Anesth Prog 38:84-89 1991
An Evaluation of 4% Prilocaine with 1:200,000 Epinephrine and 2% Mepivacaine with 1:20,000 Levonordefrn Compared with 2% Lidocaine with 1: 100,000 Epinephrine for Inferior Nerve
Block
Stewart A. Hinkley, DDS, MS,* Al Reader, DDS, MS,t Mike Beck, DDS, MA,: and William J. Meyers, DMD, MEdt *Private practice, Springfield and Columbus, Ohio; tDepartment of Endodontics, and
tDepartment of Diagnostic Services, The Ohio State University College of Dentistry, Columbus, Ohio
The purpose of this study was to measure the degree of anesthesia obtained with 4% prilocaine with 1: 200,000 epinephrine and 2% mepivacaine with 1:20,000 levonordefrin compared with 2% lidocaine with 1: 100,000 epinephrine for inferior alveolar nerve block. Using a repeated measures design, 30 subjects randomly received an inferior alveolar injection using masked cartridges of each solution at three successive appointments. The first molar, first premolar, lateral incisor, and contralateral canine (control) were blindly tested with an Analytic Technology pulp tester at 3-min cycles for 50 min. Anesthetic success was defined as no subject response to the maximum output of the pulp tester (80 reading) within 16 min and maintenance of this reading for the remainder of the testing period. Although subjects felt numb subjectively, anesthetic success as defined here occurred in 46% to 57% of the molars, in 50% to 57% of the premolars, and in 21% to 36% of the lateral incisors. No statistically significant differences in onset, success, failure, or incidence were found among the solutions. We conclude that the three preparations are equivalent for inferior alveolar nerve block of 50-min duration.
A lthough local anesthesia is the most common method used in dentistry to control pain, pulpal anesthesia is not always achieved.1'2 Kaufman et al,1 in a survey, found that 90% of responding general dentists had anesthetic difficulties during restorative visits within a 5-day period, with the greatest number of failures occurring with the inferior alveolar injection. Vreeland et al2 also reported a high incidence of potential anesthetic problems with the inferior alveolar injection. They found no significant differences in success or failure when lidocaine with epinephrine was doubled in volume (from 1.8 to 3.6 mL) or concentration (from 2% to 4%). Two percent mepivacaine with 1: 20,000 levonordefrin and 4% prilocaine with 1: 200,000 epinephrine are commonly used for dental anesthesia. Although clinical studies3-12 have evaluated these solutions, only two13'14 used standardized stimuli to quantify anesthesia, and these were in the maxillary arch. The purpose of this study was to measure the degree of anesthesia obtained with these preparations compared with 2% lidocaine with 1:100,000 epinephrine after inferior alveolar nerve block.
METHODS
Received June 7, 1991; accepted for publication August 28, 1991. Address correspondence to Dr. Al Reader, Department of Endodontics, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, Ohio 43210. This paper was adapted from a thesis submitted by Dr. Hinkley in partial fulfillment of the requirements for the MS degree at The Ohio State University. This study was supported by research funding from the J. David Brilliant Memorial Fund, Ohio Association of Endodontists.
Thirty adult subjects, 19 men and 11 women, ranging in age from 23 to 42 years and with an average age of 27 years, participated in this study. The subjects were in good health and were not taking any medications that would alter pain perception. The study was approved by The
© 1990 by the American Dental Society of Anesthesiology
ISSN 0003-3006/90/$3.50
84
Hinkley et al 85
Anesth Prog 38:84-89 1991
Ohio State University Human Subjects Review Committee, and written consent was obtained from each subject. An equal number of mandibular right and left sides were tested, with the first molar, first premolar, and lateral incisor chosen as the test teeth. The contralateral canine was used as the unanesthetized control to ensure that the pulp tester was operating properly and the subject would respond 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.
Using a repeated measures design, each subject randomly received each anesthetic solution on three successive appointments spaced at least 1 week apart. The anesthetic solutions tested were: A-1.8 mL of 4% prilocaine with 1: 200,000 epinephrine (Citanest Forte; Astra Pharmaceutical Products, Inc., Westborough, MA); B-1.8 mL of 2% mepivacaine with 1:20,000 levonordefrin (Carbocaine with Neo-Cobefrin; Cooke-Waite Laboratories, Inc., New York, NY); C-1.8 mL of 2% lidocaine with 1:100,000 epinephrine (Xylocaine with Epinephrine; Astra). The subjects were randomly assigned to one of six letter (ABC) combinations to determine the sequence of solution administration. Each anesthetic cartridge label was removed and masked with tape. A four-digit random number, corresponding to the letter designation, was written on each cartridge, and the three cartridges for each subject were placed in an autoclave bag with the numbers recorded on the outside showing the injection order. All injections were given by the senior author. At each appointment and prior to injection, the experimental teeth and control canine were tested three times with the pulp tester (Analytic Technology Corp., Redmond, WA) to record baseline vitality. Following isolation with cotton rolls and drying with gauze, toothpaste was applied to the probe tip, which was placed midway between the gingival margin and the occlusal edge. The current rate was set at 25 sec to increase from no output (0) to the maximum output (80). The number at initial sensation was recorded. Soft tissue responsiveness labial and lingual to the canine and buccal to the first molar, was tested by sticking the alveolar mucosa with a sharp explorer. Gentle pressure was placed on the sharp cowhorn explorer, which was placed on the alveolar mucose approximately 3 mm from the attached gingiva, until the subject reported feeling a sharp sensation. If no sharpness was felt, another stick was immediately performed next to the area of the first stick. The presence or absence of a response was recorded. All pre- and postinjection tests were done by trained personnel who were blinded to the solutions injected. A standard inferior alveolar injection, as described by
Table 1. Number (and Percentage) of Subjects Who Experienced Soft Tissue Anesthesia to Mucosal Probing Probing Area
Drug
Solution A-Prilocaine
B-Mepivacaine C-Lidocaine
Mental 27 (96%) 28 (100%) 26 (93%)
Lingual 28 (100%) 27 (96%) 27 (96%)
Buccal 24 (86%) 24 (86%) 19 (68%)
Jorgensen and Hayden,15 was administered with a 27gauge 1-inch needle (Monoject; Sherwood Medical, St. Louis, MO) and an aspirating syringe (Astra). After reaching the target area and performing aspiration, the solution was deposited at a rate of 60 sec/mL. At 1 min postinjection, the first molar was pulp-tested and alveolar mucosal sticks were performed. At 2 min, the first premolar and lateral incisor were tested. At 3 min, the control canine was tested, and the subject asked if the lip and tongue were numb. This cycle of testing was repeated every 3 min. When an 80 reading was recorded for two consecutive cycles the pulp testing was continued every 6 min. All testing was stopped at 50 min postinjection. Lip and tongue anesthesia was considered successful when the subject felt numbness within 20 min and/or did not respond to mucosal probing. The time for onset of lip anesthesia was recorded at the first of two consecutive positive (feeling numb) or negative (not feeling mucosal probing) responses. Pulpal anesthesia was defined as no subject response to the pulp tester at an 80 reading. The time for onset of pulpal anesthesia was recorded at the first of two consecutive 80 readings. Anesthesia was considered successful if an 80 reading was achieved within 16 min and this reading was sustained for the remainder of the 50-min test period. Anesthesia was considered a failure if the subject never achieved two consecutive 80 readings during the 50 min. Anesthesia was of slow onset if the subject achieved two consecutive 80 readings after 16 min. Anesthesia was of short duration if the subject achieved two consecutive 80 readings, lost the 80 reading, and never regained it within the 50-min period. Onset times were analyzed using a one-way repeated Table 2. Mean Onset of Lip Anesthesiaa Drug Patient Response Solution (min) A Prilocaine 6.3 ± 1.1 B-Mepivacaine 5.3 ±+ 0.8 C-Lidocaine 6.1 ±+ 0.8
Mucosal Probing (min) 10.8 ± 1.8 9.1 ±+ 1.6 10.6 ±+ 1.9
There were no significant differences among the solutions (P > 0.05). a Values are the mean ±+ SE.
Anesth Prog 38:84-89 1991
86 Local Anesthetic Comparison Table 3. Mean Onset Time of Pulpal Anesthesiaa First Molar First Premolar Lateral Incisor Drug Solution (min) (min) (min) A-Prilocaine 10.0 ±+ 2.2 10.1 ±+ 1.7 16.3 ±+ 3.2 11.0 ±+ 2.0 B-Mepivacaine 9.6 ± 1.9 11.7 ±+ 2.3 12.3 ±+ 1.9 C-Lidocaine 8.8 ± 1.8 10.6 +± 1.6 There were no significant differences among the solutions (P > 0.05). Values are the mean + SE.
measures analysis of variance. Anesthetic success and failure, and incidence of pulpal anesthesia, were analyzed nonparametrically using Bonferroni-adjusted McNemar tests. Comparisons were considered significant at P < 0.05.
RESULTS The mean baseline pulp testing readings were as follows: first molar, 37 points; first premolar, 33 points; lateral incisor, 29 points; control canine, 35 points. All control canines responded positively throughout the study, with pulp test readings remaining uniformly within 5 points of baseline for each appointment. Two of 30 subjects achieved lip numbness only after 20 min and were excluded from the data analysis. All of the remaining 28 subjects had subjective lip and tongue numbness. Mental and lingual mucosal probing revealed a high incidence (93% to 100%) of anesthesia (Table 1). Buccal anesthesia ranged from 68% to 86% (Table 1). The mean onset time of lip anesthesia, as determined by subject questioning and mucosal sticks, ranged from 5 to 11 min (Table 2). The mean onset time of pulpal
anesthesia (excluding failures) was somewhat slower (Table 3). There were no significant differences in onset among the solutions. The incidence of pulpal anesthesia at each time interval is shown in Figures 1 through 3. The highest incidences for all three solutions by tooth were as follows: first molar, 68% to 79%; first premolar, 75% to 89%; lateral incisor, 54% to 61%. Anesthetic success occurred in 46% to 57% of the molars, in 50% to 57% of the premolars, and in 21% to 36% of the lateral incisors (Table 4). Anesthetic failures occurred in 18% to 32% of the molars, in 11% to 25% of the premolars, and in 36% to 46% of the lateral incisors. The mean elevation of pulp test readings (for the 50 min) above baseline readings for all subjects with anesthetic failures were as follows: first molar, 11 points; first premolar, 14 points; lateral incisor, 13 points. Slow onset of anesthesia was noted in 11% to 25% of the molars, in 21% to 32% of the premolars, and in 14% to 39% of the lateral incisors. Anesthesia of short duration was found in 4% of the molars, in 0% to 4% of the premolars, and in 0% to 7% of the lateral incisors. There were no significant differences among the solutions for any of the measures of efficacy (ie, incidence, success, and failure). However, anesthesia of the lateral incisors was lower with respect to success and incidence and higher with respect to failure.
DISCUSSION All 28 subjects had profound lip numbness, and mental and lingual mucosal probing indicated a high incidence of success (Table 1). Since pulp testing showed a lower incidence of anesthesia (Figures 1,2, and 3), lip numbness
Figure 1. Incidence of first molar anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's) at each postinjection time interval, for the three solutions. There were no significant differences among the solutions at any time interval. ...AA%
1UU f~
Go 75 0 0 0 0
a)
50
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25 % I .· vv,vvv
'-Vl"
..
10
30 20 Time (minutes)
40
50
Hinkley et al
Anesth Prog 38:84-89 1991
87
10 0
-o O 0-
7
Go D0
0)(Uco
5
0-
c
L.
2
Time (minutes)
Figure 2. Incidence of first premolar anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's) at each postinjection time interval, for the three solutions. There were no significant differences among the
solutions at any time interval.
and negative mucosal responses may not indicate onset or guarantee successful pulpal anesthesia, at least as defined in this study. Buccal mucosal sticks demonstrated a fairly high incidence of success (Table 1). Previous studies2'16 have also shown that buccal anesthesia may be obtained with only the standard inferior alveolar injection. However, buccal mucosal probing is not completely reliable in evaluating partial soft tissue anesthesia,16 and this may account for the high success rate in this study. The onset of pulpal anesthesia was not significantly different among the solutions (Table 3); therefore, the solutions had equivalent onset times. Although subjects with anesthetic failure (Table 4) were excluded from the onset times analysis, instances of slow onset of anesthesia
did increase the mean times of onset. These cases of slow onset indicate that waiting even 16 min after an inferior alveolar injection may not guarantee complete pulpal anesthesia. Clinically, pulp testing vital teeth would identify these problems and provide a measure of pulpal anesthesia onset. Since anesthetic success (Table 4) and incidence of anesthesia (Figures 1, 2, and 3) were not significantly different among the three solutions, they can be considered equivalent for inferior alveolar nerve blocks of 50min duration. This finding agrees with clinical studies by Weil et al,4 Cowan,8 Epstein,9 and Chilton12 using these solutions for mandibular anesthesia. The results were also similar to the incidence and success reported by Vreeland et al.2
Figure 3. Incidence of lateral incisor anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's), at each postinjection time interval, for the three solutions. There were no significant differences among the
solutions at any time interval.
-d 0% 0%
1u 0
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-
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A
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°
=
o
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0
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40
50
Anesth Prog 38:84-89 1991
88 Local Anesthetic Comparison Table 4. Number (and Percentage) of Subjects Who Experienced Anesthetic Success, Anesthetic Failure, Slow Onset of Anesthesia, and Anesthesia of Short Duration Drug Solution First Molar First Premolar Lateral Incisor Anesthetic Successa 6 (21%) 16 (57%) 13 (46%) A-Prilocaine 15 (54%) 10 (36%) B-Mepivacaine 16 (57%) 14 (50%) 15 (54%) 10 (36%) C-Lidocaine Anesthetic Failurea 7 (25%) 6 (21%) 10 (36%) A-Prilocaine 3 (11%) 11 (39%) B-Mepivacaine 5 (18%) 9 (32%) 7 (25%) 13 (46%) C-Lidocaine Slow Onset of Anesthesia 7 (25%) 11 (39%) A-Prilocaine 6'(21%) 9 (32%) 6 (21%) B-Mepivacaine 3 (11%) 3 (11%) 6 (21%) 4 (14%) C-Lidocaine Anesthesia of Short Duration 1 (4%) 0 (0%) 2 (7%) A-Prilocaine 0 (0%) 0 (0%) B-Mepivacaine 1 (4%) 1 (4%) 1 (4%) 0 (0%) C-Lidocaine aThere were no significant differences among the solutions (P
>
0.05).
Pulpal anesthesia requirements will vary clinically, depending on a number of factors (tooth, procedure performed, degree of pulpal anesthesia required). Dreven et al17 previously demonstrated that lack of response to an 80 reading in asymptomatic vital teeth was coincident with complete clinical anesthesia, which is why this standard was used here as the criterion for pulpal anesthesia. The 80 reading is a rigorous definition of pulpal anesthesia and may not reflect clinical success or failure. Dahl and Lindqvist13 have stated that teeth that do not respond to drilling may still respond to an electric pulp tester. Experimentally, the 80 reading is an end point which can be used to measure pulpal anesthesia over time and allows comparisons of anesthetic solutions without the variation of nociceptive stimulation inherent in clinical procedures. Patients who have symptomatic pulpal pathosis may have special anesthetic problems, since they may report pain even though the tooth is nonresponsive to the electrical pulp tester. Anesthetic success for molar and premolar teeth (46% to 57%) indicates that periodontal ligament injections may be needed to achieve full, complete anesthesia in asymptomatic17 and symptomatic18 vital teeth. The low success rate (21% to 36%) for the lateral incisors suggests that additional infiltration injections may be routinely needed. Periodontal ligament injections may not be effective in lateral incisors, since White et a119 found a low success rate using the same testing methodology as in this study. Anesthetic failure was not significantly different among the three solutions and was higher in the lateral incisor
than in the posterior teeth (Table 4). These subjects could present meaningful clinical problems, since they may not be numb for procedures requiring profound pulpal anesthesia. Theories for inadequate anesthesia with the inferior alveolar injection (accessory innervation, cross innervation, central core theory, and accuracy of needle location) are discussed by Vreeland et al.2 The duration of pulpal anesthesia was not measured in this study since testing ended at 50 min. Short duration of anesthesia was observed in some subjects (Table 4). Overall, Figures 1 through 3 demonstrate that a duration of anesthesia extending at least 50 min after injection is likely to occur for those subjects who achieve pulpal anesthesia.
CONCLUSIONS
Concerning the anesthetic efficacy obtained with 4% prilocaine (1: 200,000 epinephrine), 2% mepivacaine (1: 20,000 levonordefrin), and 2% lidocaine (1: 100,000 epinephrine) in inferior alveolar nerve blocks of 50-min duration, the following conclusions were reached: 1. Lip numbness and negative response to mucosal probing may not indicate pulpal anesthesia as measured by the electric pulp tester in this study. Onset of lip anesthesia, using subject questioning or mucosal probing, may also not be a reliable indicator of the onset of pulpal anesthesia. 2. All three solutions were equivalent in blocking the inferior alveolar nerve. There were no statistical differences among the solutions regarding onset, incidence, success, or failure. 3. Successful pulpal anesthesia (ie, no response to electral pulp testing at the 80 setting) was more likely to occur in the first molar and first premolar than in the lateral incisor. 4. The duration of pulpal anesthesia was generally dependable for subjects who achieved pulpal anesthesia. REFERENCES 1. Kaufman E, Weinstein P, Milgrom P: Difficulties in achieving local anesthesia. J Am Dent Assoc 1984;108:205-208. 2. Vreeland DL, Reader A, Beck M, Meyers W, Weaver J: An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. J Endodon 1989;15: 6-12. 3. Mumford JM, Geddes IC: Trial of Carbocaine in conservative dentistry. Br Dent J 1961; 1 10:92-94. 4. Weil C, Santangelo C, Welham FS, Yackel RF: Clinical evaluation of mepivacaine HCL by a new method. J Am Dent Assoc 1961;63:26-32.
Anesth Prog 38:84-89 1991 5. Hiatt W: Local anesthesia: history; potential toxicity; clinical investigation of mepivacaine. Dent Clin N Am 5: 1961;243-256. 6. Stibbs GD, Korn JH: An evaluation of the local anesthetic mepivacaine hydrochloride in operative dentistry. J Prosth Dent 1964;14:355-364. 7. Cowan A: A minimum dosage technique in the clinical comparison of representative modem local anesthetic agents. J Dent Res 1964;43:1228-1248. 8. Cowan A: Further clinical evaluation of prilocaine (Citanest), with and without epinephrine. Oral Surg Oral Med Oral Pathol 1968;26:304-310. 9. Epstein S: Clinical study of prilocaine with varying concentrations of epinephrine. J Am Dent Assoc 1969;78:8590. 10. Bradley DJ, Martin ND: Clinical evaluation of mepivacaine and lidocaine. Aust Dent J 1969;14:377-381. 11. Brown G, Ward NL: Prilocaine and lignocaine plus adrenaline. Br Dent J 1969;126:557-562. 12. Chilton NW: Clinical evaluation of prilocaine hydrochlo-
Hinkley et al 89 ride 4% solution with and without epinephrine. J Am Dent Assoc 1971;83:149-154. 13. Dahl E, Lindqvist B: The effectivity of two Carbocaine solutions of different concentration. Odontol Revy 1967; 18:149-155. 14. Aberg G, Sydnes G: Studies on the duration of local anesthetics. Int J Oral Surg 1978;7:141-147. 15. Jorgensen NB, Hayden J Jr: Sedation, Local and General Anesthesia in Dentistry. 2nd ed. Philadelphia, Lea & Febiger, 1967:62-73. 16. Agren E, Danielsson K: Conduction block analgesia in the mandible. Swed Dent J 1981;5:81-89. 17. Dreven LJ, Reader A, Beck FM, Meyers WJ, Weaver J: An evaluation of an electric pulp tester as a measure of analgesia in human vital teeth. J Endodon 1987;13:233-238. 18. Walton RE, Abbott BJ: Periodontal ligament injection: a clinical evaluation. J Am Dent Assoc 1981;103:571-575. 19. White JJ, Reader A, Beck M, Meyers WJ: The periodontal ligament injection: a comparison of the efficacy in human maxillary and mandibular teeth. J Endodon 1988;14:508-514.
An Evaluation of 4% Prilocaine with 1:200,000 Epinephrine and 2% Mepivacaine with 1:20,000 Levonordefrn Compared with 2% Lidocaine with 1: 100,000 Epinephrine for Inferior Nerve
Block
Stewart A. Hinkley, DDS, MS,* Al Reader, DDS, MS,t Mike Beck, DDS, MA,: and William J. Meyers, DMD, MEdt *Private practice, Springfield and Columbus, Ohio; tDepartment of Endodontics, and
tDepartment of Diagnostic Services, The Ohio State University College of Dentistry, Columbus, Ohio
The purpose of this study was to measure the degree of anesthesia obtained with 4% prilocaine with 1: 200,000 epinephrine and 2% mepivacaine with 1:20,000 levonordefrin compared with 2% lidocaine with 1: 100,000 epinephrine for inferior alveolar nerve block. Using a repeated measures design, 30 subjects randomly received an inferior alveolar injection using masked cartridges of each solution at three successive appointments. The first molar, first premolar, lateral incisor, and contralateral canine (control) were blindly tested with an Analytic Technology pulp tester at 3-min cycles for 50 min. Anesthetic success was defined as no subject response to the maximum output of the pulp tester (80 reading) within 16 min and maintenance of this reading for the remainder of the testing period. Although subjects felt numb subjectively, anesthetic success as defined here occurred in 46% to 57% of the molars, in 50% to 57% of the premolars, and in 21% to 36% of the lateral incisors. No statistically significant differences in onset, success, failure, or incidence were found among the solutions. We conclude that the three preparations are equivalent for inferior alveolar nerve block of 50-min duration.
A lthough local anesthesia is the most common method used in dentistry to control pain, pulpal anesthesia is not always achieved.1'2 Kaufman et al,1 in a survey, found that 90% of responding general dentists had anesthetic difficulties during restorative visits within a 5-day period, with the greatest number of failures occurring with the inferior alveolar injection. Vreeland et al2 also reported a high incidence of potential anesthetic problems with the inferior alveolar injection. They found no significant differences in success or failure when lidocaine with epinephrine was doubled in volume (from 1.8 to 3.6 mL) or concentration (from 2% to 4%). Two percent mepivacaine with 1: 20,000 levonordefrin and 4% prilocaine with 1: 200,000 epinephrine are commonly used for dental anesthesia. Although clinical studies3-12 have evaluated these solutions, only two13'14 used standardized stimuli to quantify anesthesia, and these were in the maxillary arch. The purpose of this study was to measure the degree of anesthesia obtained with these preparations compared with 2% lidocaine with 1:100,000 epinephrine after inferior alveolar nerve block.
METHODS
Received June 7, 1991; accepted for publication August 28, 1991. Address correspondence to Dr. Al Reader, Department of Endodontics, College of Dentistry, The Ohio State University, 305 W. 12th Ave., Columbus, Ohio 43210. This paper was adapted from a thesis submitted by Dr. Hinkley in partial fulfillment of the requirements for the MS degree at The Ohio State University. This study was supported by research funding from the J. David Brilliant Memorial Fund, Ohio Association of Endodontists.
Thirty adult subjects, 19 men and 11 women, ranging in age from 23 to 42 years and with an average age of 27 years, participated in this study. The subjects were in good health and were not taking any medications that would alter pain perception. The study was approved by The
© 1990 by the American Dental Society of Anesthesiology
ISSN 0003-3006/90/$3.50
84
Hinkley et al 85
Anesth Prog 38:84-89 1991
Ohio State University Human Subjects Review Committee, and written consent was obtained from each subject. An equal number of mandibular right and left sides were tested, with the first molar, first premolar, and lateral incisor chosen as the test teeth. The contralateral canine was used as the unanesthetized control to ensure that the pulp tester was operating properly and the subject would respond 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.
Using a repeated measures design, each subject randomly received each anesthetic solution on three successive appointments spaced at least 1 week apart. The anesthetic solutions tested were: A-1.8 mL of 4% prilocaine with 1: 200,000 epinephrine (Citanest Forte; Astra Pharmaceutical Products, Inc., Westborough, MA); B-1.8 mL of 2% mepivacaine with 1:20,000 levonordefrin (Carbocaine with Neo-Cobefrin; Cooke-Waite Laboratories, Inc., New York, NY); C-1.8 mL of 2% lidocaine with 1:100,000 epinephrine (Xylocaine with Epinephrine; Astra). The subjects were randomly assigned to one of six letter (ABC) combinations to determine the sequence of solution administration. Each anesthetic cartridge label was removed and masked with tape. A four-digit random number, corresponding to the letter designation, was written on each cartridge, and the three cartridges for each subject were placed in an autoclave bag with the numbers recorded on the outside showing the injection order. All injections were given by the senior author. At each appointment and prior to injection, the experimental teeth and control canine were tested three times with the pulp tester (Analytic Technology Corp., Redmond, WA) to record baseline vitality. Following isolation with cotton rolls and drying with gauze, toothpaste was applied to the probe tip, which was placed midway between the gingival margin and the occlusal edge. The current rate was set at 25 sec to increase from no output (0) to the maximum output (80). The number at initial sensation was recorded. Soft tissue responsiveness labial and lingual to the canine and buccal to the first molar, was tested by sticking the alveolar mucosa with a sharp explorer. Gentle pressure was placed on the sharp cowhorn explorer, which was placed on the alveolar mucose approximately 3 mm from the attached gingiva, until the subject reported feeling a sharp sensation. If no sharpness was felt, another stick was immediately performed next to the area of the first stick. The presence or absence of a response was recorded. All pre- and postinjection tests were done by trained personnel who were blinded to the solutions injected. A standard inferior alveolar injection, as described by
Table 1. Number (and Percentage) of Subjects Who Experienced Soft Tissue Anesthesia to Mucosal Probing Probing Area
Drug
Solution A-Prilocaine
B-Mepivacaine C-Lidocaine
Mental 27 (96%) 28 (100%) 26 (93%)
Lingual 28 (100%) 27 (96%) 27 (96%)
Buccal 24 (86%) 24 (86%) 19 (68%)
Jorgensen and Hayden,15 was administered with a 27gauge 1-inch needle (Monoject; Sherwood Medical, St. Louis, MO) and an aspirating syringe (Astra). After reaching the target area and performing aspiration, the solution was deposited at a rate of 60 sec/mL. At 1 min postinjection, the first molar was pulp-tested and alveolar mucosal sticks were performed. At 2 min, the first premolar and lateral incisor were tested. At 3 min, the control canine was tested, and the subject asked if the lip and tongue were numb. This cycle of testing was repeated every 3 min. When an 80 reading was recorded for two consecutive cycles the pulp testing was continued every 6 min. All testing was stopped at 50 min postinjection. Lip and tongue anesthesia was considered successful when the subject felt numbness within 20 min and/or did not respond to mucosal probing. The time for onset of lip anesthesia was recorded at the first of two consecutive positive (feeling numb) or negative (not feeling mucosal probing) responses. Pulpal anesthesia was defined as no subject response to the pulp tester at an 80 reading. The time for onset of pulpal anesthesia was recorded at the first of two consecutive 80 readings. Anesthesia was considered successful if an 80 reading was achieved within 16 min and this reading was sustained for the remainder of the 50-min test period. Anesthesia was considered a failure if the subject never achieved two consecutive 80 readings during the 50 min. Anesthesia was of slow onset if the subject achieved two consecutive 80 readings after 16 min. Anesthesia was of short duration if the subject achieved two consecutive 80 readings, lost the 80 reading, and never regained it within the 50-min period. Onset times were analyzed using a one-way repeated Table 2. Mean Onset of Lip Anesthesiaa Drug Patient Response Solution (min) A Prilocaine 6.3 ± 1.1 B-Mepivacaine 5.3 ±+ 0.8 C-Lidocaine 6.1 ±+ 0.8
Mucosal Probing (min) 10.8 ± 1.8 9.1 ±+ 1.6 10.6 ±+ 1.9
There were no significant differences among the solutions (P > 0.05). a Values are the mean ±+ SE.
Anesth Prog 38:84-89 1991
86 Local Anesthetic Comparison Table 3. Mean Onset Time of Pulpal Anesthesiaa First Molar First Premolar Lateral Incisor Drug Solution (min) (min) (min) A-Prilocaine 10.0 ±+ 2.2 10.1 ±+ 1.7 16.3 ±+ 3.2 11.0 ±+ 2.0 B-Mepivacaine 9.6 ± 1.9 11.7 ±+ 2.3 12.3 ±+ 1.9 C-Lidocaine 8.8 ± 1.8 10.6 +± 1.6 There were no significant differences among the solutions (P > 0.05). Values are the mean + SE.
measures analysis of variance. Anesthetic success and failure, and incidence of pulpal anesthesia, were analyzed nonparametrically using Bonferroni-adjusted McNemar tests. Comparisons were considered significant at P < 0.05.
RESULTS The mean baseline pulp testing readings were as follows: first molar, 37 points; first premolar, 33 points; lateral incisor, 29 points; control canine, 35 points. All control canines responded positively throughout the study, with pulp test readings remaining uniformly within 5 points of baseline for each appointment. Two of 30 subjects achieved lip numbness only after 20 min and were excluded from the data analysis. All of the remaining 28 subjects had subjective lip and tongue numbness. Mental and lingual mucosal probing revealed a high incidence (93% to 100%) of anesthesia (Table 1). Buccal anesthesia ranged from 68% to 86% (Table 1). The mean onset time of lip anesthesia, as determined by subject questioning and mucosal sticks, ranged from 5 to 11 min (Table 2). The mean onset time of pulpal
anesthesia (excluding failures) was somewhat slower (Table 3). There were no significant differences in onset among the solutions. The incidence of pulpal anesthesia at each time interval is shown in Figures 1 through 3. The highest incidences for all three solutions by tooth were as follows: first molar, 68% to 79%; first premolar, 75% to 89%; lateral incisor, 54% to 61%. Anesthetic success occurred in 46% to 57% of the molars, in 50% to 57% of the premolars, and in 21% to 36% of the lateral incisors (Table 4). Anesthetic failures occurred in 18% to 32% of the molars, in 11% to 25% of the premolars, and in 36% to 46% of the lateral incisors. The mean elevation of pulp test readings (for the 50 min) above baseline readings for all subjects with anesthetic failures were as follows: first molar, 11 points; first premolar, 14 points; lateral incisor, 13 points. Slow onset of anesthesia was noted in 11% to 25% of the molars, in 21% to 32% of the premolars, and in 14% to 39% of the lateral incisors. Anesthesia of short duration was found in 4% of the molars, in 0% to 4% of the premolars, and in 0% to 7% of the lateral incisors. There were no significant differences among the solutions for any of the measures of efficacy (ie, incidence, success, and failure). However, anesthesia of the lateral incisors was lower with respect to success and incidence and higher with respect to failure.
DISCUSSION All 28 subjects had profound lip numbness, and mental and lingual mucosal probing indicated a high incidence of success (Table 1). Since pulp testing showed a lower incidence of anesthesia (Figures 1,2, and 3), lip numbness
Figure 1. Incidence of first molar anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's) at each postinjection time interval, for the three solutions. There were no significant differences among the solutions at any time interval. ...AA%
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Figure 2. Incidence of first premolar anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's) at each postinjection time interval, for the three solutions. There were no significant differences among the
solutions at any time interval.
and negative mucosal responses may not indicate onset or guarantee successful pulpal anesthesia, at least as defined in this study. Buccal mucosal sticks demonstrated a fairly high incidence of success (Table 1). Previous studies2'16 have also shown that buccal anesthesia may be obtained with only the standard inferior alveolar injection. However, buccal mucosal probing is not completely reliable in evaluating partial soft tissue anesthesia,16 and this may account for the high success rate in this study. The onset of pulpal anesthesia was not significantly different among the solutions (Table 3); therefore, the solutions had equivalent onset times. Although subjects with anesthetic failure (Table 4) were excluded from the onset times analysis, instances of slow onset of anesthesia
did increase the mean times of onset. These cases of slow onset indicate that waiting even 16 min after an inferior alveolar injection may not guarantee complete pulpal anesthesia. Clinically, pulp testing vital teeth would identify these problems and provide a measure of pulpal anesthesia onset. Since anesthetic success (Table 4) and incidence of anesthesia (Figures 1, 2, and 3) were not significantly different among the three solutions, they can be considered equivalent for inferior alveolar nerve blocks of 50min duration. This finding agrees with clinical studies by Weil et al,4 Cowan,8 Epstein,9 and Chilton12 using these solutions for mandibular anesthesia. The results were also similar to the incidence and success reported by Vreeland et al.2
Figure 3. Incidence of lateral incisor anesthesia as determined by lack of response to electrical pulp testing at the maximal setting (percentage of 80/80's), at each postinjection time interval, for the three solutions. There were no significant differences among the
solutions at any time interval.
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Anesth Prog 38:84-89 1991
88 Local Anesthetic Comparison Table 4. Number (and Percentage) of Subjects Who Experienced Anesthetic Success, Anesthetic Failure, Slow Onset of Anesthesia, and Anesthesia of Short Duration Drug Solution First Molar First Premolar Lateral Incisor Anesthetic Successa 6 (21%) 16 (57%) 13 (46%) A-Prilocaine 15 (54%) 10 (36%) B-Mepivacaine 16 (57%) 14 (50%) 15 (54%) 10 (36%) C-Lidocaine Anesthetic Failurea 7 (25%) 6 (21%) 10 (36%) A-Prilocaine 3 (11%) 11 (39%) B-Mepivacaine 5 (18%) 9 (32%) 7 (25%) 13 (46%) C-Lidocaine Slow Onset of Anesthesia 7 (25%) 11 (39%) A-Prilocaine 6'(21%) 9 (32%) 6 (21%) B-Mepivacaine 3 (11%) 3 (11%) 6 (21%) 4 (14%) C-Lidocaine Anesthesia of Short Duration 1 (4%) 0 (0%) 2 (7%) A-Prilocaine 0 (0%) 0 (0%) B-Mepivacaine 1 (4%) 1 (4%) 1 (4%) 0 (0%) C-Lidocaine aThere were no significant differences among the solutions (P
>
0.05).
Pulpal anesthesia requirements will vary clinically, depending on a number of factors (tooth, procedure performed, degree of pulpal anesthesia required). Dreven et al17 previously demonstrated that lack of response to an 80 reading in asymptomatic vital teeth was coincident with complete clinical anesthesia, which is why this standard was used here as the criterion for pulpal anesthesia. The 80 reading is a rigorous definition of pulpal anesthesia and may not reflect clinical success or failure. Dahl and Lindqvist13 have stated that teeth that do not respond to drilling may still respond to an electric pulp tester. Experimentally, the 80 reading is an end point which can be used to measure pulpal anesthesia over time and allows comparisons of anesthetic solutions without the variation of nociceptive stimulation inherent in clinical procedures. Patients who have symptomatic pulpal pathosis may have special anesthetic problems, since they may report pain even though the tooth is nonresponsive to the electrical pulp tester. Anesthetic success for molar and premolar teeth (46% to 57%) indicates that periodontal ligament injections may be needed to achieve full, complete anesthesia in asymptomatic17 and symptomatic18 vital teeth. The low success rate (21% to 36%) for the lateral incisors suggests that additional infiltration injections may be routinely needed. Periodontal ligament injections may not be effective in lateral incisors, since White et a119 found a low success rate using the same testing methodology as in this study. Anesthetic failure was not significantly different among the three solutions and was higher in the lateral incisor
than in the posterior teeth (Table 4). These subjects could present meaningful clinical problems, since they may not be numb for procedures requiring profound pulpal anesthesia. Theories for inadequate anesthesia with the inferior alveolar injection (accessory innervation, cross innervation, central core theory, and accuracy of needle location) are discussed by Vreeland et al.2 The duration of pulpal anesthesia was not measured in this study since testing ended at 50 min. Short duration of anesthesia was observed in some subjects (Table 4). Overall, Figures 1 through 3 demonstrate that a duration of anesthesia extending at least 50 min after injection is likely to occur for those subjects who achieve pulpal anesthesia.
CONCLUSIONS
Concerning the anesthetic efficacy obtained with 4% prilocaine (1: 200,000 epinephrine), 2% mepivacaine (1: 20,000 levonordefrin), and 2% lidocaine (1: 100,000 epinephrine) in inferior alveolar nerve blocks of 50-min duration, the following conclusions were reached: 1. Lip numbness and negative response to mucosal probing may not indicate pulpal anesthesia as measured by the electric pulp tester in this study. Onset of lip anesthesia, using subject questioning or mucosal probing, may also not be a reliable indicator of the onset of pulpal anesthesia. 2. All three solutions were equivalent in blocking the inferior alveolar nerve. There were no statistical differences among the solutions regarding onset, incidence, success, or failure. 3. Successful pulpal anesthesia (ie, no response to electral pulp testing at the 80 setting) was more likely to occur in the first molar and first premolar than in the lateral incisor. 4. The duration of pulpal anesthesia was generally dependable for subjects who achieved pulpal anesthesia. REFERENCES 1. Kaufman E, Weinstein P, Milgrom P: Difficulties in achieving local anesthesia. J Am Dent Assoc 1984;108:205-208. 2. Vreeland DL, Reader A, Beck M, Meyers W, Weaver J: An evaluation of volumes and concentrations of lidocaine in human inferior alveolar nerve block. J Endodon 1989;15: 6-12. 3. Mumford JM, Geddes IC: Trial of Carbocaine in conservative dentistry. Br Dent J 1961; 1 10:92-94. 4. Weil C, Santangelo C, Welham FS, Yackel RF: Clinical evaluation of mepivacaine HCL by a new method. J Am Dent Assoc 1961;63:26-32.
Anesth Prog 38:84-89 1991 5. Hiatt W: Local anesthesia: history; potential toxicity; clinical investigation of mepivacaine. Dent Clin N Am 5: 1961;243-256. 6. Stibbs GD, Korn JH: An evaluation of the local anesthetic mepivacaine hydrochloride in operative dentistry. J Prosth Dent 1964;14:355-364. 7. Cowan A: A minimum dosage technique in the clinical comparison of representative modem local anesthetic agents. J Dent Res 1964;43:1228-1248. 8. Cowan A: Further clinical evaluation of prilocaine (Citanest), with and without epinephrine. Oral Surg Oral Med Oral Pathol 1968;26:304-310. 9. Epstein S: Clinical study of prilocaine with varying concentrations of epinephrine. J Am Dent Assoc 1969;78:8590. 10. Bradley DJ, Martin ND: Clinical evaluation of mepivacaine and lidocaine. Aust Dent J 1969;14:377-381. 11. Brown G, Ward NL: Prilocaine and lignocaine plus adrenaline. Br Dent J 1969;126:557-562. 12. Chilton NW: Clinical evaluation of prilocaine hydrochlo-
Hinkley et al 89 ride 4% solution with and without epinephrine. J Am Dent Assoc 1971;83:149-154. 13. Dahl E, Lindqvist B: The effectivity of two Carbocaine solutions of different concentration. Odontol Revy 1967; 18:149-155. 14. Aberg G, Sydnes G: Studies on the duration of local anesthetics. Int J Oral Surg 1978;7:141-147. 15. Jorgensen NB, Hayden J Jr: Sedation, Local and General Anesthesia in Dentistry. 2nd ed. Philadelphia, Lea & Febiger, 1967:62-73. 16. Agren E, Danielsson K: Conduction block analgesia in the mandible. Swed Dent J 1981;5:81-89. 17. Dreven LJ, Reader A, Beck FM, Meyers WJ, Weaver J: An evaluation of an electric pulp tester as a measure of analgesia in human vital teeth. J Endodon 1987;13:233-238. 18. Walton RE, Abbott BJ: Periodontal ligament injection: a clinical evaluation. J Am Dent Assoc 1981;103:571-575. 19. White JJ, Reader A, Beck M, Meyers WJ: The periodontal ligament injection: a comparison of the efficacy in human maxillary and mandibular teeth. J Endodon 1988;14:508-514.
