The Orofacial Pain Clinic Questionnaire (EDOF-HC) in the evaluation and diagnosis of orofacial pain

ABSTRACT Background: Diagnostic tools are necessary for the anamnesis and examination of orofacial pain, in order to fulfill diagnostic criteria and to screen potential causes of pain. Objective: To evaluate the Orofacial Pain Clinic Questionnaire (EDOF-HC) in the assessment and diagnosis of orofacial pain. Methods: Overall, 142 patients were evaluated and classified according to the criteria of the International Headache Society and International Association for the Study of Pain. All of them were evaluated with the EDOF-HC questionnaire, which consists of the orofacial and medical history, as well as the orofacial examination. Data were statistically analyzed with chi-square test and Bonferroni correction, one-way ANOVA with Tukey post hoc test, the two-step cluster and decision tree methods. Results: There were diferences in pain descriptors, pain in maximum mouth opening, number of trigger points, and history of previous surgery between the groups, which were classified into trigeminal neuralgia, burning mouth syndrome, temporomandibular disorders and trigeminal posttraumatic neuropathic pain with classification analysis. Conclusions: The EDOF-HC is a clinical supportive tool for the assessment of orofacial pain. The instrument may be used to support data collection from anamnesis and examination of patients according to the diagnostic criteria of most common orofacial conditions. It is also useful in the investigation of local and systemic abnormalities and contributes for the diagnosis of conditions that depend on exclusion criteria.

criteria (neuropathic or controversial), such as persistent idiopathic facial pain (PIFP), atypical odontalgia (AO) and burning mouth syndrome (BMS) 5,6 , which need a careful investigation that considers other primary potential causes of pain. Besides that, temporomandibular disorder (TMD) is characterized by a dysfunction of the masticatory system, and it may be the primary or secondary diagnosis among orofacial pain conditions 7 .
Over the last decades, the Orofacial Pain Clinic Questionnaire (EDOF-HC) has been used as the main tool to obtain relevant information from patients with orofacial pain in our clinic 8 . It is in accordance with the diagnostic criteria from the International Association for the Study of Pain (IASP) 9 and the International Headache Society (IHS) 10 . Our group has published several studies on the diagnoses of orofacial conditions and characteristics that used this questionnaire in the methodology 11,12,13,14,15 , and it has shown to be effective to obtain major information from the patient's anamnesis and examination to gather clinical hypotheses for the diagnosis.
One of the main challenges in patients with orofacial pain is the identification of masticatory musculoskeletal complaints that correspond to primary TMD, myofascial symptoms that might be secondary to other orofacial diagnoses and neuropathic conditions of the craniofacial region 11 . Within this scenario the aim of the present study was to evaluate the EDOF-HC as a tool in the assessment and diagnosis of orofacial pain.

Subjects
Overall, 142 patients with orofacial pain from the Orofacial Pain Clinic of a general hospital participated in the study. All patients who came for the evaluation of neuropathic orofacial pain between 2002 and 2012 were included in research. In this sample, 121 (85.2%) were female and the mean ages were 55.9±15.6 (confidence interval: 53.3≤μ≤58.5) years.
All patients were evaluated by a trained dentist, who is specialized in orofacial pain and temporomandibular disorders. They were diagnosed according to the criteria from the IHS 10 and the criteria of IASP 8 . Of them, 42 (29.6%) had trigeminal neuralgia, 36 (25.4%) had BMS, 12 (8.5%) had PIFP, 12 (8.5%) had trigeminal posttraumatic neuropathic pain (tPTN), 30 (21.1%) had TMD, and 10 (7.0%) had AO. These diagnostic criteria aim to identify the patients of each condition, based on their clinical features and presentation, to achieve relatively homogeneous samples for a comparision between the criteria and other diagnostic tools, such as a questionnaire.

Evaluation
The EDOF-HC 14 consists of three separate sections: orofacial anamnesis, medical anamnesis, and clinical examination (Appendix 1 -English version; the Brazilian version is available trough contact with the corresponding author of the manuscript).
In this tudy, we included data from the orofacial anamnesis and clinical examination, which consists of: demographic characteristics, pain complaints and duration, pain intensity and descriptors, triggering, worsening and alleviation factors, crises characteristics, periodicity, oral habits, pain when waking-up, previous dental and surgical treatments, quality of chewing, bruxism, quality of sleep, earache, headache and body pain complaints, sensation of tired face, and the evaluation of pain in mandibular movements, articular noises, maximum mouth opening, masticatory and cervical muscular palpation, dental occlusion, evaluation of cervical movements, use of prosthesis, and characteristics of facial skin, oral mucosa, tongue, periodontal tissues and teeth.

Statistical analysis
All data were distributed in tables, and the descriptive analysis included frequencies, percentages (categorical data) and means, standard deviations and confidence intervals (quantitative data). Missing data were treated as missing and not excluded or substituted by any value. Normal distribution was assumed by the Central Limit Theorem. The following statistical tests were used: chi-square with Bonferroni correction, and one-way ANOVA with Tukey post hoc test. Data were classified after a descriptive analysis with two-steps cluster and outliers treatment, which excluded one case (0.7%), and with the decision tree (90% training sample).
The level of significance was 5% and the analysis was performed with the SPSS software 17.0 (IBM).

RESULTS
Patients with BMS and TN were older than the other patients (mean ages of 62.9±13.1 and 61.6±12.6 respectively), there were proportionally less women in the groups of TN (30; 71.4% women) and PIFP (7; 58.3% women) than in the other groups, and there were less patients working in the groups of BMS (9; 25.0%) and tPTN (3; 25.0%).
According to pain characteristics, the only difference was of pain descriptors (Table 1). TN was associated to shocklike pain, BMS to burning, and TMD to throbbing and multiple descriptors. There were no differences between the groups of pain intensity (p=0.345), number of pain descriptors (p=0.167) and duration of pain (p=0.064).
TN, BMS and TMD had specific characteristics of worsening factors and spontaneous/provoked pattern (Table 1). TN was associated to fewer oral habits and a shorter pattern of duration, and there were diferences between the groups, according to previous treatments (Table 2).
There were no diferences in the prevalence of earache (p>0.050) and the quality of sleep (p=0.166). However, patients with TMD had more headaches (26; 86.7%, p=0.005), body pain (24; 80%, p=0.005), and pain in cervical movements (22; 73.3%, p=0.005). Pain at the palpation of the temporomandibular joint was also worse in TMD patients than in the other groups (24; 80%, p<0.001, the worst in TMD). These patients had more pain at maximum mouth opening and more trigger points, whereas TN patients had the lowest mean of trigger points (Table 3).
There were no diferences in the prevalence of periodontal disease between the groups (p=0.453) or in the use of dentures (p=0.690). The groups were also  (Table 4). Cluster classification distributed the patients according to this previous descriptive analysis into three groups (TN, BMS, TMD) and one of outliers (tPTN). OA and PIFP had variable patterns and were not mostly included in only one cluster (Table 5). In the decision tree analysis, the number of trigger points was the first and only fator of classification, significant to distinguish TN from TMD ( Figure 1).

DISCUSSION
This study shows that the EDOF-HC was able to distinguish between TN, BMS, TMD and tPTN, according to the pain descriptors, pain in mouth opening and number of trigger points, and previous history of surgery. Although PIFP and OA did not present typical characteristics, these conditions are based on exclusion 10 and, in that aspect, this instrument showed to be complete due to the wide anamnesis and examination to determine potential primary causes of pain in these patients. In a certain way, the study shows that the clinical features of patients, assessed with the questionnaire, correspond to the diagnostic criteria of those conditions, making the questionnaire reliable for the clinical activity during the diagnosis of orofacial pain diseases.  From these results, it becomes evident that pain descriptors are a potential clue for the etiology of pain, as supported by literature 16 , but trigger points and pain in maximum mouth opening were important in the evaluation and determination of TMD. Other associated factors were the shock-like descriptor in TN, and burning in BMS (located at the tongue and with a high frequency of tongue abnormalities), which corresponds to the scientific literature 4,6 . tPTN was associated to the surgical procedures that are common etiological factors of this condition 3,10 . Moreover, TN was associated to provoked pain (pain triggering) and a short duration (seconds) 4 , whereas BMS had spontaneous beginning of the crises.
This instrument makes a complete evaluation of the orofacial region, including the examination of all oral tissues and the masticatory system, which turns it into a good tool for the screening of potential primary causes of pain, mostly relevant for PIFP, BMS and AO (due to the diagnostic criteria of this conditions, dependent on exclusion) 5,6 . However, it is also important for other pains, such as TN (that might have secondary causes of pain from the teethdue to lack of oral hygiene -and myofascial pain -due to facial contractions during the crises and sensitization of the masticatory muscular system from pain chronification) 11 . These secondary causes of pain may play a role in the whole complaint of the patient and need to be assessed and treated as well as the primary causes 17 . Emotional distress and temperature variations, as well as the general impairment of mandibular functions, were present in all groups of patients, with no statistical differences. These are commonly observed in pain patients in general 18 . However, the examination of mandibular movements (pain in maximum mouth opening and number of trigger points), as well as the complaint of pain in other parts of the body (including the head and neck) were more associated to TMD, indicating that these variables are more indicative of TMD than the impairment of mandibular function and chewing, which occurred in all groups. TMD is recognized as commonly associated to spread pain and other myofascial disorders 19 , as well as having a high prevalence of comorbidities 20,21 , and the EDOF-HC questionnaire was able to screen and evaluate these characteristics in patients.
One limitation of the study is the wide range of characteristics of some of the orofacial conditions that were included. However, these are important entities in the differential diagnosis and the highest challenges in the clinical assessment. The EDOF-HC evaluated a broad spectrum of symptoms and signs with a detailed anamnesis and a complete examination of orofacial tissues that may be involved in primary and secondary causes of orofacial pain.
In conclusion, the EDOF-HC seems to be a supportive tool for the assessment of orofacial pain and can be used to support data collection from anamnesis and patient examination. Moreover, the EDOF-HC is aligned with the diagnostic criteria of most common orofacial conditions and allows investigation of local and systemic abnormalities, thus assisting in the exclusion of primary causes of facial pain and the determination of underlying diagnoses.