Endo Tribune United Kingdom Edition

page 12DTà Using hand files to their full capabilities: A new look at an old yet emerging technology Author Dr Rich Mounce, USA D espite wide global ac- ceptance of rotary nickel titanium (RNT) canal enlargement, hand files remain central to endo- dontic practice. It can be argued persuasively that proper canal ne- gotiation and glide path creation are key ingredients to successful long-term treatment, along with adequate and appropriate irriga- tion, canal preparation, coronal seal, etc. Simply stated, after the preparatory steps of straight-line access and removal of the cervi- cal dentinal triangle with orifice openers, if the canal is not proper- ly negotiated and a glide path pre- pared prior to RNT enlargement, cleaning and shaping procedures cannot be optimal. This article was written pri- marily for the general dentist. It describes stainless steel (and, to a lesser degree, nickel titanium) hand files, reciprocation and their clinical application. This article is intended to be a clinical “how to” article, not a literature review, hence a lack of extensive refer- ences. The endodontist is encour- aged to compare their treatment methods with those described here. The Mani product line of files is described primarily be- cause these files are used daily by the author. Examples of equivalent files are provided alongside of Mani products throughout the article for comparison. There are myriad hand file designs, applications, materials and manufacturing methods. In recent years, multi axis grind- ing machines have provided ad- vancements of true clinical con- sequence, especially with regard to file flexibility and cutting ability. Given the wide diversity of avail- able designs and features, it is impossible to discuss the design, clinical use or precautions re- quired for every hand file on the market. Neither barbed broaches nor balanced force technique will be discussed.1 Introduction: Appreciating the unseen dimension Hand files allow the clinician to manually “feel” the unseen di- mension in canal anatomy be- yond what radiographs alone can illustrate. Specifically, by virtue of hand file resistance to apical advancement, the clinician can, by tactile feel, determine the cur- vature, calcification, length, the anatomy of the MC, and if iatro- genic events may have occurred. Only cone beam technology comes close to providing the tac- tile information provided by hand files (Planmeca). Such tactile information helps determine treatment strategies prior to shaping. Astute RNT use has, as its foundation, intimate ca- nal knowledge first by hand files. Forcing RNT files to length with- out adequate hand file negotiation and a glide path is the harbinger of file fracture, canal transporta- tion and inadequate cleaning and shaping. Hand file applications, differen- tiation and general use principles Hand files differ based on the fol- lowing (among other attributes): 1. Material of manufacture (car- bon steel, stainless steel, nickel ti- tanium, among several other less common materials). 2. Taper (0.02 tapered, variable ta- pered, greater tapered). 3. Initial cross-sectional design before manufacture (triangular, square, rhomboid, among other initial shapes). 4. Final cross-sectional design. 5. Corrosion resistance. 6. Handle design and material used for the hand file. 7. Tip sizes (of the individual in- strument). 8. Progression of tip sizes across the spectrum of a given set of in- struments. 9. How the cutting flutes are pro- duced (twisting, grinding, among other manufacturing methods). 10. Tip design (active, non-cut- ting, partially cutting). 11. Whether the file is reciprocat- ed, watch-wound (K files), rotated (K reamers), or used with a pull stroke (H files). 12. Helix angle, rake angle, cut- ting angle (if different from the rake angle) number of flutes (as well as flute width, depth and number). 13. Possible variability of the cut- ting angle along the length of the file. 14. Linear length of the cutting flutes. 15. In addition to the attributes above, hand files are designed to be stiff versus flexible, aggressive cutting versus less aggressive, fin- ishing files versus bulk shaping files, among other general classi- fications. Principles for maximising hand file effectiveness The use of hand files is based on several universal assumptions. These assumptions are: a) Optimal visualisation of the ac- cess preparation, ideally through the surgical microscope (Zeiss, Global Surgical). b) Optimal radiographic evalu- ation of the tooth prior to access preparation including where nec- essary, cone beam visualisation. For those without CBCT tech- nology, having two or optimally three different pre-operative ra- diographic angles will provide the best possible visualisation of canal anatomy short of a CBCT scan. c) Straight line access. d) Removal of the cervical den- tinal triangle prior to hand file ex- ploration. e) Copious irrigation at every stage in the procedure, especially rinsing debris from the access preparation before hand files are inserted. f) Pre-operative evaluation of the estimated and expected true working length, final taper and master apical diameter. g) Curved files negotiate curved canals more effectively than straight ones. The EndoBender pliers (Axis/Sybron) are an effective instrument to place the needed curvature onto hand files. Gen- erally, in canals that have been ledged or transported, placing an acute, 3- to 5-mm curve onto the apical portion of the hand file is beneficial. Multiple insertions of curved hand files to bypass blocked and transported canals (especially ledges) are the rule, not the exception. Alternatively, if no transportation has occurred (the canal is untouched or eas- ily negotiable) the clinician can Endo Tribune pages 11-13 A new look at old technology Handfiles Endo Tribune pages 14-15 A case report by Dr Sorin Sirbu Twisted files Endo Tribune pages 16-18 An eight-year follow up Intentional replantation Endo Tribune

Endo Tribune United Kingdom Edition

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