Clinical StudyComparative Analysis of the Effectiveness of the TopicalAdministration of Benzocaine and EMLA® on Oral Pain andTactile Sensitivity

David Gomes de Alencar Gondim ,1 Antonio Marcos Montagner,1

Ivo Cavalcante Pita-Neto,2 Romildo Jose de Siqueira Bringel,2

Francisco Aurelio Luchesi Sandrini,2 Eduardo Fernando Chaves Moreno,2

Amanda Mendes de Sousa,2 and Andreza Bastos Correia2

1São Leopoldo Mandic Institute and Research Center, Campinas, SP, Brazil2School of Dentistry, UNILEÃO-University Center, Juazeiro do Norte, CE, Brazil

Correspondence should be addressed to David Gomes de Alencar Gondim; davidalencar@gmail.com

Received 5 May 2017; Revised 8 August 2017; Accepted 20 August 2017; Published 7 February 2018

Academic Editor: Kamal M. Matar

Copyright © 2018 David Gomes de Alencar Gondim et al. 'is is an open access article distributed under the Creative CommonsAttributionLicense,whichpermitsunrestricteduse,distribution,andreproduction inanymedium,provided theoriginalwork isproperlycited.

Objectives. To compare the effectiveness of the topical administration of benzocaine and EMLA on oral pain and tactile sensitivity.Materials and Methods. A randomized, double-blind, split-mouth clinical trial was carried out with 20 volunteers. 'e sensorial andquantitative tests were applied before the contact with topical anesthetic and after the application. Results. In the superficial tactileperception test, when we compared each group singly, there were statistically significant values in the decrease of superficial tactileperception when compared to the moment prior to the application of anesthetic agents. For the sensitivity to mechanical pain, nostatistical significant difference was observed at evaluated times. In the needle penetration test, in an intergroup analysis, we founda decrease in the pain sensitivity to needle penetration at 5min (p � 0.053) and at 10min (p � 0.019) after the contact of the anestheticdrug with the oral mucosa.Conclusion.'e application of topical anesthetic drugs reduces the discomfort associated with this procedure,mainly until the first 10 minutes. Only the needle penetration sensitivity test showed sufficient sensitivity to reveal a difference in theanesthetic effect between EMLA and benzocaine. 'is trial is registered with RBR-2N2GSW.

1. Introduction

Topical anesthesia is extremely important to a wide varietyof dental procedures, such as periodontal probes, gingivalmanipulation, staple adaptation, preparation to infiltrativeanesthesia, pediatric care, and traumatic lesions in the oralmucosa [1–3]. In this context, the main purpose of usingtopical anesthetic drugs is to reduce or relieve the painfulstimulus caused by needle penetration, leading to significantcontrol of pain and anxiety of the patient [1].

'e ideal local anesthetic agent should be effective evenwhen administered topically. However, not all anestheticbases present this characteristic [4]. In dentistry, benzo-caine is one of the main commercially available topicalanesthetic drugs. It is chemically classified as an amino

ester and is available as a gel. Although this drug presentsrapid onset of action, it has limited potency and shortanesthetic duration, besides being exclusively used inmucous membranes [5].

EMLA (AstraZeneca do Brasil, Ltda., Cotia, SP, Brasil) isan anesthetic formulation defined as an eutectic mixture oflocal anesthetic drugs composed of a combination of 2.5%prilocaine and 2.5% lidocaine. 'is formulation is indicatedfor pain control in several superficial cutaneous procedures[6, 7]. Accordingly, in the oral cavity, satisfactory resultshave been evidenced in biopsies [8], periodontal probes [9],and prior to local anesthesia [10].

'erefore, the aim of this study was to compare theeffectiveness of the topical administration of benzocaine andEMLA on oral pain and tactile sensitivity.

HindawiInternational Journal of DentistryVolume 2018, Article ID 7916274, 5 pageshttps://doi.org/10.1155/2018/7916274

2. Materials and Methods

Twenty-four academics from the dentistry course ofDr. Leão Sampaio University Center were interviewed in thisstudy. 'ree of these academics were excluded because theydid not attend the second visit and another because of di-abetes and incomplete medical records. 'us, the studycontinued with 20 volunteers, including 12 women and 8menwith an average age of 22.8 years. 'e study was characterizedas randomized, double-blind, split-mouth clinical trial.

'e Research Ethics Committee of the Dr. Leão SampaioUniversity Center reviewed the procedures, including therecruitment and consenting process.

Healthy subjects (ASA I), meeting the criteria of theAmerican Society of Anesthesiology (ASA) [11], were selectedfor this research, including nonpregnant, nonsmoker,nonnursing, with no history of allergies to local anesthetics,without chronic use of medications, with complete naturaldentition and without reports of dysesthesia in the face ororal cavity. Participants who did not meet these criteria wereexcluded from the study.

Initially, we performed a molding of the maxillary archof the participants, followed by the preparation of a model inplaster and acetate molding, with involvement of the teethand palate. A relief area was created in wax and placed onthe cast model on the palate, at 2mm from the gingivalmargin, between the teeth 15 and 16 and 25 and 26, to createa reservoir for the local anesthetic drug (Figure 1). 'eparticipants of this research were comfortably seated in thedental chair at 45° in relation to the ground, with the headresting on a flat surface, in a silent room with temperatureset at 23°C. 'ey were instructed to keep their eyes closedand concentrate on the examination.

We applied 0.4 g of 20% benzocaine (DFL Industria eComercio SA, Rio de Janeiro, RJ, Brazil) to the reservoirs,and in the opposite portion, we deposited an equivalentquantity of EMLA (AstraZeneca do Brasil, Ltda., Cotia, SP,Brazil) (Figure 2). 'e sides of deposition of the topicalanesthetic were randomly selected, by sorting a sealedenvelope. 'e mucosa was previously dried with gauze, andthen the tray was positioned and maintained for 5min.Subsequently, the excess anesthetic was removed from theteeth and gingiva, and the area was dried with air jets toprevent changes in sensitivity and/or sliding of the needleor filaments, which could result in misinterpretations of theexaminations.

An examiner who was not present in the previous periodwas responsible for assessing the values related to the painstimulus, which consisted of three quantitative sensorymethods:superficial tactile perception, sensitivity to mechanical pain, andsensitivity to needle penetration. 'e tests were applied at thesame previously identified points, beginning from the patient’sright side to the left and sequentially repeated for three timeseach test.

2.1. Superficial Tactile Perception. 'is parameter was eval-uated through the application of Semmes–Weinsteinmicrofilaments (Sorria-Bauru, Bauru/SP, Brazil), consistingof a set of 7 nylon filaments with equal lengths, roundedtips, and different diameters and colors, which allowsthe application of forces of different intensities (0.05 to300 g/mm2) on a surface. 'e filaments were vertically ap-plied at the predetermined points, in ascending order ofdiameter, until perception and identification of the stimulusby the participant. 'e filament in which the stimulus wasperceived was recorded. Of note, three measurements weretaken for each side.

2.2. Sensitivity to Mechanical Pain. 'e sensitivity to me-chanical painwas determined through application of a constantforce using the orange-colored Semmes–Weinstein filament(which corresponds to a force of 10 g/mm2) in contact with themucosa, for 2 seconds. 'e evaluated patient quantified thelevel of pain through the visual analogue scale (VAS) [12],which assigns a value of 0 for “complete absence of pain” and 10for “the most intense possible pain level.”'ree measurementswere made for each side.

2.3. Sensitivity to Needle Penetration. A short 30G dentalneedle (DFL Industria e Comercio SA, Rio de Janeiro, RJ,Brazil) was vertically inserted at the points that had contactwith the topical anesthetic drugs, at a depth of 2mm, con-trolled by means of a rubber stopper. 'e evaluated patientquantified the level of pain through the visual analogue painscale [12] as previously described. 'ree measurements weretaken for each side. 'e measurements started before the traywas applied and after contact with the topical anesthetic drugsat 5, 10, 20, and 30min.

Figure 1: Acetate relief area for deposition of topical anestheticdrug.

Figure 2: Acetate splint loaded with topical anesthetic.

2 International Journal of Dentistry

3. Statistical Analysis

'e data were examined and classified as nonparametric andnonnormal, after application of the D’Agostino’s test, andmedian values were applied in the three evaluation methods.For intergroup analysis (Benzocaine x EMLA), the Wilcoxontest was applied. To perform comparisons in the same group,according to the time of contact with the topical anestheticdrug, the Friedman test was applied. All time points (5, 10, 20,and 30min) were assessed, and odds below 0.05 were clas-sified as statistically significant. All data were evaluated usingthe SPSS (SPSS, Windows version 19.0, SPSS Inc., USA).

4. Results

In the superficial tactile perception test, we observeda similar result between the side treated with EMLA and theside that was treated with benzocaine, represented by a de-crease of tactile response to higher pressures in the oralmucosa in the five minutes time point, obtained with the useof thicker Semmes–Weinstein filaments (Figure 3). However,when comparing both groups (EMLA versus benzocaine),no statistical repercussions were observed at the evaluatedtimes (Table 1).

When we compare each group singly, we observed that,at the five minutes point of measurement, there werestatistically significant values in the decrease of superficialtactile perception when compared to the moment prior tothe application of anesthetic agents. 'ese results were notstatistically significant for the other times (10, 20, and 20minutes) (Table 2).

'e test of sensitivity to mechanical pain revealed thatthe patients presented minimal discomfort as attested by theanalogue scale [12]. A comparative analysis between thetreatments with the two drugs demonstrated a slight increasein the mechanical sensitivity in the benzocaine-treated side(Figure 4), at five minutes point. However, no statisticalsignificant difference was observed at evaluated times, eitherin the intergroup analysis (Table 1) or in an isolated groupassessment (Table 2).

In the test of sensitivity to needle penetration, thebenzocaine-treated side was more sensitive to the painful

stimulus when compared to the EMLA-treated side, evi-denced by higher visual analogue pain scores (Figure 5). Inan intergroup analysis, we found a decrease in the painsensitivity to needle penetration at 5min (p � 0.053) and10min (p � 0.019) after the contact of the anesthetic drugwith the oral mucosa (Table 1), with statistical relevance.When we evaluated each group separately, we observed thatthe side in contact with benzocaine had a statistical dif-ference in point time of 30 minutes (Table 2), when comparedto the time prior to contact with the topical anesthetic. Noother information with statistical relevance was observed forthe other time evaluated and in the group treated with EMLA.

Superficial tactile perception

0

1

2

3

4

Before 5 min 10 min 20 min 30 min

Gra

m fo

rce (

gf)

EMLABenzocaine

EMLABenzocaine

Figure 3: Median values for superficial tactile perception ofbenzocaine and EMLA according to the evaluated times andexerted force.

Table 1: Intergroup comparative analysis according to themethodological test and p value for each time point.

Sensitivity to mechanical pain (10 gf)Benzocaine versus EMLA

Time point (min) 5 10 20 30p value p � 0.96 p � 0.76 p � 0.15 p � 0.18

Sensitivity to needle penetrationBenzocaine versus EMLA

Time point (min) 5 10 20 30p value p � 0.053∗ p � 0.019∗ p � 0.31 p � 0.67

Superficial tactile perceptionBenzocaine versus EMLA

Time point (min) 5 10 20 30p value p � 0.2 p � 0.6 p � 0.17 p � 1∗p< 0.05 showing significant difference between EMLA and benzocaine.

Table 2: Comparison in the same group according to the meth-odological test and p value for each time point.

Sensitivity to mechanical pain (10 gf)Benzocaine side

Time point (min) 5 10 20 30p value p � 0.50 p � 0.99 p � 0.99 p � 0.99

EMLA sideTime point (min) 5 10 20 30p value p � 0.99 p � 0.99 p � 0.99 p � 0.72

Sensitivity to needle penetrationBenzocaine side

Time point (min) 5 10 20 30p value p � 0.28 p � 0.43 p � 0.15 p � 0.02∗

EMLA sideTime point (min) 5 10 20 30p value p � 0.06 p � 0.21 p � 0.49 p � 0.23

Superficial tactile perceptionBenzocaine side

Time point (min) 5 10 20 30p value p � 0.01∗ p � 0.69 p � 0.43 p � 0.75

EMLA sideTime point (min) 5 10 20 30p value p � 0.04∗ p � 0.13 p � 0.41 p � 0.73∗p< 0.05 showing influence of the topical anesthetic in each test.

International Journal of Dentistry 3

5. Discussion

Dental anesthesia is among the main procedures associatedwith patient phobia in dental offices, leading a considerablenumber of adults to avoid dental treatments because of thefear of anesthetic puncture [13]. Nevertheless, patients withanxiety due to aversion to dental procedures usually reportgreater pain sensation during anesthesia than those who donot fear the anesthetic act [14].

Topical anesthesia has a main objective to annul painprior to anesthetic infiltration [15].'is procedure optimizesinfiltrative local anesthesia by reducing the level of anxiety ofthe patient before needle penetration, as well as decreasingthe number of perforations required and the amount ofanesthetic administered [2].

With the exception of the needle penetration sensitivitytest, the other instruments of evaluation were not sensitiveenough to show a statistical difference between EMLA andbenzocaine, unlike other reports that revealed clearer resultson the superiority of EMLA [10, 16].

'e statistically significant results in superficial tactileperception test, on both sides, when evaluated singly (Table 2),may reflect a blockade of Aβ fibers and mechanoreceptors.Although it was not possible to measure the intensity of thisblockade, previous studies have demonstrated that topicaladministration of 5% lidocaine interferes with the fibers that areresponsible for touch perception, which justifies the mainte-nance of touch sensitivity in some patients, even after contactwith the topical anesthetic drug [17].

'e influence of anesthetic bases on nociceptors and Cfibers, both associated with pain stimuli, were evaluated bythe tests of sensitivity to mechanical pain and needle pen-etration sensitivity. 'e first test was not sensitive enough toconfirm statistical differences between EMLA and benzo-caine in the two modalities of evaluation (intergroups andisolated). In our study, the VAS was used only to measurethe intensity of pain. As observed in others reports [18]. if wehad used it to quantify both degree of discomfort and pain, itmight reflect more consistent values.

In line with other studies [16], in the needle penetrationsensitivity test, the side in contact with EMLA revealed lesspain stimulation (Figure 5). When we correlated the re-percussions of the anesthetic effect over the evaluated times(5, 10, 20, and 30min), statistically significant outcomeswere obtained in the first 5 minutes and 10 minutes after

contact with the topical anesthetic, when the needle pene-tration sensitivity test was applied (Table 1). 'ese resultssupport the evidence that local anesthetic drugs affect morethe pain threshold than the sensory threshold [19].

Although we did not perform an evaluation of the timeof action of the evaluated anesthetics, the main results withstatistical relevance were present in the first 5 and 10minutes ofcontact. 'is fact is corroborated by other studies that revealduration of anesthetic effect over 20 minutes for EMLA [18].

To achieve a consistent evaluation of the topical anes-thetic action, the methods of measurement should includenot only the response to pain through the visual analoguescale, but also the influence on the somatosensory system,evaluated in this study by the superficial tactile perceptionand corroborated by other works that demonstrated favorableresults for EMLA in the effectiveness of changing sensory andpain thresholds [20]. 'us, the use of Semmes–Weinsteinneedles and filaments in the measurement of the sensitive andpainful responses in the present study were effective andsimple to acquire and apply. Accordingly, earlier reportsratified the reliability and validation of these instruments foruse in the oral cavity. However, electronic measurements haveshowed greater precision in the results [18, 20].

In contrast to benzocaine, which has specific charac-teristics for use in the mouth, the prilocaine/lidocaine com-bination (EMLA) used in this study has properties that impairits use in the oral mucosa. In fact, the unpleasant taste was oneof the complaints of the participants, and the addition of flavorwould facilitate their acceptance, especially in pediatricdentistry. In addition, the low viscosity of this productmakes difficult its administration on the palate, requiringthe formulation of a tray with a specific reservoir. Althoughbetter flavored formulations containing lidocaine/prilocainewith specific applicators are currently available, their use isrestricted to periodontics and they have limited scope [9].

Reports of local or systemic adverse effects of topicalanesthetic drugs are uncommon [21] and were not evidencedin this study. 'e absorption and bioavailability of the drugdepend on the contact surface, concentration, and time ofapplication. 'erefore, the use of these drugs in integralsurfaces, for a brief time and at a low dose, as used in thiswork, is relatively safe. Accordingly, in this study, we usedonly 1/4 (0.4 g) of the recommended maximum dose (2 g) of

VAS

(0-1

0)

0

1

Before 5 min 10 min 20 min 30 min

EMLABenzocaine

Sensitivity to mechanical pain (10 gf)

EMLABenzocaine

Figure 4: Median values for sensitivity to mechanical pain ofbenzocaine and EMLA treatments, according to the evaluated timesand visual analogue scale (VAS).

Before 5 min 10 min 20 min 30 min0

1

3

2

5

4

VAS

(0-1

0)

Sensitivity to needle penetration

BenzocaineEMLA

Figure 5: Median values for sensitivity to needle penetration ofbenzocaine and EMLA treatments, according to the evaluated timesand visual analogue scale (VAS).

4 International Journal of Dentistry

benzocaine and 1/10 of the dose that achieves plasma levelsthat are toxic to the central nervous system [22, 23].

Finally, we conclude that the application of topicalanesthetic drugs prior to anesthetic infiltration in the oralmucosa reduces the discomfort associated with this pro-cedure, mainly until the first 10 minutes. Only the needlepenetration sensitivity test showed sufficient sensitivity toreveal a difference in the anesthetic effect between EMLAand benzocaine. An improvement in the other two methods,associated with an increase in the number of participants,may provide a more complete analysis of the both topicalanesthetics.

Conflicts of Interest

'e authors declare that there are no conflicts of interestregarding the publication of this paper.

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