Learning Objectives
At the end of this chapter, the student should be able to:
- 1.
Define the basic set of armamentarium appropriate for diagnosis, emergency treatment, canal preparation, obturation, and endodontic surgery.
- 2.
Describe the general characteristics of endodontic armamentarium and show how these characteristics are related to their use.
- 3.
Describe the importance of using magnification for proper endodontic treatment.
- 4.
Present the advantages of three-dimensional (3D) versus two-dimensional (2D) radiographic imaging.
- 5.
Explain the basis for sizing and taper of hand and rotary instruments.
- 6.
Describe the basic design of the more common canal preparation instruments and their mode of use.
- 7.
Describe the various adjunct tools needed to achieve adequate disinfection.
- 8.
Identify the various temporary restorative materials used after endodontic treatment.
- 9.
Describe the various adjunct tools used during endodontic surgery.
Introduction
The goals of nonsurgical root canal therapy (RCT) are to chemomechanically débride, disinfect, and shape the root canal spaces, followed by adequately sealing all portals of entry and exit. , To achieve these goals, multitudes of solutions and dental instruments have been specially designed and used. Historically, varied attempts at endodontic treatments have been documented since ancient times. In 1728 Pierre Fauchard wrote The Surgeon Dentist , which described the dental pulp space and the procedure to access this space to relieve abscess formation. Fauchard recommended leaving the access to the pulp space open for months and then filling the opening with lead foil. Advancing on this concept, Robert Woofendale in 1766 was credited with the first endodontic procedure in the United States. He would cauterize the dental pulp with a hot instrument and place cotton in the root canals. From this idea, the concept of pulp extirpation took hold. In 1838 Edwin Maynard fabricated the first endodontic instrument. He ground a watch spring into a broach, which he would then use to extirpate the dental pulp. Over the next several decades, endodontic instruments continued to evolve into the instruments and materials we use today. Over the past two decades, the endodontic armamentarium has undergone major renovations in nonsurgical and surgical treatment that have allowed endodontic treatment to become more successful.
This chapter provides an overview of basic and advanced endodontic armamentarium and describes their use in the clinical setting. Proper knowledge of the various instruments, materials, and equipment, together with their design, composition, and function, is critical to provide patients with proper diagnosis and treatment options. The field of endodontics is constantly evolving with improved armamentarium to assist clinicians with diagnosis and treatment. Clinicians should always consider using newer instruments, materials, and equipment to provide the best possible treatment for their patients. It will not be possible to include all armamentarium used in every endodontic procedure in this chapter. However, the most widely used instruments and materials will be covered in detail.
Examination and Diagnosis
Clinical Examination
The primary aim during endodontic diagnosis is to determine the vitality of the pulp and the status of the supporting periodontal structure. For that, clinicians use a basic examination kit, which is very similar to instruments used for restorative dentistry. It is composed of a mouth mirror, Shepherd’s hook explorer, periodontal probe, and cotton pliers ( Fig. 7.1 ). The vitality of the dental pulp is routinely examined using sensibility tests that aim to stimulate the pulp through temperature (cold or hot) or electric stimulation ( Figs. 7.2 and 7.3 ). The supporting periapical tissues can be examined with the back of the mirror (percussion), the index finger (palpation), and the periodontal probe. Other instruments can be used to determine the presence or absence of a coronal crack or a root fracture, such as a “Tooth Slooth,” a transilluminator, methylene blue, or caries detection dye.
Radiographic Examination
Radiographic examination is the key diagnostic tool used to evaluate the periapex. Different types of radiographs can be used for endodontic diagnosis. Two-dimensional (2D) intraoral radiographs, periapical and bitewing, are used to evaluate the teeth, their supporting structures, and any existing restorations. Three-dimensional (3D) radiographs and cone beam computed tomography (CBCT) have become routinely used in endodontic diagnosis due to their ability to provide 3D images of the area of interest. In 2017 a survey sent to members of the American Association of Endodontists (AAE) showed that almost 50% of the endodontists in the United States have a CBCT machine in their offices. CBCT use among endodontists is increasing because it can further assist clinicians in proper diagnosis and treatment planning. Rodriguez et al. investigated the influence of CBCT imaging on clinical decision-making choices of different specialists among cases with different levels of difficulty. The results showed that examiners altered their treatment plan after viewing the CBCT scan in 27.3% of the cases and up to 52.9% in high-difficulty-level cases. Although periapical radiographs are still used as the standard radiographic technique for endodontic diagnosis and treatment, there are several clinical situations in which 2D radiographs may not be able to properly assess the clinical condition. Periapical lesions have to reach a certain size and erode the inner cortical plates of the jaws to be visible on a periapical radiograph. , In addition, 2D radiographs have significant limitations in the detection, assessment, and treatment planning of external cervical root resorption compared with CBCT imaging. In a joint statement by the AAE and the American Association of Oral and Maxillofacial Radiology (AAOMR), they outlined several circumstances in which CBCT can be very useful for better clinical examination (see Chapter 3 ). These conditions include cases with external and internal resorptive defects, trauma and fracture cases, presurgical treatment planning, and vertical root fracture cases. In addition, they recommend using CBCT to evaluate the nonhealing of previous endodontic treatment, in intra-appointment identification and localization of calcified canals, for initial treatments with potential existence of extra canals and suspected complex morphology, and for the diagnosis of patients who present with contradictory or nonspecific clinical signs and symptoms associated with untreated or previously endodontically treated teeth. It should be noted, however, that the accuracy of CBCT relies to a great extent on the specifications and settings of the equipment used (field of view, voxel size, and artifact correction). Additionally, some lesions may not be accurately detected if they are smaller than 1.4 mm in diameter.
Magnification
The dental operating microscope (DOM) is considered standard equipment in the endodontic office. Before the early 1990s, dental loops were used for magnification. The loops were limiting in two ways: first, only low-level magnification was possible; second, because the practitioner had to wear the loops, neck strain and postural problems often resulted. A web-based survey sent to AAE members in 2007 showed that 90% of endodontists were using a DOM during treatment in comparison with only 52% in 1999. The clinician can better visualize the root canal anatomy as a result of the magnification and illumination provided by the DOM. Khalighinejad et al. showed that maxillary first molars with nonhealed RCT in which DOM was not used were significantly more likely to have a missed MB2 canal in the affected MB root. This study indirectly shows the value of using the DOM on the outcome of nonsurgical root canal treatment, at least in this situation. Other studies also showed that practitioners were better able to locate and negotiate canals when the DOM was used. , Although dental loops can be used during endodontic treatment, the DOM offers multiple advantages: a wider field of view, improved illumination, and less physical strain on the practitioner. DOM is also among the instruments and materials that have significantly improved the treatment outcome of endodontic surgery. , In addition to allowing excellent visualization, it is a great tool for documentation as well. Clinicians can easily take images and videos of the various procedures and use them for better patient communication and education ( Fig. 7.4 ) ( ) 
.
Isolation
In 1862 Dr. Sanford Barnum developed the rubber dam to allow a saliva-free field in the mouth. Later, Dr. G. A. Bowman improved the rubber dam by inventing the rubber dam clamp, which allowed the stabilization of the rubber dam to a tooth. The rubber dam is intended to isolate the tooth/teeth to be treated from the oral cavity to ensure no microbial contamination. In addition, it offers other kinds of benefits, such as enhancing visualization, providing a clean operative field, and preventing ingestion or aspiration of any instrument, material, or irrigant during treatment. The 2010 AAE Position Statement on Dental Dams indicated that “tooth isolation using the dental dam is … integral and essential for any nonsurgical endodontic treatment.” It is also considered the standard of care in today’s practice.
An isolation kit is composed of (1) clamps that clasp the tooth and are available in different shapes and sizes, depending on the tooth to be isolated ( Fig. 7.5 ); (2) rubber dam sheet, a physical barrier to isolate the tooth from the oral cavity; (3) rubber dam hole punch used to create a hole in the rubber dam sheet that allows for placement of the rubber dam clamp; and (4) a rubber dam frame used to hold the rubber dam sheet in place ( Fig. 7.6 ). In some clinical cases, rubber dam placement alone may not sufficiently allow adequate isolation of the tooth before initiating treatment. Supplementary material such as OraSeal or OpalDam (Ultradent Products, Inc., South Jordan, Utah, USA) may be applied around the tooth/clamp junction to enhance tooth isolation ( Fig. 7.7 ). In clinical cases in which an extensive amount of tooth structure is lost, restoration of the tooth to allow for proper isolation is recommended. This restoration can be achieved using glass ionomer or composite restorative materials ( Fig. 7.8 ). If placing a clamp on the tooth might result in damage of an existing restoration, a dental dam stabilizing cord, such as Wedjets (Coltene/Whaledent GmbH), can be used to stabilize the rubber dam in place without the use of a clamp ( Fig. 7.9 ).
Nonsurgical Root Canal Treatment
Nonsurgical Cassette
The nonsurgical treatment cassette includes all the instruments that are needed during RCT ( Fig. 7.10 ). The cassette contains the instruments used in diagnosis in addition to other procedure-specific instruments, such as (1) local anesthesia syringe; (2) endodontic explorer (DG 16), an instrument that aids in the identification of root canal orifices; (3) a ruler used to measure the instruments for length control during the root canal procedure ( Fig. 7.11 ); (4) endodontic spreaders, used for lateral condensation of gutta-percha; and (5) endodontic pluggers, used for vertical gutta-percha condensation during obturation. Endodontic spreaders and pluggers come in different sizes as well as both finger and handle design ( Figs. 7.11 and 7.12 ). Finally, the cassette includes a metal or plastic instrument that is used to place the temporary filling into the pulp chamber.
Length Determination
To ensure proper length control during root canal treatment, electronic apex locators (EAL) have been used to determine the position of the apical foramen and/or constriction and thus the apical extent for root canal instrumentations. The first EAL was introduced in 1962 by Sunada. Since their development, EAL have evolved to improve their accuracy and reliability in the various clinical conditions. Currently, EAL are consistently used by endodontists and widely used by general dentists. EAL have been shown to be more accurate than standard 2D radiographs in working length determination. When use of EAL is combined with a radiograph, clinicians can reduce the risk of over- or underinstrumentation during root canal treatment, and thereby achieve more predictable results. ,
Instrumentation Armamentarium
Endodontic Access
The endodontic access is the opening in the crown of the tooth that allows for localization of the root canal space. Classically, the outline form for the access has been governed by G. V. Black’s principles of cavity preparation. However, the access for each tooth should be directed by the anatomy of both the pulp chamber and the curvature of the root. Existing restorations and decay can alter the outline form of the access. Due to the implementation of the DOM, modern endodontic accesses can be smaller and more precise in their location on the crown of the tooth. The access is prepared using a high-speed handpiece and burs with water coolant. The selection of burs for access depends on the material(s) in the crown of the tooth. Ceramic restorations and porcelain are best approached using diamonds burs. Carbide burs are acceptable for metal (amalgam, gold, crown undercasting) and composite restoration. The typical armamentarium consists of sizes 2, 4, and 6 round diamond burs and size 4 round carbide or #1157 carbide burs. After achieving access to the pulp chamber, safe end burs (Endo Z) can be used to avoid any unnecessary damage to the floor of the pulp chamber.
Additional instruments are sometimes required to localize the root canal orifices/canals ( Fig. 7.13 ). Root canal localization can be complicated by calcification in the form of pulp stones and dystrophic calcification of the root canal space. To remove these calcified structures, Munce burs, Mueller burs, or Swiss LN burs can be used. They are long shanked rotary burs that can be used for precise troughing to expose root canal orifices. These burs come in different sizes to facilitate drilling at different levels without the root canal space and are used without water coolant, which can generate a significant amount of debris. Specialized endodontic ultrasonic tips can also be used for root canal localization. The advantages of ultrasonic tips are that they can be used very precisely and, if desired, used with water irrigation. Irrigants, dyes, and light can also help in root canal localization. A drop of sodium hypochlorite (NaOCl) can be placed in the pulp chamber and viewed under the DOM. The solution will often bubble and “light up” a canal orifice. Caries detection dye or other stains can also locate hard-to-find root canal orifices. Transillumination of the pulp chamber with a curing light has also been suggested to help locate root canal orifices. In summary, precise endodontic access is essential to a successful root canal treatment.
Cleaning and Shaping Instruments
Once access to the root canal system has been achieved, disinfection of the root canal space can be initiated. The goal of root canal disinfection is removing all pulp tissue and infected debris from the root canal system. Because achieving a sterile environment is currently impossible, the root canal space is then filled with a special filling material to “entomb” any remaining bacteria. Root canal disinfection is achieved through a step called “cleaning and shaping.” Although the primary goal is only cleaning, the root canal space needs to be shaped by endodontic instruments to facilitate the cleaning process. It should be noted that the current disinfection process derives from the instruments and materials currently used. With the advancement in technology, noninstrumentation techniques may be used, and the need to further shape the canal to facilities cleaning may be no longer needed. Cleaning and shaping of the root canal space with the current endodontic armamentarium have two primary objectives: (1) the enlargement of the root canal space, and (2) creation of a space amenable to the filling “obturation” method being used. The instruments used for cleaning and shaping are classified by the ISO-Federation Dentaire Internationale. Instruments used by hand only are Group I. Instruments similar to Group I but which are used with a rotary engine or motor are Group II. Rotary engine–driven drills are Group III. All three groups are typically used for an endodontic procedure. Initially, small hand files can be inserted to “scout” the root canal space. After providing a glide path, rotary instrumentation can be commenced. Rotary instrumentation is performed using an endodontic electric motor ( Fig. 7.14 ). The electric motor allows for more precise control of the speed of rotation than that allowed by an air-driven handpiece. Electric motors can also control the allowable torque, which can be set to maximize file performance and minimize file separation (breakage).
Hand and rotary files use standardized systems for sizing and identification. The size of a file is defined by 100 times the tip size. The taper of the file (the increase in diameter from the tip of the file to the handle) is based on 1/100th of a millimeter. The color-coded identification system is based on file size. With the exception of the three smallest file sizes (6, 8, and 10), the color pattern repeats to aid in file size identification ( Fig. 7.15 ). Hand and rotary files come with different cross-sections and accordingly can be used in different motions and at different parts of the treatment. An illustration of the different hand instrument is shown in Fig. 7.16 . The application and use of each of these instruments will be discussed in detail in Chapter 14 . The taper for a standardized instrument is constant for the full length of the cutting flutes (typically 16 mm). The taper of the instrument refers to the incremental enlargement of the instrument diameter every 1 mm ( Table 7.1 ). Some rotary endodontic files are variable in their taper, which means that the taper is not constant for the full extent of the cutting flutes and varies for different segments of the file.
| File Size (Color) | Tip Size in mm | Diameter 3 mm from Tip with 02 Taper in mm | Diameter 3 mm from Tip with 04 Taper in mm | Diameter 3 mm from Tip with 06 Taper in mm |
|---|---|---|---|---|
| 6 (Pink) | .06 | .12 | .18 | .24 |
| 8 (Gray) | .08 | .14 | .20 | .26 |
| 10 (Purple) | .10 | .16 | .22 | .28 |
| 15 (White) ∗ | .15 | .21 | .27 | .33 |
| 20 (Yellow) ∗ | .20 | .26 | .32 | .38 |
| 25 (Red) ∗ | .25 | .31 | .37 | .43 |
| 30 (Blue) ∗ | .30 | .36 | .42 | .48 |
| 35 (Green) ∗ | .35 | .41 | .47 | .53 |
| 40 (Black) ∗ | .40 | .46 | .52 | .58 |
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