ARTICLE 2

ASSESSING THE DURATION

OF MANDIBULAR SOFT TISSUE ANESTHESIA
ELLIOT V. HERSH, D.M.D., M.S., PH.D.; DORIT G. HERMANN, D.M.D.;
CLAUDIA J. LAMP, B.S.N., R.N.; PAUL D. JOHNSON, M.A.;
KENNETH A. MACAFEE, D.M.D.

Ohe pain control afforded by local anesthetics is a mainstay of

modern dentistry. The presence of a vasoconstrictor in the anes-
Dentists often employ solutions thetic cartridge has a major influence on the duration of pulpal
of 3 percent mepivacaine or 4 anesthesia. Generally speaking, preparations that contain a vaso-
percent prilocaine without a constrictor offer more prolonged pulpal anesthesia than solutions
that do not.`5
vasoconstrictor in pediatric pa- The duration of soft tissue anesthesia after mandibular block
tients in an attempt to reduce injections exceeds that of pulpal anesthesia by at least twofold to
the duration of mandibular soft threefold.'5 For example, mandibular block injections with 2 per-
cent lidocaine plus 1:100,000 epinephrine produce pulpal anesthe-
tissue anesthesia. The authors sia for 60 to 90 minutes, while soft tissue anesthesia can last for
compared the time course of three to four hours. Many clinicians perceive this extended dura-
soft tissue anesthesia produced tion of soft-tissue anesthesia as problematic, especially in pedi-
atric patients. While an adult can be cautioned to avoid biting his
by these solutions with that of 2 or her tongue and lip, a young child might not be attentive to such
percent lidocaine plus 1:100,000 warnings and can traumatize these structures.
epinephrine in 60 adults. They To reduce the incidence of such soft tissue damage in children,
some clinicians use solutions of 3 percent mepivacaine or 4 percent
found no reduction in the dura- prilocaine without a vasoconstrictor instead of 2 percent lido-epi,
tion of soft tissue anesthesia in the belief that the two former solutions will produce a shorter
when employing 3 percent me- duration of lip and tongue anesthesia.4 Advertisements by two
leading dental manufacturers suggest that in treating children
pivacaine or 4 percent prilocaine there is some advantage of using non-vasoconstrictor-containing
instead of 2 percent lido-epi. solutions over those that contain a vasoconstrictor. One advertise-
Combining these observations ment for 4 percent prilocaine without vasoconstrictor (Citanest
Plain, Astra USA, Inc.) states that the solution is "epinephrine free
with local anesthetic dosage ... ideal for pediatric or high-risk patients." The other advertise-
considerations, the authors rec- ment states that 3 percent mepivacaine plain (Carbocaine, Sanofi
ommend that 2 percent lido-epi Winthrop Pharmaceuticals) is "recommended for use on both chil-
dren and adults." However, if one reviews a series of clinical trials
be used when performing in which the duration of soft tissue anesthesia was assessed by pa-
mandibular block injections in tients simply recording the clock time at which their sensations of
young children. "numbness" disappeared following mandibular block injections,
there was little difference between 2 percent lido-epi and the plain
solutions of 3 percent mepivacaine or 4 percent prilocaine.69 While
no attempt was made to evaluate the intensity of soft-tissue anes-

JADA, Vol. 126, November 1995 1531

CUNICAL PRACTICE-

ITABLE I

thesia over time, the results of caine or 4 percent prilocaine cent lido-epi is not likely to
these studies suggest that the would deliver 108 mg and 144 shorten the duration of lip and
presumed advantage of a short- mg of local anesthetic, respec- tongue anesthesia. To test our
ened lip and tongue anesthesia tively, both of which exceed the hypothesis, we compared the
duration with 3 percent mepiva- maximum recommended anes- intensity of soft tissue anesthe-
caine and 4 percent prilocaine thesia dose for a 40-pound child sia over a five-hour period fol-
plain compared with 2 percent (MRD is 80 mg for mepivacaine lowing mandibular block injec-
lido-epi may not really exist. and 108 mg for prilocaine).3 By tions of 2 percent lido-epi, 3
Dosage considerations are percent mepivacaine and 4 per-
extremely important when cent prilocaine.
using local anesthetic solutions, I Study results suggest that
especially in young children. MATERIALS AND
the presumed advantage METHODS
12 According to a leading dental
local anesthesia text, the maxi- of a shortened lip and Sixty students were selected
mum recommended dose of li- tongue anesthesia dura- from the University of
docaine or mepivacaine is 2 tion with 3 percent mepi- Pennsylvania dental school to
milligrams per pound of body vacaine and 4 percent participate in this study. Before
weight, while that of prilocaine entering the study, all partici-
is 2.7 mg/lb body weight3 (pack- prilocaine plain compared pants signed an informed con-
age insert maximum dosage with 2 percent lido-epi sent form, which had been ap-
recommendations are some- may not really exist. proved by the University
what higher).'2 Table 1 outlines Committee on Studies Involving
the milligrams of local anes- Human Beings. Participants
thetic contained in increasing contrast, the same volume of 2 had to be in good general health
volumes of 2 percent lido-epi, 3 percent lido-epi would equal a and have no contraindications
percent mepivacaine and 4 per- total lidocaine dose of 72 mg, to local anesthetics or vasocon-
cent prilocaine. These totals which is still below the MRD of strictors.
translate into a narrower ther- 80 mg.3 Unfortunately, inatten- Study participants were ran-
apeutic window on a volume tion to local anesthetic dosage domly assigned to receive a sin-
basis when 3 percent mepiva- guidelines have led to a number gle cartridge (1.8 mL) of 2 per-
caine or 4 percent prilocaine of cases of morbidity and mor- cent lido-epi, 3 percent
are used instead of 2 percent tality in young children.10,13-19 mepivacaine or 4 percent prilo-
lido-epi. This table illustrates We hypothesized that using caine. To maintain double-blind
that two 1.8-milliliter car- 3 percent mepivacaine or 4 per- conditions, we instructed a den-
tridges of 3 percent mepiva- cent prilocaine instead of 2 per- tal assistant who was not di-

1532 JADA, Vol. 126, November 1995

 CLINICAL PRACTICE

analyzed with the one-

way ANOVA and the
E X2 test.

The demographics of
each treatment group
are illustrated in
Table 2. The ratio of
women to men, age,
height and weight
were very similar be-
tween the groups with
no significant differ-
ences.
Of the 60 partici-
pants, 45 (75 percent)
achieved a numbness
Figure 1. Visual analog scales (100 mm) used to measure the intensity of Ilip and score of at least 50
tongue numbness.
mm on the lip, while
41 (68 percent)
rectly involved in the study to ensure that they understood achieved a similar degree of
remove the product identifica- how to complete the scales. anesthesia on the tongue. There
tion label from each cartridge Participants who did not rate was no statistical difference be-
before loading it into a syringe. numbness at 50 mm or greater tween treatment groups in the
Without applying topical anes- on the scale by 45 minutes after percentage of participants
thetic, an investigator adminis- the injection were considered as achieving a score of 50 mm or
tered a single right-sided man- "injection technique failures." greater at either anatomical
dibular block injection to each We did not analyze data from site.
patient using standard aspirat- these participants for that par- The onset of soft tissue
ing techniques over 45 seconds. ticular numbness scale. numbness, peak numbness ef-
Participants rated the inten- From the data reported on fects and numbness duration
sity of lip and tongue anesthe- each numbness scale, time-ac- were quite similar for the three
sia they were experiencing by tion curves expressing the mean local anesthetic solutions
completing two visual analog intensity of lip and tongue anes- (Figures 2 and 3). Lip and
scales five and 15 minutes after thesia were constructed for each tongue anesthesia were evident
the injection and then every 15 treatment group. The area within five minutes; peak ef-
minutes for up to five hours. under each curve was cal- fects of roughly equal magni-
The scales consisted of a 100- culated by summing each indi- tude occurred between 30 and
millimeter bar connecting the vidual numbness score over the 45 minutes; and a recession of
words "not numb" and "com- five-hour study period. We peak effects began to occur be-
pletely numb" (Figure 1). called this measurement the tween 90 and 120 minutes. At
Participants placed a mark on summed numbness score. Using 180 minutes after the injection,
each scale indicating the inten- one-way analysis of variance, lip numbness scores still aver-
sity of numbness they were ex- we compared numbness scores aged between 30 and 40 percent
periencing on their lips or at each time point as well as the of the scale's maximum (100
tongues at each time interval. summed numbness scores among mm), while tongue numbness
Scores on these scales were the three treatment groups. We scores averaged between 20 and
measured to the nearest mil- used repeated measures ANOVA 25 percent of the scale's maxi-
limeter from the left. Study par- to evaluate if an overall differ- mum.
ticipants remained in the oral ence in the time-action curves From a statistical standpoint,
surgery clinic for the first 15 existed. Differences between there were no significant differ-
minutes after the injection to participant characteristics were ences between treatment

JADA, Vol. 126, November 1995 1533

CiLNICAL PRACTICE-

area under the lip and

tongue numbness
curves (summed
numbness.scores) also
revealed a lack of sig-
nificant differences be-
tween treatments.
~DISUSSON
Dentists often use
anesthetic solutions of
3percent mepivacaine
or 4 percent prilocaine
without a vasoconstric-
tor instead of 2 percent
lido-epi for mandibular
block injections in
young children. Many
assume that the ab-
sence of a vasoconstric-
tor in the two former
solutions will lead to a
shorter soft
a duration ofand
Figure 2. Time-effect curves of 2 percent lidocaine with 1:100,000 opineDphrine, 3
.
percent mepivacalne and 4 percent prilocaine. Mean lip numbness scor ms are tissue anesthesia and
plotted against time In minutes. ultimately less lip and
tongue mutilation in
groups at any observation point. percent mepivacaine group ex- this patient population. Our in-
For lip anesthesia, a statistical periencing the least intense vestigation demonstrates that
trend (P=.08) was noted at 105 anesthesia. Repeated measures this assumption is equivocal.
minutes, with patients in the 3 ANOVA and an analysis of the We found that the time-course

TABLE 2

1534 JADA, Vol. 126, November 1995

 CLINICAL PRACTICE

and the maximum in-

tensity of lip and
tongue anesthesia for
3 percent mepiva-
caine and 4 percent
prilocaine were very
similar to that of 2
percent lido-epi.
While we performed
this study in an adult
patient population,
other researchers
have reported that
mandibular block in-
jections of 2 percent
lido-epi and 3 percent
mepivacaine produce
almost identical dura-
tions of soft tissue
anesthesia in chil-
dren.7
When one reviews Figure 3. Time-effect curves of 2 percent lidocaine with 1:100,000 epinephrine, 3
published reports of percent nnepivacaine and 4 percent prilocaine. Mean tongue numbness scores are
gainst time in minutes.
morbidity and mor-
tality involving the
use of local anesthetics in the tridges of the mepivacaine and tissue anesthesia time-courses
dental setting,10" 1"3-'9 three con- priolcaine plain solutions that observed in this study, we think
tributing factors stand out: can be given safely. Phar- it is clear that there is no ad-
- these mishaps typically occur macokinetic studies by Goebel vantage of employing 3 percent
in young children; and colleagues have demon- mepivacaine or 4 percent prilo-
- local anesthetic doses have caine instead of 2 percent lido-
been pushed beyond their rec- epi for mandibular block anes-
ommended limits; The increased concentra- thesia in young children. Not
- other central nervous system tion of local anesthetic only will attempts to signifi-
depressants that potentiate cantly
plus the absence of a vaso- lip andshorten the duration of
local anesthetic toxicity are tongue anesthesia fail,
being used. constrictor both contribute but also the likelihood of poten-
Of the 17 published reports to the reduced number of tially serious morbidity will be
in which the identity of the local cartridges of the mepiva- increased. We thus recommend
anesthetic agent was that clinicians employ 2 percent
known,10,13,14,16-19 3 percent mepi- caine and prlocaine plain lido-epi or a comparable vaso-
vacaine or 4 percent prilocaine solutions that can be given constrictor-containing solution
had been administered in nine safely. (2 percent mepivacaine with
cases. 1:20,000 levonordefrin) for
Maximum dosage limits are mandibular block anesthesia in
reached more quickly with 3 strated that peak anesthetic young children.
percent mepivacaine or 4 per- blood levels of 3 percent mepi-
cent prilocaine than with 2 per- vacaine exceeded that of an CONCLUSION
cent lido-epi (Table 1). The in- equal volume (1.8 mL) of 2 per- This study compared the soft
creased concentration of local cent lido-epi by approximately tissue anesthesia time-course of
anesthetic plus the absence of a threefold after maxillary infil- 2 percent lidocaine plus
vasoconstrictor both contribute tration injections.20'21 Combining 1:100,000 epinephrine with that
to the reduced number of car- these safety data with the soft of 3 percent mepivacaine and 4

JADA, Vol. 126, November 1995 1535

-C LINICAL PRACTICE-

percent prilocaine after mandib- served no significant differences Carbocaine in conservative dentistry. Br Dent
J 1961;110:92-4.
ular block injections. Partici- among the anesthetics at any 7. Bradley DJ, Martin ND. Clinical evalua-
pants were randomly assigned time. We did not detect any re- tion of mepivacaine and lidocaine. Aust Dent
J 1969;14(6):377-81.
to one of the three treatment duction in the duration of lip 8. Brown G, Ward NL. Prilocaine and ligno-
groups and received a single and tongue anesthesia when caine plus adrenaline: a clinical comparison.
Br Dent J 1969;126:557-62.
(1.8 mL) right-sided mandibular using 3 percent mepivacaine or 9. Chilton NW. Clinical evaluation of prilo-
block injection under double- 4 percent prilocaine instead of 2 caine 4 percent solution with and without
epinephrine. JADA 1971;83(1):149-54.
blind conditions. At five min- percent lido-epi. 10. Goodson JM, Moore PA. Life-threaten-
utes, 15 minutes and subse- Combining these observa- ing reactions after pedodontic sedation: an as-
sessment of narcotic, local anesthetic, and
quent 15-minute intervals for tions with local anesthetic dose antiemetic drug interactions. JADA
up to five hours following the considerations, we recommend 1983;107(2):239-45.
11. Moore PA. Pain control in dentistry: pe-
injection, participants subjec- that 2 percent lido-epi or a com- diatric pharmacosedation. Compend Contin
tively rated their lip and tongue parable vasoconstrictor-contain- Educ Dent 1987;8(1):28-39.
12. Jastak JT, Yagiela JA, Donaldson D.
numbness intensity by complet- ing solution be employed when Local anesthesia of the oral cavity.
ing two 100-mm visual analog performing mandibular block Philadelphia: Saunders; 1995.
13. Tarsitano JJ. Children, drugs and local
scales. injections in young children. m anesthesia. JADA 1965;70(5):1153-8.
The time-course of soft tissue 14. Berquist HC. The danger of 3 percent
mepivacaine toxicity in children. CDA J
anesthesia-including the 1. Jastak JT, Yagiela JA. Vasoconstrictors 1975;3(9):13.
onset, peak effects and overall and local anesthesia: a review and rationale 15. Zinman EJ. Toxicity and mepivacaine
for use. JADA 1983;107(4):623-9. (letter). JADA 1976;92(5):858.
duration was very similar 2. Yagiela JA. Local anesthetics: a century 16. California Board of Dental Examiners.
among the of progress. Anesth Prog 1985;32(2):47-56. Dentist loses license in child death case.
3. Malamed SF. Handbook of local anesthe- Anesth Prog 1979;26(1):24-5.
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Prog 1991;38(4/5):128-41. 1985;32(4):129-39.
lutions; we ob- 5. Hersh EV. Local anesthetics in dentistry: 18. Hersh EV, Helpin ML, Evans OB. Local
clinical considerations, drug interactions and anesthetic mortality: report of case. J Dent
novel formulations. Compend Contin Educ Child 1991;58(6):489-91.
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Dr. Hersh Is an asso- fect of commercial vasoconstrictor prepara-
cIate professor of tions on the circulat-
oral surgery and ing venous serum
pharmacology, level of mepivacaine
University of Penn- and lidocaine. J Oral
sylvania, School of Med 1980;35(4):91-6.
Dental Medicine, Dr. Hermann Is a 21. Goebel W, Allen
Department of Oral postgraduate clinical G, Randall F.
and Maxillofaclal fellow In special pa- Circulating serum
Surgery and Phar- tiont care In pedl- Mr. Johnson Is a
levels of mepivacaine
macology, 4001 atric dentistry, statistician and sen-
after dental injection.
Spruce Street, Columbia Pres- Ms. Lamp is a clinl- ior dental student, Dr. MacAfee Is In Anesth Prog
Philadelphia 19104- byterian Medical cal safety assistant, University of Penn- pr-lv-gq pFUqcIzQq I" 1978;25(2):52-6.
6003. Address Center, Department Coming Philadelphia sylvania School of oral maxillofaclal
reprlnt requests to of Pediatric Alliance of Clinical Dental Medicine, surgery, Waltham,
Dr. Hersh. Dentistry, New York. Trials, Radnor, Penn. Philadelphla. Mass.

1536 JADA, Vol. 126, November 1995