Intraosseous Anesthesia: A Review

The recent introduction of intraosseous injection devices has renewed interest in the modality of local anesthesia. Three devices currently available are the Stabident System, the Hypo Brand Intraosseous Needle, and the Cyberjet System. The Stabident System is the most popular and the only one for which published research is available. Primary intraosseous anesthesia is 45 percent to 93 percent effective but of short duration. Supplemental intraosseous anesthesia is 80 percent to 90 percent effective and provides profound anesthesia of long duration (60 minutes or longer). It is used when a prior conventional infiltration or nerve block is inadequate. During use of an anesthetic solution with a vasoconstrictor for intraosseous anesthesia, 46 percent to 100 percent of patients reported an increase in heart rate. There was a 2 percent to 27 percent incidence of moderate and sometimes severe pain during the intraosseous procedure. Postoperative complications occurred in 2 percent to 15 percent of patients and lasted one to 14 days.

Intraosseous anesthesia involves the injection of anesthetic solution directly into cancellous bone to produce anesthesia of the neighboring soft tissue, bone, and teeth.

Historically, due to the lack of a standardized armamentarium, great ingenuity was needed to administer intraosseous anesthesia. Magnus,¹ seeking an alternative to the inferior alveolar nerve block, used a standard 27 gauge needle to both penetrate the cortical plate and inject anesthetic directly into bone. He found this method successful for deciduous molars and adult mandibular incisors and bicuspids. Bourke² used a No. 4 beutelrock drill in a straight handpiece to penetrate the cortical plate. He then injected anesthetic with a 3/4 inch, 26 gauge needle placed in the hole made by the drill. He used this method for both maxillary and mandibular teeth. Lilienthal³ used a No. 4 root canal reamer in a straight handpiece to drill into bone and then injected anesthetic with an extra short needle. Pearce⁴ used intraosseous anesthesia for the endodontic treatment of mandibular molars when conventional block anesthesia was not totally effective. He penetrated the cortex into cancellous bone with a No. 3 beutelrock drill mounted in a slow-speed contra-angle handpiece. He then used a 30 gauge needle cut 1/2 inch from the hub to inject anesthetic solution.

Regardless of these early efforts, intraosseous anesthesia was seldom used in the past. Recently, however, intraosseous injection systems have become available, and there is renewed interest in this method of administering local anesthetic.

Intraosseous Injection Devices

Figure 1. The Stabident System.

There are currently three commercial devices for the intraosseous injection. The most widely used is the Stabident System (Fairfax, Dental, Inc., Miami, Fla.). This system consists of a perforator and an injection needle. The perforator is 0.9 mm in length and has a diameter of 0.43 mm. It is driven by a slow-speed contra-angle handpiece. The injection needle is also 0.9 mm in length but has a slightly smaller diameter of 0.40 mm. The injection needle attaches to a standard dental anesthetic syringe (Figure 1).

Figure 2. The site of injection for the Stabident System is usually distal to the tooth to be anesthetized at a point 2 mm below the intersection of a horizontal line through the gingival margins of the adjacent teeth and vertical line through the center for the interproximal papilla.

The site of injection for the Stabident System is a point 2 mm below the intersection of a horizontal line through the gingival margins of the adjacent teeth and a vertical line through the center of the interproximal papilla (Figure 2). If this site is in alveolar mucosa, it is moved up to attached gingiva. The area is first anesthetized with a few drops of anesthetic. Then the rotary perforator, held perpendicular to the cortical plate, is pushed through the gingiva and activated in short bursts with slow speed until a feeling of "give" is felt or until two to five seconds have elapsed. Next, the syringe is held in a "pen-grip" fashion and the needle inserted through the perforation into cancellous bone. The anesthetic is injected slowly over the course of one to two minutes. For posterior injections, the needle is bent 45 degree at the hub to facilitate placement. If back pressure is felt during injection, the needle is rotated one quarter turn and reinjection attempted. If this is not successful, the needle is removed and checked for blockage. If not blocked, the site is reperforated with a new perforator and the injection completed.

Figure 3. The Hypo Brand Intraosseous Needle.

A second device is the Hypo Brand Intraosseous Needle (MPL Technologies, Inc., Franklin Park, Ill.) which is a 30 gauge needle, 1/8 inch long. It is reinforced with a plastic sheath that allows direct injection into interproximal bone. The needle is stabilized with a stainless steel sheath that retracts into the needle body and prevents the needle from bending or breaking during perforation. The Hypo Brand Intraosseous Needle allows for a single-step procedure for both perforation and injection (Figure 3). The site of injection for this system is the base of the interproximal papilla at the mesial of the tooth to be anesthetized. Mandibular molars require a second injection at the crest of bone between the mesial and distal roots. After the placement of topical anesthetic, the needle is placed against the tissue and angled apically. Injection of anesthetic is started as soon as the point of the needle is below the surface.

Pressure is increased on the syringe (not the plunger) with a slight turning motion until the cortical plate is penetrated. The injection is then completed. A second method is to inject within 2 to 3 mm of the root apex. This latter technique is useful in the maxillary anterior and premolar regions where the cortical bone is usually thin. It is recommended that only 0.5 ml of anesthetic be injected at each site. This provides 15 to 20 minutes of operative anesthesia (Figure 4).

Figure 4a. The site of injection for the Hypo Brand Intraosseous Needle is the base of the interproximal papilla at the mesial of the tooth to be anesthetized.

Figure 4b. Using the Hypo Brand Intraosseous Needle for mandibular molars requires two injections, one at the base of the mesial interproximal papilla and a second at the crest of bone between the mesial and distal roots.

Figure 4c. A second method of using the Hypo Brand Intraosseous Needle is to inject within 2 to 3 mm of the root apex on either the mesial or distal side.

The newest device is the Cyberjet System (Cyberdent Inc., Novato, Calif.). This system consists of a special air-driven handpiece, a disposable 27 gauge needle that also acts as a drill, and a disposable plastic transfuser that conducts the anesthetic from a standard dental anesthetic carpule.

Figure 5. The Cyberjet Intraosseous System.

Figure 6. The angle of penetration for the Cyberjet System is 30 to 40 degrees from the long axis of the tooth.

The handpiece is operated by foot control. Perforation and injection are carried out in a single step by moving a clutch button on the handpiece (Figure 5). The site of perforation is the center of the base of the interproximal papilla for maxillary teeth and 2 mm below this point for mandibular teeth. Topical anesthetic is applied for a few minutes. The needle is placed at the selected penetration site and angled at 30 to 40 degrees from the long axis of the tooth (Figure 6). The clutch button is moved toward the motor drive to disengage rotation and a few drops of anesthetic are injected by stepping on the foot pedal. The clutch is then released and the foot pedal is pressed down completely until perforation is felt. The clutch is again pulled back and the remaining anesthetic injected. The rate of injection depends on the amount of pressure on the foot pedal. The needle is removed from the perforation site by starting rotation and withdrawing rapidly.

Review of Recent Studies

Several recent studies have investigated the administration of intraosseous anesthesia as either a primary injection technique (Table 1)^5-8 or a supplemental injection technique (Table 2).^9-12

Table 2 Supplemental Intraosseous Anesthesia
Principal author of study	Type of study	Anesthetic used	% Effective anesthesia	Onset	Duration	Pain IO procedure	Side effects	Post-op complications
Dunbar D9	Experimental pulp tester* mandibular posterior teeth asymptomatic	1.8 ml 2% lidocaine 1:100,000 epinephrine	100% immediate. 90% 60 minues or longer.	Immediate	95% for 30 minutes. 90% at least 60 minutes.	2-12% mild-moderate pain	80% increased heart rate	2% pain 3% swelling 10% teeth "felt high"
Reisman D10	Clinical mandibular posterior teeth – Dx irreversible pulpitis-endo treatment	1.8 ml 2% lidocaine 1:100,000 epinephrine IAN block. 1.8 ml 3% mepivacaine supplemental	80% 1st supplemental-increased to 98% with 2nd supplemental	Waited three minutes before starting treatment	N/R but duration sufficient to complete endodontic procedure	9% moderate-severe pain performation. 27% moderate pain. 6% severe pain injection.	No increase in heart rate with 3% mepivacaine	N/R
Nusstein J11	Clinical mandibular posterior teeth-Dx irreversible pulpitis-endo treatment	1.8 ml 2% lidocaine 1:100,000 epinephrine	88% success with supplemental intraosseous injection	N/R	Sufficient time to complete endodontic procedure	8% moderate to severe pain perforation. 4% severe pain injection.	46% increased heart rate	N/R
Parante SA12	Clinical –DX irreversible pulpitis-endo treatment	0.45-0.90 ml 2% lidocaine 1:100,000 epinephrine	89% success used 0.45 to 0.90 ml anesthetic for supplemental 4/33 teeth needed a 2nd IO injection	Immediate	Sufficeitn time to complete endodontic procedure	N/R	Advised to caution patients- increased heart rate with IO injection	1/37 patients reported mild post-operative discomfort
N/R – not reported in study * Anesthesia was considered successful when there was no subjective response to the maximum output of the pulp tester (80 reading – Analytic Technology pulp tester)

Primary intraosseous anesthesia is the use of the intraosseous injection instead of a conventional anesthetic technique. Supplemental intraosseous anesthesia is the use of the intraosseous injection in addition to a conventional injection technique.

The studies cited in Table 1 and Table 2 all used the Stabident System. There are no published reports evaluating the Hypo Brand Intraosseous Needle or the Cyberjet System.

The effectiveness of primary intraosseous anesthesia varies from 90 percent for maxillary molars to 75 percent for mandibular molars when 1.8 ml of 2 percent lidocaine with 1:100,000 epinephrine is used as the anesthetic. The onset of anesthesia is immediate but the duration decreases rapidly. When using 3 percent mepivacaine (without vasoconstrictor), both the effectiveness and duration are further decreased. The area of anesthesia is limited with the primary intraosseous injection; but, when used in the posterior mandible, lip numbness is reported to occur in 50 percent to 76 percent of the cases (Table 1). Goggins and colleagues,⁷ however, reported that most subjects said the lip numbness was not as profound as after an inferior alveolar nerve block. Tongue and cheek numbness do not occur with primary intraosseous anesthesia.⁵

Supplemental intraosseous anesthesia is used when pain persists following a "clinically successful" conventional injection. When using an anesthetic with a vasoconstrictor such as 2 percent lidocaine with 1:100,000 epinephrine, the effectiveness is about 90 percent and the duration at least 60 minutes. Using anesthetics without a vasoconstrictor such as 3 percent mepivacaine, the effectiveness is about 80 percent, even in teeth diagnosed with irreversible pulpitis. It increases to 98 percent with a second intraosseous injection. The onset of anesthesia is immediate. The volume of anesthetic solution needed for supplemental intraosseous anesthesia varied from 0.45 ml to 3.6 ml (Table 2).

In some of the studies included in this review,^6-9 a lack of response to the maximum output of the Analytic Technology pulp tester (Analytic Technology Corp., Redmond, Wash.) was used to indicate pulpal anesthesia. However, this test was not reliable in teeth with a diagnosis of irreversible pulpitis,^10,11 and some teeth that tested negative required supplemental injections. Similar findings were reported by Dreven and colleagues.¹³ They found that "no response" to the maximum output of the electric pulp tester was 100 percent accurate in evaluating pulpal analgesia in asymptomatic teeth but only 73 percent accurate when the teeth were diagnosed with irreversible pulpitis.

Intraosseous anesthesia is accompanied by a number of side effects. An immediate increase in heart rate that lasts for two to three minutes occurs in 46 percent to 80 percent of patients when using 2 percent lidocaine with 1:100,000 epinephrine (Tables 1 and 2). Guglielmo and colleagues¹⁴ reported increased heart rate identical to 2 percent lidocaine with 1:000,000 epinephrine when using 2 percent mepivacaine with 1:20,000 levonordefrin for supplemental intraosseous anesthesia. Lillienthal¹⁵ stated that increased heart rate occurred in 100 percent of patients after a primary intraosseous injection of 1.8 ml 4 percent prilocaine with 1:200,000 epinephrine. In those studies where 3 percent mepivacaine (without vasoconstrictor) was used for intraosseous anesthesia, there was no increase in heart rate (Tables 1 and 2).

In most studies, there was a 2 percent to 15 percent incidence of moderate to severe pain during perforation, needle insertion, or injection of the anesthetic solution. However, Reisman and colleagues¹⁰ reported that 27 percent had moderate pain and 6 percent severe pain during injection. There was a 2 percent to 15 percent incidence of postoperative pain at the intraosseous injection site that was gone in a few days and a 4 percent to 5 percent incidence of swelling, bruising, or purulence that healed in less than two weeks. Four percent to 13 percent of the subjects reported that the teeth "felt high" for a few days after the intraosseous injection (Tables 1 and 2). There were some instances in which perforators broke during use, but they were easily removed with a hemostat.^7,8

Contraindications to the intraosseous injection include severe periodontal disease, a narrow zone of attached gingiva, and close proximity of the teeth.^7,8 Also, there may be some areas where it is not possible to administer a successful intraosseous injection due to thick or dense bone or lack of anesthetic distribution due to constricted cancellous bone.⁹

Replogle and colleagues¹⁶ have recommended that in patients whose medical condition, drug therapies, or epinephrine sensitivity suggest caution in administering epinephrine-containing solutions, 3 percent mepivacaine is an acceptable alternative for intraosseous injections.

Conclusions

The revival of intraosseous anesthesia is a significant addition to dental anesthetic techniques. Primary intraosseous anesthesia is useful for short procedures where it is desirable to minimize the feeling of numbness and the ballooning of tissue. The most valuable intraosseous technique, however, is the supplemental injection, which provides profound anesthesia and sufficient duration for most dental procedures and is particularly useful for those situations that are refractory to conventional anesthetic techniques.

Acknowledgements/

The author acknowledges Alan H. Gluskin, DDS, professor and chairman, Department of Endodontics, University of the Pacific School of Dentistry, for his advice and comments on preparing the manuscript. The author also acknowledges Graham Metcalfe, Department of Communication Services, UOP School of Dentistry, for providing the illustrations.

Author

Ronald Brown, DDS, MS, is a clinical associate professor in the Department of Endodontics at University of the Pacific School of Dentistry.

References/

1. Magnus GD, Intraosseous anesthesia. Anesth Prog 15:264-7, 1968.

2. Bourke K, Intra-osseous anaesthesia. Dent Anaesth Sedat 3:13-9, 1974.

3. Lilienthal B, A clinical appraisal of intraosseous anesthesia. Oral Surg Oral Med Oral Path 39:692-7, 1975.

4. Pearce JH, Intraosseous injection for profound anesthesia of the lower molar. J Colo Dent Assoc 54:24-6, 1976.

5. Leonard MS, The efficacy of an intraosseous injection system of delivering local anesthetic. J Am Dent Assoc 126:81-6, 1995.

6. Replogle K, Reader Al, et al, Anesthetic efficacy and cardiovascular effects of the intraosseous injection. J Endodon 21:227, 1995. (abstract)

7. Goggins R, Reader A, et al, Anesthetic efficacy of the intraosseous injection in maxillary and mandibular teeth. Oral Surg Oral Med Oral Path Oral Radiol Endod 81:634-41, 1996.

8. Replogle K, Reader A, et al, 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 Path Oral Radiol Endod 83:30-7, 1997.

9. Dunbar D, Reader A, et al, Anesthetic efficacy of the intraosseous injection after an inferior alveolar nerve block. J Endodon 22:481-6, 1996.

10. Reisman D, Reader A, et al, Anesthetic efficacy of the supplemental intraosseous injection of 3% mepivacaine in irreversible pulpitis. Oral Surg Oral Med Oral Path Oral Radiol Endod 84:676-82, 1997.

11. Nusstein J, Reader A, et al, Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis. J Endodon 24:487-91, 1998.

12. Parente SA, Anderson RW, et al, Anesthetic efficacy of the supplemental intraosseous injection for teeth with irreversible pulpitis. J Endodon 24:826-8, 1998.

13. Dreven LJ, Reader A, et al, An evaluation of an electric pulp tester as a measure of analgesia in human vital teeth. J Endodon 13:233-8, 1987.

14. Guglielmo A, Reader A, et al, The supplemental intraosseous injection of 2% mepivacaine with 1:20,000 levonordefrin. J Endodon 23:266, 1997. (abstract)

15. Lilienthal B, Cardiovascular responses to intraosseous injections of prilocaine containing vasoconstrictors. Oral Surg Oral Med Oral Path 42:552-8, 1976.

16. Replogle K, Reader A, et al, Cardiovascular effects of intraosseous injections of 2 percent lidocaine with 1:100,000 epinephrine and 3 percent mepivacaine. J Am Dent Assoc 30:649-57, 1999.

To request a printed copy of this article, please contact/ Ronald Brown, DDS, MS, Department of Endodontics, UOP School of Dentistry, 2155 Webster St., San Francisco, CA 94115.