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Anesthetic efficacy of the intraosseous injection of 0.9 mL of 2% lidocaine (1:100,000 epinephrine) to augment an inferior alveolar nerve block
Anesthetic efficacy of the intraosseous injection of 0.9 mL of 2 % lidocaine (1:100,000 epinephrine) to augment an inferior alveolar nerve block Jonathan Reitz, DDS, MS, a A1 Reader, DDS, MS, b Robert Nist, DDS, MS, c Mike Beck, DDS, MA, d and William J. Meyers, DMD, MEd, e Columbus, Ohio THE OHIO STATEUNIVERSITY
Objective. The purpose
of this study was to determine the anesthetic efficacy of an intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine to augment an inferior alveolar nerve block in mandibular posterior teeth. Study design. With the use of a repeated-measures design, each of 38 subjects randomly received one or the other of 2 combinations of injections at 2 separate appointments. The combinations were inferior alveolar nerve block + intraosseous injection (on the distal of the second premolar) through use of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine and inferior alveolar nerve block + mock intraosseous injection. The first molar, second premolar, and second molar were blindly tested with an Analytic Technology pulp tester at 2-minute cycles for 120 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. Results. One hundred percent of the subjects had lip numbness with the inferior alveolar nerve block + intraosseous injection combination technique. The respective anesthetic success rates for the inferior alveolar nerve block + mock intraosseous injection combination and the inferior alveolar nerve block + intraosseous injection combination were 60% and 100% for the second premolar, 71% and 95% for the first molar, and 74% and 87% for the second molar. The differences were significant (P < .05) for the second premolar through 50 minutes and for the first molar through 20 minutes. There were no significant (P > .05) differences for the second molar. Sixty-eight percent of the subjects had a subjective increase in heart rate with the intraosseous injection. Conclusions. The results of this study indicate that4he supplemental intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, given distal to the second premolar, significantly increased the success of pulpal anesthesia in the second premolar (for 50 minutes) and first molar (for 20 minutes) in comparison with the inferior alveolar nerve block alone. The intraosseous injection did not statistically increase success in the second molar.
(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;86:516-23)
The Stabident intraosseous (IO) injection system allows placement of a local anesthetic solution directly into the cancellous bone adjacent to the tooth to be anesthetized. This system has been evaluated as both a primary and a supplemental injection system. Leonard 1 reported that most extractions were successful with this system. Coggins et al 2 used the Stabident system as a primary injection in various groups of maxillary and mandibular teeth. They reported a success rate of 75% for the mandibular first molar. Replogle et al3 reported that the primary IO injection of 2% lidocaine with 1:100,000 epinephrine was more successful and resulted in a longer duration of pulpal anesthesia than 3% mepivacaine in mandibular first molars. Dunbar et al 4 evaluated the Stabident IO system in mandibular This study was supportedby GraduateEndodontic Research Funds. aFormerGraduate Student in Endodontics. bProfessorand ProgramDirector, Graduate Endodontics. CAssociateClinical Professor,Division of Endodontics. dAssociate Professor,Departmentof Health ServicesResearch. eprofessorand Director, Division of Endodontics. Received for publication Mar. 25, 1998; returned for revision May 11, 1998; acceptedfor publication June 16, 1998. Copyright © 1998 by Mosby,Inc. 1079-2104/98/$5.00 + 0 7/12/92656 516
first molars as a supplemental injection to the inferior alveolar nerve (IAN) block. They recorded a high incidence of pulpal anesthesia (100%), with 90% of the first molars still anesthetized at 60 minutes. Nusstein et al,5 in a clinical study, found a supplemental mandibular I t injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine to be 90% successful in gaining total pulpal anesthesia for teeth diagnosed with irreversible pulpitis. Reisman et al 6 reported that supplemental I t injection of 1.8 mL of 3% mepivacaine increased success in mandibular teeth diagnosed with irreversible pulpitis to 80% in comparison with the IAN block alone (25% success). A repeated I t injection of 3% mepivacalne increased success to 98%. Coggins et al, z Replogle et al,3 and Dunbar et al4 all used a distal I t injection site to the first molar and 1.8 mL of anesthetic solution. No objective study has evaluated the I t Stabident technique as a supplement to the IAN block using a distal injection site to the second premolar and half a cartridge of solution. The purpose of this study was to determine the anesthetic efficacy Of an I t injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, given distal to the second premolar, to augment an IAN block in mandibular posterior teeth. Injection pain,
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Table I. Percentages and discomfort ratings of infiltration and intraosseous injections Injection phase
Infiltration injection Needle insertion Infiltration Mock Solution deposition Infiltration Mock Intraosseous technique Perforation Intraosseous Mock Solution deposition Intraosseous Mock
None
Mild
Moderate
Severe
50% (19/38) 100% (38/38)
47% (18/38) 0% (0/38)
3% (1/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 100% (38/38)
8% (3/38) 0% (0/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
90% (34/38) 97% (37/38)
8% (3/38) 3% (1/38)
3% (1/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 100% (38/38)
8% (3/38) 0% (0/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
subjective heart rate increase, and healing postoperatively were also assessed for the IO injection.
MATERIAL AND METHODS Thirty-eight adult subjects, 28 male and 10 female, ranging in age from 18 to 43 years (average age, 25 years) participated. The subjects were in good health and were not taking any medications that would alter pain perception. The study was approved by The Ohio State University Human Subjects Review Committee; written informed consent was obtained from each subject. An equal number of mandibular right and left sides were tested, with the second premolar, first molar, and second molar chosen as the test teeth. The contralateral canine was used as the unanesthetized control to ensure that the pulp tester was operating properly and that the subject was responding appropriately during the experiment. Clinical examinations indicated that all teeth were free of caries, large restorations, and periodontal disease and that none had a history of trauma or sensitivity. Two appointments at least 2 weeks apart were scheduled for each of the 38 subjects. With a repeatedmeasures design, each subject randomly received either the combination of an IAN block plus an IO injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine or the combination of an IAN block plus a mock IO injection. Each subject was randomly assigned to 1 of the 2 combinations to determine the order in which the IO or mock IO injections were administered. All IAN blocks and IO injections were given by the principal investigator (J.R.). At the beginnning of each appointment and before any injections were given, the experimental teeth and control canine were tested 3 times with an Analytic Technology pulp tester (Analytic Technology Corp, Redmond, Wash) to record baseline vitality. After isolation with cotton rolls and drying with gauze,
Table II. Percentages and number of subjects who experienced anesthetic success and failure Tooth
Anesthetic success Second premolar First molar Second molar Anesthetic failure Second premolar First molar Second molar
IAN alone
1AN+IO combination
60% (23/38) 71% (27/38) 74% (28/38)
100% (38/38)* 95% (36/38)* 87% (33/38)
40% (15/38) 29% (11/38) 26% (10/38)
0% (0/38)* 5% (2/38)* 13% (5/38)
*Significantlydifferentwhen IAN alone was comparedwith IAN + IO combination (P < .05),
toothpaste was applied to the probe tip, which was placed midway between the gingival margin and the occlusal edge of the tooth to be tested. The current rate was set at 25 seconds to increase from no output (0) to the maximum output (80). The number at initial sensation was recorded. All preinjection and postinjection tests were performed by trained personnel who were blinded to the IO or mock IO injections administered. The standard ]AN block was administered with a 27gauge 1½-inch needle (Monoject; Sherwood Medical, St Louis, Mo) using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine (Astra Pharmaceutical Products Inc, Westborough, Mass). After the target area was reached and aspiration was performed, the solution was deposited over a period of 1 minute. The IO injection or mock IO injection was administered 5 minutes after completion of the IAN block if subjective lip numbness was recorded by the subject. Each subject was asked "Is your lip numb?" every minute for 5 minutes. If lip numbness did not occur within 5 minutes, the subject was reappointed. McLean et al7 found the mean onset of lip numbness to be 5
518 Reitz et al
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
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Fig 1. Incidence of second premolar anesthesia as determined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. Significant differences (P < .05) between IAN alone and IAN + IO combination are indicated (asterisk).
minutes for the IAN block, and this time was used for onset of lip numbness. All subjects had profound lip numbness after the IAN block. Mucosal sticks could have been used to determine success of the IAN block; previous studies7,10,11a 3 demonstrated that 90% to 100% of the patients felt no response to mucosal sticks in the distribution of the mental nerve after receiving an IAN block. However, the percentage of patients with pulpal anesthesia, as measured with the electric pulp tester, was much lower and similar to the findings of this study. Therefore, mucosal sticks are not an objective indicator of success of the IAN block nor of pulpal anesthesia. The IO injection was given by means of the Stabident system (Fairfax Dental Inc, Miami, Fla). With the subject in a reclining position, the area of perforation was determined by the horizontal line of the buccal gingival margins of the first molar and second premolar and a vertical line that passed through the interdental papilla on the distal aspect of the second premolar. A point approximately 2 mm below the intersection of these lines was selected as the perforation site if the site was in attached gingiva. If this point was in alveolar mucosa (1 subject), the injection site was moved just above the junction of the attached gingiva and alveolar mucosa. The soft tissue at the determined perforation site was anesthetized with an infiltration injection of approximately 0.1 mL of 2% lidocaine with 1:100,000 epinephrine deposited through a 27-gauge needle attached to a standard aspirating syringe. The mock infiltration injection simulated the actual infiltration injection except that no anesthetic solution was
deposited. The cortical bone was perforated with the Stabident perforator (a beveled-ended solid wire attached to a plastic hub) in a contra-angle, slow-speed handpiece. The perforator was placed through the gingiva at the infiltration site and was oriented perpendicular to the cortical plate. With the point gently resting against bone, the handpiece was activated in a series of short bursts under light pressure until either a "breakthrough" feeling was observed or 2 to 5 seconds had elapsed. The mock IO perforation was performed through use of a prophy cup in the slow-speed handpiece, which was activated in a series of short bursts after being placed on the buccal surface of the first molar. We felt that this technique was better than running the prophy cup on the gingiva at the perforation site because the latter might have caused gingival abrasion. Although the procedure was not ideal, inasmuch as it was not at the point of injection, we subjectively felt the subjects could not differentiate this procedure from the actual trephination. Before the IO injection was given, the 27-gauge ultra-short Stabident needle was bent at the hub to a 45degree angle to allow for ease of insertion. The area of perforation was blotted with a sterile cotton roll to control hemorrhage and identify the perforation site (a small dot of hemorrhage on the blanched gingiva). The standard syringe was held in a pen-gripping fashion, the needle was inserted into the perforation site, and 0.9 mL of 2% lidocaine with 1:100,000 epinephrine was delivered over a 1-minute time period. The mock IO injection was performed in a similar manner except that the needle was not inserted into the perforation
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Time (Minutes) Fig 2. Incidence of first molar anesthesia as detemined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. Significant differences (P < .05) between IAN alone and IAN + IO combination are indicated (asterisk).
(through the gingiva) and no anesthetic solution was deposited. The length of time for the mock perforation and mock solution deposition was identical to that for the actual IO injection. In addition, each subject was instructed to close his or her eyes during all IO injections to blind the techniques. Each subject was questioned during solution deposition and for 2 minutes after the IO or mock IO injection to determine whether he or she noticed an increase in heart rate. The subjects were instructed to rate the pain of the infiltration, IO, and mock injections. The rating scale was as follows: 0, no pain; 1, mild pain (pain that is recognizable but not discomforting); 2, moderate pain (pain that is discomforting but bearable); and 3, severe pain (pain that causes considerable discomfort and is difficult to bear). At 1 minute after the IO or mock IO injection (9 minutes after completion of the IAN block), the first and second molars were pulp tested. At 2 minutes, the second premolar and contralateral (control) canine were tested. This cycle of testing was repeated every 2 minutes. The control canine was tested every third cycle with an inactive pulp tester to test the reliability of the subjects. All testing was stopped at 120 minutes post-intraosseous injection. No subject response to the maximum output (80 reading) of the pulp tester was used as the criterion for pulpal anesthesia. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. Anesthesia was considered a failure if the subject never achieved 2 consecutive 80 readings. A postinjection questionnaire asked the subjects to rate
the pain and report any side effects in the area of the IO or mock IO injection at the time initial numbness wore off and each morning for 3 days after the appointment. Comparisons between the IAN + mock IO and IAN + IO injection combinations for anesthetic success and failure were analyzed nonparametrically through use of Bonferroni-adjusted McNemar tests. Between-technique comparisons at each 10-minute time period for percentage of pulpal anesthesia (80 readings) were analyzed through use of Bonferroni-adjusted Wilcoxon signed-ranks tests. Comparisons were considered significant at P < .05.
RESULTS The discomfort ratings for the infiltration, IO, and mock injections are presented in Table I. Most ratings were in the none to mild categories. No perforators broke during this study. One hundred percent of the subjects had profound lip numbness with the IAN + mock IO and IAN + IO techniques. Anesthetic success and failure are presented in Table II. For the first molar and second premolar, anesthetic success and failure for the IAN + IO combination was significantly different (P < .05) from that of the IAN + mock IO combination. Sixty-eight percent (26/38) of the subjects had a subjective increase in heart rate with the IO injection of 2% lidocaine with 1:100,000 epinephrine. The incidence of pulpal anesthesia at different time intervals postinjection and significant differences between the 2 techniques are presented in Figs 1 through 3. For the IAN + IO technique, significant
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY November 1998
S20 Reitz et al
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Time (Minutes) Fig 3. Incidence of second molar anesthesia as determined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. There were no significant differences (P > .05) between TAN alone and IAN + IO combination.
differences were shown in the second premolar from 10 through 50 minutes (Fig 1) and in the first molar from 9 through 20 minutes (Fig 2); in the second molar, no significant differences were shown (Fig 3). The postinjection discomfort ratings for the IO injection are presented in Table III. Most ratings were in the none to mild categories.
DISCUSSION The use of the 80 reading as a criterion for pulpal anesthesia was based on the studies of Dreven et al 8 and Certosimo and Archer. 9 These studies8, 9 showed that an 80 reading ensured pulpal anesthesia in vital asymptomatic teeth. In addition, Certosimo and Archer 9 demonstrated that EPT readings less than 80 resulted in pain during operative procedures in asymptomatic teeth. Anesthetic failure with the IAN block occurred in 29% of the first molars, 40% of second premolars, and 26% of the second molars (Table II). The failure rates are similar to the results of previous studies 4,7,10-15 in which a similar method was used. Therefore, even after a "clinically successful" block (lip numbness), pulpal anesthesia may not be guaranteed. Theories for anesthetic failure with the I A N block (relating to accessory innervation, central core theory, and accuracy of needle placement) were previously discussed by Vreeland et al. 1° The addition of the IO injection to the IAN block was based on the studies of Coggins et al, 2 Replogle et al, 3 and Dunbar et al. 4 When IO injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine was used as a
primary injection, Coggins et al 2 and Replogle et al 3 found that it resulted in an approximately 75% success rate in mandibular first molars. They2, 3 also reported that the duration of IO anesthesia declined steadily over an hour. The IO injection could be used as a primary method when only a short anesthesia duration is required, as shown by Leonard 1 for extractions. However, in operative and restorative procedures of 60 minutes' duration, the true value of the IO injection may be in its use as a supplemental injection. 4 Dunbar et al 4 evaluated a distal IO injection in mandibular first molars using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine as a supplemental injection to the IAN block. They recorded a high incidence of pulpal anesthesia (100%), with 90% of the fwst molars still anesthetized at 60 minutes. As shown in Figs 1 and 2, onset of pulpal anesthesia (the highest percentage of initial 80 readings) was fairly rapid with the IO injection of 2% lidocaine with 1:100,000 epinephrine. Dunbar et al 4 also reported that the addition of the IO injection after the IAN block resulted in a fairly quick onset of pulpal anesthesia. For the IAN + IO combination, anesthetic success was 100% for the second premolar, with approximately 83% of the premolars still anesthetized at 60 minutes (Table II and Fig 1). In comparison with that of the IAN block by itself, the IAN + IO combination's anesthetic success rate was statistically significant (P < .05; Table II), with significant differences shown for the incidence of pulpal anesthesia at 10 through 50 minutes post-intraosseous injection (Fig 1). The addition of the IO injection therefore increased success in the second
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l a b l e III. Summary of pain ratings for postinjection survey with the intraosseous injection Pain rating Time Day 0* IO Mock Day 1 IO Mock Day 2 IO Mock Day 3 IO Mock
None (0)
Mild (1)
Moderate (2)
Severe (3)
71% (27/38) 87% (33/38)
18% (7/38) 13% (5/38)
11% (4/38) 0% (0/38)
0% (0/38) 0% (0/38)
71% (27/38) 95% (36/38)
24% (9/38) 5% (2/38)
5% (2/38) 0% (0/38)
0% (0/38) 0% (0/38)
82% (31/38) 97% (37/38)
18% (7/38) 3% (1/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 97% (37/38)
8% (3/38) 3% (1/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
*Rating at time subjective numbness wore off.
premolar over the IAN block alone. For a supplemental IO injection distal to the first molar with 1.8 mL of 2% lidocaine with 1:100,000 epinephrine, Dunbar et al4 reported a 93% incidence of pulpal anesthesia for the second premolars, with approximately 80% of the premolars still anesthetized at 60 minutes. Although one half the amount of anesthetic solution (0.9 mL) was used in the current study, we recorded a higher success rate, the duration being comparable to the results of Dunbar et al 4 at 60 minutes. The most likely reason for this finding is the use of the distal IO injection site to the second premolar used in this study. Replogle et al, 3 Coggins et al, 2 and Dunbar et al 4 all found that the success rates and incidence of anesthesia were lower for the second premolar when a distal IO injection site to the first molar was selected. Using a distal IO injection site to the first molar, Coggins et al 2 and Replogle et al 3 speculated that the anesthetic solution would have to spread past the first molar or block the nerve trunk near to or at the site of injection to achieve equivalent pulpal anesthesia for the second premolar. Because neither occurred readily enough to result in anesthesia of the second premolar at a level equal to that for the first molar, they concluded that an IO injection distal to the second premolar may result in better anesthesia of this tooth. 2,3 The results of our study would support a higher success rate for the second premolar through use of a distal IO injection site to this tooth. Because this study addressed itself to results with 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, further studies could investigate the use of 1.8 mL and the use of solutions without vasoconstrictors. Fig 1 shows a decline in pulpal anesthesia at approximately 30 minutes. Therefore, another avenue of research would be to study the effects of additional solution delivered through the same perforation site to determine whether anesthesia would be increased or prolonged.
For the IAN + IO combination, anesthetic success was 95% for the first molar, with approximately 76% of the first molars still anesthetized at 60 minutes (Table II and Fig 2). In comparison with that for the IAN by itself, the IAN + IO anesthetic success rate was statistically significant (P < :05; Table II), with significant differences shown for the incidence of pulpal anesthesia at 9 through 20 minutes post-intraosseous injection (Fig 2). Therefore, the addition of the IO injection increased success in the first molar in comparison with use of the IAN block alone. Dunbar et al 4 recorded a higher success rate (100%), a longer duration of pulpal anesthesia (60 minutes), and a higher percentage (90%) of subjects still anesthetized at 60 minutes than were found in this study. This could be attributed to the decreased amount (0.9 mL) of anesthetic solution used in this study; less anesthetic would be available for diffusion through the cancellous bone. Another factor is use of the distal IO injection site to the second premolar in our study, in contrast with use of the distal IO injection site to the first molar used by Dunbar et al. 4 It may be that using a distal IO injection site to the first molar with 0.9 mL of 2% lidocaine (1:100,000 epinephrine) results in better anesthesia of the first molar than using a distal IO injection site to the second premolar. Because the volume of solution and site of the IO injection varied in this study, further research is needed to resolve this issue. For the IAN + IO combination, anesthetic success was 87% for the second molar, with approximately 76% of the second molars still anesthetized at 60 minutes (Table II and Fig 3). In comparison with that of the IAN alone, the IAN + IO combination's anesthetic success rate was not statistically significant (P >.05; Table II), and no significant differences were shown for the incidence of pulpal anesthesia postinjection (Fig 3). Therefore, the addition of the IO injection
522 Reitzetal
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did not statistically increase success in the second molar over the IAN block alone. Dunbar et al,4 using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine and a distal IO injection site to the first molar after an IAN block, recorded a high incidence of pulpal anesthesia (100%) in the second molars, with approximately 88% of the teeth still anesthetized at 60 minutes. Coggins et al, 2 Replogle et al, 3 and Dunbar et al4 all showed that the second molar had similar or increased success rates in comparison with the first molar when a distal IO injection site to the first molar was selected. The lower success rate in this study could be attributed to the decreased amount (0.9 mL) of anesthetic solution and the use of the distal IO injection site to the second premolar. Therefore, not enough of the 0.9 mL of anesthetic solution spread to the second molar from a distal IO injection site to the second premolar to change the success of pulpal anesthesia appreciably. Clinically, it may be preferable to choose a mesial site to the second molar to increase anesthetic success. 4 No study has addressed the duration of a supplemental IO injection past 65 minutes. Figs 1 through 3 show the duration of pulpal anesthesia for 120 minutes post-intraosseous injection. There were no significant differences past 60 minutes for any of the teeth. The figures show a slow decline of pulpal anesthesia over 120 minutes, with the IAN + IO injection combination approaching the percentages of anesthesia achieved with the IAN injection alone. Researchers in future studies may want to address ways to increase anesthesia past 60 minutes with the IO technique. The anesthetic failure rate with the IAN + IO injection combination was 0% for the second premolar, 5% for the first molar, and 13% for the second molar (Table II). The difference between the IAN and IAN + IO techniques was statistically significant for the second premolar and first molar (Table II). The fact that the failure rates for the first and second molars were higher than the rate for the second premolar may be related to the amount of anesthetic solution administered (0.9 mL) or to the selection of the distal IO injection site to the second premolar, as discussed previously. Clinically, the addition of the IO injection, as used in this study, to the 1AN block will decrease anesthetic failure. However, it may be preferable to use a distal IO injection site to the first molar to further decrease the anesthetic failure rate in both the first and second molars, as shown by Dunbar et al. 4 The infiltrations, perforations, and IO injections resulted in low pain ratings, with a few reports of moderate pain (Table I). The tow ratings were probably due to the anesthesia provided by the IAN block and initial infiltration injection. Similar results for the
supplemental IO injection after the IAN block have been reported by Dunbar et al. 4 Therefore, the infiltration, perforation, and IO injection have a fairly low potential for moderate pain after an IAN block. Postinjection pain for the IO injection was rated as none to mild at the time subjective numbness wore off in 100% of the mock injections and in 89% of the IO injections; 11% of patients reported moderate pain (Table III). The pain ratings decreased over the next 3 days. The pain rating when subjective numbness wore off has been reported by Dunbar et al4 as 2% moderate pain, by Coggins et al 2 as 2% to 15% moderate pain, and by Replogle et al 3 as 2% to 5% moderate pain. Therefore, the IO injection has a 2% to 15% potential for moderate postinjection pain. Various authors 2-5 have reported a transient increase in heart rate (46% to 85% of the time) with the Stabident IO injection of epinephrine-containing solutions. Sixty-eight percent of the subjects in this study reported a subjective increase in heart rate during deposition or for 2 minutes after the IO injection; this compared with 5% reporting such an increase during the mock IO injection. The subjective reporting of heart rate changes was found to correlate with objective electrocardiogram recordings by Replogle et al. 16 Clinically, it appears that most subjects will report an increased heart rate after the IO injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine when the Stabident system is used. Patients should be informed of this to lessen their anxiety. Although no animal study has investigated the effects of the Stabident IO injection on gingiva and bone, Dunbar et al,4 Coggins et al, 2 and Replogle et al 3 have reported swelling and purulence at Stabident IO injection sites. Generally, the incidence in these studies 2-4 has been less than 5%. These changes are probably related to gingival or bone trauma during perforation. In the current study, no subjects reported postinjection swelling or exudate. Clinically, the chance is small that swelling or exudate will occur postoperatively. None of the subjects reported that the first molar felt "high" postoperatively. Other studies 2-~ using the Stabident technique have reported the incidence of such a feeling as 4% to 13%. This feeling is most likely an increased awareness to biting that results from soreness in the area caused by damage from perforation or inflammation of the bone. No subjects reported symptoms of a pulpal nature postoperatively, and all subjects who received the IO injection at the first appointment had similar baseline pulp test readings at the second appointment. Pulpal anesthesia requirements will vary clinically, depending on a number of factors (tooth, procedure performed, degree of pulpal anesthesia required, and
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w h e t h e r the patient is s y m p t o m a t i c ) ; the clinical implications o f this study w o u l d therefore be d e p e n d e n t on these factors, and the clinician should evaluate his or her r e q u i r e m e n t s in light o f the results o f our study. In conclusion, the s u p p l e m e n t a l I O injection of 0.9 m L o f 2 % l i d o c a i n e w i t h 1:100,000 epinephrine, g i v e n distal to the s e c o n d premolar, significantly i n c r e a s e d the success o f pulpal anesthesia in the second p r e m o l a r (for 50 m i n u t e s ) and first m o l a r (for 20 m i n u t e s ) in c o m p a r i s o n with administration o f the inferior a l v e o l a r n e r v e b l o c k alone.
(1:100,000 epinephrine) for inferior alveolar nerve block. Journal of Endodontics 1993;19:146-50. Dreven L, Reader A, Beck M, Meyers W, Weaver J. An evaluation of the electric pulp tester as a measure of analgesia in human vital teeth. Journal of Endodontics 1987;13:233-8. Certosimo A, Archer R. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Operative Dentistry 1996;21:25-30. Vreeland D, Reader A, Beck M, Meyers W, Weaver J. An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. Journal of Endodontics 1989;15:6-12. Hinldey S, Reader A, Beck M, Meyers W. An evaluation of 4% prilocalne with 1:200,000 epinephrine and 2% mepivacaine with levonordefrin compared to 2% lidocaine with l:100,000 epinephrine for inferior alveolar nerve block. Anesthesia Progress 1991;38:84-9. Nist R, Reader A, Beck M, Meyers W. An evaluation of the incisive nerve block and combination inferior alveolar and incisive nerve blocks in mandibular anesthesia. Journal of Endodontics 1992;18:455-9. Chaney M, Kerby R, Reader A, Beck M, Meyers W, Weaver J. An evaluation of lidocaine hydrocarbonate compared with lidocaine hydrochloride for inferior alveolar nerve block. Anesthesia Progress 1991;38:212-6. Childers M, Reader A, Nist R, Beck M, Meyers W. The anesthetic efficacy of the periodontal ligament injection after an inferior alveolar nerve block. Journal of Endodontics 1996;22:317-20. Bou Dagher F, Yared GM, Machtou P. The anesthetic efficacy of volumes of lidocaine in inferior alveolar nerve blocks. Journal of Endodontics 1997;23:178-80. Replogle K, Reader A, Nist R, Beck M, Weaver J, Meyers W. Cardiovascular effects of the intraosseous injection of 2% lidocaine with 1:100,000 epinephrine and 3% mepivacalne. J Am Dent Assoc. In press 1998.
REFERENCES 1. Leonard M. The efficacy of an intraosseous injection system of delivering local anesthetic. J Am Dent Assoc 1995;126:81-6. 2. Coggins R, Reader A, Nist R, Beck M, Meyers W. Anesthetic efficacy of the intraosseous injection in maxillary and mandibular teeth. Oral Surg Oral Med Oral Oral Pathol Oral Radiol Endod 1996;81:634-41. 3. Replogle K, Reader A, Nist R, Beck M, Weaver J, Meyers W. 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. 4. Dunbar D, Reader A, Nist R, Beck M, Meyers W. Anesthetic efficacy of the intraosseous injection after an inferior alveolar nerve block. Journal of Endodontics 1996;22:481-6. 5. 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. Journal of Endodontics 1998;24:487-91. 6. 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. 7. McLean C, Reader A, Beck M, Meyers WJ. An evaluation of 4% prilocaine and 3% mepivacaine compared to 2% lidocaine
8. 9. 10. 11.
12.
13.
14. 15. 16.
Reprint requests: A1 Reader, DDS, MS Graduate Endodontics College of Dentistry The Ohio State University 305 W. 12th Avenue Columbus, OH 43210
Objective. The purpose
of this study was to determine the anesthetic efficacy of an intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine to augment an inferior alveolar nerve block in mandibular posterior teeth. Study design. With the use of a repeated-measures design, each of 38 subjects randomly received one or the other of 2 combinations of injections at 2 separate appointments. The combinations were inferior alveolar nerve block + intraosseous injection (on the distal of the second premolar) through use of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine and inferior alveolar nerve block + mock intraosseous injection. The first molar, second premolar, and second molar were blindly tested with an Analytic Technology pulp tester at 2-minute cycles for 120 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. Results. One hundred percent of the subjects had lip numbness with the inferior alveolar nerve block + intraosseous injection combination technique. The respective anesthetic success rates for the inferior alveolar nerve block + mock intraosseous injection combination and the inferior alveolar nerve block + intraosseous injection combination were 60% and 100% for the second premolar, 71% and 95% for the first molar, and 74% and 87% for the second molar. The differences were significant (P < .05) for the second premolar through 50 minutes and for the first molar through 20 minutes. There were no significant (P > .05) differences for the second molar. Sixty-eight percent of the subjects had a subjective increase in heart rate with the intraosseous injection. Conclusions. The results of this study indicate that4he supplemental intraosseous injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, given distal to the second premolar, significantly increased the success of pulpal anesthesia in the second premolar (for 50 minutes) and first molar (for 20 minutes) in comparison with the inferior alveolar nerve block alone. The intraosseous injection did not statistically increase success in the second molar.
(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;86:516-23)
The Stabident intraosseous (IO) injection system allows placement of a local anesthetic solution directly into the cancellous bone adjacent to the tooth to be anesthetized. This system has been evaluated as both a primary and a supplemental injection system. Leonard 1 reported that most extractions were successful with this system. Coggins et al 2 used the Stabident system as a primary injection in various groups of maxillary and mandibular teeth. They reported a success rate of 75% for the mandibular first molar. Replogle et al3 reported that the primary IO injection of 2% lidocaine with 1:100,000 epinephrine was more successful and resulted in a longer duration of pulpal anesthesia than 3% mepivacaine in mandibular first molars. Dunbar et al 4 evaluated the Stabident IO system in mandibular This study was supportedby GraduateEndodontic Research Funds. aFormerGraduate Student in Endodontics. bProfessorand ProgramDirector, Graduate Endodontics. CAssociateClinical Professor,Division of Endodontics. dAssociate Professor,Departmentof Health ServicesResearch. eprofessorand Director, Division of Endodontics. Received for publication Mar. 25, 1998; returned for revision May 11, 1998; acceptedfor publication June 16, 1998. Copyright © 1998 by Mosby,Inc. 1079-2104/98/$5.00 + 0 7/12/92656 516
first molars as a supplemental injection to the inferior alveolar nerve (IAN) block. They recorded a high incidence of pulpal anesthesia (100%), with 90% of the first molars still anesthetized at 60 minutes. Nusstein et al,5 in a clinical study, found a supplemental mandibular I t injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine to be 90% successful in gaining total pulpal anesthesia for teeth diagnosed with irreversible pulpitis. Reisman et al 6 reported that supplemental I t injection of 1.8 mL of 3% mepivacaine increased success in mandibular teeth diagnosed with irreversible pulpitis to 80% in comparison with the IAN block alone (25% success). A repeated I t injection of 3% mepivacalne increased success to 98%. Coggins et al, z Replogle et al,3 and Dunbar et al4 all used a distal I t injection site to the first molar and 1.8 mL of anesthetic solution. No objective study has evaluated the I t Stabident technique as a supplement to the IAN block using a distal injection site to the second premolar and half a cartridge of solution. The purpose of this study was to determine the anesthetic efficacy Of an I t injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, given distal to the second premolar, to augment an IAN block in mandibular posterior teeth. Injection pain,
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Reitz et al 517
Table I. Percentages and discomfort ratings of infiltration and intraosseous injections Injection phase
Infiltration injection Needle insertion Infiltration Mock Solution deposition Infiltration Mock Intraosseous technique Perforation Intraosseous Mock Solution deposition Intraosseous Mock
None
Mild
Moderate
Severe
50% (19/38) 100% (38/38)
47% (18/38) 0% (0/38)
3% (1/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 100% (38/38)
8% (3/38) 0% (0/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
90% (34/38) 97% (37/38)
8% (3/38) 3% (1/38)
3% (1/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 100% (38/38)
8% (3/38) 0% (0/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
subjective heart rate increase, and healing postoperatively were also assessed for the IO injection.
MATERIAL AND METHODS Thirty-eight adult subjects, 28 male and 10 female, ranging in age from 18 to 43 years (average age, 25 years) participated. The subjects were in good health and were not taking any medications that would alter pain perception. The study was approved by The Ohio State University Human Subjects Review Committee; written informed consent was obtained from each subject. An equal number of mandibular right and left sides were tested, with the second premolar, first molar, and second molar chosen as the test teeth. The contralateral canine was used as the unanesthetized control to ensure that the pulp tester was operating properly and that the subject was responding appropriately during the experiment. Clinical examinations indicated that all teeth were free of caries, large restorations, and periodontal disease and that none had a history of trauma or sensitivity. Two appointments at least 2 weeks apart were scheduled for each of the 38 subjects. With a repeatedmeasures design, each subject randomly received either the combination of an IAN block plus an IO injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine or the combination of an IAN block plus a mock IO injection. Each subject was randomly assigned to 1 of the 2 combinations to determine the order in which the IO or mock IO injections were administered. All IAN blocks and IO injections were given by the principal investigator (J.R.). At the beginnning of each appointment and before any injections were given, the experimental teeth and control canine were tested 3 times with an Analytic Technology pulp tester (Analytic Technology Corp, Redmond, Wash) to record baseline vitality. After isolation with cotton rolls and drying with gauze,
Table II. Percentages and number of subjects who experienced anesthetic success and failure Tooth
Anesthetic success Second premolar First molar Second molar Anesthetic failure Second premolar First molar Second molar
IAN alone
1AN+IO combination
60% (23/38) 71% (27/38) 74% (28/38)
100% (38/38)* 95% (36/38)* 87% (33/38)
40% (15/38) 29% (11/38) 26% (10/38)
0% (0/38)* 5% (2/38)* 13% (5/38)
*Significantlydifferentwhen IAN alone was comparedwith IAN + IO combination (P < .05),
toothpaste was applied to the probe tip, which was placed midway between the gingival margin and the occlusal edge of the tooth to be tested. The current rate was set at 25 seconds to increase from no output (0) to the maximum output (80). The number at initial sensation was recorded. All preinjection and postinjection tests were performed by trained personnel who were blinded to the IO or mock IO injections administered. The standard ]AN block was administered with a 27gauge 1½-inch needle (Monoject; Sherwood Medical, St Louis, Mo) using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine (Astra Pharmaceutical Products Inc, Westborough, Mass). After the target area was reached and aspiration was performed, the solution was deposited over a period of 1 minute. The IO injection or mock IO injection was administered 5 minutes after completion of the IAN block if subjective lip numbness was recorded by the subject. Each subject was asked "Is your lip numb?" every minute for 5 minutes. If lip numbness did not occur within 5 minutes, the subject was reappointed. McLean et al7 found the mean onset of lip numbness to be 5
518 Reitz et al
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Fig 1. Incidence of second premolar anesthesia as determined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. Significant differences (P < .05) between IAN alone and IAN + IO combination are indicated (asterisk).
minutes for the IAN block, and this time was used for onset of lip numbness. All subjects had profound lip numbness after the IAN block. Mucosal sticks could have been used to determine success of the IAN block; previous studies7,10,11a 3 demonstrated that 90% to 100% of the patients felt no response to mucosal sticks in the distribution of the mental nerve after receiving an IAN block. However, the percentage of patients with pulpal anesthesia, as measured with the electric pulp tester, was much lower and similar to the findings of this study. Therefore, mucosal sticks are not an objective indicator of success of the IAN block nor of pulpal anesthesia. The IO injection was given by means of the Stabident system (Fairfax Dental Inc, Miami, Fla). With the subject in a reclining position, the area of perforation was determined by the horizontal line of the buccal gingival margins of the first molar and second premolar and a vertical line that passed through the interdental papilla on the distal aspect of the second premolar. A point approximately 2 mm below the intersection of these lines was selected as the perforation site if the site was in attached gingiva. If this point was in alveolar mucosa (1 subject), the injection site was moved just above the junction of the attached gingiva and alveolar mucosa. The soft tissue at the determined perforation site was anesthetized with an infiltration injection of approximately 0.1 mL of 2% lidocaine with 1:100,000 epinephrine deposited through a 27-gauge needle attached to a standard aspirating syringe. The mock infiltration injection simulated the actual infiltration injection except that no anesthetic solution was
deposited. The cortical bone was perforated with the Stabident perforator (a beveled-ended solid wire attached to a plastic hub) in a contra-angle, slow-speed handpiece. The perforator was placed through the gingiva at the infiltration site and was oriented perpendicular to the cortical plate. With the point gently resting against bone, the handpiece was activated in a series of short bursts under light pressure until either a "breakthrough" feeling was observed or 2 to 5 seconds had elapsed. The mock IO perforation was performed through use of a prophy cup in the slow-speed handpiece, which was activated in a series of short bursts after being placed on the buccal surface of the first molar. We felt that this technique was better than running the prophy cup on the gingiva at the perforation site because the latter might have caused gingival abrasion. Although the procedure was not ideal, inasmuch as it was not at the point of injection, we subjectively felt the subjects could not differentiate this procedure from the actual trephination. Before the IO injection was given, the 27-gauge ultra-short Stabident needle was bent at the hub to a 45degree angle to allow for ease of insertion. The area of perforation was blotted with a sterile cotton roll to control hemorrhage and identify the perforation site (a small dot of hemorrhage on the blanched gingiva). The standard syringe was held in a pen-gripping fashion, the needle was inserted into the perforation site, and 0.9 mL of 2% lidocaine with 1:100,000 epinephrine was delivered over a 1-minute time period. The mock IO injection was performed in a similar manner except that the needle was not inserted into the perforation
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
Reitz et al 519
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Time (Minutes) Fig 2. Incidence of first molar anesthesia as detemined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. Significant differences (P < .05) between IAN alone and IAN + IO combination are indicated (asterisk).
(through the gingiva) and no anesthetic solution was deposited. The length of time for the mock perforation and mock solution deposition was identical to that for the actual IO injection. In addition, each subject was instructed to close his or her eyes during all IO injections to blind the techniques. Each subject was questioned during solution deposition and for 2 minutes after the IO or mock IO injection to determine whether he or she noticed an increase in heart rate. The subjects were instructed to rate the pain of the infiltration, IO, and mock injections. The rating scale was as follows: 0, no pain; 1, mild pain (pain that is recognizable but not discomforting); 2, moderate pain (pain that is discomforting but bearable); and 3, severe pain (pain that causes considerable discomfort and is difficult to bear). At 1 minute after the IO or mock IO injection (9 minutes after completion of the IAN block), the first and second molars were pulp tested. At 2 minutes, the second premolar and contralateral (control) canine were tested. This cycle of testing was repeated every 2 minutes. The control canine was tested every third cycle with an inactive pulp tester to test the reliability of the subjects. All testing was stopped at 120 minutes post-intraosseous injection. No subject response to the maximum output (80 reading) of the pulp tester was used as the criterion for pulpal anesthesia. Anesthesia was considered successful when 2 consecutive 80 readings were obtained. Anesthesia was considered a failure if the subject never achieved 2 consecutive 80 readings. A postinjection questionnaire asked the subjects to rate
the pain and report any side effects in the area of the IO or mock IO injection at the time initial numbness wore off and each morning for 3 days after the appointment. Comparisons between the IAN + mock IO and IAN + IO injection combinations for anesthetic success and failure were analyzed nonparametrically through use of Bonferroni-adjusted McNemar tests. Between-technique comparisons at each 10-minute time period for percentage of pulpal anesthesia (80 readings) were analyzed through use of Bonferroni-adjusted Wilcoxon signed-ranks tests. Comparisons were considered significant at P < .05.
RESULTS The discomfort ratings for the infiltration, IO, and mock injections are presented in Table I. Most ratings were in the none to mild categories. No perforators broke during this study. One hundred percent of the subjects had profound lip numbness with the IAN + mock IO and IAN + IO techniques. Anesthetic success and failure are presented in Table II. For the first molar and second premolar, anesthetic success and failure for the IAN + IO combination was significantly different (P < .05) from that of the IAN + mock IO combination. Sixty-eight percent (26/38) of the subjects had a subjective increase in heart rate with the IO injection of 2% lidocaine with 1:100,000 epinephrine. The incidence of pulpal anesthesia at different time intervals postinjection and significant differences between the 2 techniques are presented in Figs 1 through 3. For the IAN + IO technique, significant
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY November 1998
S20 Reitz et al
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Time (Minutes) Fig 3. Incidence of second molar anesthesia as determined by lack of response to electrical pulp testing at maximal setting (percentage of 80 readings) at each postinjection time interval for 2 injection techniques. There were no significant differences (P > .05) between TAN alone and IAN + IO combination.
differences were shown in the second premolar from 10 through 50 minutes (Fig 1) and in the first molar from 9 through 20 minutes (Fig 2); in the second molar, no significant differences were shown (Fig 3). The postinjection discomfort ratings for the IO injection are presented in Table III. Most ratings were in the none to mild categories.
DISCUSSION The use of the 80 reading as a criterion for pulpal anesthesia was based on the studies of Dreven et al 8 and Certosimo and Archer. 9 These studies8, 9 showed that an 80 reading ensured pulpal anesthesia in vital asymptomatic teeth. In addition, Certosimo and Archer 9 demonstrated that EPT readings less than 80 resulted in pain during operative procedures in asymptomatic teeth. Anesthetic failure with the IAN block occurred in 29% of the first molars, 40% of second premolars, and 26% of the second molars (Table II). The failure rates are similar to the results of previous studies 4,7,10-15 in which a similar method was used. Therefore, even after a "clinically successful" block (lip numbness), pulpal anesthesia may not be guaranteed. Theories for anesthetic failure with the I A N block (relating to accessory innervation, central core theory, and accuracy of needle placement) were previously discussed by Vreeland et al. 1° The addition of the IO injection to the IAN block was based on the studies of Coggins et al, 2 Replogle et al, 3 and Dunbar et al. 4 When IO injection of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine was used as a
primary injection, Coggins et al 2 and Replogle et al 3 found that it resulted in an approximately 75% success rate in mandibular first molars. They2, 3 also reported that the duration of IO anesthesia declined steadily over an hour. The IO injection could be used as a primary method when only a short anesthesia duration is required, as shown by Leonard 1 for extractions. However, in operative and restorative procedures of 60 minutes' duration, the true value of the IO injection may be in its use as a supplemental injection. 4 Dunbar et al 4 evaluated a distal IO injection in mandibular first molars using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine as a supplemental injection to the IAN block. They recorded a high incidence of pulpal anesthesia (100%), with 90% of the fwst molars still anesthetized at 60 minutes. As shown in Figs 1 and 2, onset of pulpal anesthesia (the highest percentage of initial 80 readings) was fairly rapid with the IO injection of 2% lidocaine with 1:100,000 epinephrine. Dunbar et al 4 also reported that the addition of the IO injection after the IAN block resulted in a fairly quick onset of pulpal anesthesia. For the IAN + IO combination, anesthetic success was 100% for the second premolar, with approximately 83% of the premolars still anesthetized at 60 minutes (Table II and Fig 1). In comparison with that of the IAN block by itself, the IAN + IO combination's anesthetic success rate was statistically significant (P < .05; Table II), with significant differences shown for the incidence of pulpal anesthesia at 10 through 50 minutes post-intraosseous injection (Fig 1). The addition of the IO injection therefore increased success in the second
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY
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Volume 86, Number 5
l a b l e III. Summary of pain ratings for postinjection survey with the intraosseous injection Pain rating Time Day 0* IO Mock Day 1 IO Mock Day 2 IO Mock Day 3 IO Mock
None (0)
Mild (1)
Moderate (2)
Severe (3)
71% (27/38) 87% (33/38)
18% (7/38) 13% (5/38)
11% (4/38) 0% (0/38)
0% (0/38) 0% (0/38)
71% (27/38) 95% (36/38)
24% (9/38) 5% (2/38)
5% (2/38) 0% (0/38)
0% (0/38) 0% (0/38)
82% (31/38) 97% (37/38)
18% (7/38) 3% (1/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
92% (35/38) 97% (37/38)
8% (3/38) 3% (1/38)
0% (0/38) 0% (0/38)
0% (0/38) 0% (0/38)
*Rating at time subjective numbness wore off.
premolar over the IAN block alone. For a supplemental IO injection distal to the first molar with 1.8 mL of 2% lidocaine with 1:100,000 epinephrine, Dunbar et al4 reported a 93% incidence of pulpal anesthesia for the second premolars, with approximately 80% of the premolars still anesthetized at 60 minutes. Although one half the amount of anesthetic solution (0.9 mL) was used in the current study, we recorded a higher success rate, the duration being comparable to the results of Dunbar et al 4 at 60 minutes. The most likely reason for this finding is the use of the distal IO injection site to the second premolar used in this study. Replogle et al, 3 Coggins et al, 2 and Dunbar et al 4 all found that the success rates and incidence of anesthesia were lower for the second premolar when a distal IO injection site to the first molar was selected. Using a distal IO injection site to the first molar, Coggins et al 2 and Replogle et al 3 speculated that the anesthetic solution would have to spread past the first molar or block the nerve trunk near to or at the site of injection to achieve equivalent pulpal anesthesia for the second premolar. Because neither occurred readily enough to result in anesthesia of the second premolar at a level equal to that for the first molar, they concluded that an IO injection distal to the second premolar may result in better anesthesia of this tooth. 2,3 The results of our study would support a higher success rate for the second premolar through use of a distal IO injection site to this tooth. Because this study addressed itself to results with 0.9 mL of 2% lidocaine with 1:100,000 epinephrine, further studies could investigate the use of 1.8 mL and the use of solutions without vasoconstrictors. Fig 1 shows a decline in pulpal anesthesia at approximately 30 minutes. Therefore, another avenue of research would be to study the effects of additional solution delivered through the same perforation site to determine whether anesthesia would be increased or prolonged.
For the IAN + IO combination, anesthetic success was 95% for the first molar, with approximately 76% of the first molars still anesthetized at 60 minutes (Table II and Fig 2). In comparison with that for the IAN by itself, the IAN + IO anesthetic success rate was statistically significant (P < :05; Table II), with significant differences shown for the incidence of pulpal anesthesia at 9 through 20 minutes post-intraosseous injection (Fig 2). Therefore, the addition of the IO injection increased success in the first molar in comparison with use of the IAN block alone. Dunbar et al 4 recorded a higher success rate (100%), a longer duration of pulpal anesthesia (60 minutes), and a higher percentage (90%) of subjects still anesthetized at 60 minutes than were found in this study. This could be attributed to the decreased amount (0.9 mL) of anesthetic solution used in this study; less anesthetic would be available for diffusion through the cancellous bone. Another factor is use of the distal IO injection site to the second premolar in our study, in contrast with use of the distal IO injection site to the first molar used by Dunbar et al. 4 It may be that using a distal IO injection site to the first molar with 0.9 mL of 2% lidocaine (1:100,000 epinephrine) results in better anesthesia of the first molar than using a distal IO injection site to the second premolar. Because the volume of solution and site of the IO injection varied in this study, further research is needed to resolve this issue. For the IAN + IO combination, anesthetic success was 87% for the second molar, with approximately 76% of the second molars still anesthetized at 60 minutes (Table II and Fig 3). In comparison with that of the IAN alone, the IAN + IO combination's anesthetic success rate was not statistically significant (P >.05; Table II), and no significant differences were shown for the incidence of pulpal anesthesia postinjection (Fig 3). Therefore, the addition of the IO injection
522 Reitzetal
ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY November 1998
did not statistically increase success in the second molar over the IAN block alone. Dunbar et al,4 using 1.8 mL of 2% lidocaine with 1:100,000 epinephrine and a distal IO injection site to the first molar after an IAN block, recorded a high incidence of pulpal anesthesia (100%) in the second molars, with approximately 88% of the teeth still anesthetized at 60 minutes. Coggins et al, 2 Replogle et al, 3 and Dunbar et al4 all showed that the second molar had similar or increased success rates in comparison with the first molar when a distal IO injection site to the first molar was selected. The lower success rate in this study could be attributed to the decreased amount (0.9 mL) of anesthetic solution and the use of the distal IO injection site to the second premolar. Therefore, not enough of the 0.9 mL of anesthetic solution spread to the second molar from a distal IO injection site to the second premolar to change the success of pulpal anesthesia appreciably. Clinically, it may be preferable to choose a mesial site to the second molar to increase anesthetic success. 4 No study has addressed the duration of a supplemental IO injection past 65 minutes. Figs 1 through 3 show the duration of pulpal anesthesia for 120 minutes post-intraosseous injection. There were no significant differences past 60 minutes for any of the teeth. The figures show a slow decline of pulpal anesthesia over 120 minutes, with the IAN + IO injection combination approaching the percentages of anesthesia achieved with the IAN injection alone. Researchers in future studies may want to address ways to increase anesthesia past 60 minutes with the IO technique. The anesthetic failure rate with the IAN + IO injection combination was 0% for the second premolar, 5% for the first molar, and 13% for the second molar (Table II). The difference between the IAN and IAN + IO techniques was statistically significant for the second premolar and first molar (Table II). The fact that the failure rates for the first and second molars were higher than the rate for the second premolar may be related to the amount of anesthetic solution administered (0.9 mL) or to the selection of the distal IO injection site to the second premolar, as discussed previously. Clinically, the addition of the IO injection, as used in this study, to the 1AN block will decrease anesthetic failure. However, it may be preferable to use a distal IO injection site to the first molar to further decrease the anesthetic failure rate in both the first and second molars, as shown by Dunbar et al. 4 The infiltrations, perforations, and IO injections resulted in low pain ratings, with a few reports of moderate pain (Table I). The tow ratings were probably due to the anesthesia provided by the IAN block and initial infiltration injection. Similar results for the
supplemental IO injection after the IAN block have been reported by Dunbar et al. 4 Therefore, the infiltration, perforation, and IO injection have a fairly low potential for moderate pain after an IAN block. Postinjection pain for the IO injection was rated as none to mild at the time subjective numbness wore off in 100% of the mock injections and in 89% of the IO injections; 11% of patients reported moderate pain (Table III). The pain ratings decreased over the next 3 days. The pain rating when subjective numbness wore off has been reported by Dunbar et al4 as 2% moderate pain, by Coggins et al 2 as 2% to 15% moderate pain, and by Replogle et al 3 as 2% to 5% moderate pain. Therefore, the IO injection has a 2% to 15% potential for moderate postinjection pain. Various authors 2-5 have reported a transient increase in heart rate (46% to 85% of the time) with the Stabident IO injection of epinephrine-containing solutions. Sixty-eight percent of the subjects in this study reported a subjective increase in heart rate during deposition or for 2 minutes after the IO injection; this compared with 5% reporting such an increase during the mock IO injection. The subjective reporting of heart rate changes was found to correlate with objective electrocardiogram recordings by Replogle et al. 16 Clinically, it appears that most subjects will report an increased heart rate after the IO injection of 0.9 mL of 2% lidocaine with 1:100,000 epinephrine when the Stabident system is used. Patients should be informed of this to lessen their anxiety. Although no animal study has investigated the effects of the Stabident IO injection on gingiva and bone, Dunbar et al,4 Coggins et al, 2 and Replogle et al 3 have reported swelling and purulence at Stabident IO injection sites. Generally, the incidence in these studies 2-4 has been less than 5%. These changes are probably related to gingival or bone trauma during perforation. In the current study, no subjects reported postinjection swelling or exudate. Clinically, the chance is small that swelling or exudate will occur postoperatively. None of the subjects reported that the first molar felt "high" postoperatively. Other studies 2-~ using the Stabident technique have reported the incidence of such a feeling as 4% to 13%. This feeling is most likely an increased awareness to biting that results from soreness in the area caused by damage from perforation or inflammation of the bone. No subjects reported symptoms of a pulpal nature postoperatively, and all subjects who received the IO injection at the first appointment had similar baseline pulp test readings at the second appointment. Pulpal anesthesia requirements will vary clinically, depending on a number of factors (tooth, procedure performed, degree of pulpal anesthesia required, and
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w h e t h e r the patient is s y m p t o m a t i c ) ; the clinical implications o f this study w o u l d therefore be d e p e n d e n t on these factors, and the clinician should evaluate his or her r e q u i r e m e n t s in light o f the results o f our study. In conclusion, the s u p p l e m e n t a l I O injection of 0.9 m L o f 2 % l i d o c a i n e w i t h 1:100,000 epinephrine, g i v e n distal to the s e c o n d premolar, significantly i n c r e a s e d the success o f pulpal anesthesia in the second p r e m o l a r (for 50 m i n u t e s ) and first m o l a r (for 20 m i n u t e s ) in c o m p a r i s o n with administration o f the inferior a l v e o l a r n e r v e b l o c k alone.
(1:100,000 epinephrine) for inferior alveolar nerve block. Journal of Endodontics 1993;19:146-50. Dreven L, Reader A, Beck M, Meyers W, Weaver J. An evaluation of the electric pulp tester as a measure of analgesia in human vital teeth. Journal of Endodontics 1987;13:233-8. Certosimo A, Archer R. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Operative Dentistry 1996;21:25-30. Vreeland D, Reader A, Beck M, Meyers W, Weaver J. An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. Journal of Endodontics 1989;15:6-12. Hinldey S, Reader A, Beck M, Meyers W. An evaluation of 4% prilocalne with 1:200,000 epinephrine and 2% mepivacaine with levonordefrin compared to 2% lidocaine with l:100,000 epinephrine for inferior alveolar nerve block. Anesthesia Progress 1991;38:84-9. Nist R, Reader A, Beck M, Meyers W. An evaluation of the incisive nerve block and combination inferior alveolar and incisive nerve blocks in mandibular anesthesia. Journal of Endodontics 1992;18:455-9. Chaney M, Kerby R, Reader A, Beck M, Meyers W, Weaver J. An evaluation of lidocaine hydrocarbonate compared with lidocaine hydrochloride for inferior alveolar nerve block. Anesthesia Progress 1991;38:212-6. Childers M, Reader A, Nist R, Beck M, Meyers W. The anesthetic efficacy of the periodontal ligament injection after an inferior alveolar nerve block. Journal of Endodontics 1996;22:317-20. Bou Dagher F, Yared GM, Machtou P. The anesthetic efficacy of volumes of lidocaine in inferior alveolar nerve blocks. Journal of Endodontics 1997;23:178-80. Replogle K, Reader A, Nist R, Beck M, Weaver J, Meyers W. Cardiovascular effects of the intraosseous injection of 2% lidocaine with 1:100,000 epinephrine and 3% mepivacalne. J Am Dent Assoc. In press 1998.
REFERENCES 1. Leonard M. The efficacy of an intraosseous injection system of delivering local anesthetic. J Am Dent Assoc 1995;126:81-6. 2. Coggins R, Reader A, Nist R, Beck M, Meyers W. Anesthetic efficacy of the intraosseous injection in maxillary and mandibular teeth. Oral Surg Oral Med Oral Oral Pathol Oral Radiol Endod 1996;81:634-41. 3. Replogle K, Reader A, Nist R, Beck M, Weaver J, Meyers W. 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. 4. Dunbar D, Reader A, Nist R, Beck M, Meyers W. Anesthetic efficacy of the intraosseous injection after an inferior alveolar nerve block. Journal of Endodontics 1996;22:481-6. 5. 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. Journal of Endodontics 1998;24:487-91. 6. 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. 7. McLean C, Reader A, Beck M, Meyers WJ. An evaluation of 4% prilocaine and 3% mepivacaine compared to 2% lidocaine
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Reprint requests: A1 Reader, DDS, MS Graduate Endodontics College of Dentistry The Ohio State University 305 W. 12th Avenue Columbus, OH 43210