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Comparison of the Anesthetic Efficacy of the Conventional Inferior Alveolar, Gow-Gates, and Vazirani-Akinosi Techniques
Clinical Research
Comparison of the Anesthetic Efficacy of the Conventional Inferior Alveolar, Gow-Gates, and Vazirani-Akinosi Techniques Steven Goldberg, DDS, MS,† Al Reader, DDS, MS,* Melissa Drum, DDS, MS,* John Nusstein, DDS, MS,* and Mike Beck, DDS, MA‡ Abstract The purpose of this prospective, randomized study was to compare the degree of pulpal anesthesia obtained with the conventional inferior alveolar, the Gow-Gates, and the Vazirani-Akinosi techniques in vital, asymptomatic teeth. With a crossover design, 40 subjects received all 3 techniques in a random manner by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine at 3 separate appointments. An electric pulp tester was used to test for anesthesia in 3-minute cycles for 60 minutes of the first molars, first premolars, and lateral incisors. Anesthesia was considered successful when 2 consecutive 80 readings were obtained within 15 minutes, and the 80 reading was continuously sustained through the 60th minute. The ranges of successful anesthesia were as follows: inferior alveolar technique, 25%– 62%; Gow-Gates technique, 16%– 44%; and for the VaziraniAkinosi technique, 13%–50%. There was no significant difference (P ⬎ .05) in success among the 3 techniques. However, the Gow-Gates and Vazirani-Akinosi techniques resulted in a statistically slower onset of pulpal anesthesia than the inferior alveolar nerve block. We concluded that in vital, asymptomatic teeth and for the subjects who achieved lip numbness, the conventional inferior alveolar nerve block is similar to the Gow-Gates and Vazirani-Akinosi techniques regarding anesthetic success but has a faster onset of pulpal anesthesia. (J Endod 2008;34:1306 –1311)
Key Words Gow-Gates, inferior alveolar nerve block, local anesthesia, Vazirani-Akinosi
From the *Division of Endodontics and ‡Department of Oral Biology, The Ohio State University, Columbus, Ohio. † Deceased. Address requests for reprints to Dr Al Reader, Department of Endodontics, College of Dentistry, The Ohio State University, 305 W 12th Ave, Columbus, OH 43210. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright © 2008 American Association of Endodontists. doi:10.1016/j.joen.2008.07.025
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T
he inferior alveolar nerve block is the most frequently used injection technique for achieving local anesthesia for mandibular restorative and surgical procedures. However, the inferior alveolar nerve block does not always result in successful pulpal anesthesia (1). Failure rates of 10%–39% have been reported in experimental studies (1). Gow-Gates (2) introduced a new technique for mandibular anesthesia in 1973. The injection uses extraoral landmarks, and the target site is the neck of the mandibular condyle. A number of studies (2–7) have shown higher success rates with the GowGates technique (92%–100%) than the conventional inferior alveolar nerve technique (65%– 86%). However, Todorovic et al. (8) found a higher success rate with the conventional inferior alveolar nerve block than the Gow-Gates block, whereas Ågren and Danielsson (9), Montagnese et al. (10), and Hung et al. (11) found the 2 techniques were equivalent. Akinosi (12) introduced his technique for mandibular anesthesia in 1977. However, Vazirani (13) also described a similar technique in 1960; hence the name was changed to the Vazirani-Akinosi technique (14). The injection is a closed mouth technique, with the landmarks for needle insertion being the mucogingival junction of the maxillary second molar. This technique is indicated when there is limited mandibular opening, for example trismus, which precludes the use of the inferior alveolar or Gow-Gates techniques. Sisk et al. (15) and Todorovic et al. (8) found the VaziraniAkinosi technique was equivalent to the conventional inferior alveolar nerve block. However, Donkor et al. (16), Yücel et al. (17), and Gonzales et al. (18) found the conventional inferior alveolar nerve block was superior to the Vazirani-Akinosi technique. Further studies of the Gow-Gates and Vazirani-Akinosi techniques are warranted to ensure their appropriate clinical use. The purpose of this prospective, randomized study was to compare the degree of pulpal anesthesia obtained with a conventional inferior alveolar, Gow-Gates, and Vazirani-Akinosi techniques by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine in vital, asymptomatic teeth. In addition, the pain of the 3 injections and extent of soft tissue anesthesia were evaluated.
Materials and Methods Forty adult subjects participated in this study. The subjects were in good health and were not taking any medications that would alter their perception of pain (nonsteroidal anti-inflammatory drugs, opioids, antidepressants). Exclusion criteria were as follows: younger than 18; older than 65 years of age; allergies to local anesthetics or sulfites; pregnancy; history of significant medical conditions; taking any medications that might affect anesthetic assessment (nonsteroidal anti-inflammatory drugs, opioids, antidepressants, alcohol); active sites of pathosis in area of injection; inability to give informed consent. The Ohio State University Human Subjects Review Committee approved both the protocol and informed consent document, and written informed consent was obtained from each subject. The forty subjects randomly received each of the 3 mandibular injection techniques at 3 separate appointments, spaced at least 1 week apart, in a crossover design. All subjects received an inferior alveolar nerve block, a Gow-Gates nerve block, and a Vazirani-Akinosi nerve block by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine (Xylocaine; Astra Pharmaceuticals, Inc, Worchester, MA) for all 3 blocks. With the
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Clinical Research crossover design, there were 120 total injections administered, and each subject served as his or her own control. Sixty block injections were administered on the right side, and 60 injections were administered on the left side. The same side randomly chosen for the first injection was used again for the second and third injections. The test teeth chosen for the experiment were the first molars, first premolars, and lateral incisors. 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 each experimental portion of the study. Clinical examinations indicated that all teeth were free of caries, large restorations, and periodontal disease; none had histories of trauma or sensitivity. Before the experiment, the 3 anesthetic techniques were randomly assigned 4-digit numbers from a random number table. Each subject was randomly assigned to each of the 3 techniques to determine which anesthetic solution was to be administered at each appointment. Only the random numbers were recorded on the data collection sheets to blind the experiment. At the beginning of each appointment and before any injections were given, the experimental teeth and control contralateral canine were tested 3 times with the pulp tester (Kerr, Analytic Technology Corp, Redmond, WA) to record baseline vitality. After the tooth to be tested was isolated with cotton rolls and dried with gauze, toothpaste was applied to the probe tip, which was then placed midway between the gingival margin and the occlusal or incisal edge of the tooth. The current rate was set at 25 seconds to increase from no output (0) to the maximum output (80). The number associated with the initial sensation was recorded. Alveolar mucosal sticks with an explorer were performed by placing pressure on the mucosa approximately 3 mm inferior to the mucogingival junction until the subject reported a sharp sensation. If no sensation was felt, another stick was immediately performed next to the area of the first stick. The presence or absence of a response was recorded. Trained research personnel performed all preinjection and postinjection tests. The trained research assistants were dental or hygiene students specifically trained in conducting clinical trials. Before the injection, each subject was instructed on how to rate the pain for needle insertion and deposition of anesthetic solution by using a 4-point scale. Zero was no pain. One was mild pain (pain that was recognizable but not discomforting). Two was moderate pain (pain that was discomforting but bearable). Three was severe pain (pain that caused considerable discomfort and was difficult to bear). Immediately after the nerve block, each subject rated the pain for each injection phase. Needle placement pain was not recorded. A total of 3.6 mL of 2% lidocaine with 1:100,000 epinephrine was loaded into a sterile 5 mL Luer-Lok syringe (Becton, Dickinson and Co, Rutherford, NJ) by using standard anesthetic cartridges. The cartridges were checked to ensure that the anesthetic solution had not expired. The needle used for all injections was a 27-gauge 1½-inch needle
(Monoject; Sherwood Medical, St Louis, MO). Topical anesthetic gel (20% benzocaine; Patterson Dental Supply, Inc, St Paul, MN) was passively placed at all block injection sites for 60 seconds by using a cotton tip applicator. Forty subjects received a conventional inferior alveolar nerve block as described by Jorgensen and Hayden (19). The patient was placed in the supine position, with the neck extended and the mouth open as wide as possible. A cotton roll was placed in the external auditory meatus on the side of the injection to help blind the inferior alveolar and Gow-Gates techniques. The injection site was the soft tissue overlying the medial surface of the ramus, lateral to the pterygomandibular raphe, at a height determined by the coronoid notch on the anterior border of the ramus. The thumb of the noninjecting hand was used to palpate the coronoid notch, and the first or second finger of the noninjecting hand was used to palpate the posterior border of the ramus, finding a slight depression. The line between the thumb and finger established the height of the injection site. The syringe was held parallel to the mandibular occlusal plane and was directed from the premolars on the contralateral side. A sterile rubber stopper was placed on the needle 20 mm from the tip to help gauge needle depth. The needle was placed through the mucosa (needle insertion) and then advanced slowly until gentle contact was made with the bone. After contact, the needle was withdrawn 1 mm, aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solution deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds. Forty subjects received the Gow-Gates nerve block as described by Gow-Gates (2). The patient was placed in the supine position, with the neck extended and the mouth open as wide as possible. A cotton roll was placed in the external auditory meatus on the side of the injection to identify this extraoral landmark. The cheek was retracted laterally. The injection site was just distal to the maxillary second molar at a height established by the mesiolingual cusp of that tooth. The syringe was directed from the corner of the mouth on the contralateral side toward the cotton roll in the ipsilateral ear. The needle was situated in a plane extending from the cotton roll in the ear to the corner of the mouth on the ipsilateral side and was parallel to the angle created by the ear and the side of the face. A sterile rubber stopper was placed on the needle 25 mm from the tip to help gauge needle depth. The needle penetrated the mucosa (needle insertion) and then was advanced slowly until anterolateral contact was made with the neck of the condyle, or until a depth of penetration of approximately 25 mm was reached (9). If contact was not made with the neck of the condyle on the initial attempt, the needle was withdrawn slightly, and the needle was redirected at a different angle. A concerted effort was made to contact the neck of the condyle. The needle was withdrawn 1 mm, aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solu-
TABLE 1. Pain Ratings for Each Injection Phase for the 3 Techniques Injection Phase
None
Mild
Moderate
Severe
12% (5/40) 10% (4/40) 18% (7/40)
65% (26/40) 63% (25/40) 55% (22/40)
22% (9/40) 25% (10/40) 25% (10/40)
0% (0/40) 2% (1/40) 2% (1/40)
38% (15/40) 32% (13/40) 35% (14/40)
48% (19/40) 55% (22/40) 52% (21/40)
15% (6/40) 12% (5/40) 12% (5/40)
0% (0/40) 0% (0/40) 0% (0/40)
,
Needle insertion* † Inferior alveolar Gow-Gates Vazirani-Akinosi Solution deposition*,† Inferior alveolar Gow-Gates Vazirani-Akinosi
n ⫽ 40. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
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Clinical Research TABLE 2. Incidence and Percentage of Soft Tissue Anesthesia Soft Tissue Evaluated
Inferior Alveolar
Gow-Gates
VaziraniAkinosi
Lingual*,† Buccal*,†
100% (32/32) 81% (26/32)
94% (30/32) 84% (27/32)
100% (30/30) 80% (24/30)
n ⫽ 32 for the inferior alveolar and Gow-Gates techniques; n⫽ 30 for the Vazirani-Akinosi technique. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
tion deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds. Forty subjects received the Vazirani-Akinosi nerve block described by Akinosi (12), Vazirani (13), and Gustainis and Peterson (20). The subject was placed in a supine position and asked to bring the teeth into occlusion, with the muscles of mastication relaxed. The cheek was retracted laterally. The injection site was the soft tissue overlying the medial surface of the ramus, adjacent to the maxillary tuberosity, at a height established by the mucogingival junction in the area of the maxillary second molar. The syringe was held parallel to the maxillary occlusal plane and directed posteriorly. A sterile rubber stopper was placed on the needle 30 mm from the tip to help gauge needle depth. The needle penetrated the mucosa (needle insertion) and then was advanced slowly to a depth of approximately 30 mm. Aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solution deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds to help blind the techniques. Because holding the mouth open differed from the recommended technique, it is not known whether this affected the success rate of the block. However, considering the innocuous nature of leaving the mouth open, we believe it would have little impact on success. All injections were given by the senior author (S.G.). At 1 minute after each block, the first molar was pulp tested. Alveolar mucosal sticks were performed buccal and lingual to the first molar. At 2 minutes, the first premolar and lateral incisor were tested. At 3 minutes, the contralateral canine was pulp tested, and the subject was asked whether his/her lip was numb. This cycle of testing was repeated every 3 minutes. The mucosal sticks were continued until 2 consecutive negative responses were recorded. At every third cycle the control tooth, the contralateral canine, was tested by a pulp tester without batteries to test the reliability of the subject. If profound lip numbness was not recorded within 21 minutes of the injection, the block was considered unsuccessful (missed block), and the injection was eliminated from the statistical analysis. Without lip numbness, pulpal anesthesia will not be obtained. Generally, clinicians would reinject if lip numbness were not achieved within 21 minutes. However, in experimental studies, reinjection presents problems with bias toward additional volumes. Lack of lip numbness would indicate that the injected solution was not close enough to the nerve or did not diffuse in close proximity to the nerve to
result in lip numbness. Therefore, these subjects were not analyzed statistically for soft tissue anesthesia and anesthetic success. All testing was stopped at the 60th minute after injection. No response from the subject at 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 within 15 minutes of the injection and the 80 reading was continuously sustained through the 60th minute. For most restorative procedures, we would want the patient numb within 15 minutes and to remain numb through the 60th minute. With a nondirectional alpha risk of .05 and a power of 80%, a sample size of 30 subjects for each technique was required to demonstrate a difference of ⫾35% in anesthetic success. Onset of anesthesia was recorded when the first of 2 consecutive 80 readings occurred. The success of soft tissue anesthesia was determined when 2 consecutive negative mucosal sticks were recorded. Comparisons between the 3 injection techniques for anesthetic success, incidence of pulpal anesthesia, and soft tissue anesthesia incidence were analyzed with multiple McNemar tests and the step-down Bonferroni method of Holm. Mean onset times of pulpal anesthesia were analyzed with a repeated-measures analysis of variance and TukeyKramer test. Needle insertion and solution deposition pain were assessed with the Friedman test. Comparisons were considered significant at P ⬍.05.
Results Forty adult subjects, 2 women and 38 men, aged 23–33 years with an average age of 25 years, participated. A total of 18 subjects, 8 Gow-Gates injections and 10 VaziraniAkinosi injections, did not have profound lip numbness at 21 minutes (unsuccessful blocks) and were eliminated from the statistical analysis. Because 8 subjects were removed in the Gow-Gates technique, the corresponding 8 subjects were removed from the inferior alveolar nerve block group because equal numbers were required for statistical comparison. By the same token, 10 corresponding subjects were removed from the inferior alveolar nerve block group when comparing the Vazirani-Akinosi technique. One hundred percent of the subjects used for data analysis had profound lip anesthesia with all 3 techniques. The discomfort ratings of solution deposition for the 3 block techniques are presented in Table 1. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Table 2 lists the incidence of soft tissue anesthesia. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Mean onset times of pulpal anesthesia are presented in Table 3. There were significant differences (P ⬍ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Anesthetic success is presented in Table 4. For the inferior alveolar technique, successful pulpal anesthesia ranged from 25%– 62%. With
TABLE 3. Mean Onset Times of Pulpal Anesthesia for the 3 Techniques (Minutes ⫾ Standard Deviation) Tooth First molar*,† First premolar*,† Lateral incisor*
Anesthetic Technique No. of Teeth Analyzed ⴞ
Inferior Alveolar
Gow-Gates
Vazirani-Akinosi
24 27 15
8 ⫾ 5.8 7 ⫾ 4.4 12 ⫾ 5.5
17 ⫾ 12.8 16 ⫾ 9.5 25 ⫾ 11.8
18 ⫾ 12.1 16 ⫾ 11.4 18 ⫾ 8.8
⫾ Subjects who did not achieve pulpal anesthesia (80 readings) were excluded from onset time analysis. *There were significant differences (P ⬍ .05) between the inferior alveolar and Gow-Gates techniques. †There were significant differences (P ⬍ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
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Clinical Research TABLE 4. Percentages and Number of Subjects Who Experienced Anesthetic Success Anesthetic Technique Inferior Alveolar Anesthetic success*,† First molar First premolar Lateral incisor
Gow-Gates
VaziraniAkinosi
53% (17/32) 38% (12/32) 27% (8/30) 62% (20/32) 44% (14/32) 50% (15/30) 25% (8/32) 16% (5/32) 13% (4/30)
n ⫽ 32 for the inferior alveolar and Gow-Gates techniques; n ⫽ 30 for the Vazirani-Akinosi technique. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
the Gow-Gates technique, successful pulpal anesthesia ranged from 16%– 44%. For the Vazirani-Akinosi technique, successful pulpal anesthesia ranged from 13%–50%. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Figs. 1–3 present the incidence of pulpal anesthesia (80 readings) for the 3 anesthetic techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. When administering the Gow-Gates injections, the neck of the condyle was not contacted with the needle in 7 of 40 injections. All 7 injections produced profound lip numbness within 21 minutes and were included in the statistical analysis.
Figure 2. Incidence of first premolar anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
We based our use of the pulp test reading of 80, signaling maximum output, as a criterion for pulpal anesthesia on the studies of Dreven et al. (21) and Certosimo and Archer (22). These studies showed that no patient response to an 80 reading ensured pulpal anesthesia in vital, asymptomatic teeth. In addition, Certosimo and Archer demonstrated that electric pulp test readings less than 80 resulted in pain during operative procedures in asymptomatic teeth. Therefore, using the electric pulp tester before beginning dental procedures on asymptomatic, vital teeth will provide the clinician a reliable indicator of
pulpal anesthesia. Because all subjects included in the data analysis felt profound lip numbness, but pulp testing revealed that subjects did not always have pulpal anesthesia (80 readings), asking the patient whether the lip is numb only indicates soft tissue anesthesia but does not guarantee successful pulpal anesthesia. The 18 patients (10 Vazirani-Akinosi and 8 Gow-Gates) who failed to have subjective lip numbness within 21 minutes and were eliminated from the statistical analysis would indicate that the anesthetic solution was probably deposited outside the pterygomandibular space. After reviewing the literature and practicing the Gow-Gates and VaziraniAkinosi techniques for 2 months before beginning the study, it is unlikely the senior author was so unfamiliar with the techniques to cause technical failure. Reasons for failure of the Gow-Gates technique include directing the needle too far laterally and too far superiorly (2) and the diffusion of the anesthetic solution medially, which might be limited by the lateral pterygoid muscle and its associated fascia (23). Donkor et al. (16) found that 13% of the subjects given the Vazirani-Akinosi nerve block required an additional block injection before inferior alveolar nerve anesthesia was obtained. They believed that failure with the
Figure 1. Incidence of first molar anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
Figure 3. Incidence of lateral incisor anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
Discussion
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Clinical Research Vazirani-Akinosi technique was related to the lack of bony landmarks in the target area, which made depth of needle insertion somewhat variable (16). In 7 of the Gow-Gates injections, the neck of the condyle was not contacted with the needle, but all of these injections resulted in lip numbness within 21 minutes, demonstrating that anesthetic solution was most likely deposited in the pterygomandibular space. Possible explanations for not contacting the neck of the condyle might be widely divergent mandibles, or the angle of the ear to the face might not always be an accurate indicator of the location of the neck of the condyle. Even though a concerted effort was made in this study to contact the neck of the condyle, clinically it might not always be possible. Anesthetic success was not significantly different between the conventional inferior alveolar and Gow-Gates techniques (Table 4). Kohler et al. (24) demonstrated a higher success rate for extractions with the Gow-Gates technique when the volume was increased from 1.8 to 3.6 mL (18% versus 82%). All 3 techniques in the current study used a 3.6-mL volume to maximize the amount of anesthetic solution used. Some studies have shown higher success rates with the Gow-Gates technique (95%–96%) versus the conventional inferior alveolar nerve block (65%–79%) during surgery (3– 6). Robertson (3) and GowGates (2) used restorative procedures and reported a 92%–98% success rate for the Gow-Gates technique versus a 71%– 86% success rate with the conventional inferior alveolar nerve block. Malamed (5) reported a 97% success rate for the Gow-Gates technique, but a number of these injections were given in addition to a failed conventional inferior alveolar nerve block. With an extraction model, Todorovic et al. (8) found that the conventional inferior alveolar nerve block was better than the Gow-Gates technique. It is difficult to compare the results of these previous studies with the current study because extractions and the variations in restorative procedures might not be a good measure of pulpal anesthesia. Ågren and Danielsson (9), Montagnese et al. (10), and Hung et al. (11) used the pulp tester to evaluate anesthesia and found no difference between the Gow-Gates and conventional inferior alveolar nerve blocks. Therefore, for pulpal anesthesia, success should not be significantly different between the 2 techniques. Anesthetic success was not significantly different between the conventional inferior alveolar and Vazirani-Akinosi techniques (Table 4). Previous studies (16 –18) of the Vazirani-Akinosi technique, evaluating either lip anesthesia or extractions, reported a higher success rate with the conventional inferior alveolar nerve block than the Vazirani-Akinosi technique. With an extraction model, Sisk (15) and Todorovic et al. (8) found the 2 techniques were equivalent. Again, extractions might not always indicate pulpal anesthesia. In general, the Vazirani-Akinosi technique might be equivalent for pulpal anesthesia to the conventional inferior alveolar nerve block. Interestingly, Akinosi (12) did not claim his technique was superior to the inferior alveolar nerve block. Generally, the conventional inferior alveolar nerve block had similar rates of anesthetic success as other studies with the inferior alveolar nerve block (1). For example, Nusstein et al. (1) found that success rates ranged from 44%–53% for the first molar, 61%– 67% for the first premolar, and 32%–35% for the lateral incisor. These are similar to the success rate of 53% for the first molar, 62% for the first premolar, and 25% for the lateral incisor in the current study (Table 4). None of the 3 techniques provided complete pulpal anesthesia for the mandibular teeth (Table 4, Figs. 1–3), which could present meaningful clinical problems because the teeth might not be numb for procedures requiring complete pulpal anesthesia. Practitioners should consider supplemental techniques such as intraosseous (25–27) or periodontal ligament injections (28) when any of the 3 techniques fails to provide pulpal anesthesia for a particular tooth. Because we studied a young adult population, the results of this study might not apply to 1310
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children or the elderly. In addition, the results would probably not apply to patients presenting with irreversible pulpitis. Generally, there was a fairly high incidence of anesthesia for the lingual and buccal soft tissues for all 3 techniques (Table 2). Hung et al. (11) found similar high rates of soft tissue anesthesia. Gow-Gates (2) and Akinosi (12) state that a separate buccal injection is not required for soft tissue anesthesia with their techniques. In the current study, the incidence of buccal nerve anesthesia was 84% with the Gow-Gates technique and 80% with the Vazirani-Akinosi technique by using 3.6 mL of anesthetic solution. Previous studies have found an incidence of 62% (3), 68% (6), 77% (5), 78% (7), 20% (10), and 89% (11) for buccal nerve anesthesia with the Gow-Gates technique, with some authors finding no difference between the conventional inferior alveolar nerve block and the Gow-Gates technique (9, 11). Vreeland et al. (29) found an incidence of 30% for buccal nerve anesthesia with the conventional inferior alveolar nerve block. For the Vazirani-Akinosi technique, previous studies have found buccal nerve anesthesia occurred 80% (15) and 71% (16) of the time. Gonzalez et al. (18) found that patients anesthetized with the Vazirani-Akinosi technique required more buccal nerve reinforcements than those with the conventional inferior alveolar nerve block. Generally, some buccal nerve anesthesia can be obtained with all 3 techniques because the long buccal nerve can be anesthetized as it crosses the anterior border of the mandibular ramus (30) if anesthetic solution is deposited as the needle is inserted or on withdrawal, or enough volume is injected to diffuse to the nerve. Regardless of the incidence reported for the 3 techniques, buccal nerve anesthesia was not 100%. Therefore, a separate long buccal injection should be given when soft tissue anesthesia is required in the molar teeth. Both the Gow-Gates and Vazirani-Akinosi techniques had slower mean onset times of pulpal anesthesia than the conventional inferior alveolar nerve block (Table 3). Significant differences were shown for all 3 teeth except when the inferior alveolar was compared with the Vazirani-Akinosi in the lateral incisor. Figs. 1–3 demonstrate an initial higher rate of pulpal anesthesia for the inferior alveolar technique. However, because the definition of anesthetic success did not include 80 readings before 15 minutes, slower onset times did not have a statistical effect on overall anesthetic success. The lateral incisor requires a longer waiting time for pulpal anesthesia than the posterior teeth (Table 3). If the clinician begins restorative procedures requiring pulpal anesthesia before 15 minutes, the Gow-Gates and Vazirani-Akinosi techniques might not have taken full effect. Previous studies of the Gow-Gates technique have also reported a slower onset of anesthesia (7–9). Ågren and Danielsson (9) believed that the pool of anesthetic solution is positioned much farther away from the inferior alveolar nerve with the Gow-Gates technique than with the conventional inferior alveolar nerve block. Donkor et al. (16) also found a slower rate of anesthesia with the Vazirani-Akinosi technique when compared with the conventional inferior alveolar nerve block. Therefore, a slower onset of pulpal anesthesia can be expected with both the Gow-Gates and Vazirani-Akinosi techniques. The duration of complete pulpal anesthesia was not measured in our studies because testing ended at 60 minutes. Overall, Figs. 1–3 demonstrate that duration of pulpal anesthesia of at least 60 minutes after the 3 techniques is likely to occur for those subjects who achieved pulpal anesthesia. Needle insertion caused moderate pain in 22%–25% of the subjects and severe pain in 0%–2%. Nusstein and Beck (31) found a 13%– 19% incidence of moderate pain and a 1%–3% incidence of severe pain with needle insertion for the conventional inferior alveolar nerve block. The numbers are similar to the current study. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques
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Clinical Research (Table 1). Montagnese et al. (10), Jacobs et al. (32), and Todorovic et al. (8) also found no difference among the 3 mandibular block techniques. Donkor et al. (16) found a higher incidence of pain in female patients with the inferior alveolar technique than with the VaziraniAkinosi technique. Solution deposition had an incidence of around 12%–15% moderate pain with no reports of severe pain. Other studies (33–35) of the inferior alveolar nerve block have reported similar findings. In general, the pain ratings indicate that all 3 techniques have the potential to be moderately painful from 12%–15% of the time, even though the solution is deposited slowly during a period of 2 minutes. We concluded that for the subjects who achieved lip numbness, the conventional inferior alveolar nerve block is similar to the Gow-Gates and Vazirani-Akinosi techniques regarding anesthetic success in vital, asymptomatic teeth. Both the Gow-Gates and Vazirani-Akinosi techniques will result in a slower onset of pulpal anesthesia than the conventional inferior alveolar nerve block.
Acknowledgments This study was supported by the Graduate Students Research Support Fund, The Ohio State University.
References 1. Nusstein J, Reader A, Beck M. Anesthetic efficacy of different volumes of lidocaine with epinephrine for inferior alveolar nerve blocks. Gen Dent 2002;50:372–5. 2. Gow-Gates GAE. Mandibular conduction anesthesia: a new technique using extraoral landmarks. Oral Surg Oral Med Oral Pathol 1973;36:321– 8. 3. Robertson WD. Clinical evaluation of mandibular conduction anaesthesia. Gen Dent 1979;27:49 –51. 4. Levy TP. An assessment of the Gow-Gates mandibular block for third molar surgery. J Am Dent Assoc 1981;103:37–9. 5. Malamed SF. The Gow-Gates mandibular block: evaluation after 4,275 cases. Oral Surg Oral Med Oral Pathol 1981;51:463–7. 6. Sisk AL. Evaluation of the Gow-Gates mandibular block for oral surgery. Anesth Prog 1985;32:143– 6. 7. Cruz EV, Quengua JB, Gutierrez IL, Abreu MA, Uy HG. A comparative study: classical, Akinosi, and Gow-Gates techniques of mandibular nerve block. J Philipp Dent Assoc 1994;46:13–9. 8. 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. 9. Ågren E, Danielsson K. Conduction block analgesia in the mandible. Swed Dent J 1981;5:81–9. 10. Montagnese TA, Reader A, Melfi R. A comparative study of the Gow-Gates technique and a standard technique for mandibular anesthesia. J Endod 1984;10:158 – 63. 11. Hung PC, Chang HH, Yang PJ, Kuo YS, Lan WH, Lin CP. Comparison of the Gow-Gates mandibular block and inferior alveolar nerve block using a standardized protocol. J Formos Med Assoc 2006;105:139 – 46. 12. Akinosi JO. A new approach to the mandibular block. Br J Oral Surg 1977;15:83–7.
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13. Vazirani SJ. Closed mouth mandibular nerve block: a new technique. Dent Dig 1960;66:10 –3. 14. Malamed SF. Handbook of local anesthesia. 4th ed. St Louis, MO: Mosby, 1997:208. 15. Sisk AL. Evaluation of the Akinosi mandibular block technique in oral surgery. J Oral Maxillofac Surg 1986;44:113–5. 16. Donkor P, Wong J, Punnia-Moorthy A. An evaluation of the closed mouth mandibular block technique. Int J Oral Maxillofac Surg 1990;19:216 –9. 17. Yücel E, Hutchison IL. A comparative evaluation of the conventional and closedmouth technique for inferior alveolar nerve block. Aust Dent J 1995;40:15– 6. 18. Gonzalez M, Pena B, Caliz F, Marin SH, Diago P. A comparative study of direct mandibular block and the Akinosi technique. Med Oral 2003;8:143–9. 19. Jorgensen NB, Hayden J Jr. Local and general anesthesia in dentistry. 2nd ed. Philadelphia, PA: Lea & Febiger, 1967. 20. Gustaninis JF, Peterson LJ. An alternative method of mandibular nerve block. J Am Dent Assoc 1981;103:33– 6. 21. 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. J Endod 1987;13:233– 8. 22. Certosimo A, Archer R. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Oper Dent 1996;21:25–30. 23. Coleman RD, Smith RA. The anatomy of mandibular anesthesia: review and analysis. Oral Surg Oral Med Oral Pathol 1982;54:148 –53. 24. Kohler BR, Castellon L, Laissle G. Gow-Gates technique: a pilot study for extraction procedures with clinical evaluation and review. Anesth Prog 2008;55:2– 8. 25. 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. 26. 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. 27. 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. 28. Cohen HP, Cha BY, Spangberg LSW. Endodontic anesthesia in mandibular molars: a clinical study. J Endod 1993;19:370 –3. 29. Vreeland D, Reader A, Beck M, Meyers W, Weaver J. An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. J Endod 1989;15:6 –12. 30. Monheim LM. Local anesthesia and pain control in dental practice. 4th ed. St Louis, MO: Mosby, 1969:103. 31. Nusstein J, Beck M. Effectiveness of 20% benzocaine as a topical anesthetic for intraoral injections. Anesth Prog 2003;50:159 – 63. 32. Jacobs S, Haas DA, Meechan JG, May S. Injection pain: comparison of three mandibular block techniques and modulation by nitrous oxide/oxygen. J Am Dent Assoc 2003;134:869 –76. 33. 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. J Endod 1992;18:455–9. 34. Ridenour S, Reader A, Beck M, Weaver J. Anesthetic efficacy of a combination of hyaluronidase and lidocaine with epinephrine in inferior alveolar nerve blocks. Anesth Prog 2001;48:9 –15. 35. Mikesell P, Nusstein J, Reader A, Beck M, Weaver J. A comparison of articaine and lidocaine for inferior alveolar nerve blocks. J Endod 2005;31:265–70.
Comparison of Anesthetic Efficacy of Three Mandibular Techniques
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Comparison of the Anesthetic Efficacy of the Conventional Inferior Alveolar, Gow-Gates, and Vazirani-Akinosi Techniques Steven Goldberg, DDS, MS,† Al Reader, DDS, MS,* Melissa Drum, DDS, MS,* John Nusstein, DDS, MS,* and Mike Beck, DDS, MA‡ Abstract The purpose of this prospective, randomized study was to compare the degree of pulpal anesthesia obtained with the conventional inferior alveolar, the Gow-Gates, and the Vazirani-Akinosi techniques in vital, asymptomatic teeth. With a crossover design, 40 subjects received all 3 techniques in a random manner by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine at 3 separate appointments. An electric pulp tester was used to test for anesthesia in 3-minute cycles for 60 minutes of the first molars, first premolars, and lateral incisors. Anesthesia was considered successful when 2 consecutive 80 readings were obtained within 15 minutes, and the 80 reading was continuously sustained through the 60th minute. The ranges of successful anesthesia were as follows: inferior alveolar technique, 25%– 62%; Gow-Gates technique, 16%– 44%; and for the VaziraniAkinosi technique, 13%–50%. There was no significant difference (P ⬎ .05) in success among the 3 techniques. However, the Gow-Gates and Vazirani-Akinosi techniques resulted in a statistically slower onset of pulpal anesthesia than the inferior alveolar nerve block. We concluded that in vital, asymptomatic teeth and for the subjects who achieved lip numbness, the conventional inferior alveolar nerve block is similar to the Gow-Gates and Vazirani-Akinosi techniques regarding anesthetic success but has a faster onset of pulpal anesthesia. (J Endod 2008;34:1306 –1311)
Key Words Gow-Gates, inferior alveolar nerve block, local anesthesia, Vazirani-Akinosi
From the *Division of Endodontics and ‡Department of Oral Biology, The Ohio State University, Columbus, Ohio. † Deceased. Address requests for reprints to Dr Al Reader, Department of Endodontics, College of Dentistry, The Ohio State University, 305 W 12th Ave, Columbus, OH 43210. E-mail address: [email protected]. 0099-2399/$0 - see front matter Copyright © 2008 American Association of Endodontists. doi:10.1016/j.joen.2008.07.025
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T
he inferior alveolar nerve block is the most frequently used injection technique for achieving local anesthesia for mandibular restorative and surgical procedures. However, the inferior alveolar nerve block does not always result in successful pulpal anesthesia (1). Failure rates of 10%–39% have been reported in experimental studies (1). Gow-Gates (2) introduced a new technique for mandibular anesthesia in 1973. The injection uses extraoral landmarks, and the target site is the neck of the mandibular condyle. A number of studies (2–7) have shown higher success rates with the GowGates technique (92%–100%) than the conventional inferior alveolar nerve technique (65%– 86%). However, Todorovic et al. (8) found a higher success rate with the conventional inferior alveolar nerve block than the Gow-Gates block, whereas Ågren and Danielsson (9), Montagnese et al. (10), and Hung et al. (11) found the 2 techniques were equivalent. Akinosi (12) introduced his technique for mandibular anesthesia in 1977. However, Vazirani (13) also described a similar technique in 1960; hence the name was changed to the Vazirani-Akinosi technique (14). The injection is a closed mouth technique, with the landmarks for needle insertion being the mucogingival junction of the maxillary second molar. This technique is indicated when there is limited mandibular opening, for example trismus, which precludes the use of the inferior alveolar or Gow-Gates techniques. Sisk et al. (15) and Todorovic et al. (8) found the VaziraniAkinosi technique was equivalent to the conventional inferior alveolar nerve block. However, Donkor et al. (16), Yücel et al. (17), and Gonzales et al. (18) found the conventional inferior alveolar nerve block was superior to the Vazirani-Akinosi technique. Further studies of the Gow-Gates and Vazirani-Akinosi techniques are warranted to ensure their appropriate clinical use. The purpose of this prospective, randomized study was to compare the degree of pulpal anesthesia obtained with a conventional inferior alveolar, Gow-Gates, and Vazirani-Akinosi techniques by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine in vital, asymptomatic teeth. In addition, the pain of the 3 injections and extent of soft tissue anesthesia were evaluated.
Materials and Methods Forty adult subjects participated in this study. The subjects were in good health and were not taking any medications that would alter their perception of pain (nonsteroidal anti-inflammatory drugs, opioids, antidepressants). Exclusion criteria were as follows: younger than 18; older than 65 years of age; allergies to local anesthetics or sulfites; pregnancy; history of significant medical conditions; taking any medications that might affect anesthetic assessment (nonsteroidal anti-inflammatory drugs, opioids, antidepressants, alcohol); active sites of pathosis in area of injection; inability to give informed consent. The Ohio State University Human Subjects Review Committee approved both the protocol and informed consent document, and written informed consent was obtained from each subject. The forty subjects randomly received each of the 3 mandibular injection techniques at 3 separate appointments, spaced at least 1 week apart, in a crossover design. All subjects received an inferior alveolar nerve block, a Gow-Gates nerve block, and a Vazirani-Akinosi nerve block by using 3.6 mL of 2% lidocaine with 1:100,000 epinephrine (Xylocaine; Astra Pharmaceuticals, Inc, Worchester, MA) for all 3 blocks. With the
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Clinical Research crossover design, there were 120 total injections administered, and each subject served as his or her own control. Sixty block injections were administered on the right side, and 60 injections were administered on the left side. The same side randomly chosen for the first injection was used again for the second and third injections. The test teeth chosen for the experiment were the first molars, first premolars, and lateral incisors. 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 each experimental portion of the study. Clinical examinations indicated that all teeth were free of caries, large restorations, and periodontal disease; none had histories of trauma or sensitivity. Before the experiment, the 3 anesthetic techniques were randomly assigned 4-digit numbers from a random number table. Each subject was randomly assigned to each of the 3 techniques to determine which anesthetic solution was to be administered at each appointment. Only the random numbers were recorded on the data collection sheets to blind the experiment. At the beginning of each appointment and before any injections were given, the experimental teeth and control contralateral canine were tested 3 times with the pulp tester (Kerr, Analytic Technology Corp, Redmond, WA) to record baseline vitality. After the tooth to be tested was isolated with cotton rolls and dried with gauze, toothpaste was applied to the probe tip, which was then placed midway between the gingival margin and the occlusal or incisal edge of the tooth. The current rate was set at 25 seconds to increase from no output (0) to the maximum output (80). The number associated with the initial sensation was recorded. Alveolar mucosal sticks with an explorer were performed by placing pressure on the mucosa approximately 3 mm inferior to the mucogingival junction until the subject reported a sharp sensation. If no sensation was felt, another stick was immediately performed next to the area of the first stick. The presence or absence of a response was recorded. Trained research personnel performed all preinjection and postinjection tests. The trained research assistants were dental or hygiene students specifically trained in conducting clinical trials. Before the injection, each subject was instructed on how to rate the pain for needle insertion and deposition of anesthetic solution by using a 4-point scale. Zero was no pain. One was mild pain (pain that was recognizable but not discomforting). Two was moderate pain (pain that was discomforting but bearable). Three was severe pain (pain that caused considerable discomfort and was difficult to bear). Immediately after the nerve block, each subject rated the pain for each injection phase. Needle placement pain was not recorded. A total of 3.6 mL of 2% lidocaine with 1:100,000 epinephrine was loaded into a sterile 5 mL Luer-Lok syringe (Becton, Dickinson and Co, Rutherford, NJ) by using standard anesthetic cartridges. The cartridges were checked to ensure that the anesthetic solution had not expired. The needle used for all injections was a 27-gauge 1½-inch needle
(Monoject; Sherwood Medical, St Louis, MO). Topical anesthetic gel (20% benzocaine; Patterson Dental Supply, Inc, St Paul, MN) was passively placed at all block injection sites for 60 seconds by using a cotton tip applicator. Forty subjects received a conventional inferior alveolar nerve block as described by Jorgensen and Hayden (19). The patient was placed in the supine position, with the neck extended and the mouth open as wide as possible. A cotton roll was placed in the external auditory meatus on the side of the injection to help blind the inferior alveolar and Gow-Gates techniques. The injection site was the soft tissue overlying the medial surface of the ramus, lateral to the pterygomandibular raphe, at a height determined by the coronoid notch on the anterior border of the ramus. The thumb of the noninjecting hand was used to palpate the coronoid notch, and the first or second finger of the noninjecting hand was used to palpate the posterior border of the ramus, finding a slight depression. The line between the thumb and finger established the height of the injection site. The syringe was held parallel to the mandibular occlusal plane and was directed from the premolars on the contralateral side. A sterile rubber stopper was placed on the needle 20 mm from the tip to help gauge needle depth. The needle was placed through the mucosa (needle insertion) and then advanced slowly until gentle contact was made with the bone. After contact, the needle was withdrawn 1 mm, aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solution deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds. Forty subjects received the Gow-Gates nerve block as described by Gow-Gates (2). The patient was placed in the supine position, with the neck extended and the mouth open as wide as possible. A cotton roll was placed in the external auditory meatus on the side of the injection to identify this extraoral landmark. The cheek was retracted laterally. The injection site was just distal to the maxillary second molar at a height established by the mesiolingual cusp of that tooth. The syringe was directed from the corner of the mouth on the contralateral side toward the cotton roll in the ipsilateral ear. The needle was situated in a plane extending from the cotton roll in the ear to the corner of the mouth on the ipsilateral side and was parallel to the angle created by the ear and the side of the face. A sterile rubber stopper was placed on the needle 25 mm from the tip to help gauge needle depth. The needle penetrated the mucosa (needle insertion) and then was advanced slowly until anterolateral contact was made with the neck of the condyle, or until a depth of penetration of approximately 25 mm was reached (9). If contact was not made with the neck of the condyle on the initial attempt, the needle was withdrawn slightly, and the needle was redirected at a different angle. A concerted effort was made to contact the neck of the condyle. The needle was withdrawn 1 mm, aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solu-
TABLE 1. Pain Ratings for Each Injection Phase for the 3 Techniques Injection Phase
None
Mild
Moderate
Severe
12% (5/40) 10% (4/40) 18% (7/40)
65% (26/40) 63% (25/40) 55% (22/40)
22% (9/40) 25% (10/40) 25% (10/40)
0% (0/40) 2% (1/40) 2% (1/40)
38% (15/40) 32% (13/40) 35% (14/40)
48% (19/40) 55% (22/40) 52% (21/40)
15% (6/40) 12% (5/40) 12% (5/40)
0% (0/40) 0% (0/40) 0% (0/40)
,
Needle insertion* † Inferior alveolar Gow-Gates Vazirani-Akinosi Solution deposition*,† Inferior alveolar Gow-Gates Vazirani-Akinosi
n ⫽ 40. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
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Clinical Research TABLE 2. Incidence and Percentage of Soft Tissue Anesthesia Soft Tissue Evaluated
Inferior Alveolar
Gow-Gates
VaziraniAkinosi
Lingual*,† Buccal*,†
100% (32/32) 81% (26/32)
94% (30/32) 84% (27/32)
100% (30/30) 80% (24/30)
n ⫽ 32 for the inferior alveolar and Gow-Gates techniques; n⫽ 30 for the Vazirani-Akinosi technique. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
tion deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds. Forty subjects received the Vazirani-Akinosi nerve block described by Akinosi (12), Vazirani (13), and Gustainis and Peterson (20). The subject was placed in a supine position and asked to bring the teeth into occlusion, with the muscles of mastication relaxed. The cheek was retracted laterally. The injection site was the soft tissue overlying the medial surface of the ramus, adjacent to the maxillary tuberosity, at a height established by the mucogingival junction in the area of the maxillary second molar. The syringe was held parallel to the maxillary occlusal plane and directed posteriorly. A sterile rubber stopper was placed on the needle 30 mm from the tip to help gauge needle depth. The needle penetrated the mucosa (needle insertion) and then was advanced slowly to a depth of approximately 30 mm. Aspiration was performed, and the anesthetic solution was deposited during a period of 2 minutes (solution deposition). After the injection, the subject was asked to keep his/her mouth wide open for approximately 60 seconds to help blind the techniques. Because holding the mouth open differed from the recommended technique, it is not known whether this affected the success rate of the block. However, considering the innocuous nature of leaving the mouth open, we believe it would have little impact on success. All injections were given by the senior author (S.G.). At 1 minute after each block, the first molar was pulp tested. Alveolar mucosal sticks were performed buccal and lingual to the first molar. At 2 minutes, the first premolar and lateral incisor were tested. At 3 minutes, the contralateral canine was pulp tested, and the subject was asked whether his/her lip was numb. This cycle of testing was repeated every 3 minutes. The mucosal sticks were continued until 2 consecutive negative responses were recorded. At every third cycle the control tooth, the contralateral canine, was tested by a pulp tester without batteries to test the reliability of the subject. If profound lip numbness was not recorded within 21 minutes of the injection, the block was considered unsuccessful (missed block), and the injection was eliminated from the statistical analysis. Without lip numbness, pulpal anesthesia will not be obtained. Generally, clinicians would reinject if lip numbness were not achieved within 21 minutes. However, in experimental studies, reinjection presents problems with bias toward additional volumes. Lack of lip numbness would indicate that the injected solution was not close enough to the nerve or did not diffuse in close proximity to the nerve to
result in lip numbness. Therefore, these subjects were not analyzed statistically for soft tissue anesthesia and anesthetic success. All testing was stopped at the 60th minute after injection. No response from the subject at 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 within 15 minutes of the injection and the 80 reading was continuously sustained through the 60th minute. For most restorative procedures, we would want the patient numb within 15 minutes and to remain numb through the 60th minute. With a nondirectional alpha risk of .05 and a power of 80%, a sample size of 30 subjects for each technique was required to demonstrate a difference of ⫾35% in anesthetic success. Onset of anesthesia was recorded when the first of 2 consecutive 80 readings occurred. The success of soft tissue anesthesia was determined when 2 consecutive negative mucosal sticks were recorded. Comparisons between the 3 injection techniques for anesthetic success, incidence of pulpal anesthesia, and soft tissue anesthesia incidence were analyzed with multiple McNemar tests and the step-down Bonferroni method of Holm. Mean onset times of pulpal anesthesia were analyzed with a repeated-measures analysis of variance and TukeyKramer test. Needle insertion and solution deposition pain were assessed with the Friedman test. Comparisons were considered significant at P ⬍.05.
Results Forty adult subjects, 2 women and 38 men, aged 23–33 years with an average age of 25 years, participated. A total of 18 subjects, 8 Gow-Gates injections and 10 VaziraniAkinosi injections, did not have profound lip numbness at 21 minutes (unsuccessful blocks) and were eliminated from the statistical analysis. Because 8 subjects were removed in the Gow-Gates technique, the corresponding 8 subjects were removed from the inferior alveolar nerve block group because equal numbers were required for statistical comparison. By the same token, 10 corresponding subjects were removed from the inferior alveolar nerve block group when comparing the Vazirani-Akinosi technique. One hundred percent of the subjects used for data analysis had profound lip anesthesia with all 3 techniques. The discomfort ratings of solution deposition for the 3 block techniques are presented in Table 1. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Table 2 lists the incidence of soft tissue anesthesia. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Mean onset times of pulpal anesthesia are presented in Table 3. There were significant differences (P ⬍ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Anesthetic success is presented in Table 4. For the inferior alveolar technique, successful pulpal anesthesia ranged from 25%– 62%. With
TABLE 3. Mean Onset Times of Pulpal Anesthesia for the 3 Techniques (Minutes ⫾ Standard Deviation) Tooth First molar*,† First premolar*,† Lateral incisor*
Anesthetic Technique No. of Teeth Analyzed ⴞ
Inferior Alveolar
Gow-Gates
Vazirani-Akinosi
24 27 15
8 ⫾ 5.8 7 ⫾ 4.4 12 ⫾ 5.5
17 ⫾ 12.8 16 ⫾ 9.5 25 ⫾ 11.8
18 ⫾ 12.1 16 ⫾ 11.4 18 ⫾ 8.8
⫾ Subjects who did not achieve pulpal anesthesia (80 readings) were excluded from onset time analysis. *There were significant differences (P ⬍ .05) between the inferior alveolar and Gow-Gates techniques. †There were significant differences (P ⬍ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
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Clinical Research TABLE 4. Percentages and Number of Subjects Who Experienced Anesthetic Success Anesthetic Technique Inferior Alveolar Anesthetic success*,† First molar First premolar Lateral incisor
Gow-Gates
VaziraniAkinosi
53% (17/32) 38% (12/32) 27% (8/30) 62% (20/32) 44% (14/32) 50% (15/30) 25% (8/32) 16% (5/32) 13% (4/30)
n ⫽ 32 for the inferior alveolar and Gow-Gates techniques; n ⫽ 30 for the Vazirani-Akinosi technique. *There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques. †There were no significant differences (P ⬎ .05) between the inferior alveolar and Vazirani-Akinosi techniques.
the Gow-Gates technique, successful pulpal anesthesia ranged from 16%– 44%. For the Vazirani-Akinosi technique, successful pulpal anesthesia ranged from 13%–50%. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. Figs. 1–3 present the incidence of pulpal anesthesia (80 readings) for the 3 anesthetic techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques. When administering the Gow-Gates injections, the neck of the condyle was not contacted with the needle in 7 of 40 injections. All 7 injections produced profound lip numbness within 21 minutes and were included in the statistical analysis.
Figure 2. Incidence of first premolar anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
We based our use of the pulp test reading of 80, signaling maximum output, as a criterion for pulpal anesthesia on the studies of Dreven et al. (21) and Certosimo and Archer (22). These studies showed that no patient response to an 80 reading ensured pulpal anesthesia in vital, asymptomatic teeth. In addition, Certosimo and Archer demonstrated that electric pulp test readings less than 80 resulted in pain during operative procedures in asymptomatic teeth. Therefore, using the electric pulp tester before beginning dental procedures on asymptomatic, vital teeth will provide the clinician a reliable indicator of
pulpal anesthesia. Because all subjects included in the data analysis felt profound lip numbness, but pulp testing revealed that subjects did not always have pulpal anesthesia (80 readings), asking the patient whether the lip is numb only indicates soft tissue anesthesia but does not guarantee successful pulpal anesthesia. The 18 patients (10 Vazirani-Akinosi and 8 Gow-Gates) who failed to have subjective lip numbness within 21 minutes and were eliminated from the statistical analysis would indicate that the anesthetic solution was probably deposited outside the pterygomandibular space. After reviewing the literature and practicing the Gow-Gates and VaziraniAkinosi techniques for 2 months before beginning the study, it is unlikely the senior author was so unfamiliar with the techniques to cause technical failure. Reasons for failure of the Gow-Gates technique include directing the needle too far laterally and too far superiorly (2) and the diffusion of the anesthetic solution medially, which might be limited by the lateral pterygoid muscle and its associated fascia (23). Donkor et al. (16) found that 13% of the subjects given the Vazirani-Akinosi nerve block required an additional block injection before inferior alveolar nerve anesthesia was obtained. They believed that failure with the
Figure 1. Incidence of first molar anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
Figure 3. Incidence of lateral incisor anesthesia as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80/80s), at each postinjection time interval, for the 3 techniques. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques.
Discussion
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Clinical Research Vazirani-Akinosi technique was related to the lack of bony landmarks in the target area, which made depth of needle insertion somewhat variable (16). In 7 of the Gow-Gates injections, the neck of the condyle was not contacted with the needle, but all of these injections resulted in lip numbness within 21 minutes, demonstrating that anesthetic solution was most likely deposited in the pterygomandibular space. Possible explanations for not contacting the neck of the condyle might be widely divergent mandibles, or the angle of the ear to the face might not always be an accurate indicator of the location of the neck of the condyle. Even though a concerted effort was made in this study to contact the neck of the condyle, clinically it might not always be possible. Anesthetic success was not significantly different between the conventional inferior alveolar and Gow-Gates techniques (Table 4). Kohler et al. (24) demonstrated a higher success rate for extractions with the Gow-Gates technique when the volume was increased from 1.8 to 3.6 mL (18% versus 82%). All 3 techniques in the current study used a 3.6-mL volume to maximize the amount of anesthetic solution used. Some studies have shown higher success rates with the Gow-Gates technique (95%–96%) versus the conventional inferior alveolar nerve block (65%–79%) during surgery (3– 6). Robertson (3) and GowGates (2) used restorative procedures and reported a 92%–98% success rate for the Gow-Gates technique versus a 71%– 86% success rate with the conventional inferior alveolar nerve block. Malamed (5) reported a 97% success rate for the Gow-Gates technique, but a number of these injections were given in addition to a failed conventional inferior alveolar nerve block. With an extraction model, Todorovic et al. (8) found that the conventional inferior alveolar nerve block was better than the Gow-Gates technique. It is difficult to compare the results of these previous studies with the current study because extractions and the variations in restorative procedures might not be a good measure of pulpal anesthesia. Ågren and Danielsson (9), Montagnese et al. (10), and Hung et al. (11) used the pulp tester to evaluate anesthesia and found no difference between the Gow-Gates and conventional inferior alveolar nerve blocks. Therefore, for pulpal anesthesia, success should not be significantly different between the 2 techniques. Anesthetic success was not significantly different between the conventional inferior alveolar and Vazirani-Akinosi techniques (Table 4). Previous studies (16 –18) of the Vazirani-Akinosi technique, evaluating either lip anesthesia or extractions, reported a higher success rate with the conventional inferior alveolar nerve block than the Vazirani-Akinosi technique. With an extraction model, Sisk (15) and Todorovic et al. (8) found the 2 techniques were equivalent. Again, extractions might not always indicate pulpal anesthesia. In general, the Vazirani-Akinosi technique might be equivalent for pulpal anesthesia to the conventional inferior alveolar nerve block. Interestingly, Akinosi (12) did not claim his technique was superior to the inferior alveolar nerve block. Generally, the conventional inferior alveolar nerve block had similar rates of anesthetic success as other studies with the inferior alveolar nerve block (1). For example, Nusstein et al. (1) found that success rates ranged from 44%–53% for the first molar, 61%– 67% for the first premolar, and 32%–35% for the lateral incisor. These are similar to the success rate of 53% for the first molar, 62% for the first premolar, and 25% for the lateral incisor in the current study (Table 4). None of the 3 techniques provided complete pulpal anesthesia for the mandibular teeth (Table 4, Figs. 1–3), which could present meaningful clinical problems because the teeth might not be numb for procedures requiring complete pulpal anesthesia. Practitioners should consider supplemental techniques such as intraosseous (25–27) or periodontal ligament injections (28) when any of the 3 techniques fails to provide pulpal anesthesia for a particular tooth. Because we studied a young adult population, the results of this study might not apply to 1310
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children or the elderly. In addition, the results would probably not apply to patients presenting with irreversible pulpitis. Generally, there was a fairly high incidence of anesthesia for the lingual and buccal soft tissues for all 3 techniques (Table 2). Hung et al. (11) found similar high rates of soft tissue anesthesia. Gow-Gates (2) and Akinosi (12) state that a separate buccal injection is not required for soft tissue anesthesia with their techniques. In the current study, the incidence of buccal nerve anesthesia was 84% with the Gow-Gates technique and 80% with the Vazirani-Akinosi technique by using 3.6 mL of anesthetic solution. Previous studies have found an incidence of 62% (3), 68% (6), 77% (5), 78% (7), 20% (10), and 89% (11) for buccal nerve anesthesia with the Gow-Gates technique, with some authors finding no difference between the conventional inferior alveolar nerve block and the Gow-Gates technique (9, 11). Vreeland et al. (29) found an incidence of 30% for buccal nerve anesthesia with the conventional inferior alveolar nerve block. For the Vazirani-Akinosi technique, previous studies have found buccal nerve anesthesia occurred 80% (15) and 71% (16) of the time. Gonzalez et al. (18) found that patients anesthetized with the Vazirani-Akinosi technique required more buccal nerve reinforcements than those with the conventional inferior alveolar nerve block. Generally, some buccal nerve anesthesia can be obtained with all 3 techniques because the long buccal nerve can be anesthetized as it crosses the anterior border of the mandibular ramus (30) if anesthetic solution is deposited as the needle is inserted or on withdrawal, or enough volume is injected to diffuse to the nerve. Regardless of the incidence reported for the 3 techniques, buccal nerve anesthesia was not 100%. Therefore, a separate long buccal injection should be given when soft tissue anesthesia is required in the molar teeth. Both the Gow-Gates and Vazirani-Akinosi techniques had slower mean onset times of pulpal anesthesia than the conventional inferior alveolar nerve block (Table 3). Significant differences were shown for all 3 teeth except when the inferior alveolar was compared with the Vazirani-Akinosi in the lateral incisor. Figs. 1–3 demonstrate an initial higher rate of pulpal anesthesia for the inferior alveolar technique. However, because the definition of anesthetic success did not include 80 readings before 15 minutes, slower onset times did not have a statistical effect on overall anesthetic success. The lateral incisor requires a longer waiting time for pulpal anesthesia than the posterior teeth (Table 3). If the clinician begins restorative procedures requiring pulpal anesthesia before 15 minutes, the Gow-Gates and Vazirani-Akinosi techniques might not have taken full effect. Previous studies of the Gow-Gates technique have also reported a slower onset of anesthesia (7–9). Ågren and Danielsson (9) believed that the pool of anesthetic solution is positioned much farther away from the inferior alveolar nerve with the Gow-Gates technique than with the conventional inferior alveolar nerve block. Donkor et al. (16) also found a slower rate of anesthesia with the Vazirani-Akinosi technique when compared with the conventional inferior alveolar nerve block. Therefore, a slower onset of pulpal anesthesia can be expected with both the Gow-Gates and Vazirani-Akinosi techniques. The duration of complete pulpal anesthesia was not measured in our studies because testing ended at 60 minutes. Overall, Figs. 1–3 demonstrate that duration of pulpal anesthesia of at least 60 minutes after the 3 techniques is likely to occur for those subjects who achieved pulpal anesthesia. Needle insertion caused moderate pain in 22%–25% of the subjects and severe pain in 0%–2%. Nusstein and Beck (31) found a 13%– 19% incidence of moderate pain and a 1%–3% incidence of severe pain with needle insertion for the conventional inferior alveolar nerve block. The numbers are similar to the current study. There were no significant differences (P ⬎ .05) between the inferior alveolar and Gow-Gates techniques and the inferior alveolar and Vazirani-Akinosi techniques
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Clinical Research (Table 1). Montagnese et al. (10), Jacobs et al. (32), and Todorovic et al. (8) also found no difference among the 3 mandibular block techniques. Donkor et al. (16) found a higher incidence of pain in female patients with the inferior alveolar technique than with the VaziraniAkinosi technique. Solution deposition had an incidence of around 12%–15% moderate pain with no reports of severe pain. Other studies (33–35) of the inferior alveolar nerve block have reported similar findings. In general, the pain ratings indicate that all 3 techniques have the potential to be moderately painful from 12%–15% of the time, even though the solution is deposited slowly during a period of 2 minutes. We concluded that for the subjects who achieved lip numbness, the conventional inferior alveolar nerve block is similar to the Gow-Gates and Vazirani-Akinosi techniques regarding anesthetic success in vital, asymptomatic teeth. Both the Gow-Gates and Vazirani-Akinosi techniques will result in a slower onset of pulpal anesthesia than the conventional inferior alveolar nerve block.
Acknowledgments This study was supported by the Graduate Students Research Support Fund, The Ohio State University.
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13. Vazirani SJ. Closed mouth mandibular nerve block: a new technique. Dent Dig 1960;66:10 –3. 14. Malamed SF. Handbook of local anesthesia. 4th ed. St Louis, MO: Mosby, 1997:208. 15. Sisk AL. Evaluation of the Akinosi mandibular block technique in oral surgery. J Oral Maxillofac Surg 1986;44:113–5. 16. Donkor P, Wong J, Punnia-Moorthy A. An evaluation of the closed mouth mandibular block technique. Int J Oral Maxillofac Surg 1990;19:216 –9. 17. Yücel E, Hutchison IL. A comparative evaluation of the conventional and closedmouth technique for inferior alveolar nerve block. Aust Dent J 1995;40:15– 6. 18. Gonzalez M, Pena B, Caliz F, Marin SH, Diago P. A comparative study of direct mandibular block and the Akinosi technique. Med Oral 2003;8:143–9. 19. Jorgensen NB, Hayden J Jr. Local and general anesthesia in dentistry. 2nd ed. Philadelphia, PA: Lea & Febiger, 1967. 20. Gustaninis JF, Peterson LJ. An alternative method of mandibular nerve block. J Am Dent Assoc 1981;103:33– 6. 21. 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. J Endod 1987;13:233– 8. 22. Certosimo A, Archer R. A clinical evaluation of the electric pulp tester as an indicator of local anesthesia. Oper Dent 1996;21:25–30. 23. Coleman RD, Smith RA. The anatomy of mandibular anesthesia: review and analysis. Oral Surg Oral Med Oral Pathol 1982;54:148 –53. 24. Kohler BR, Castellon L, Laissle G. Gow-Gates technique: a pilot study for extraction procedures with clinical evaluation and review. Anesth Prog 2008;55:2– 8. 25. 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. 26. 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. 27. 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. 28. Cohen HP, Cha BY, Spangberg LSW. Endodontic anesthesia in mandibular molars: a clinical study. J Endod 1993;19:370 –3. 29. Vreeland D, Reader A, Beck M, Meyers W, Weaver J. An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. J Endod 1989;15:6 –12. 30. Monheim LM. Local anesthesia and pain control in dental practice. 4th ed. St Louis, MO: Mosby, 1969:103. 31. Nusstein J, Beck M. Effectiveness of 20% benzocaine as a topical anesthetic for intraoral injections. Anesth Prog 2003;50:159 – 63. 32. Jacobs S, Haas DA, Meechan JG, May S. Injection pain: comparison of three mandibular block techniques and modulation by nitrous oxide/oxygen. J Am Dent Assoc 2003;134:869 –76. 33. 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. J Endod 1992;18:455–9. 34. Ridenour S, Reader A, Beck M, Weaver J. Anesthetic efficacy of a combination of hyaluronidase and lidocaine with epinephrine in inferior alveolar nerve blocks. Anesth Prog 2001;48:9 –15. 35. Mikesell P, Nusstein J, Reader A, Beck M, Weaver J. A comparison of articaine and lidocaine for inferior alveolar nerve blocks. J Endod 2005;31:265–70.
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