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Endo Tribune Asia Pacific Edition

20 Endo Tribune Asia Pacific Edition | 11/2016 ENDO BUSINESS A commitment to German quality By Marc Chalupsky In the field of endodontics, instru- ments of different sizes and angles and with various handles have been developed for root canal therapy— from simple stainless-steel files to today’s high-tech instrumentation systems. VDW is one of the most well-known manufacturers of en- dodontic products in the world. Most of the 52 million instruments it produces annually are manufac- tured in Munich in Germany. For more than 145 years, VDW has been operating from its site in the heart of Europe, where it manufactures endodontic instruments in a shift operation. The company granted Dental Tribune an exclusive look behind the scenes of its high-tech facility, spanning 3,000 m2 . Every dentist knows that opti- mal root canal preparation re- quires a highly flexible file system with extremely good cutting per- formance and low material fatigue. Furthermore, the file system must be easy and quick to use and suit- able for preparing even severely curved root canals. Today, there is a range of systems available to dental specialists including those based on reciprocating or continuously rotating motion, as well as hand instruments. With its single-file reciprocating system RECIPROC, for example, VDW of- fers a safe solution for optimal root canal preparation. Not all files are equal Endodontic instruments are essentiallyofthreedesigns:K-type- files, reamers and Hedstrom files. Reamers and K-type-files have a triangular or square cross-section and a cutting edge angle that deter- mines the cutting and debriding performance and therefore the effectiveness of the instrument. The design of the instrument tip, which cuts either actively or pas- sively, is crucial. An inactive tip advances the instrument safely within the canal. The instruments generally have a handle, a shaft and a working part. While the length of the working part always remains the same at 16 mm, the length of the shaft can measure between 5 mm and 15 mm. A colour-coding system is used for easy visual identification of the diameter. The ISO standard speci- fies the lengths, dimensions, toler- ances and minimum requirements for mechanical resistance. Colour coding of white, yellow, red, blue, green and black, and various sym- bols indicate the individual types and sizes of instruments. The standard also precisely specifies the conicity, accurate to the milli- metre. The tolerance range is less than 0.02 mm, but the measure- ment of the tolerance may be sig- nificantly over the limit, depend- ing on the manufacturer. Addition- ally, silicone stoppers are used to determine the length of the root canals. The manufacturing process for Hedstrom files consists of eight steps: straightening the wire, grinding, washing, ring marking, injection moulding of the handle, printing, attaching the stopper and packaging. For barbed broaches, the wire is also first straightened, then machined, washed and straightened again, the handle in- jection moulded and the instru- ment finally packaged. Reamers and files are generally machined into a triangular or square form and then twisted. In this way, depending on the bending mo- ment, torsion and deflection, in- struments are formed that have absolute flexibility and the highest possible fracture resistance. The bending moment indicates that moment of the bending of the in- strument during production when it no longer reverts to its original form. An instrument once bent cannot be bent again, otherwise there is a risk of brittleness and fracture. The torsion, that is the twisting of the files, differs depend- ing on the force effect and material. The instrument’s cross-section and the material used play an impor- tant part here, and this in turn has an effect on the production. Finally, the angle of twisting (deflection) and the strength determine the quality of the instrument, espe- cially the cutting performance. Sharpness decreases with repeated use. Visions of endodontic heaven Dental Tribune was granted di- rect access to operations at one of the most innovative manufactur- ers in the field of endodontics. While the company has a 145-year history, the well-maintained busi- ness premises look very modern. VDW was one of the first Euro- pean manufacturers of endodon- tic instruments, and today offers products for the entire treatment process—including preparation and irrigation, root canal filling and post-endodontic maintenance. VDW emphasises simplicity and efficiency in its systems, allowing both general practitioners and spe- cialists to provide optimal treat- ment in a few steps. At the facility in Munich, Gregor Picard, Director of Operations at VDW, took us through the entire production process for the company’s manual, rotating and reciprocating instru- ments. Just in front of the main en- trance, visitors are given an over- view of VDW’s products, such as file and reamer sets for root canal preparation with rotational cut- ting, debriding and filing action, divided into sterile and non-sterile instruments. Using the Flexicut and NiTi K-type-files, preparation is problem-free even in the case of severely curved and narrow root canals. The company is particularly proud of its RECIPROC system, consisting of reciprocating instru- ments for mechanical preparation, paper points and gutta-percha. Apex locators, obturation systems such as GUTTAFUSION, an ultra- sonic device and materials for filling root canals are displayed in another glass case. The tour began with the ma- chines for cutting and straighten- ing the wires (Fig. 1). Most file systems use highly flexible, frac- ture-resistant stainless steel com- bined with a special alloy. For almost 30 years, the industry has relied not only on chromium– nickel–stainless-steel alloys but also on nickel–titanium alloy (NiTi), known for its pseudo-elastic- ity. NiTi files are used particularly in severely curved root canals. Owing to other beneficial proper- ties, including shape memory (the material returns to its original form), super-elastic behaviour and good biocompatibility, dentists are increasingly opting for NiTi files, but not dispensing with stain- less-steel files. “We are constantly working on new alloys, materials and geometries. However, it is just a question of refinements these days; the conical tapered form of the in- struments and the NiTi alloy have proven themselves,” said Picard. The wires are subsequently machined. Straight after this pro- cedure, an employee checks the finished instruments using a digi- tal measuring system and visually inspecting them under a micro- scope. This system, like the entire production process, is fully auto- mated (Fig. 2). The process is prop- erly validated to ensure that VDW can always provide the same qual- ity and reliable monitoring. The washing plant cleans the instru- ments and completely removes the oil used in production, for exam- ple. A gripper then takes the depos- ited instruments and machines in the ring marking. The colouring is done within a few seconds. The ink is then dried and the instrument is inspected again by camera (Fig. 3). The next procedure is attaching the handle. The robot trims the instrument at the top so that it is wide enough to connect the wire firmly to the handle. “This step is often left out with fake copies so that the handle slips off,” said Picard, referring to the counterfeit products on the market, which is a global concern for both manufac- turers and dentists. This is followed by the injection process to form handles around the wires, which are first placed into moulds, de- pending on the ISO diameter of the instruments. The plastic used is a high-performance polymer that can be sterilised repeatedly and can therefore be used in autoclaves. The granules are recycled to a certain extent. Injection moulding is applied gently, but extremely quickly. The precise injection moulding machines are some of the fastest in the industry. Injec- tion moulding of the handles re- quires a great deal of expertise and experience. The high-performance robot produces 16 instruments in 14 seconds. The instruments are printed on using tampography (pad printing), a special process used for printing on the front and side of the in- strument. The silicone stoppers are then applied according to instru- mentlength.Thestopperisbrought from the hopper machine in an au- tomated process and a collet chuck holds it firmly while the instru- ment is pushed through the stop- per. The instruments go into large machines during the washing pro- cess, and here a technician must constantly ensure a sterile environ- ment. Therefore, a machine creates a clean room environment in order 1 2 3 4 5 12 345

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