- Email: [email protected]
The Efficacy of IntraFlow Intraosseous Injection as a Primary Anesthesia Technique
Clinical Research
The Efficacy of IntraFlow Intraosseous Injection as a Primary Anesthesia Technique Todd Remmers, DMD,* Gerald Glickman, DDS, MS,* Robert Spears, PhD,† and Jianing He, DMD, PhD* Abstract The purpose of this study was to compare the efficacy of intraosseous injection and inferior alveolar (IA) nerve block in anesthetizing mandibular posterior teeth with irreversible pulpitis. Thirty human subjects were randomly assigned to receive either intraosseous injection using the IntraFlow system (Pro-Dex Inc, Santa Ana, CA) or IA block as the primary anesthesia method. Pulpal anesthesia was evaluated via electric pulp testing at 4-minute intervals for 20 minutes. Two consecutive 80/80 readings were considered successful pulpal anesthesia. Anesthesia success or failure was recorded and groups compared. Intraosseous injection provided successful anesthesia in 13 of 15 subjects (87%). The IA block provided successful anesthesia in 9 of 15 subjects (60%). Although this difference was not statistically significant (p ⫽ 0.2148), the results of this preliminary study indicate that the IntraFlow system can be used as the primary anesthesia method in teeth with irreversible pulpitis to achieve predictable pulpal anesthesia. (J Endod 2008;34:280 –283)
Key Words Anesthesia, IntraFlow, intraosseous, pulpitis
From the Departments of *Endodontics and †Biomedical Sciences, Baylor College of Dentistry, The Texas A&M University System Health Science Center, Dallas, Texas. Address requests for reprints to Dr Jianing He, Department of Endodontics, Baylor College of Dentistry, 3302 Gaston Ave, Dallas, TX 75246. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright © 2008 by the American Association of Endodontists. doi:10.1016/j.joen.2007.12.005
A
dequate anesthesia is of critical importance when delivering root canal treatment. Inadequate anesthesia may result in increased chair time and undue stress on the patient and clinician, potentially leading to a less than optimum result. Therefore, it is incumbent on the operator to determine the best methodology to achieve this goal. Anesthesia of mandibular teeth traditionally has been delivered via an inferior alveolar (IA) nerve block (1). Success using this technique has been unpredictable, especially in teeth diagnosed with irreversible pulpitis (2– 4). The clinical failure rate of this method when anesthetizing teeth with irreversible pulpitis has been reported to be 44% to 81% (2– 6). This irregularity is multifactorial and may be caused by anatomic variation, local inflammatory processes, or neuronal sprouting (7–10). It can also be affected by individual variability in response to anesthetics, patient anxiety, needle deflection, type of anesthetic, and operator technique (6 – 8, 11). IA blocks are also associated with discomfort during delivery and lingering postoperative anesthesia (12). Variations of this technique have been explored to improve predictability including the Gow-Gates and Vazirani-Akinosi injections. Success rates have been shown to be greater than 90% (13, 14) and 76% to 93% (15–17), respectively. Intraosseous injection has been reported to be successful as a supplemental technique after failure of the IA block. In teeth exhibiting irreversible pulpitis, success rates range between 71% and 98% (2, 3, 18-20). Intraosseous injection involves perforation of the cortical bone adjacent to the tooth to be operated on. After perforation, a short needle is inserted into the site, and anesthetic is deposited directly into the cancellous bone. The porosity of bone allows for rapid diffusion of the drug and almost immediate onset of profound anesthesia. This technique also claims to be simple, quick, and more comfortable and to have minimal lingering numbness. Few studies have been performed using intraosseous injection as a primary anesthesia technique for teeth with irreversibly inflamed pulps. In addition, few studies have evaluated the IntraFlow system (Pro-Dex Inc, Santa Ana, CA), a dental handpiece with a perforator in the latch head and an integrated air pressure– driven injection system (Fig. 1). This system allows single-step perforation and deposition of anesthetic through the lumen of the perforator. Other intraosseous systems typically involve two separate steps: perforation with a standard slow-speed handpiece and injection using a standard dental syringe. This may be perceived as more cumbersome and time-consuming. As a result, IntraFlow claims to be more simple and predictable than other intraosseous techniques. The primary objective of this study was to compare the efficacy of IntraFlow intraosseous injection and IA block when used as the primary anesthesia technique for irreversibly inflamed pulps.
Materials and Methods All treatment protocols used in this study were approved by the Institutional Review Board of Baylor College of Dentistry, Texas A&M University System Health Science Center. Informed consent was obtained from all human subjects who participated. Inclusion criteria were as follows: (1) adults aged 18 to 65, (2) no major systemic or cardiovascular disease, (3) no history of taking any medication that would alter the inflammatory response of the pulp or provide analgesia for the previous 14 days, and (4) one mandibular posterior tooth diagnosed with irreversible pulpitis. The diagnosis of irreversible pulpitis was made by the application of Endo Ice refrigerant (Hygenic Corp, Akron, OH) to the affected tooth, and the patient reporting lingering pain. Match-
280
Remmers et al.
JOE — Volume 34, Number 3, March 2008
Clinical Research
Figure 1. A schematic diagram of the IntraFlow device.
ing contralateral teeth were also tested to ensure an accurate diagnosis and to serve as controls. Thirty patients scheduled for either endodontic treatment or extraction meeting the inclusion criteria were enrolled in the study. Patients were randomly assigned into 2 groups of 15 (Random Allocation Software, v1.0, Isfahan, Iran): group 1 underwent traditional IA block and group 2 underwent IntraFlow intraosseous injection as the primary anesthesia technique. Matching contralateral teeth served as negative controls and received no anesthetic. All procedures including diagnosis, injection, and anesthesia evaluation were performed by a single operator. The technique used for the IntraFlow intraosseous system was performed according to the manufacturer’s instructions, and the IA block was performed by standard technique. For the IntraFlow group, the site of perforation was selected near the junction of the attached and unattached gingival tissues, immediately distal to the test tooth. Radiographs were used to evaluate root proximity. A small volume of 2% lidocaine with 1:100,000 epinephrine (⬍0.1 mL) was infiltrated at the perforation site to ensure comfort during the procedure. Perforation was accomplished by operating the IntraFlow handpiece at full speed with the transfuser slider retracted. Constant moderate pressure was maintained until the perforator was felt to “drop” into the cancellous bone. The transfuser slider was then engaged forward, and one carpule (1.8 mL) of 2% lidocaine with 1:100,000 epinephrine was injected over a 60-second period. The transfuser slider was again retracted and, with the perforator rotating, removed from the injection site. The IA block group received the same type and volume of anesthetic. Efficacy of anesthesia was determined by electric pulp test response at 4-minute intervals for a period of 20 minutes. Baseline readings were obtained before application of the anesthetic. The contralateral tooth was also tested and served as a negative control. No subject response to the electric pulp test (80/80) for two consecutive cycles was the criterion for anesthesia (21). Anesthesia success/failure and time to onset for each technique was recorded. Success/failure was compared between groups by using a Fisher exact test; the time to onset was compared by using the Mann-Whitney U test. A p value less than 0.05 was considered statistically significant. The evaluation of perforators exhibiting leakage was also conducted by using scanning electron microscopy (SEM). Samples were dehydrated in a graded series of ethanol, critical point dried, mounted on 23-mm aluminum SEM stubs with double-sided carbon tape, and subsequently sputter coated with gold palladium. Each sample was examined via scanning electron microscopy (JSM-6300; JEOL, Tokyo, Japan) at magnifications of 27⫻, 45⫻, and 85⫻. Physical deformation and debris clogging the lumen were recorded.
JOE — Volume 34, Number 3, March 2008
Results The age of tests subjects ranged from 19 to 62 years (mean, 39 years). Gender distribution was 53% male and 47% female. The distribution of tooth type was 10% second premolar, 53% first molar, and 37% second molar. No intraoperative or postoperative complications were reported during the procedure or at follow-up visits. Control teeth all responded normally to both thermal and electric pulp testing throughout the test period. Group 1 (IA block) was successful in 9 of the 15 cases attempted (60%). The time to onset of profound anesthesia averaged 8.5 minutes (standard deviation ⫾ 3.96). If anesthesia was successful, the minimum amount of time for onset was 4 minutes, and the maximum was 16 minutes (Fig. 2). Group 2 (intraosseous) was successful in 13 of the 15 cases attempted (87%). The leakage of anesthetic solution was noted from the transfuser assembly in both cases of failure. The time to onset of profound anesthesia averaged 4.6 minutes (standard deviation ⫾ 1.50). The minimum amount of time for onset was less than 4 minutes, and the maximum was 8 minutes (Fig. 2). The time to onset of anesthesia was found to be statistically more rapid than the IA block (p ⫽ 0.017). Overall, the use of the IntraFlow system for intraosseous injection was 27% more successful than the traditional IA block (87% vs 60%). This difference, however, was not statistically significant (p ⫽ 0.2148). Gross SEM evaluation of the two perforators exhibiting leakage during injection revealed partial clogging of the perforator lumen and minor blunting of the perforator tip (Fig. 3).
Figure 2. Time response curves for the two injection techniques. IANB, inferior alveolar nerve block.
IntraFlow Intraosseous Injection for Primary Anesthesia
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Clinical Research
Figure 3. SEM observations showing blunting of the perforator tip and partial clogging of the lumen (original magnification 85⫻).
Discussion There has been a paradigm in dentistry that the primary method of obtaining pulpal anesthesia in the mandible has been the IA block. Even with the reported lack of reliability, especially when used in cases of irreversible pulpitis, it has remained the gold standard for more than a century. Intraosseous injection, on the other hand, has been reported to be very reliable for both normal pulps when used as the primary anesthesia and for inflamed pulps when used as a supplemental technique. There are limitations, however, to any intraosseous technique. First, the duration of anesthesia is reduced when compared with the block because of the vascularity of the cancellous bone into which the anesthetic is injected. In normal teeth with healthy pulp, the average duration of anesthesia of intraosseous injection of the mandible has been reported to steadily decline over a period of 60 minutes (11, 22), whereas the IA nerve block has been reported to linger on average more than 140 minutes (23). For minor restorative procedures and emergency endodontic treatment, the duration of intraosseous injection is generally considered sufficient. For more protracted procedures or procedures that may accompany significant postoperative discomfort, IA block may be preferred. Additionally, intraosseous injection is contraindicated when infection is present at the site of perforation or when there is close proximity of vital structures, tooth roots, or developing teeth. In this current study, it was shown that intraosseous injection using the IntraFlow system was successful in obtaining pulpal anesthesia 87% of the time. Traditional inferior alveolar nerve block carried a reduced rate of success of 60%. This is in agreement with the findings of Nusstein et al. (19) who found similar rates of success (82%) when using intraosseous injection as supplemental anesthesia for irreversibly inflamed pulps and Coggins et al. (24) who used primary intraosseous anesthesia for noninflamed pulps (75%–93%). In the two cases in which the IntraFlow system failed to obtain adequate anesthesia, leakage of anesthetic solution was noted from the transfuser head during the injection phase. This leakage may have contributed to failure. Possible causes for the leakage may include faulty assembly of the transfuser to the handpiece by the clinician or clogging of the perforator with debris during the perforation process. This could lead to excessive anesthetic pressure within the device during injection and leakage at the perforator/transfuser connection. SEM evaluation of the two perforator tips that exhibited leakage in this study clearly showed debris partially clogging the device (Fig. 2). Further evaluation 282
Remmers et al.
of the effect of perforator clogging on anesthetic delivery may be indicated. Additionally, successful clinical anesthesia is not only dependent on pulpal anesthesia but also periradicular anesthesia. This is obviated by the finding that more than 50% of teeth diagnosed with irreversible pulpitis also exhibit acute periradicular periodontitis and greater perceived pain than teeth with a normal periradicular diagnosis (25). Khan et al. (26) showed a 62% decrease in periradicular mechanical allodynia after the administration of anesthetic for teeth diagnosed with irreversible pulpitis. Because intraosseous injections deposit the anesthetic solution in close proximity to the root apices and associated periradicular tissues, a greater reduction in mechanical allodynia may be possible. Given that the status of the periradicular tissues were not evaluated as a part of this study, further research should be considered to evaluate the effectiveness of intraosseous injection in reducing periradicular mechanical allodynia. Within the limitations of this study, it was found that anesthesia was more rapid and more reliable when delivered by the IntraFlow system than by the traditional IA block technique. However the difference in success was not statistically significant. This lack of significance may likely be caused by the relatively small sample size. In light of the disparity in reported reliability of IA blocks and taking into account the findings of this study, further research should be conducted using larger sample sizes to more reliably determine the significance, validity, and reliability of IntraFlow intraosseous anesthesia.
Acknowledgment IntraFlow intraosseous injection units and disposable IntraFlow transfuser assemblies were provided by Pro-Dex, Inc, Santa Ana, CA.
References 1. Malamed SF. Handbook of Local Anesthesia. 5th ed. St Louis: Mosby; 2004. 2. Nusstein J, Reader A, Nist R, Beck M, Meyers WJ. Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis. J Endod 1998;24:487–91. 3. Reisman D, Reader A, Nist R, Beck M, Weaver J. Anesthetic efficacy of the supplemental intraosseous injection of 3% mepivacaine in irreversible pulpitis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:676 – 82. 4. Cohen HP, Cha BY, Spangberg LS. Endodontic anesthesia in mandibular molars: a clinical study. J Endod 1993;19:370 –3. 5. Nusstein J, Reader A, Beck FM. Anesthetic efficacy of different volumes of lidocaine with epinephrine for inferior alveolar nerve blocks. Gen Dent 2002;50:372–5; quiz 376 –7. 6. Kennedy S, Reader A, Nusstein J, Beck M, Weaver J. The significance of needle deflection in success of the inferior alveolar nerve block in patients with irreversible pulpitis. J Endod 2003;29:630 –3. 7. Wong MK, Jacobsen PL. Reasons for local anesthesia failures. J Am Dent Assoc 1992;123:69 –73. 8. Meechan JG. How to overcome failed local anaesthesia. Br Dent J 1999;186:15–20. 9. 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 Oral Med Oral Pathol 1985;59:517–21. 10. Byers MR, Taylor PE, Khayat BG, Kimberly CL. Effects of injury and inflammation on pulpal and periapical nerves. J Endod 1990;16:78 – 84. 11. Replogle K, Reader A, Nist R, Beck M, Weaver J, Meyers WJ. Anesthetic efficacy of the intraosseous injection of 2% lidocaine (1:100,000 epinephrine) and 3% mepivacaine in mandibular first molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83:30 –7. 12. Kaufman E, Epstein JB, Naveh E, Gorsky M, Gross A, Cohen G. A survey of pain, pressure, and discomfort induced by commonly used oral local anesthesia injections. Anesth Prog 2005;52:122–7. 13. Levy TP. An assessment of the Gow-Gates mandibular block for third molar surgery. J Am Dent Assoc 1981;103:37– 41. 14. Malamed SF. The Gow-Gates mandibular block. Evaluation after 4,275 cases. Oral Surg Oral Med Oral Pathol 1981;51:463–7. 15. Akinosi JO. A new approach to the mandibular nerve block. Br J Oral Surg 1977;15:83–7.
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Clinical Research 16. Sisk AL. Evaluation of the Akinosi mandibular block technique in oral surgery. J Oral Maxillofac Surg 1986;44:113–5. 17. Todorovic L, Stajcic Z, Petrovic V. Mandibular versus inferior dental anaesthesia: clinical assessment of 3 different techniques. Int J Oral Maxillofac Surg 1986;15:733– 8. 18. Bigby J, Reader A, Nusstein J, Beck M, Weaver J. Articaine for supplemental intraosseous anesthesia in patients with irreversible pulpitis. J Endod 2006;32:1044 –7. 19. Nusstein J, Kennedy S, Reader A, Beck M, Weaver J. Anesthetic efficacy of the supplemental X-tip intraosseous injection in patients with irreversible pulpitis. J Endod 2003;29:724 – 8. 20. Parente SA, Anderson RW, Herman WW, Kimbrough WF, Weller RN. Anesthetic efficacy of the supplemental intraosseous injection for teeth with irreversible pulpitis. J Endod 1998;24:826 – 8. 21. Certosimo AJ, Archer RD. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Oper Dent 1996;21:25–30.
JOE — Volume 34, Number 3, March 2008
22. Gallatin J, Reader A, Nusstein J, Beck M, Weaver J. A comparison of two intraosseous anesthetic techniques in mandibular posterior teeth. J Am Dent Assoc 2003; 134:1476 – 84. 23. Fernandez C, Reader A, Beck M, Nusstein J. A prospective, randomized, double-blind comparison of bupivacaine and lidocaine for inferior alveolar nerve blocks. J Endod 2005;31:499 –503. 24. Coggins R, Reader A, Nist R, Beck M, Meyers WJ. Anesthetic efficacy of the intraosseous injection in maxillary and mandibular teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:634 – 41. 25. Owatz CB, Khan AA, Schindler WG, Schwartz SA, Keiser K, Hargreaves KM. The incidence of mechanical allodynia in patients with irreversible pulpitis. J Endod 2007;33:552– 6. 26. Khan AA, Owatz CB, Schindler WG, Schwartz SA, Keiser K, Hargreaves KM. Measurement of mechanical allodynia and local anesthetic efficacy in patients with irreversible pulpitis and acute periradicular periodontitis. J Endod 2007;33:796 –9.
IntraFlow Intraosseous Injection for Primary Anesthesia
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The Efficacy of IntraFlow Intraosseous Injection as a Primary Anesthesia Technique Todd Remmers, DMD,* Gerald Glickman, DDS, MS,* Robert Spears, PhD,† and Jianing He, DMD, PhD* Abstract The purpose of this study was to compare the efficacy of intraosseous injection and inferior alveolar (IA) nerve block in anesthetizing mandibular posterior teeth with irreversible pulpitis. Thirty human subjects were randomly assigned to receive either intraosseous injection using the IntraFlow system (Pro-Dex Inc, Santa Ana, CA) or IA block as the primary anesthesia method. Pulpal anesthesia was evaluated via electric pulp testing at 4-minute intervals for 20 minutes. Two consecutive 80/80 readings were considered successful pulpal anesthesia. Anesthesia success or failure was recorded and groups compared. Intraosseous injection provided successful anesthesia in 13 of 15 subjects (87%). The IA block provided successful anesthesia in 9 of 15 subjects (60%). Although this difference was not statistically significant (p ⫽ 0.2148), the results of this preliminary study indicate that the IntraFlow system can be used as the primary anesthesia method in teeth with irreversible pulpitis to achieve predictable pulpal anesthesia. (J Endod 2008;34:280 –283)
Key Words Anesthesia, IntraFlow, intraosseous, pulpitis
From the Departments of *Endodontics and †Biomedical Sciences, Baylor College of Dentistry, The Texas A&M University System Health Science Center, Dallas, Texas. Address requests for reprints to Dr Jianing He, Department of Endodontics, Baylor College of Dentistry, 3302 Gaston Ave, Dallas, TX 75246. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright © 2008 by the American Association of Endodontists. doi:10.1016/j.joen.2007.12.005
A
dequate anesthesia is of critical importance when delivering root canal treatment. Inadequate anesthesia may result in increased chair time and undue stress on the patient and clinician, potentially leading to a less than optimum result. Therefore, it is incumbent on the operator to determine the best methodology to achieve this goal. Anesthesia of mandibular teeth traditionally has been delivered via an inferior alveolar (IA) nerve block (1). Success using this technique has been unpredictable, especially in teeth diagnosed with irreversible pulpitis (2– 4). The clinical failure rate of this method when anesthetizing teeth with irreversible pulpitis has been reported to be 44% to 81% (2– 6). This irregularity is multifactorial and may be caused by anatomic variation, local inflammatory processes, or neuronal sprouting (7–10). It can also be affected by individual variability in response to anesthetics, patient anxiety, needle deflection, type of anesthetic, and operator technique (6 – 8, 11). IA blocks are also associated with discomfort during delivery and lingering postoperative anesthesia (12). Variations of this technique have been explored to improve predictability including the Gow-Gates and Vazirani-Akinosi injections. Success rates have been shown to be greater than 90% (13, 14) and 76% to 93% (15–17), respectively. Intraosseous injection has been reported to be successful as a supplemental technique after failure of the IA block. In teeth exhibiting irreversible pulpitis, success rates range between 71% and 98% (2, 3, 18-20). Intraosseous injection involves perforation of the cortical bone adjacent to the tooth to be operated on. After perforation, a short needle is inserted into the site, and anesthetic is deposited directly into the cancellous bone. The porosity of bone allows for rapid diffusion of the drug and almost immediate onset of profound anesthesia. This technique also claims to be simple, quick, and more comfortable and to have minimal lingering numbness. Few studies have been performed using intraosseous injection as a primary anesthesia technique for teeth with irreversibly inflamed pulps. In addition, few studies have evaluated the IntraFlow system (Pro-Dex Inc, Santa Ana, CA), a dental handpiece with a perforator in the latch head and an integrated air pressure– driven injection system (Fig. 1). This system allows single-step perforation and deposition of anesthetic through the lumen of the perforator. Other intraosseous systems typically involve two separate steps: perforation with a standard slow-speed handpiece and injection using a standard dental syringe. This may be perceived as more cumbersome and time-consuming. As a result, IntraFlow claims to be more simple and predictable than other intraosseous techniques. The primary objective of this study was to compare the efficacy of IntraFlow intraosseous injection and IA block when used as the primary anesthesia technique for irreversibly inflamed pulps.
Materials and Methods All treatment protocols used in this study were approved by the Institutional Review Board of Baylor College of Dentistry, Texas A&M University System Health Science Center. Informed consent was obtained from all human subjects who participated. Inclusion criteria were as follows: (1) adults aged 18 to 65, (2) no major systemic or cardiovascular disease, (3) no history of taking any medication that would alter the inflammatory response of the pulp or provide analgesia for the previous 14 days, and (4) one mandibular posterior tooth diagnosed with irreversible pulpitis. The diagnosis of irreversible pulpitis was made by the application of Endo Ice refrigerant (Hygenic Corp, Akron, OH) to the affected tooth, and the patient reporting lingering pain. Match-
280
Remmers et al.
JOE — Volume 34, Number 3, March 2008
Clinical Research
Figure 1. A schematic diagram of the IntraFlow device.
ing contralateral teeth were also tested to ensure an accurate diagnosis and to serve as controls. Thirty patients scheduled for either endodontic treatment or extraction meeting the inclusion criteria were enrolled in the study. Patients were randomly assigned into 2 groups of 15 (Random Allocation Software, v1.0, Isfahan, Iran): group 1 underwent traditional IA block and group 2 underwent IntraFlow intraosseous injection as the primary anesthesia technique. Matching contralateral teeth served as negative controls and received no anesthetic. All procedures including diagnosis, injection, and anesthesia evaluation were performed by a single operator. The technique used for the IntraFlow intraosseous system was performed according to the manufacturer’s instructions, and the IA block was performed by standard technique. For the IntraFlow group, the site of perforation was selected near the junction of the attached and unattached gingival tissues, immediately distal to the test tooth. Radiographs were used to evaluate root proximity. A small volume of 2% lidocaine with 1:100,000 epinephrine (⬍0.1 mL) was infiltrated at the perforation site to ensure comfort during the procedure. Perforation was accomplished by operating the IntraFlow handpiece at full speed with the transfuser slider retracted. Constant moderate pressure was maintained until the perforator was felt to “drop” into the cancellous bone. The transfuser slider was then engaged forward, and one carpule (1.8 mL) of 2% lidocaine with 1:100,000 epinephrine was injected over a 60-second period. The transfuser slider was again retracted and, with the perforator rotating, removed from the injection site. The IA block group received the same type and volume of anesthetic. Efficacy of anesthesia was determined by electric pulp test response at 4-minute intervals for a period of 20 minutes. Baseline readings were obtained before application of the anesthetic. The contralateral tooth was also tested and served as a negative control. No subject response to the electric pulp test (80/80) for two consecutive cycles was the criterion for anesthesia (21). Anesthesia success/failure and time to onset for each technique was recorded. Success/failure was compared between groups by using a Fisher exact test; the time to onset was compared by using the Mann-Whitney U test. A p value less than 0.05 was considered statistically significant. The evaluation of perforators exhibiting leakage was also conducted by using scanning electron microscopy (SEM). Samples were dehydrated in a graded series of ethanol, critical point dried, mounted on 23-mm aluminum SEM stubs with double-sided carbon tape, and subsequently sputter coated with gold palladium. Each sample was examined via scanning electron microscopy (JSM-6300; JEOL, Tokyo, Japan) at magnifications of 27⫻, 45⫻, and 85⫻. Physical deformation and debris clogging the lumen were recorded.
JOE — Volume 34, Number 3, March 2008
Results The age of tests subjects ranged from 19 to 62 years (mean, 39 years). Gender distribution was 53% male and 47% female. The distribution of tooth type was 10% second premolar, 53% first molar, and 37% second molar. No intraoperative or postoperative complications were reported during the procedure or at follow-up visits. Control teeth all responded normally to both thermal and electric pulp testing throughout the test period. Group 1 (IA block) was successful in 9 of the 15 cases attempted (60%). The time to onset of profound anesthesia averaged 8.5 minutes (standard deviation ⫾ 3.96). If anesthesia was successful, the minimum amount of time for onset was 4 minutes, and the maximum was 16 minutes (Fig. 2). Group 2 (intraosseous) was successful in 13 of the 15 cases attempted (87%). The leakage of anesthetic solution was noted from the transfuser assembly in both cases of failure. The time to onset of profound anesthesia averaged 4.6 minutes (standard deviation ⫾ 1.50). The minimum amount of time for onset was less than 4 minutes, and the maximum was 8 minutes (Fig. 2). The time to onset of anesthesia was found to be statistically more rapid than the IA block (p ⫽ 0.017). Overall, the use of the IntraFlow system for intraosseous injection was 27% more successful than the traditional IA block (87% vs 60%). This difference, however, was not statistically significant (p ⫽ 0.2148). Gross SEM evaluation of the two perforators exhibiting leakage during injection revealed partial clogging of the perforator lumen and minor blunting of the perforator tip (Fig. 3).
Figure 2. Time response curves for the two injection techniques. IANB, inferior alveolar nerve block.
IntraFlow Intraosseous Injection for Primary Anesthesia
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Clinical Research
Figure 3. SEM observations showing blunting of the perforator tip and partial clogging of the lumen (original magnification 85⫻).
Discussion There has been a paradigm in dentistry that the primary method of obtaining pulpal anesthesia in the mandible has been the IA block. Even with the reported lack of reliability, especially when used in cases of irreversible pulpitis, it has remained the gold standard for more than a century. Intraosseous injection, on the other hand, has been reported to be very reliable for both normal pulps when used as the primary anesthesia and for inflamed pulps when used as a supplemental technique. There are limitations, however, to any intraosseous technique. First, the duration of anesthesia is reduced when compared with the block because of the vascularity of the cancellous bone into which the anesthetic is injected. In normal teeth with healthy pulp, the average duration of anesthesia of intraosseous injection of the mandible has been reported to steadily decline over a period of 60 minutes (11, 22), whereas the IA nerve block has been reported to linger on average more than 140 minutes (23). For minor restorative procedures and emergency endodontic treatment, the duration of intraosseous injection is generally considered sufficient. For more protracted procedures or procedures that may accompany significant postoperative discomfort, IA block may be preferred. Additionally, intraosseous injection is contraindicated when infection is present at the site of perforation or when there is close proximity of vital structures, tooth roots, or developing teeth. In this current study, it was shown that intraosseous injection using the IntraFlow system was successful in obtaining pulpal anesthesia 87% of the time. Traditional inferior alveolar nerve block carried a reduced rate of success of 60%. This is in agreement with the findings of Nusstein et al. (19) who found similar rates of success (82%) when using intraosseous injection as supplemental anesthesia for irreversibly inflamed pulps and Coggins et al. (24) who used primary intraosseous anesthesia for noninflamed pulps (75%–93%). In the two cases in which the IntraFlow system failed to obtain adequate anesthesia, leakage of anesthetic solution was noted from the transfuser head during the injection phase. This leakage may have contributed to failure. Possible causes for the leakage may include faulty assembly of the transfuser to the handpiece by the clinician or clogging of the perforator with debris during the perforation process. This could lead to excessive anesthetic pressure within the device during injection and leakage at the perforator/transfuser connection. SEM evaluation of the two perforator tips that exhibited leakage in this study clearly showed debris partially clogging the device (Fig. 2). Further evaluation 282
Remmers et al.
of the effect of perforator clogging on anesthetic delivery may be indicated. Additionally, successful clinical anesthesia is not only dependent on pulpal anesthesia but also periradicular anesthesia. This is obviated by the finding that more than 50% of teeth diagnosed with irreversible pulpitis also exhibit acute periradicular periodontitis and greater perceived pain than teeth with a normal periradicular diagnosis (25). Khan et al. (26) showed a 62% decrease in periradicular mechanical allodynia after the administration of anesthetic for teeth diagnosed with irreversible pulpitis. Because intraosseous injections deposit the anesthetic solution in close proximity to the root apices and associated periradicular tissues, a greater reduction in mechanical allodynia may be possible. Given that the status of the periradicular tissues were not evaluated as a part of this study, further research should be considered to evaluate the effectiveness of intraosseous injection in reducing periradicular mechanical allodynia. Within the limitations of this study, it was found that anesthesia was more rapid and more reliable when delivered by the IntraFlow system than by the traditional IA block technique. However the difference in success was not statistically significant. This lack of significance may likely be caused by the relatively small sample size. In light of the disparity in reported reliability of IA blocks and taking into account the findings of this study, further research should be conducted using larger sample sizes to more reliably determine the significance, validity, and reliability of IntraFlow intraosseous anesthesia.
Acknowledgment IntraFlow intraosseous injection units and disposable IntraFlow transfuser assemblies were provided by Pro-Dex, Inc, Santa Ana, CA.
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Clinical Research 16. Sisk AL. Evaluation of the Akinosi mandibular block technique in oral surgery. J Oral Maxillofac Surg 1986;44:113–5. 17. Todorovic L, Stajcic Z, Petrovic V. Mandibular versus inferior dental anaesthesia: clinical assessment of 3 different techniques. Int J Oral Maxillofac Surg 1986;15:733– 8. 18. Bigby J, Reader A, Nusstein J, Beck M, Weaver J. Articaine for supplemental intraosseous anesthesia in patients with irreversible pulpitis. J Endod 2006;32:1044 –7. 19. Nusstein J, Kennedy S, Reader A, Beck M, Weaver J. Anesthetic efficacy of the supplemental X-tip intraosseous injection in patients with irreversible pulpitis. J Endod 2003;29:724 – 8. 20. Parente SA, Anderson RW, Herman WW, Kimbrough WF, Weller RN. Anesthetic efficacy of the supplemental intraosseous injection for teeth with irreversible pulpitis. J Endod 1998;24:826 – 8. 21. Certosimo AJ, Archer RD. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Oper Dent 1996;21:25–30.
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22. Gallatin J, Reader A, Nusstein J, Beck M, Weaver J. A comparison of two intraosseous anesthetic techniques in mandibular posterior teeth. J Am Dent Assoc 2003; 134:1476 – 84. 23. Fernandez C, Reader A, Beck M, Nusstein J. A prospective, randomized, double-blind comparison of bupivacaine and lidocaine for inferior alveolar nerve blocks. J Endod 2005;31:499 –503. 24. Coggins R, Reader A, Nist R, Beck M, Meyers WJ. Anesthetic efficacy of the intraosseous injection in maxillary and mandibular teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:634 – 41. 25. Owatz CB, Khan AA, Schindler WG, Schwartz SA, Keiser K, Hargreaves KM. The incidence of mechanical allodynia in patients with irreversible pulpitis. J Endod 2007;33:552– 6. 26. Khan AA, Owatz CB, Schindler WG, Schwartz SA, Keiser K, Hargreaves KM. Measurement of mechanical allodynia and local anesthetic efficacy in patients with irreversible pulpitis and acute periradicular periodontitis. J Endod 2007;33:796 –9.
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