March 1, 2007
by Richard Mounce DDS
1) Carefully study the tooth before beginning treatment. Anticipating clinical challenges and developing strategies is always far preferable to dealing with iatrogenic problems after they occur.
2) Always use a rubber dam, always. If the patient will not tolerate one, the tooth should be extracted.
3) Break treatment into a number of smaller steps, each completed well. For example, a correct diagnosis, ideal anesthesia, straight-line access, etc each done sequentially to a high standard will take the clinician toward the best possible final result. Skipping steps or rushing through any stage is almost always unproductive.
4) To place a rotary nickel titanium (RNT) file into a canal which has not first been pre enlarged with hand files is to risk fracture very quickly especially if it is inserted with too much force in a canal of any appreciable calcification or curvature. As a general rule, use hand K files first as negotiators and pathfinders and for creation of a glide path to make room for RNT. RNT files are not meant, unless the canal is wide open, to open and negotiate canals.
Know your rotary nickel titanium file system well. How many uses per file can it withstand? How much apical pressure can the system withstand comfortably without risking fracture? What is the ideal rotational speed? Do you need to use torque control? For every system these answers may be slightly different. In my hands, for a durable and efficient flexible system like K3 (SybronEndo, Orange, CA) the files can be run from 350-900 RPM operator experience dependent, with the torque control off, with minimal apical pressure and minimal engagement of the canal walls, ideally 1-2mm per insertion and done so in approximately five teeth before discarding (with several caveats). Larger tip sizes and tapers can be used more often than smaller and the .02 tapered instruments are usually single use devices and then discarded. In addition, if there is any deformation of a file, it is discarded immediately. Always create a glide path before using RNT files if the canal is not easily open as described above. A glide path for RNT use can be said to be created once a #15 file will spin freely in the canal.
As an aside, using the torque control feature on electric motors as an arbitrary means with which to determine how much pressure one can apply is ill advised and a precursor to fracture. If for example, a file should become locked in a previously untouched canal fin, it may fracture easily should it become locked at the tip.
5) Never lock an irrigating needle in a canal, irrigation should be passive, gentle, done with intention and done with the estimated or true working length kept in mind at all times.
6) Recapitulation should be frequent, ideally after every insertion of a RNT to prevent blockages. Achieving and maintaining apical patency is considered by many endodontists a key component of providing excellent treatment.
7) I use a sharps container during every procedure to discard needles, used files, etc. I do not have my assistant take needles off the syringes so as to avoid any realistic possibility of puncture injury.
8) Create straight-line access with the goal of creating the straightest approach to the apical third possible without altering the position of the canal within the tooth. Such a straight-line approach will maximize the tactile control over the files, enhance irrigation and reduce iatrogenic events of all types.
9) Vital teeth can generally be completed in one visit. A comprehensive discussion of non-vital teeth and retreatment performed in one visit is beyond the scope of this column, but having enough time available to finish treatment when indicated can go far toward creating profitability and efficiency.
10) Wipe the flutes of the RNT files after every insertion and evaluate them often for wear spots, thin and stretched areas. A RNT file that is deformed in any way should be immediately discarded, it will fracture if used again, and usually very quickly.
11) If you do not know which is the offending tooth refer the patient or delay the treatment until you are sure.
12) I use hand K files once. They are single use instruments. Using a hand K file once makes them always sharp and gives them the most effective use in the canal for the given indication, whether path finding or creation of a glide path. It is not cost effective to sterilize hand K files repeatedly. Aside from the lack of economy, the loss of sharpness and ability to track a curve are overcome by always using new files.
13) Expect to find anatomical variances and extra roots and canals. Some such canals are predictable, others take time and practice to see. For example, lower canines have a second canal about 5-6% of the time; upper first pre molars also have 3 roots about the same percentage. Alternatively, upper first molars have an MB2 canal 95% of the time and while this canal may not always be negotiable, it should be looked for and be expected. Having the visualization and magnification and lighting of a SOM can make location and management of these clinical events far more predictable. I use Global microscopes (Global Surgical, St. Louis Mo) for its modular functionality and quality of optics, expandability and cost effectiveness.
A series of clinical suggestions have been made to improve the quality of endodontics for the general practitioner. I welcome your questions and feedback.
Dr. Mounce lectures globally and is widely published. He is in private practice in endodontics in Vancouver, WA. Amongst other appointments, he is the endodontic consultant for the Belau National Hospital Dental Clinic in the Republic of Palau. Korror, Palau (Micronesia). He can be reached at RichardMounce@MounceEndo.com.