Erdogan O, Malek M, Gibbs JL. J Endod. 2021 Sep;47(9):1376-1382.

1. Associations between Pain Severity,
Clinical Findings, and Endodontic
Disease: A Cross-Sectional Study
Erdogan O, Malek M, Gibbs JL.
J Endod. 2021 Sep;47(9):1376-1382.
Presented by
Dr Nadeem Aashiq
MDS 2nd year

2. INTRODUCTION
• Dental pulp is elegantly confined within enamel and dentin. Similarly, the
teeth are confined within the periodontal ligament and alveolar bone.
• Therefore, it is very challenging to assess the true status of endodontic
pathology, including that of the pulp and the periapical tissues, during
diagnosis.
• Endodontic disease, either when the pulp is severely inflamed or when it
becomes necrotic, can produce severe pain or patients can present with
very advanced disease without any history of painful symptoms.
• Therefore, a thorough and careful assessment of how pain relates to other
clinical findings can provide valuable insight toward better inferring the
degree of pulpal and periapical inflammation and infection.

3. • After acquiring the detailed pain history, surrogate test like cold, thermal tests
and mechanical are critical for assessment for periapical and pulpal diagnosis.
• Cold sensibility testing is a reliable diagnostic tool with high specificity and
sensitivity to differentiate vital from necrotic pulp.
• On the other hand, the diagnostic utility of mechanical sensory testing,
including percussion, palpation, and the bite test, is less clear.
• An abnormal or painful response to mechanical sensory testing could be due to
inflammation or infection of the periapical tissues, and indeed this is the
common interpretation.
• However, it is also possible that percussion hypersensitivity may be detecting
peripheral and central sensitization–induced mechanical allodynia, originating
from inflamed and hypersensitive pulpal neuronal afferents, while the
periapical tissues remain free of any pathology

4. MATERIALS AND METHODS
• Patients who visited emergency dental clinics due to dental pain with at
least 3 out of 10 intensity on a numeric rating scale (NRS) were included in
the study.
• Also, there had to be a clear endodontic pathology localized to a single
tooth. Patients were excluded if there was another suspected source of
chronic or acute orofacial pain.
• We verbally administered a questionnaire and collected patients’
demographic information and pain history. Patients’ current pain intensity
was asked on an NRS between 0 and 10.

5. • Calibrated study personnel, who were either endodontic faculty or
endodontic residents, performed standardized endodontic diagnostic testing
procedures, including a cold test and mechanical sensory testing (bite,
percussion, and palpation).
• For each test, first, a healthy intact contralateral tooth and a healthy intact
adjacent tooth followed by the causative tooth in question were evaluated.
• For each test, the unpleasantness of the sensation was rated from 1 to 3,
with 1 being not or mildly unpleasant, 2 moderately unpleasant, and 3
severely unpleasant.
• For analysis, this result was scored as either non painful (score of 1) or
painful (score of 2 or 3; i.e., hypersensitive) percussion.
• Periapical pathology and the presence of any visible swelling were also
recorded. The pulpal and periapical diagnosis were ultimately determined by
2 endodontic faculty members using the American Association of
Endodontists guidelines.

6. RESULTS
• The study sample consisted of 228 subjects who attended a dental
emergency clinic due to dental pain.
• The mean age was 41 years, and 53% of the cohort were females. The
most common etiology of endodontic disease was caries (57%). The most
common pulpal diagnosis were irreversible pulpitis (IP) (34%) followed by
pulp necrosis (36%).
• The most common periapical diagnosis were symptomatic apical
periodontitis (67%) followed by acute apical abscess (14%). The average
pain intensity at the time of the evaluation was 5.2 on the NRS, and 72%
reported using some type of medication for pain relief.

7. Prediction of Acute Endodontic Pain: Univariate
Analysis
• Based on a univariate analysis, female patients and those below the age of
50 years, when presenting for an urgent endodontic visit, reported higher
intensity overall pain.
• Also, patients who described the temporal nature of their pain as variable
or constant pain (variable pain, constant pain but pain type and intensity
change over time; constant pain, pain that remains constant over time) as
opposed to intermittent pain (pain that comes and goes with some
periods with no pain) reported significantly higher pain levels (P , .05).
• Interestingly, patients with existing chronic pain conditions did not report
higher intensity pain levels

8. • We then determined the association between clinical testing and
examination findings and the intensity of pain. Patients who had a tooth
that responded to cold stimulation reported less severe pain intensity than
those with a negative response.
• Patients who reported moderate or severe pain to the percussion
hypersensitivity or palpation hypersensitivity test on the causative tooth or
the adjacent tooth and those who had swelling on clinical examination also
had higher levels of overall pain.
• Percussion and palpation hypersensitivity on the adjacent tooth showed
the strongest association with higher pain intensity reporting. The
presence of a periapical radiolucency was not associated with higher pain
intensity

9. Prediction of Acute Endodontic Pain: Multiple
Regression Analysis
• In order to better understand the relative contribution of predictors identified in the
univariate analysis to pain intensity, 2 consecutive multivariate regression models
were constructed .
• We found that age and sex were not predictors of preoperative pain intensity in
regression models. However, we should acknowledge the observable trend for
females to have higher pain intensity, even though it was not statistically significant .
• In the first model, in line with the univariate analysis, we found that patients with a
positive cold response reported less severe pain.
• On the other hand, painful palpation hypersensitivity did not predict higher pain
intensity as was observed with the univariate analysis. In the second model,
percussion hypersensitivity on the adjacent tooth was a strong predictor of higher
pain intensity.
• These results point out that percussion hypersensitivity on the healthy adjacent
tooth strongly predicted higher acute endodontic pain intensity, whereas palpation
hypersensitivity on the causative tooth did not predict higher pain intensity.

10. Associations between Mechanical Sensory Testing and
Pulpal Diagnosis
• We next evaluated the frequency of reporting of painful response to different
mechanical sensory tests in teeth with varying pulpal diagnoses to investigate
what these tests might capture about endodontic disease.
• We found that a painful response to percussion was frequently observed in
teeth with IP (64%), necrotic pulp (91%), and previously initiated/ treated teeth
(PIT) (68%). A subgroup analysis with Bonferroni adjustment (P 5 .017)
determined that painful percussion was more frequently reported by patients
diagnosed with pulpal necrosis compared with PIT and IP.
• The frequency of reporting of painful percussion on the adjacent tooth was
equally frequent in these 3 groups (IP: 30%, necrotic pulp: 33%, and PIT: 32%).
Variability was also observed in the frequency of observing painful palpation in
teeth with different pulpal diagnoses (IP: 36%, necrotic pulp: 58%, and PIT: 79%).

11. • Unlike percussion, painful palpation was more frequently reported by patients
diagnosed with PIT compared with both necrotic pulp and IP. Painful palpation
was more frequently reported by patients diagnosed with necrotic pulp
compared with IP.
• Finally, to better understand these findings, we investigated whether the
frequency of percussion and palpation pain in the necrotic pulp and PIT groups
could berelated to unequal distribution of teeth with frank periapical pathology
in these groups.
• To assess this, we looked at the frequencies of swelling and periapical
radiolucencies in these groups. Again, with a subgroup analysis with a Bonferroni
adjustment (P 5 .025), we found there was no difference in the frequency of the
presence of periapical radiolucency and swelling between these 2 groups.
• Therefore, the variation in frequencies of painful percussion and palpation in
teeth with pulpal necrosis or previously initiated/treated pulpal status were not
because of an unequal distribution of teeth with swelling and periapical
radiolucency in these groups.

12. DISCUSSION
• In endodontics, the relationship between the underlying pathophysiology of the
endodontic condition and the experience of pain is not well understood.
• Investigating this relationship can provide insight into the biological processes
underlying endodontic disease. In this study, we found that the presence of
periapical radiolucency was not associated with pain, whereas subjects with
swelling and/or a negative response to cold testing reported higher levels of pain.
• It has been reported that who have emergency endodontic treatment,
symptomatic pulpitis and symptomatic necrotic cases reported similar pain levels.
• On the other hand, both of these studies also reported that patients who were
diagnosed with symptomatic pulpitis were able to wait longer than patients who
were diagnosed with symptomatic necrotic teeth before seeking treatment.
suggesting that pain became less tolerable more often in necrotic cases.

13. • In clinical practice, we often use mechanical sensory testing including percussion,
palpation, and bite hypersensitivity testing. However, previous studies have
challenged the sensitivity and specificity of these tests, especially percussion
hypersensitivity, to differentiate the degree or the presence of endodontic disease.
• We found that in a multiple regression analysis, although a painful response to
palpation did not predict higher levels of pain, a painful response to percussion on
the adjacent healthy tooth was highly predictive of higher acute pain intensity.
• To evaluate further, we looked at the frequency of identifying painful percussion
and palpation with different pulpal diagnoses. Interestingly, painful percussion was
reported by the majority of patients who had necrotic pulp, whereas painful
palpation was more frequently reported by patients who had PIT, even though
there was no difference in the frequency of swelling or periapical radiolucency in
these 2 groups.
• These findings suggest that percussion and palpation testing may be capturing
different aspects of endodontic pathology.

14. • It has been proposed that percussion hypersensitivity, especially in teeth with vital
pulp, may actually reflect peripheral or central sensitization rather than indicating
inflammation of the periapical tissues.
• This study demonstrated that painful percussion on the healthy adjacent tooth was
a strong predictor of higher overall levels of pain. It is likely that pain on the
adjacent tooth represents central sensitization because it is coming from a non
affected site.
• We also found that reports of painful percussion on the adjacent tooth were
equally present in groups diagnosed with IP, pulp necrosis, and PIT Interestingly, in
all 3 of these groups, about one third of the patients reported that percussion on
the adjacent tooth was painful.
• We found that in the univariate analysis, females reported higher levels of pain.
Although not statistically significant, when modeled in multiple regression analysis,
females seemed to report higher acute endodontic pain, which is in line with the
literature reporting that females experience more severe pain.

15. • Moreover, we found that age did not predict preoperative pain. A previous
report found that pain intensity is inversely proportionate with age when
teeth with vital pulp were tested.
• The difference could be due to the fact that in our study population, only
about half of the cases had vital pulp. In addition, in this study, chronic pain
did not predict higher levels of preoperative pain, although it is generally
accepted that sensitization of the pain modulation system due to chronic
pain increases acute pain severity.
• The reason why age, sex, and the presence of chronic pain did not
unequivocally predict higher levels of odontalgia could be due to the
characteristics of the study population.
• It could also be due to unique features of endodontic pain; when pain due to
either pulpal inflammation or endodontic infection is severe enough to make
an emergency dental visit, factors such as sex, age, and the presence of
chronic pain may not so clearly influence the degree of pain experienced.

16. • First, there was the potential variability in the performance of clinical
testing in the study. In order to minimize provider variability, study
personnel were trained and calibrated, and patients were given a visual
scale to help specify their responses more accurately. However, because
pain reporting is inherently variable, there certainly was variability in
patient responses to mechanical testing.
• Another limitation of the study is that pulp vitality was inferred by vitality
(cold) tests instead of a more direct method like direct visualization. We
were not able to observe and record the intraoperative status of the pulp
by direct visualization because after the patients had been triaged during
the emergency visit, they were referred for various treatment modalities.
However, we know that cold testing has been shown to have high
sensitivity and specificity to differentiate pulpal vitality.
LIMITATIONS OF THE STUDY

17. CONCLUSIONS
• Percussion hypersensitivity on the healthy adjacent tooth is a frequent
observation in teeth with different pulpal diagnoses, and it strongly
predicted the overall severity of pain experienced. This suggested that
percussion hypersensitivity may identify a lowered pain threshold and
heightened pain sensitization and at times is primarily due to central
sensitization.
• Also, 2 different mechanical sensory tests (percussion hypersensitivity
and palpation hypersensitivity) differentially predicted the severity of
acute dental pain. Furthermore, they were identified with different
frequencies in patients with different pulpal diagnosis, suggesting that
these tests may be revealing different aspects of endodontic
pathophysiology and dental nociception. Importantly, pain as a highly
individualized, multifaceted phenomena may generally be a problematic
measure for inferring an endodontic diagnosis.

18. REFERENCES
• Sensory testing associates with pain quality descriptors during acute dental pain
Erdogan O, Malek M, Janal MN, Gibbs JL. Eur J Pain. 2019 Oct;23(9):1701-1711.
• Background: Pain descriptors capture the multidimensional nature of pain and
can elucidate underlying pathophysiological mechanisms. This study determined
whether the pain descriptors chosen by subjects experiencing acute dental pain
associate with the outcomes of two commonly performed dental sensory tests.
The goal of the study is to clarify whether pain descriptors are useful in
discriminating the underlying biological processes contributing to dental pain.
• Methods: Participants (n = 228) presenting with acute toothache underwent
standardized clinical dental sensory testing and described their pain in reference
to 22 pain quality descriptors. Univariate and two-way ANOVA determined the
relationship between groups defined by cold detection (positive or negative) and
percussion hypersensitivity (painful or not) on the affected tooth, and pain
descriptor reporting.

19. • Results: Subjects experiencing painful toothache most frequently reported evoked
pain to temperature and chewing, and pain descriptors such as "throbbing" and
"aching." They also reported neuropathic pain descriptors such as "tingling" and
"electric shock." Subjects who detected a cold stimulus (thermal) on the affected
tooth, frequently reported high intensity paroxysmal shooting pain compared to
those that did not detect cold. By contrast, patients with percussion (mechanical)
hypersensitivity on the affected tooth, reported higher levels of global pain intensity
at rest and in function, and reported significantly higher intensity "radiating" and
"throbbing" pain, than subjects with non-painful percussion.
• Conclusions: The reporting of neuropathic pain descriptors by subjects experiencing
acute toothache was more frequent than expected, suggesting that neuropathic
mechanisms could contribute to typical toothache pain. Subjects experiencing
toothache with mechanical hypersensitivity experience more intense pain overall.
• Significance: In subjects experiencing acute toothache, specific pain descriptors
associate with the responses to routine clinical sensory tests performed on the
injured tooth. The frequent reporting of neuropathic pain descriptors suggests that
neuropathic mechanisms could create a diagnostic challenge to differentiate
toothache from intraoral neuropathic conditions. Persons experiencing toothache
with mechanical hypersensitivity experience more intense pain overall, suggesting
patients with this clinical feature will have distinct clinical pain management needs.

20. Preoperative pain and medications used in emergency patients with
irreversible acute pulpitis or acute apical periodontitis: a prospective
comparative study Touré B, Kane AW, Diouf A, Faye B, Boucher Y. J Orofac Pain. 2007 Fall;21(4):303-8.
• Aims: To determine the pain characteristics of and medications used for
patients seeking emergency care for irreversible acute pulpitis (IAP) or
acute apical periodontitis (AAP).
• Methods: General (age, sex, weight, general health) and specific (pain
intensity, localization, tooth mobility, lymphadenopathy, use of
medications) information was noted in 209 patients who appeared for
emergency care in 2 dental centers of Dakar with either IAP or AAP.
Statistical analysis was performed with the Mann-Whitney and chi-square
tests.

21. • Results: The sample comprised 97 IAP patients (46.4%) and 112 AAP patients
(53.6%); there were no significant differences between the 2 groups with
respect to age, sex, or weight. Of the involved teeth, 62% were mandibular and
38% were maxillary. IAP patients waited 6.6 +/- 5.3 days before seeking an
emergency consultation versus 5.0 +/- 3.8 days for AAP patients (P < .05). Severe
pain was reported in 75% of the IAP and 76% of AAP patients (not significant).
Percussion and apical palpation were painful only in AAP, in 98% and 40% of
patients, respectively. Mobility and adenopathies were noted only in AAP, in 87%
and 46% of patients, respectively (P < .001). Seventy-five percent of IAP patients
and 80% of AAP patients used medications, mainly non-narcotic analgesics,
which offered relief in 62% of IAP patients and 46% of AAP patients.
• Conclusions: Patients with IAP waited longer than those with AAP before
seeking treatment. Self-medication offered better relief in cases of IAP than in
cases of AAP. Pain to percussion and palpation, lymphadenopathies, and dental
mobility were strong indicators for AAP.