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Topical anesthetic as an adjunct to local anesthesia during pulpectomies
0099-2399/98/2403-0202503.00/0 JOURNALOF ENDODONTICS Copyright © 1998 by The American Association of Endodontists
Printed in U.S.A. VOL. 24, No. 3, MARCH1998
CLINICAL AID Topical Anesthetic as an Adjunct to Local Anesthesia during Pulpectomies Mark DeNunzio, DDS
A technique is described using topical anesthetic to supplement local anesthesia. It is the author's opinion that it enhances patient comfort during pulpectomies on teeth with irreversible pulpitis.
Topical anesthetics have been used in dentistry for many years, principally to reduce the discomfort of needle injections. They have also been used during the extraction of deciduous teeth, for the removal of arch wires after orthognathic surgery and during scaling and probing procedures. Research literature regarding the efficacy of topical anesthesia before needle injections is equivocal. Some studies support topical anesthesia as a useful adjunct for enhancing patient comfort during local anesthesia injections (7), whereas others do not (8). Topical anesthetic formulations generally contain high percentages (up to 20%) of esther-type anesthetic agents, usually benzocaine (9), which allow them to reach high concentrations at the sensory nerve endings. The duration of action is short, usually 15-30 min. Topical anesthetics are thought to function by blocking signal transmission in the terminal fibers of sensory nerves (10). Their effects are thought to be limited to the control of painful stimulation occurring in or just beneath the mucosa.
Patient comfort during endodontic procedures is paramount for patient satisfaction and acceptance of root canal therapy. Many techniques for achieving anesthesia during endodontic procedures are documented in the literature, and entire textbooks are dedicated to dental anesthesia. These techniques are useful because of the difficulty achieving adequate anesthesia during root canal procedures on some patients or during certain situations. McLean et al. (1) had a success rate for inferior alveolar injections of 43 to 67% for molar and premolar teeth. These low rates may be the reason for the popularity of alternative anesthesia techniques, including periodontal ligament injection (2) and intraosseous injection. Many experienced endodontists would agree that their most challenging anesthesia problems occur on patients who present with irreversible pulpitis requiring a pulpectomy. Wallace et al. (3), in a survey of Diplomates of the American Board of Endodontics, found that 210 of 268 diplomates answered yes to the question, "Do you find it more difficult to regionally anesthetize a painful tooth versus a nonpainful tooth?" The presence of a variety of inflammatory products (4) and the hemodynamic regulation within the pulp (5) are thought to add to the magnitude of pain perceived by these patients and contribute to the fact that these teeth can be extremely difficult to anesthetize. Wallace et al. (3) proposed that nerves arising in inflamed tissue had altered resting potentials and excitability thresholds. These changes were not restricted to the inflamed pulp itself, but affected the entire neuron cell membrane in every involved fiber. They also found that local anesthesia was not sufficient to prevent impulse transmission due to the lowered excitability thresholds of nerves in histamine-induced pulpal inflammation. In a study by Dreven et al. (6), anesthesia on inflamed teeth was unable to be attained in 27% of the cases, despite inferior alveolar blocks and periodontal ligament injection. Personal experience has shown that, even after opening into the pulp chamber and giving intrapulpal anesthesia, some patients can still sense pain when files are placed into the canals.
TECHNIQUE An adjunctive technique to augment infiltration, block, and intrapulpal injections is the use of topical anesthetic introduced into the inflamed root canal system. The technique can be used after intrapulpal anesthesia is attempted or as an alternative to intrapulpal anesthesia. The pulp chamber is unroofed and coronal pulpal tissue removed. If the patient feels discomfort when files are placed into the canals, the adjunctive topical technique is used. To reduce the risk of cross-contamination, a sterile cotton tip applicator is used to draw a quantity of topical anesthetic from its container. The author uses Hurricaine brand (Beutlich, LP, Waukegan, IL) topical gel, which contains 20% benzocaine. Any type of topical anesthetic with a high percentage of benzocaine and sufficient viscosity should work equally as well. A quantity of topical gel the size of the cotton tip is usually sufficient for one tooth, including molars with four canals. Holding the cotton tip applicator upright, a #10 or #15 file is drawn through the topical starting at the middle of the file and ending with the tip. As the tip is drawn through the topical, the file is pulled laterally to deposit a small bolus of topical on the last 3 to 4 mm of the file tip. If the temperature in the operating room is too high, the viscosity of the topical gel may not be sufficient to allow an adequate quantity to
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adhere to the file. If this occurs, the topical could be cooled in a refrigerator to increase the viscosity and help it adhere to the file tip. With the topical on the file tip, the file is placed into the canal. Using a watchwinding motion with an alternating pumping action, the topical gel is pushed down the canal. The objective is to push the gel ahead of the file so that it can anesthetize the remaining nerve tissue in the canal before the file stimulates the nerve and causes pain sensations. The patient usually feels some minor discomfort during this phase, but it only lasts - 1 0 s. Most canals are completely anesthetized with one or two applications of topical with the file. If the patient is extremely sensitive, more time is taken to push the topical down the canal. Any topical that remains in the pulp chamber serves as a reservoir for use in the remaining canals to be anesthetized. When the nerve tissue in all the canals is anesthetized, copious irrigation is used to clear the canal system of the residual topical. The author has used this technique for 6 years on >1000 teeth and had only one instance where the patient was not totally anesthetized. On patients who are extremely sensitive, the technique takes longer to perform but the results are the same. This technique is effective for all teeth but requires more time and more topical applications, up to 3 or 4 per canal, for extremely narrow and tortuous canals. One adverse effect observed is that sodium hypochlorite turns some topical anesthetics a dark reddish orange color, which could be mistaken for hemorrhage.
DISCUSSION One drawback to this technique is that residual topical anesthetic may remain in the root canal after instrumentation and irrigation and adversely effect the sealing ability of the sealer. Another potential problem is topical may be forced into periradicular tissues and have inflammatory effects. Because of the small amounts of topical anesthetic needed within the canals, it is unlikely that serum concentrations would ever approach the
Topical Anesthetic for Pulpectomies
203
toxic level. This technique has proven to be a safe and effective technique to reduce discomfort in patients who are not totally anesthetized by conventional local anesthetic techniques during pulpectomy procedures. The author thanks Dr. Frank Parreira for his assistance in preparing this article. The assertions contained herein are those of the author and are not to be construed as official or as reflecting the views of the Department of the Navy, Department of Defense, or the United States government. Dr. DeNunzio is Diplomate, Commander, Dental Corps, U.S. Navy, former resident, Naval Dental School, Bethesda, MD, and is currently the director of the Naval Air Technical Training Center, Branch Dental Clinic, Pensacola, FL. Address requests for reprints to Dr. Mark DeNunzio, 5180 Willow Run Drive, Pensacola, FL 32504.
References 1. McLean C, Reader A, Beck M, Meyers WJ. An evaluation of 4% prilocaine and 3% mepivacaine compared with 2% lidocaine (1:100,000 epinephrine) for inferior alveolar block. J Endodon 1993;19:146-50. 2. Walton RE, Abbott BJ. Periodontal ligament injection: a clinical evaluation. J Am Dent Assoc 1981 ;103:571-5. 3. Wallace JA, Michanowicz AE, Mundell RD, Wilson EG. A pilot study of the clinical problem of regionally anesthetizing the pulp of an acutely inflamed mandibular molar. Oral Surg 1985;59:517-21. 4. Olgart L, Hokfelt T, Nilsson G, Pernow B. Localization of substance P-like immunoreactivity in nerves in the tooth pulp. Pain 1977;4:153-9. 5. Kim S, Dorscher-Kim J. Hemodynamic regulation of the dental pulp in a low compliance environment. J Endodon 1989;15:404-8. 6. Dreven LJ, Reader A, Beck FM, Meyers W J, Weaver J. An evaluation of an electric pulp tester as a measure of analgesia in human vital teeth. J Endodon 1987;13:233-8. 7. Rosivack RG, Koenigsberg SR, Maxwell KC. An analysis of the effectiveness of two topical anesthetics. Anesth Prog 1990;37:290-2. 8. Gill C J, Orr DL. A double-blind crossover comparison of topical anesthetics. J Am Dent Assoc 1979;98:213-4. 9. Martin MD, Ramsay DS, Whitney C, Fiset L, Weinstein P. Topical anesthesia: differentiating the pharmacological and psychological contributions to efficacy. Anesth Prog 1994;41:40-7. 10. Adriani J, Beuttler WA, Brihmadesam L, Naraghi M. Topical anesthetics: use and misuse. South Med J 1985;78:1224-9.
Printed in U.S.A. VOL. 24, No. 3, MARCH1998
CLINICAL AID Topical Anesthetic as an Adjunct to Local Anesthesia during Pulpectomies Mark DeNunzio, DDS
A technique is described using topical anesthetic to supplement local anesthesia. It is the author's opinion that it enhances patient comfort during pulpectomies on teeth with irreversible pulpitis.
Topical anesthetics have been used in dentistry for many years, principally to reduce the discomfort of needle injections. They have also been used during the extraction of deciduous teeth, for the removal of arch wires after orthognathic surgery and during scaling and probing procedures. Research literature regarding the efficacy of topical anesthesia before needle injections is equivocal. Some studies support topical anesthesia as a useful adjunct for enhancing patient comfort during local anesthesia injections (7), whereas others do not (8). Topical anesthetic formulations generally contain high percentages (up to 20%) of esther-type anesthetic agents, usually benzocaine (9), which allow them to reach high concentrations at the sensory nerve endings. The duration of action is short, usually 15-30 min. Topical anesthetics are thought to function by blocking signal transmission in the terminal fibers of sensory nerves (10). Their effects are thought to be limited to the control of painful stimulation occurring in or just beneath the mucosa.
Patient comfort during endodontic procedures is paramount for patient satisfaction and acceptance of root canal therapy. Many techniques for achieving anesthesia during endodontic procedures are documented in the literature, and entire textbooks are dedicated to dental anesthesia. These techniques are useful because of the difficulty achieving adequate anesthesia during root canal procedures on some patients or during certain situations. McLean et al. (1) had a success rate for inferior alveolar injections of 43 to 67% for molar and premolar teeth. These low rates may be the reason for the popularity of alternative anesthesia techniques, including periodontal ligament injection (2) and intraosseous injection. Many experienced endodontists would agree that their most challenging anesthesia problems occur on patients who present with irreversible pulpitis requiring a pulpectomy. Wallace et al. (3), in a survey of Diplomates of the American Board of Endodontics, found that 210 of 268 diplomates answered yes to the question, "Do you find it more difficult to regionally anesthetize a painful tooth versus a nonpainful tooth?" The presence of a variety of inflammatory products (4) and the hemodynamic regulation within the pulp (5) are thought to add to the magnitude of pain perceived by these patients and contribute to the fact that these teeth can be extremely difficult to anesthetize. Wallace et al. (3) proposed that nerves arising in inflamed tissue had altered resting potentials and excitability thresholds. These changes were not restricted to the inflamed pulp itself, but affected the entire neuron cell membrane in every involved fiber. They also found that local anesthesia was not sufficient to prevent impulse transmission due to the lowered excitability thresholds of nerves in histamine-induced pulpal inflammation. In a study by Dreven et al. (6), anesthesia on inflamed teeth was unable to be attained in 27% of the cases, despite inferior alveolar blocks and periodontal ligament injection. Personal experience has shown that, even after opening into the pulp chamber and giving intrapulpal anesthesia, some patients can still sense pain when files are placed into the canals.
TECHNIQUE An adjunctive technique to augment infiltration, block, and intrapulpal injections is the use of topical anesthetic introduced into the inflamed root canal system. The technique can be used after intrapulpal anesthesia is attempted or as an alternative to intrapulpal anesthesia. The pulp chamber is unroofed and coronal pulpal tissue removed. If the patient feels discomfort when files are placed into the canals, the adjunctive topical technique is used. To reduce the risk of cross-contamination, a sterile cotton tip applicator is used to draw a quantity of topical anesthetic from its container. The author uses Hurricaine brand (Beutlich, LP, Waukegan, IL) topical gel, which contains 20% benzocaine. Any type of topical anesthetic with a high percentage of benzocaine and sufficient viscosity should work equally as well. A quantity of topical gel the size of the cotton tip is usually sufficient for one tooth, including molars with four canals. Holding the cotton tip applicator upright, a #10 or #15 file is drawn through the topical starting at the middle of the file and ending with the tip. As the tip is drawn through the topical, the file is pulled laterally to deposit a small bolus of topical on the last 3 to 4 mm of the file tip. If the temperature in the operating room is too high, the viscosity of the topical gel may not be sufficient to allow an adequate quantity to
202
Vol. 24, No. 3, March 1998
adhere to the file. If this occurs, the topical could be cooled in a refrigerator to increase the viscosity and help it adhere to the file tip. With the topical on the file tip, the file is placed into the canal. Using a watchwinding motion with an alternating pumping action, the topical gel is pushed down the canal. The objective is to push the gel ahead of the file so that it can anesthetize the remaining nerve tissue in the canal before the file stimulates the nerve and causes pain sensations. The patient usually feels some minor discomfort during this phase, but it only lasts - 1 0 s. Most canals are completely anesthetized with one or two applications of topical with the file. If the patient is extremely sensitive, more time is taken to push the topical down the canal. Any topical that remains in the pulp chamber serves as a reservoir for use in the remaining canals to be anesthetized. When the nerve tissue in all the canals is anesthetized, copious irrigation is used to clear the canal system of the residual topical. The author has used this technique for 6 years on >1000 teeth and had only one instance where the patient was not totally anesthetized. On patients who are extremely sensitive, the technique takes longer to perform but the results are the same. This technique is effective for all teeth but requires more time and more topical applications, up to 3 or 4 per canal, for extremely narrow and tortuous canals. One adverse effect observed is that sodium hypochlorite turns some topical anesthetics a dark reddish orange color, which could be mistaken for hemorrhage.
DISCUSSION One drawback to this technique is that residual topical anesthetic may remain in the root canal after instrumentation and irrigation and adversely effect the sealing ability of the sealer. Another potential problem is topical may be forced into periradicular tissues and have inflammatory effects. Because of the small amounts of topical anesthetic needed within the canals, it is unlikely that serum concentrations would ever approach the
Topical Anesthetic for Pulpectomies
203
toxic level. This technique has proven to be a safe and effective technique to reduce discomfort in patients who are not totally anesthetized by conventional local anesthetic techniques during pulpectomy procedures. The author thanks Dr. Frank Parreira for his assistance in preparing this article. The assertions contained herein are those of the author and are not to be construed as official or as reflecting the views of the Department of the Navy, Department of Defense, or the United States government. Dr. DeNunzio is Diplomate, Commander, Dental Corps, U.S. Navy, former resident, Naval Dental School, Bethesda, MD, and is currently the director of the Naval Air Technical Training Center, Branch Dental Clinic, Pensacola, FL. Address requests for reprints to Dr. Mark DeNunzio, 5180 Willow Run Drive, Pensacola, FL 32504.
References 1. McLean C, Reader A, Beck M, Meyers WJ. An evaluation of 4% prilocaine and 3% mepivacaine compared with 2% lidocaine (1:100,000 epinephrine) for inferior alveolar block. J Endodon 1993;19:146-50. 2. Walton RE, Abbott BJ. Periodontal ligament injection: a clinical evaluation. J Am Dent Assoc 1981 ;103:571-5. 3. Wallace JA, Michanowicz AE, Mundell RD, Wilson EG. A pilot study of the clinical problem of regionally anesthetizing the pulp of an acutely inflamed mandibular molar. Oral Surg 1985;59:517-21. 4. Olgart L, Hokfelt T, Nilsson G, Pernow B. Localization of substance P-like immunoreactivity in nerves in the tooth pulp. Pain 1977;4:153-9. 5. Kim S, Dorscher-Kim J. Hemodynamic regulation of the dental pulp in a low compliance environment. J Endodon 1989;15:404-8. 6. Dreven LJ, Reader A, Beck FM, Meyers W J, Weaver J. An evaluation of an electric pulp tester as a measure of analgesia in human vital teeth. J Endodon 1987;13:233-8. 7. Rosivack RG, Koenigsberg SR, Maxwell KC. An analysis of the effectiveness of two topical anesthetics. Anesth Prog 1990;37:290-2. 8. Gill C J, Orr DL. A double-blind crossover comparison of topical anesthetics. J Am Dent Assoc 1979;98:213-4. 9. Martin MD, Ramsay DS, Whitney C, Fiset L, Weinstein P. Topical anesthesia: differentiating the pharmacological and psychological contributions to efficacy. Anesth Prog 1994;41:40-7. 10. Adriani J, Beuttler WA, Brihmadesam L, Naraghi M. Topical anesthetics: use and misuse. South Med J 1985;78:1224-9.