sterilization Guide\u003c\/a\u003e gives the validated steps.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eRelated resources:\u003c\/strong\u003e \u003ca href=\"\/pages\/us-bur-numbers\"\u003eUS Bur Number Finder\u003c\/a\u003e · \u003ca href=\"\/pages\/bur-comparison-chart\"\u003eBur Comparison Chart\u003c\/a\u003e · \u003ca href=\"\/pages\/dental-bur-speed-chart\"\u003eSpeed Chart\u003c\/a\u003e · \u003ca href=\"\/pages\/dental-bur-glossary\"\u003eBur Glossary\u003c\/a\u003e · Nearby sizes: \u003ca href=\"\/collections\/us-38-bur\"\u003eUS No. 38\u003c\/a\u003e, \u003ca href=\"\/collections\/us-39-bur\"\u003eUS No. 39\u003c\/a\u003e, \u003ca href=\"\/collections\/us-41-bur\"\u003eUS No. 41\u003c\/a\u003e\u003c\/p\u003e","products":[{"product_id":"inverted-cone-steel-dental-bur-hp-us-40-pack-of-6","title":"US No. 40 Busch Steel Inverted Cone Bur | Busch No. 2 021 – HP | Pack of 6","description":"\u003cp\u003eThe \u003cstrong\u003einverted cone steel dental bur\u003c\/strong\u003e from Busch \u0026amp; Co. GmbH is a precision-engineered cutting instrument designed for demanding professional applications. Crafted from high-quality steel, this taper (cone) inverted cutter delivers reliable, controlled material removal across a variety of technical and clinical workflows.\u003c\/p\u003e\u003ch2\u003eProduct Overview\u003c\/h2\u003e\u003cp\u003eThis bur is classified under ISO standard 310 104 010 001 021, ensuring compatibility and consistent performance within internationally recognized tooling systems. As an \u003cstrong\u003einverted cone steel dental bur\u003c\/strong\u003e, it features a tapered taper (cone) profile that is ideal for undercutting and precise cavity preparation, making it a trusted choice for professionals who demand accuracy.\u003c\/p\u003e\u003ch2\u003eApplications\u003c\/h2\u003e\u003cp\u003eThe \u003cstrong\u003einverted cone steel dental bur\u003c\/strong\u003e is well-suited for the following dental laboratory applications:\u003c\/p\u003e\u003ctable role=\"presentation\" style=\"border:0;border-collapse:collapse;width:100%;max-width:640px;margin:0 0 1em 0;background:transparent;\"\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:6px 14px 6px 4px;text-align:center;vertical-align:middle;width:52px;background:transparent;line-height:0;font-size:0;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/files\/Plastics_Tech.png?v=1767131648\" alt=\"Plastics Technology\" width=\"34\" height=\"34\" loading=\"lazy\" style=\"display:block;margin:0 auto;width:34px;height:34px;\"\u003e\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:6px 0;text-align:left;vertical-align:middle;background:transparent;\"\u003e\n\u003cstrong\u003ePlastics Technology\u003c\/strong\u003e — Shaping, trimming and finishing of acrylic dentures and appliances.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border:0;padding:6px 14px 6px 4px;text-align:center;vertical-align:middle;width:52px;background:transparent;line-height:0;font-size:0;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/files\/Model_Making.png?v=1767131647\" alt=\"Model Making\" width=\"34\" height=\"34\" loading=\"lazy\" style=\"display:block;margin:0 auto;width:34px;height:34px;\"\u003e\u003c\/td\u003e\n\u003ctd style=\"border:0;padding:6px 0;text-align:left;vertical-align:middle;background:transparent;\"\u003e\n\u003cstrong\u003eModel Making\u003c\/strong\u003e — Trimming and detailing of plaster and stone models.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eMaterial: Steel construction for durability and consistent cutting performance\u003c\/li\u003e\n\u003cli\u003eStyle: Taper (Cone) Inverted (Cutter)\u003c\/li\u003e\n\u003cli\u003eISO Classification: 310 104 010 001 021\u003c\/li\u003e\n\u003cli\u003eUS No. 40 designation\u003c\/li\u003e\n\u003cli\u003eHP (Handpiece) shank type\u003c\/li\u003e\n\u003cli\u003eSupplied as a pack of 6\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eEach \u003cstrong\u003einverted cone steel dental bur\u003c\/strong\u003e in this pack is manufactured in Germany, reflecting Busch \u0026amp; Co. GmbH's long-standing commitment to quality craftsmanship and precision engineering.\u003c\/p\u003e\u003cdiv style=\"text-align: center;\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/files\/MadeInGermanySmall.png?v=1775134964\" alt=\"Dental Instruments, Tools, Burs, Diamonds and Polishers Made In Germany\"\u003e\u003c\/div\u003e\u003ch2\u003eFAQ\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eWhat is the ISO classification for this bur?\u003c\/strong\u003e This \u003cstrong\u003einverted cone steel dental bur\u003c\/strong\u003e is classified as ISO 310 104 010 001 021.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many burs are included in this pack?\u003c\/strong\u003e This listing includes a pack of 6 burs.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shank type does this bur use?\u003c\/strong\u003e It uses an HP (Handpiece) shank, compatible with standard HP handpiece systems.\u003c\/p\u003e","brand":"Busch \u0026 Co. GmbH","offers":[{"title":"Default Title","offer_id":50367821775134,"sku":"010481","price":17.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/files\/2-stahl-zt-base_af897b92-268d-4c2a-86a2-67018569d57d.png?v=1766499997"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0943\/1318\/5566\/collections\/2-stahl-zt-base_af897b92-268d-4c2a-86a2-67018569d57d.png?v=1789481584","url":"https:\/\/deutschedt.com\/collections\/us-40-bur.oembed","provider":"Deutsche Dental Technologien","version":"1.0","type":"link"}