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대한치과보존학회지: Vol. 31, No. 4, 2006
Effect of local anesthesia on pulpal blood flow
in mechanically stimulated teeth
1
Wan-Sik Chu, Seung-Ho Park, Dong-Kuk Ahn , Sung Kyo Kim*
1
Department of Conservative Dentistry and Department of Oral Physiology, School of Dentistry,
Kyungpook National University, Daegu, Korea
ABSTRACT
The aims of the study were to evaluate the effect of epinephrine-containing local anesthetics on
pulpal blood flow (PBF) and to investigate its effect on cavity preparation-induced PBF change. PBF
was recorded using a laser Doppler flowmeter (Perimed Co., Sweden) from canines of nine cats
under general anesthesia before and after injection of local anesthetics and after cavity preparation.
2% lidocaine hydrochloride with 1 : 100,000 epinephrine was administered by local infiltration given
apical to the mandibular canine at the vestibular area and the same volume of isotonic saline was
injected on the contralateral tooth as a control. A round carbide bur was operated at slow speed with
isotonic saline flushing to grind spherical cavities with increasing depth through the enamel and into
the dentin on both teeth. The obtained data was analyzed with paired t-test.
Cavity preparation caused significant increase of PBF (n = 9, p < 0.05).
Local infiltration of lidocaine with epinephrine resulted in decreases of PBF (n = 9, p < 0.05),
whereas there was no significant change of PBF with the physiologic saline as a control.
Cavity preparation on tooth anesthetized with lidocaine with epinephrine caused significantly less
increase of PBF than in control tooth (p < 0.05).
Therefore, the result of the present study demonstrates that local infiltration of 2% lidocaine with
1 : 100,000 epinephrine effectively reduces PBF increase caused by cavity preparation. [J Kor Acad
Cons Dent 31(4):257-262, 2006]
Key words : Pulpal blood flow, Epinephrine, Lidocaine, Cavity preparation, Local anesthetics,
Neurogenic inflammation
- Received 2005.8.23., revised 2006.1.24., accepted 2006.2.9.
Ⅰ. INTRODUCTION and abrasion, pulpal response to these injuries
1)
can stimulate inflammatory activity . Although
Whenever the tooth dentin-pulp complex is the pulp injury caused by these irritants can be
affected by caries, attrition, erosion, chemicals important, in many cases the most severe tissue
trauma is not a direct result of these environmen-
* Corresponding Author: Sung Kyo Kim tal or accidental events, instead, it results from
Department of Conservative Dentistry, the surgical techniques such as tooth preparation
School of Dentistry, Kyungpook National University used to restore tooth structure following these
188-1, Samdeok-Dong, 2-Ga, Jung-Gu, 2-4)
events .
Daegu, Korea, 700-412 As a result of noxious stimulation, inflammatory
Tel: 82-53-420-5935 Fax: 82-53-426-8958 mediators and neuropeptides are released. These
E-mail: skykim@knu.ac.kr
257
대한치과보존학회지: Vol. 31, No. 4, 2006
mediators alter normal neural and vascular func- mg/kg) through the femoral vein. To monitor sys-
tions, which results in an increase in blood flow. temic blood pressure continuously, a femoral
Increased blood flow facilitates the removal of the artery was cannulated. Air way was maintained
inflammatory mediators and thereby helps to heal through the tracheostomy. Body temperature was
the tissue. However, these inflammatory reactions monitored with a rectal thermometer and main-
can cause many pulpal complications in low com- tained between 36℃ and 39℃ with a heating pad.
pliance environment of the pulp. The mandible was immobilized by intermaxillary
Once the pulp becomes inflamed, it becomes splinting with dental plaster and a steel rod that
hypersensitive so that thermal, mechanical or was anchored to a base by a fixing device.
osmotic stimuli encountered in normal function
can cause intense pain. Consequently, it is impor- 2. PBF measurement
tant to ensure that potential sources of injury
that stimulate inflammatory activity be mini- Enamel of both mandibular canine was removed
mized. Management of pulpal inflammation may by a high-speed dental round bur on the labial
reduce the incidence of post-operative pulpal com- surface of the crown over the cervical third. The
plications. Therefore, a more complete under- laser Doppler flowmeter probe (PF416, Perimed
standing of the relationship between pulpal Co., Stockholm, Sweden) was positioned on the
inflammation and cavity preparation events may exposed dentin for recording PBF. To avoid drying
also lead to further improvements in the clinical of the dentin, isotonic saline was flooded between
5)
management of pain . the dentin surface and the probe tip. The PBF
In tooth grinding procedures, local anesthesia is was monitored with a laser Doppler flowmetry
usually used to control patient’s pain and dis- (Periflux 4001, Perimed Co., Stockholm, Sweden,
comfort. Many previous studies investigated the Figure 1). Systemic blood pressure (in ㎜Hg) and
effect of epinephrine-containing local anesthetics PBF (in perfusion unit) were monitored continu-
6-8)
on pulpal blood flow (PBF) and the effect of ously and simultaneously throughout the experi-
9,10)
cavity preparation on PBF . However, few stud- ments and recorded with a computer software,
ies investigated on the effect of local anesthetics Digidata 1200 and Axoscope (Axon Instruments
on cavity preparation-induced PBF change. Inc., Foster City, CA, USA).
Therefore, the purposes of this study were to
evaluate the effect of epinephrine-containing local
anesthetics on PBF and to investigate its effect
on cavity preparation-induced PBF change.
Ⅱ. MATERIALS AND METHODS Laser Doppler Flowmeter
Probe
1. Animal preparation Saline
Nine cats of average weight of 2.8 kg were used.
All procedures involving the use of animals were
approved by the Institutional Animal Care and Laser Doppler Flowmetry
Use Committee of the School of Dentistry,
Kyungpook National University. Animals were Figure 1. Schematic drawing of devices used to
initially anesthetized with intra-muscular injec- record pulpal blood flow.
tion of ketamine (75 mg/kg) and acepromazine
(2.5 mg/kg) followed by intra-venous injection of
alpha-chloralose (40 mg/kg) and urethane (500
258
Effect of local anesthesia on pulpal blood flow in mechanically stimulated teeth
3. Administration of local anesthetics and paired variables of control and experimental data
preparation of cavities were compared by paired t-test and differences
with p < 0.05 were considered statistically signifi-
To determine the PBF and systemic blood pres- cant.
sure during resting state, they were recorded for
30 minutes. 0.1 ㎖ of local anesthetic solution was Ⅲ. RESULTS
administered by local infiltration given apical to
the mandibular canine at the buccal vestibular 1. Effect of cavity preparation on PBF
area. The local anesthetic was 2% lidoocaine
hydrochloride with 1 : 100,000 epinephrine A typical strip-chart recording of systemic blood
(Kwang Myung Lidocaine, Kwang Myung, pressure and PBF in response to cavity prepara-
Kyunggi-Do, Korea). The same volume of isotonic tion on both teeth is presented in Figure 2.
saline was injected on the controlateral tooth as a Cavity preparation caused significant increases of
control. PBF was recorded for 10 minutes after PBF by 96.7 ± 4.9% from the baseline value
injection. (n = 9, p < 0.05).
A round carbide bur was operated at slow speed
to grind spherical cavities with increasing depth 2. Effect of 2% lidocaine with 1 : 100,000 ep-
through the enamel and into the dentin on both inephrine on PBF
teeth. The grinding procedure was intermittent
and accompanied by flushing with isotonic saline Percentage changes of PBF in response to local
to minimize the heat production. After cavity infiltration of 2% lidocaine with 1 : 100,000 epi-
preparation, PBF was also recorded on both teeth nephrine and saline as a control are given in
for 30 minutes. Figure 3. Local infiltration of 2% lidocaine with
1 : 100,000 epinephrine resulted in decreases of
4. Statistics PBF by 31.2 ± 2.5% from the baseline value (n
= 9, p < 0.05), whereas there was no significant
All numerical data in the text and tables are change of PBF with the physiologic saline as a
expressed as percent change from control and control (n = 9, p > 0.05).
mean ± standard error of the mean (SEM). The
0
-5 Control
(Saline injection)
-10
-15
-20
Experimental
-25 (2% lidocaine
hydrochloride
-30 with 1:100,000
epinephrine
-35 injection)
-40
Figure 2. Changes in pulpal blood flow in response to Figure 3. Changes in pulpal blood flow PBF in
the cavity preparation. response to local infiltration of 2% lidocaine with
1 : 100,000 epinephrine (mean ± SEM).
*Statistically significant in paired t-test (p < 0.05).
259
대한치과보존학회지: Vol. 31, No. 4, 2006
100 on many other factors. These include thermal
90 injury, especially frictional heat; transsection of
Control
80 (Saline injection) the odontoblastic processes; and vibration. As
70 14)
studied by vital microscopy , a clearance tech-
60 15,16) 17)
nique , or laser Doppler flowmetry , PBF has
50 been shown to be increased by heating and
40 Experimental
(2% lidocaine decreased by cooling of the tooth in anesthetized
30 hydrochloride
with 1:100,000 18)
20 epinephrine animals. Kim et al. , measured the changes in
10 injection) PBF (in ㎖/min/100g pulpal tissue) in dogs in
0 response to an incremental increase in tooth sur-
Figure 4. Changes in pulpal blood flow PBF in face temperature using the Xenon133 washout
response to cavity preparation (mean ± SEM). method. PBF increased slightly and gradually as
*Statistically significant in paired t-test (p < 0.05). the tooth surface temperature was raised from 35
to 40℃. However, PBF increased sharply (40%
above control) when the surface temperature was
elevated from 35 to 55℃. In the present study,
3. Effect of local anesthesia on cavity prepa- saline cooling was applied during the cavity
ration-induced PBF change preparation to avoid heating.
Local infiltration of 2% lidocaine with 1 :
Cavity preparation on tooth anesthetized with 100,000 epinephrine resulted in significant
2% lidocaine with 1 : 100,000 epinephrine caused decreases of PBF, whereas there was no signifi-
increases of PBF by 33.8 ± 43.6% (n = 9). Local cant change of PBF with the physiologic saline as
infiltration of 2% lidocaine with 1 : 100,000 epi- a control in the present study. This result is in
nephrine caused significantly less increase of PBF 7,8,19)
agreement with the previous studies . In a pre-
induced by cavity preparation than in control (p < liminary study for the present investigation, plain
0.05, Figure 4). 2% lidocaine injection induced no change in PBF
as in the control with saline. 1 : 100,000 epi-
Ⅳ. DISCUSSION nephrine injection caused decrease of PBF while
there was no change in PBF with saline as a con-
In the present study, tooth cavity preparation trol. Therefore, the PBF reduction in the present
caused increase of PBF significantly. This obser- study can be interpreted by the action of epineph-
vation of strong vasodilatation effect in the feline rine. This phenomenon may also be explained by
dental pulp is similar to the findings by Olgart et the study of Kim et al.19) who investigated effects
9) 10)
al. and Kim . This vascular reaction in the pulp of vasoconstrictor contained local anesthetics on
might be explained by the complex interactions pulpal blood flow in the dog teeth. In their study,
occurring within the pulp between the dental an infiltration injection of 2% lidocaine with 1 :
nerves and pulp vessels, mediated by neurovascu- 100,000 epinephrine caused a temporary reduc-
9,11,12)
lar regulators . A simple tooth preparation can tion of PBF in the maxillary canine teeth in dogs
cause the release of a significant amount of sub- and a similar injection with epinephrine only
13)
stance P-like or bradykinin-like substances , and caused the same flow reduction, suggesting that
noxious stimuli of mechanical, thermal, and the flow reduction to local anesthesia was due to
chemical characters, which excite C-fibers, can the epinephrine.
trigger the release of neuropeptides. These, in Epinephrine acts on the adrenergic receptors in
turn, have an effect on PBF and pulpal tissue the smooth muscle wall of the arterioles causing
10)
pressure . vasoconstriction. It is known that stimulation of
Pulpal responses to cavity preparation depend α-adrenergic receptors causes vasoconstriction
260
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