CHAPTER 8 Instruments, Materials, and Devices ZVI METZGER, BETTINA BASRANI and HAROLD GOODIS Chapter Outline DIAGNOSTIC MATERIALS AND DEVICES Iodine Potassium Iodide Assessment of Pulp Sensibility Choosing the Ideal Irrigant Assessment of Pulp Vascularity Intracanal Medication Assessment of Cracks and Fractures New Irrigation and Disinfection Techniques and Devices Assessment of Images ROOT CANAL FILLING MATERIALS ENDODONTIC INSTRUMENTS Solid Materials Hand Instruments Sealers and Cements Instruments for Cleaning and Shaping the Root Standards and Properties Canal Space DELIVERY SYSTEMS FOR ROOT CANAL Devices for Periapical Débridement Through a Root OBTURATION MATERIALS Canal Access Carrier-Based Systems Devices for Measuring Root Canal Length Injection Techniques Instruments for Root Canal Obturation Rotary Techniques Devices for Removing Root Canal Obstructions TEMPORARY RESTORATIONS MATERIALS FOR DISINFECTING THE PULP SPACE LASERS Chemomechanical Preparation Neodymium-Doped Yttrium Aluminum Garnet Lasers Sodium Hypochlorite Erbium-Doped Yttrium Aluminum Garnet Lasers Chlorhexidine Diode Lasers MTAD and Tetraclean Erbium/Chromium-Doped Yttrium Scandium Gallium Ethylenediamine Tetra-acetic Acid Garnet Lasers Hydrogen Peroxide The past decades have seen many changes in the practice of validity or appropriateness in different clinical situations. endodontics, such as in materials, techniques, equipment, When tests are evaluated, there are some terms that may lead instrument design, and the types of metals used to manufac- to more definitive and possibly quantifiable endodontic diag- ture endodontic instruments. However, the goals of non- noses. These terms are sensitivity, the ability of a test to identify surgical endodontic therapy has not changed: “Root canal teeth with disease; specificity, the ability of a test to identify systems must be cleaned and shaped: cleaned of their organic teeth without disease; and predictive value, the ability of a test remnants and shaped to receive a three-dimensional hermetic to foretell what the diagnosis actually is. (fluid-tight seal) filling of the entire root canal space.”332 Pulp stimulation with cold or heat is the oldest method of evaluating the pulp’s health and its ability to respond to exter- DIAGNOSTIC MATERIALS AND DEVICES nal stimulation, but evaluation of pulpal response must not be confused with vitality testing, which requires assessment of Assessment of Pulp Sensibility pulpal circulation.140 One of the greatest diagnostic challenges in clinical practice is the accurate assessment of pulp status. A variety of pulp testing Cold Tests approaches exist, and there may be confusion as to their Cold thermal testing causes contraction of the dentinal fluid within the dentinal tubules, resulting in a rapid outward flow of fluid within the patent tubules. This rapid movement of dentinal fluid results in hydrodynamic forces acting on the δA The authors acknowledge the excellent scholarship of Drs. Van Himel and K John McSpadden in authoring previous editions of this chapter. nerve fibers within the pulp-dentin complex, leading to a sharp 223 Hargreaves_Chapter 8_main.indd 223 12/7/2009 5:36:35 PM 224 PART I • THe CORe SCienCe Of endOdOnTiCS sensation lasting for the duration of the thermal test. A variety prepared by delivering CO2 into a custom-made plastic cylin- of cold tests may be employed; the major difference between der, and the stick is applied to the buccal surface of the tooth. them is the degree of cold applied to the tooth.140 This method is particularly effective when trying to assess A simple means of applying a cold stimulus to a tooth is to teeth that have been restored with full-coverage metal restora- 397 314 wrap a sliver of ice in wet gauze and place it against the buccal tions. Rickoff reported that CO2 snow applied to a tooth surface, comparing the reaction between the test tooth and a for 5 minutes did not jeopardize the health of the pulp, nor control tooth. Pencils of ice can be made by filling a plastic does it damage the surface of the enamel.300 On the other hand, straw with water and freezing it in an upright position in a CO2 may cause pitting of the surface of porcelain restorations freezer.352 when applied for as little as 5 seconds.203 When testing with a ethyl chloride (−41° C) may be sprayed onto a cotton cold stimulus, the advantage of refrigerant sprays and frozen pledget, resulting in the formation of ice crystals (Fig. 8-1) carbon dioxide is that the cold stimulus does not go into a prior to application to the tooth. dichlorodifluoromethane liquid phase but rather a gas phase. This allows testing to be (ddM) (−50° C) is a compressed refrigerant spray that can also specific to one tooth at a time, without cold water from melted be sprayed onto a cotton pledget for cold testing (Fig. 8-2). ice stimulating adjacent teeth. More recently, ozone-friendly non-chlorofluorocarbon sprays ice-cold water is another useful and inexpensive test. The have been introduced in certain countries. tooth being tested should be isolated with a rubber dam and Another effective cold stimulus is frozen carbon then bathed with water from a syringe. Cold tests should be dioxide (CO2), also known as dry ice or carbon dioxide snow applied until the patient definitely responds or the stimulus 121 (−78.5° C). for testing purposes, a solid stick of CO2 is has been applied for a maximum of 15 seconds. One of the significant benefits of ice-water testing is that it can be used on any tooth regardless of the type of restoration that may be present. Overall, cold tests appear to be more reliable than heat tests,93,341 and there is a general consensus that the colder the stimulus, the more effective the assessment of tooth innerva- tion status. Heat Test Warm thermal testing is not employed as often as cold testing because most patients are more sensitive to cold stimuli, and warm thermal tests have been traditionally more difficult to perform. Heat testing can be undertaken using a stick of heated gutta-percha or hot water. A gutta-percha stick, preferably base-plate gutta-percha, is heated with a naked flame or an 149 FIG. 8-1 ethyl chloride sprayed onto a cotton pledget, resulting in electric heater until it becomes soft and glistens. it is then the formation of ice crystals. (Courtesy Dr. R. Portigliatti.) applied to the Vaseline-coated surface of the test tooth. it is purported that a tooth surface temperature as high as 150° C can be achieved with this technique319: gutta-percha softens at 65° C and may be heated in delivery devices up to 200° C. This test may be difficult to use on posterior teeth because of limited access. A further disadvantage is that excessive heating may result in pulp damage.280 Prolonged heat application will result in biphasic stimulation of Aδ fibers initially, followed by the pulpal C fibers. Activation of C fibers may result in a lingering pain, therefore heat tests should be applied for no more than 5 seconds. However, inadequate heating of the gutta-percha stick could result in the stimulus being too weak to elicit a response from the pulp.140 The use of hot water, administered through an irrigating syringe under rubber dam isolation, has also been described as a means of thermal testing. frictional heat may be generated by using a rubber cup intended for prophylaxis (without paste) against the buccal aspect of a tooth. The normal use of thermal tests on teeth has been shown not to be harmful to healthy pulp tissue.170 The System B (Sybronendo, Orange, CA) allows dentists to set specific temperatures for warm thermal testing. After the surface of the tooth has been lubricated, a test tip can be attached to the handle of the System B and the temperature set at 150° f. The preheated tip is placed on the surface of the tooth, and the patient’s response is evaluated. FIG. 8-2 Hygenic endo-ice. (Courtesy Colténe/Whaledent, Cuyahoga One of the problems of testing with heat is that often a K Falls, OH.) nonvital tooth increases in pain secondary to heat stimuli. in Hargreaves_Chapter 8_main.indd 224 12/7/2009 5:36:37 PM chapter 8 • Instruments, Materials, and Devices 225 the clinical situation whereby a patient reports pain to heat There are several considerations regarding optimal place- and relief with cold stimuli, the application of cold to individu- ment of the tester electrode. The response threshold is reached ally selected teeth may eliminate the patient’s tooth pain. when an adequate number of nerve terminals are activated to Therefore, in these situations, the application of cold with attain what is termed a summation effect.281 An area of high relief of pain can be diagnostic for a nonvital pulp. neural density should have a relatively fast and strong response and requires the least electric current. Therefore, the most Electric Pulp Test desirable area of assessment in incisor teeth is at the incisal The objective of the electric pulp test (ePT) is to stimulate edge.32 The tester should be applied on the tooth surface adja- intact Aδ nerves in the pulpal-dentin complex by applying an cent to a pulp horn, the area of highest nerve density within electric current to the tooth surface. A positive result stems the pulp. This position equates to the incisal third region of from an ionic shift in the dentinal fluid within the tubules, anterior teeth and the mid-third region of posterior teeth. The causing local depolarization and subsequent generation of an threshold for response may be influenced by the thickness of action potential from intact Aδ nerves.292 the enamel and dentin overlying the pulp. Thus, the response The electric pulp tester is a battery-operated instrument threshold for healthy teeth may be lowest in incisors, slightly connected to a probe that is applied to the tooth under inves- greater in premolars, and greatest in molar teeth.