Introduction Intermittent administration of parathyroid hormone (PTH) promotes oral osseous wound healing and protects against ligature-induced alveolar bone loss. However, its therapeutic value on periapical periodontitis is unknown. The goal of this study was to determine the effect of intermittent PTH administration on the progression of periapical periodontitis. Methods Seven lymphotoxin alpha deficient mice received pulp exposures of mandibular first and second molars. Exposed pulp in the right mandible was covered with plaque-contaminated fibrin, while exposed pulp in the left mandible was left open. After four weeks, the periapical tissues were examined to determine the effect of plaque-contaminated fibrin to induce periapical lesions. Fourteen mice received pulp exposure covered with plaque-contaminated fibrin. PTH (40μg/kg/day) was administered intermittently to half of the mice for three weeks beginning one week after pulp exposure. The remaining half received saline injections as vehicle control. At sacrifice, mandibles and tibiae were harvested and processed for histological examination. Evaluation of neutrophils and blood vessels was performed after staining with immunofluorescence and periradicular bone was histomorphometrically analyzed. Results The exposed pulp covered with plaque-contaminated fibrin resulted in significantly larger periapical lesions compared to control. Intermittent PTH administration reduced the size of periapical lesions significantly. Significantly less neutrophil infiltration around the root apex was found in PTH-treated animals compared to control. Conclusions PTH treatment suppressed periapical inflammation by reducing neutrophil infiltration and protected against tissue destruction by periapical periodontitis.

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We describe a case of pulsatile anterior communicating artery aneurysm (A-com AN) with a peculiar angiographic appearance. An 81-year-old man was referred to the department of neurosurgery for a large A-com AN artery aneurysm, which was detected incidentally. The patient hoped not to be treated but to be followed up. After 4 months, magnetic resonance imaging (MRI) revealed the presence of a cerebral edema and hematoma around the aneurysm, and partial thrombus in the upper wall of the aneurysm was suspected. Based on these findings, the patient underwent an immediate coil embolization a day after admission. However, the portion of the neck remnant increased in size after the first procedure. Therefore, 8 months after the initial procedure, he was treated with stent coil embolization. Contrary to the first procedure, angiographic evaluation revealed an active pulsating aneurysm. Moreover, MRI revealed the presence of a partial thrombus in the upper neck segment of the aneurysm, with an intensity that changed over time. The patient underwent cautious treatment and was discharged without any symptoms. This is the first case study to reveal an A-com AN with active pulsation and the relationship between the pulsatile portion of the aneurysm and thrombosed portion by MRI.