ORIGINAL ARTICLE

Incidence and Characteristics of Acute Referred

Orofacial Pain Caused by a Posterior Single

Tooth Pulpitis in an Iranian Population

Maryam Alsadat Hashemipour, DDS, MSc; Roya Borna, DDS

Kerman Oral and Dental Diseases Research Center, Kerman University of Medical Sciences,Kerman, Iran

& Abstract

Introduction: This study was designed to evaluate incidence

and characteristics of acute referred orofacial pain caused by

a posterior single tooth pulpitis in an Iranian population.

Methods: In this cross-sectional study, 3,150 patients (1,400

males and 1,750 females) with pain in the orofacial region

were evaluated via clinical and radiographic examination to

determine their pain source. Patients completed a stan-

dardized clinical questionnaire consisting of a numerical

rating scale for pain intensity and chose verbal descriptors

from short form McGill questionnaire to describe the quality

of their pain. Visual analog scale (VAS) was used to score

pain intensity. In addition, patients indicated sites to which

pain referred by drawing on an illustration of the head and

neck. Data were analyzed using chi-square, fisher exact, and

Mann–Whitney tests.

Results: Two thousand and hundred twenty patients (67/

3%) reported pain in sites that diagnostically differed from

the pain source. According to statistical analysis, sex

(P = 0.02), intensity of pain (0.04), and quality (P = 0.001) of

pain influenced its referral nature, while age of patients and

kind of stimulus had no considerable effect on pain referral

(P > 0.05).

Conclusion: The results of the present study show the

prevalence of referred pain in the head, face, and neck

region is moderately high. Therefore, in patients with

orofacial pain, it is essential to carefully examination before

carrying out treatment that could be inappropriate. &

Key Words: incidence, referred pain, orofacial, pulpitis

INTRODUCTION

Referred pain is common in the orofacial region and

can cause considerable difficulties in diagnosis.

Referred pain is defined as pain that is referred to a

part of the body other than the site of origin, and as a

result, severe pain may arise without an associated

causative lesion.1–3

Referred pain may also be detected in the face and

teeth, for example, a toothache may be referred to

nondental anatomic structures and vise versa pain from

other regions may be perceived in teeth.4–8

A mechanism that has been proposed to explain

referral pain is convergence, in which primary afferent

fibers from different sites converge on the same second-

order neuron in the brainstem nucleus.9 A successful

dental treatment requires detection of the source of pain.

If the origin of pain is not found, it may lead to

inappropriate dental care-like extraction or root canal

therapy. These illogical therapies are very common as

attempts to decrease pain, but they are ineffective and

cause complications for patients and legal liability for

dentists.10

Address correspondence and reprint requests to: Maryam AlsadatHashemipour, Department of Oral Medicine, Faculty of Dentistry, KermanUniversity of Medical Sciences, Shafa Street, PO Box 7619816398, Kerman,Iran. E-mails: m_s_hashemipour@yahoo.com; m_hashemipoor@kmu.ac.ir.

Submitted: July 08, 2012; Revision accepted: December 03, 2012DOI. 10.1111/papr.12034

© 2013 The Authors

Pain Practice © 2013 World Institute of Pain, 1530-7085/13/$15.00

Pain Practice, Volume ��, Issue �, 2013 ��–��

Referred pain is frequently distinguished by local

irritation and elective local anesthesia. Whenever the

pain referral or local irritation such as heat and

percussion do not increase pain, local anesthesia in site

of pain does not alleviate it.11

The greatest concern is pain referral by serious and

progressive pathology, including infections, vascular

disorders, and neoplastic disease. Well-known sources

of pain referred to the jaws include the pain of ischemic

cardiac disease, esophageal pathology, and central

lesions that cause increased intracranial pressure or

produce compression of one or more of the cranial

nerves.12

One of the most important sources of pain referral to

the jaws comes from symptoms generated during

attacks of angina in ischemic heart disease. Therefore,

referred pain may interfere with diagnosis as the basic

step for treatment. They do not follow a uniform

pattern and new referral modalities may always be

encountered.12

Inadequacy of research regarding referred pain makes

it necessary to design studies about similar subjects.

Therefore, the aim of this study was to investigate the

incidence and characteristics of acute referred orofacial

pain caused by a posterior single tooth pulpitis in an

Iranian population.

METHODS

This study included 3,785 patients referred to the oral

medicine department of dental school of Kerman, Iran

from October 2008 to December 2010 because of the

pain in the head, face, and neck regions. 3,150 cases

(83.2%) recruited from these patients with complaint of

posterior toothache. From the resting 635 patients, 347

cases had anterior toothache, 268 cases with both

anterior and posterior teeth pain, and the rest (20 cases)

had nonodontogenic pain. The ethic committee of

Kerman University of Medical Sciences (No.K.90.62)

approved this study.

An inclusion criterion was subjective report of pain in

head and neck region and involvement of single poster-

ior teeth. Pulpal origin for pain confirmed by diagnostic

aids (periapical radiography and vital tests) and exclu-

sion criteria were pain attributed to anterior teeth,

involvement of multiple posterior teeth, gingival and

periodontal diseases, and nonodontogenic sources such

as sinusitis, temporomandibular disorders, or salivary

gland diseases.4 The principal author conducted all

examinations.

Prior to examination, a clinic questionnaire regarding

demographics, health history, duration, and timing of

toothache were completed (Appendix 1). Also, patients

were asked to describe the nature and quality of their

pain by selecting from a list of pain descriptors adapted

from the short formMcGill Pain Questionnaire (Appen-

dix 2).13 Pain intensity was measured by having patients

circle the appropriate number on a numerical rating

scale ranging from 0 to 10 in whole integer units,

anchored on each end by the words “no pain” and

“extreme pain,” respectively (visual analog scale - VAS)

(Appendix 1).14 In addition, subjects circled painful

intraoral areas on an illustration of the mouth and teeth

(Appendix 2) and also outlined any areas of pain felt in

extraoral facial, neck, or head areas by drawing on an

illustration (Appendix 2).

At the first stage of this study, each patient received

appendix 2 and they were asked to indicate the location

of pain on the head and neck diagram. If there was no

agreement between the real pain location with those

predicated by patients on the diagram after examination

of each patient, the pain was distinguished as a referral

pain. Also, if the pain location on the diagram was not

predicted by the patients, the dentist requested they

mark the pain location before examination and this item

was added to appendix 2.

After the interview and clinical examination, the

practitioner’s clinical verification and appropriate peri-

apical radiograph were taken to confirm the diagnosis.

The interpretation was recorded on the questionnaire.

If the pain source and site were the same after recogni-

tion, the pain was considered as a primary (or nonre-

ferred); otherwise, it was considered as a referred pain.

The chi-square test was applied to test the degree of

association between the presence of referred pain and

each of the variables of gender, duration of pain, and

specific verbal descriptors of pain, that is, spontaneous

or provoked, dull or sharp, throbbing or not, longevity

of provoked pain, and kind of stimulus (eg, thermal or

pressure). The mean score on the numerical rating scale

for pain intensity was compared between those patients

with referred pain and those without, using a 2-sample

t-test. Finally, composite diagrams were constructed

from patient drawings depicting the pain referral pattern

to the face, head, and neck for each posterior.

RESULTS

Of those studied, 3,150 patients (1,400 males and 1,750

females) reported pain in the head, face, and neck

2 � HASHEMIPOUR AND BORNA

region. The patients’ ages ranged from 16–69 years

(mean age � SD = 37.2 � 5.8). Referred pain was

reported by 2,120 patients (67.3%). Chi-square analysis

revealed gender differences in report of referred pain

(P = 0.02) (female > male) (Figure 1). The most com-

monly reported site of referred pain was to adjacent

teeth (75.5% of subjects, n = 1600). 15.1% (n = 320)

reported pain referral to teeth in the opposite arch, 120

(5.7%) subjects reporting referral from maxillary to

mandibular teeth and 80 cases (3.7%) from mandibular

to maxillary teeth. The duration of toothache ranged

from 24 hours to more than 42 days (Mean of pain

duration = 25 days) (Table 1).

There was association between pain intensity score

among those subjects with referred pain, compared with

those without referred pain (P = 0.02). Among patients

with referred pain, 4.7% had spontaneous pain, 29.2%

had provoked pain, and 74.5% had both of them.

Lingering was reported in 88.2%, 11.8% reported

temperature provoked pain, 89.1% experienced dull

pain, and others had sharp pain (Table 2).

All pain characteristics had significant association

with pain referral status (P < 0.01), while stimulus like

temperature (ie, cold and warm irritation), mastication,

and pressure had no effect on prevalence of referred

pain. Table 3 shows pain characteristics based on short

form McGill Pain Questionnaire. Mean pain intensity,

according to VAS among those with referred and

nonreferred pain, was 8.2 and 4.6, respectively. Statis-

tically, intensity of pain was associated with its referral

nature. Pain referral did not show any difference among

the various age groups.

DISCUSSION

Orofacial pain affects millions of people around the

world on a daily basis. It constitutes any symptom that

occurs from a large number of disorders and diseases

that result in discomfort or pain felt in the region of the

face, mouth, nose, ears, eyes, neck, and head.15 The

diagnosis of orofacial pain is often complicated by

referral of pain to the face, jaws, and teeth from

pathologic conditions in nearby structures. The process

leading to referred sensation is not completely under-

stood but appears to involve a number of mechanisms,

including peripheral and central neural synaptic con-

nections, as well as multiple converging ascending

sensory and nociceptive paths within major nerves

serving regional areas and the convergence of nerves

supplying distant sites. Failure to clearly and decisively

identify the source of pain should result in a systematic

search for other sources rather than an assumption that

the painful symptom is caused by an atypical presenta-

tion of local pathology. Endodontic treatment of sound

teeth and extraction of otherwise healthy dentition

frequently occurs when pain is referred to the mouth.12

This study examined the effects of the intensity,

quality, and duration of odontogenic pain on the

incidence, pattern, and clinical characteristics of pain

referral in the orofacial region. This study shows pain

Table 1. Pain Duration Related to Pain Referral Statue

Pain Number (%) Minimum MaximumMain of PainDuration

Referred 2120 (67.3) 1 days 22 days 13 daysNonreferred 1030 (32.7) 5 days 42 days 37 daysTotal 3150 (100) 1 days 42 days 25 days

Referral pain Non referral

painTotal

male 770 630 1400

Female 1350 400 1750

Total 2120 1030 3150

0

500

1000

1500

2000

2500

3000

3500

Num

ber o

f pat

ient

s

Gender

Male

Female

Total

Figure 1. Gender differences related to pain referral statue.

Table 2. Pain Referred Status Related to Pain Qualities

Pain Characteristics

Referred Nonreferred Total

N Percent N Percent N Percent

Spontaneous 100 4.7 80 7.7 180 5.7Provoke 620 29.2 520 50.5 1140 36.2Both of the above 1580 74.5 480 46.6 2060 65.4Brief 250 11.8 350 34 600 19.1Lingering 1870 88.2 410 39.8 2280 72.4Sharp 850 40.1 220 21.3 1070 34Dull 1890 89.1 150 14.6 2040 64.8Temperature

provoked250 11.8 290 28.1 540 17.1

Mastication &pressure provoked

280 13.2 260 25.2 540 17.1

Both of the above 890 42 750 72.8 1640 52.1Throbbing 620 29.2 610 59.2 1230 39Nonthrobbing 780 36.8 440 42.7 1220 38.7

Acute Referred Orofacial Pain � 3

intensity was found to significantly affect the presence of

referred pain that it is in agreement with the finding in

the research work by Falace et al., and Khedmat

et al.9,16 The association of intensity and referral is

attributed to the central nervous system hyperexcitabil-

ity, causing expansion of receptive fields and spread,

along with referral of pain.9 Although Mardani et al.

indicated that pain intensity does not affect referred

pain.4

In this study, the prevalence of referred pain was

67.3%, which is almost in agreement with the research

by Khedmat et al. (69.5%) and Mardani et al.

(65%).4,16 Falace’s study shows 89.8% of samples

reported referred pain,9 and the difference may be due

to study design. We examined the intra- and extraoral

tissues and it was unlike Falace’s study in which only

subjective reports and clinical verification were used.

Falace et al. and Khedmat et al.9,16 show the most

common site for referred pain was neighboring teeth

(80% and 76%), and the frequency of pain radiating

to opposite dental arch was 24% for both studies. This

report is consistent with our study (75.5% and

19.8%).

In this study, patients with referred pain include

4.7% had spontaneous pain; 29.2% had provoked pain;

and 74.5% had both. Lingering pain was reported in

88.2%, 11.8% reported temperature provoked pain,

89.1% experienced dull pain, and others had sharp pain.

These results are almost in agreement with Mardani

et al.4

In our study, it was determinate that the mean pain

severity for the referred pain group is significantly higher

than those subjects without referred pain, which are

consistent with Falace et al. and Khedmat et al.9,16

Stohler and Lund 15 show that with increasing intensity

of acute and tonic experimental noxious stimuli, pain

radiates from the site of stimulation to distant ipsilateral

areas of the face.

In addition, we found a relationship between the

duration of pain and its referral nature. In cases with

referred pain, the mean duration of pain was lower than

that of nonreferred pain because the latter is more

tolerable. This was agreement with Mardani et al.4 and

disagreement with Falace’s et al. and Khedmat et al.9,16

This contrary may be due to dentophobia, economic

problems, or consumption of analgesics, which may

cause delay to visit a dentist.

CONCLUSION AND RECOMMENDATIONS

In this study, (67.3%) have referred pain (adjacent teeth,

opposite side, from the maxilla to mandible, or mandi-

ble to maxilla), which mandates exact diagnosis.

Therefore, dentists need to carefully evaluate all tooth-

ache patients to ensure the diagnosis is correct prior to

the initiation of irreversible treatment. The following

can be recommended:

1. A structured orofacial pain history and clinical

examination of the orofacial region, along with

adjacent structures (tooth and surrounding struc-

tures, temporomandibular joint, muscle, mucosa,

sinus, bone, salivary glands, etc.), should be

conducted.

2. Be aware that there are objective and validated tests

and procedures used for differential diagnosis

orofacial pain. These tests and procedures include

tooth pulp vitality and tooth percussion tests,

muscle palpation tests, salivary tests, quantitative

Table 3. Pain Characteristics Based on Short form McGill Pain Questionnaire

Pain Characteristics

Referred (N) Nonreferred (N) Total (N)

None Mild Moderate Severe None Mild Moderate Severe None Mild Moderate Severe

Throbbing 20 110 1570 420 40 180 590 220 60 290 2160 640Shooting 10 120 1740 250 20 190 670 150 30 310 2410 400Stabbing 30 80 1660 350 50 220 580 180 80 300 2240 530Sharp 20 90 1320 690 30 240 340 420 50 330 1660 1110Cramping 50 50 1130 890 20 120 680 210 70 170 1810 1100Gnawing 40 40 1480 560 60 110 750 110 100 150 2230 670Hot-burning 0 130 1120 870 70 210 600 150 70 340 1720 1020Aching 10 170 1420 520 20 140 700 170 30 310 2120 690Heavy 410 220 1080 410 50 180 490 310 460 400 1570 720Tender 280 100 1460 280 10 160 580 280 290 260 2040 560Splitting 10 80 1710 320 0 110 870 50 10 190 2580 370Tiring-exhausting 210 90 1680 140 60 100 780 90 270 190 2460 230Sickening 10 70 1870 170 50 80 780 120 60 150 2650 290Fearful 20 60 1690 350 40 150 660 180 60 210 2350 530Cruel-punishing 90 120 1650 260 30 100 800 100 120 220 2450 360

4 � HASHEMIPOUR AND BORNA

sensory and neurophysiological tests, and other

physical exams: behavioral and psychosocial

assessments; radiographs and other imaging tech-

niques; microbiological and serological tests;

biopsies; and controlled nerve blocks.

3. Know the common orofacial patterns of pain

referral. Be aware that orofacial pain may some-

times be referred from remote sites (eg, earache,

cardiac pain, intracranial lesions, trigeminal neu-

ralgia).

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Acute Referred Orofacial Pain � 5

APPENDIX 1

6 � HASHEMIPOUR AND BORNA

APPENDIX 2

Acute Referred Orofacial Pain � 7