A functional endocannabinoid system is present in several mammalian organs and tissues. The endogenous cannabinoid anandamide (AEA) is a bioactive lipid neurotransmitter that is present in a variety of tissues and has multiple functions. Recently, this cannabinoid system was reported to play important roles in osteoblastic and osteoclastic cells. Human periodontal ligament (hPDL) cells modulate alveolar bone remodeling by producing cytokines when stimulated by many factors. The aim of this study was to investigate the AEA level in periodontal regions and the osteogenic effect of AEA on hPDL cells.

  The levels of AEA in the gingival crevicular fluid (GCF) of periodontitis patients were measured using liquid chromatography/mass spectrometry (LC/MS). Expressions of cannabinoid receptor mRNA were detected by RT-PCR in hPDL cells and expression of the transient receptor potential cation channel subfamily V member 1 (TRPV1) was observed by confocal laser scanning microscope (CLSM). IL-11 production from hPDL cells was measured using an ELISA, with or without AEA in the presence or absence of capsazepine, a selective TRPV1 antagonist.

  AEA secreted into GCF was detected, but there was no correlation between the probing pocket depth (PPD) and AEA level. TRPV1 mRNA was detected in hPDL cells and the TRPV1 expression was observed by CLSM. IL-11 production from hPDL cells was significantly enhanced by AEA stimulation and this IL-11 production was suppressed by capsazepine.

  Our findings indicate that this endogenous cannabinoid system has a possible role in bone metabolism in periodontitis through TRPV1.

  Cranial neural crest cells migrate to the craniofacial primordia and differentiate into skeletal tissues of the jaw such as Meckel's cartilage. It has not been clearly demonstrated how neural crest cells are committed to differentiate into these tissues. In this study, the conditions that are required for the formation of Meckel's cartilage were investigated. In situ hybridization in chick embryos indicated that Fgf8 and Shh involved in the pattern formation of limb cartilages were expressed in the neural tube of the midbrain-hindbrain border, the buccopharyngeal membrane and the oro-proximal site of the 1st branchial arch (oro-proximal BA1). Cell-tracing with DiI confirmed that the neural crest cells derived from both the posterior midbrain and rhombomere 1 migrated to the buccopharyngeal membrane, which subsequently forms oro-proximal BA1, by passing through the mesenchyme lateral to the midbrain-hindbrain boundary. Based on the above results, we carried out two types of ectopic transplantation experiments by chick-quail chimera. The graft of oro-proximal BA1, the complex of epithelium and mesenchyme, formed a Meckel's cartilage-like structure in a self-differentiation manner, whereas neither epithelium only nor mesenchyme formed any elongated cartilage. The ectopic transplant of the buccopharyngeal membrane into the mesenchyme lateral to the neural tube of the mid-hindbrain border in which neural crest cells were migrating formed a Meckel's cartilage-like structure. These results suggest that the cranial neural crest cells derived from the mid-hindbrain region are committed to the cell fate during migration, and receive further signaling to differentiate into Meckel's cartilage in their destination.

  Calcifying cystic odontogenic tumors are benign tumors, characterized by the presence of ghost cells and calcified materials. We evaluated clinical characteristics of calcifying cystic odontogenic tumors in 21 cases at the Maxillofacial Surgery, Tokyo Medical and Dental University Hospital, between January 1979 and December 2006.

  Of the 21 lesions that were studied, 12 were observed in male patients, and 9 in female patients. The median age was 13.0 years (range, 4-69 years). Of the 21 lesions, 11 were located in the maxilla (intraosseous), 9 in the mandible (intraosseous), and 1 in the lower gingiva (extraosseous). Radiographically, 18 lesions appeared as unilocular radiolucencies, and 2 lesions as multilocular radiolucencies. Impacted teeth were observed in 15 cases. In 20 cases, the lesions were treated by enucleation. The follow-up duration ranged from 2 years, 5 months to 28 years, 8 months, and in 1 case, the lesion recurred and showed a malignant transformation 2 years 10 months after the treatment.

  Histopathologically, the lining epithelium consisted of cuboidal or columnar odontogenic cells. Ghost cells were frequently calcified, and the tissue was hardened. In 14 cases, the tumor was associated with odontoma.