Purpose: Pain is a physical stressor in humans and the common symptom for dental patients in clinical setting. However, the effects of pain as a stressor on the hypothalamic-pituitary-adrenocortical （HPA） axis have not yet been fully elucidated. In this study, plasma adrenocorticotropic hormone （ACTH） and corticosterone, in addition to corticotropin-releasing hormone （CRH） hnRNA and mRNA expression were examined to know how glossodynia by capsaicin injection into the tongue tip will influence on HPA axis.
Methods: Wistar rats （n=48） were divided into two groups of 24 animals each: a capsaicin-injected, a vehicle-injected. Rats were sacrificed at 5, 15, 30, or 60 min （n=6 each） after the injections into the left side of the tongue tip. Additionally, control-group rats （n=6） were sacrificed before any treatment （injection and anesthesia）. The blood was collected to measure plasma adrenocorticotropic hormone （ACTH） and corticosterone to make sure the hypothalamic-pituitary-adrenocortical （HPA） axis activation for stress response, and the tissues of hypothalamic paraventricular nucleus was used to detect CRH hnRNA and mRNA expression by quantitative real-time PCR analysis.
Results: ACTH secretion reached a peak at 30 min after glosso-injection prior to a gradual increase in plasma corticosterone. CRH hnRNA and mRNA expression was upregulated about 3-fold at 15 and 60 min, respectively, compared to control rats.
Conclusions: Glosso-injection of capsaicin can activate HPA axis through CRH gene expression.

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Abstract: To examine the characteristics of cases of patients referred to the Nihon University School of Dentistry at Matsudo Hospital for unknown causes who were ultimately diagnosed with odontogenic disease as the underlying disease, particularly among those clinically diagnosed with pulpitis.
Methods: The study subjects were patients referred to us for unknown causes during the three-year period between January 2016 and December 2018（“patients of unknown causes”）.
Results: Of 13,152 patients who visited us during the study period, 2,147 were referred from another hospital. Of these 2,147 patients, 287 were patients of unknown causes. The chief complaint in 76.3％ of these patients of unknown causes was orofacial pain. The percentage of women among the patients of unknown causes was significantly greater than that among the overall patients and referral patients. No characteristic age distribution was identified. Odontogenic disease was diagnosed as the underlying disease in 107 cases of the patients of unknown causes, of whom 32 cases had pulpitis, the most common disease. Diagnoses that had been made instead of pulpitis included the following: 7 cases of caries under inlay（5 cases） or in prosthesis（2 cases）; 6 cases of pulpitis after treatment for deep caries; and 5 cases of tooth crown crack or fracture. In addition, a diagnosis of non-odontogenic disease was made for 131 cases; the most common disease was TMD in 29 cases, followed by BMS in 25 cases and neuropathic pain in 10 cases.
Conclusions: Odontogenic disease was diagnosed in 40％ or more of the patients referred for unknown causes. If orofacial pain is caused by odontogenic disease, the pain tends to be readily treatable. These results demonstrate the significance of correctly differentiating odontogenic disease from non-odontogenic disease when diagnosing the cause of orofacial pain.

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Purpose: The aim of this study was to compare the effect of low-level laser treatment（LLLT）in stellate ganglion area irradiation（SGR）with that of stellate ganglion block（SGB）at the right 6th vertebra on blood flow in and the surface temperature of the cheek.
Methods: Twenty-one healthy male volunteers were enrolled. The Lumix2^Ⓡ was used to provide LLLT（wave length, 904〜910nm; maximum and average output, 45W and 0.3W, respectively; irradiation time, 30min; total irradiation energy, 486J）. Baseline measurements comprised average blood flow and temperature over 5min prior to each treatment（LLLT in SGR or SGB）. Average blood flow and buccal surface temperature were then measured again every 5min for 30min after.
Results: Significant increases were observed in blood flow and surface temperature after LLLT in SGR in comparison with in the control group. These increases were detected between 10 and 30min after commencement of treatment. The SGB group showed a significant increase in blood flow and temperature at 25 and 10min, respectively, in comparison with in the LLLT in SGR group.
Conclusion: Low-level laser treatment in SGR resulted in increases in buccal blood flow and temperature. Even though LLLT in SGR is not necessary effective compared with SGB, the less invasive LLLT in SGR may be a useful treatment for patients with oral-facial disease avoiding side effect.

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Purpose: Burning mouth syndrome（BMS）causes an intractable burning pain in the tongue, and primarily affects women after menopause. Therefore, it is considered that abnormal endocrine function through sex hormone deficiency is involved in the pathogenesis of BMS. However, there is no definite cause of BMS and it is still considered idiopathic. Here, we examined the involvement of ovariectomy（OVX）of female rats associated with tongue hypersensitivity.
Methods: The tongue-withdrawal reflex thresholds（TWT）to mechanical and thermal stimuli of the tongue of OVX and trinitrobenzene sulfonate（TNBS）treated rats were measured. The lymphocytes were evaluated using HE staining.
Results: The TWT was significantly decreased in OVX rats and OVX treated with TNBS rats to mechanical stimulation, but not to thermal stimulation after OVX. The lymphocyte accumulation in the tongue epithelium was not observed in OVX rats.
Conclusion: The present findings suggest that sex hormone might be involved in the pathogenesis of tongue pain of BMS. The pain might not be caused by inflammation of tongue epithelium. Further basic researches are needed to investigate the involvement of nerve afferents in the tongue epithelium in BMS.

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Patients: A 54-year-old female patient complained of intractable pain after pulpectomy. Despite the dentist’s assurance that the tooth could be saved and did not need to be removed, the patient was not convinced and got the tooth extracted at another clinic.
Discussion: Non-odontogenic toothache is a disease in which the cause of the pain does not originate from the dental structures. Nonetheless, it is not rare that patients with this type of pain persistently desire to have the tooth extracted. Patients think that the cause of the toothache is the tooth itself, and thus, want to have it extracted. Why do they think that way?
Consider a case in which a patient says, “I have a toothache, but I think I have a bad tooth.” In this case, “I have a toothache” is a symptom, whereas “I have a bad tooth” is the diagnosis. Between the symptom and diagnosis, the patient’s reasoning that “I have a toothache because I have a bad tooth”; “When you have a toothache, you often have a bad tooth”; or “A bad tooth causes a toothache” is omitted. These three types of reasoning might appear to be similar, but are, in fact, classic examples of deduction, induction, and abduction. Therefore, it is important to provide explanations to the patient based on the type of reasoning.
Conclusions: Patients do not accept explanations even though they are based on valid reasoning unless the reasoning is consistent with the ideas derived from their experience or knowledge.

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