Accidental mandibular nerve injury may occur during tooth extraction or implant procedures, causing ectopic orofacial pain. The exact mechanisms underlying ectopic orofacial pain following mandibular nerve injury is still unknown. Here, we investigated the role of macrophages and tumor necrosis factor alpha (TNFα) in the trigeminal ganglion (TG) in ectopic orofacial pain following inferior alveolar nerve transection (IANX). IANX was performed and the mechanical head-withdrawal threshold (MHWT) in the whisker pad skin ipsilateral to IANX was measured for 15 days. Expression of Iba1 in the TG was examined on day 3 after IANX, and the MHWT in the whisker pad skin ipsilateral to IANX was measured following successive intra-ganglion administration of the macrophage depletion agent liposomal clodronate Clophosome-A (LCCA). TNFα expression in the TG and the MHWT in the whisker pad skin ipsilateral to IANX following successive intra-ganglion administration of the TNFα blocker etanercept were measured on day 3 after IANX, and tumor necrosis factor receptor-1 (TNFR1) immunoreactive (IR) cells in the TG were analyzed immunohistochemically on day 3. The MHWT in the whisker pad skin was significantly decreased for 15 days, and the number of Iba1-IR cells was significantly increased in the TG on day 3 after IANX. Successive intra-ganglion administration of the macrophage depletion agent LCCA significantly reduced the increased number of Iba1-IR cells in the TG and reversed the IANX-induced decrease in MHWT in the whisker pad skin. TNFα expression was increased in the TG on day 3 after IANX and was reduced following successive intra-ganglion administration of the TNFα inhibitor etanercept. The decreased MHWT was also recovered by etanercept administration, and TNFR1-IR cells in the TG were increased on day 3 following IANX. These findings suggest that signaling cascades resulting from the production of TNFα by infiltrated macrophages in the TG contributes to the development of ectopic mechanical allodynia in whisker pad skin following IANX.

Dentigerous cysts are one of the most prevalent types of odontogenic cysts and are associated with the crown of an unerupted tooth, especially of the mandibular third molar. In this study, the characteristics of a dentigerous cyst developed around a mandibular third molar on panoramic radiographs were investigated. The panoramic images of 257 consecutive dentigerous cyst cases associated with a mandibular third molar were analyzed. The mean age of the patients was 45.9 ± 13.3 years. The size of the cyst did not significantly correlate to the age of the patient. The unilocular type (89.1%) and the crown side type (68.5%) were significant. The associated mandibular third molars had a high frequency of class III (64.6%) and position B (48.3%) in Pell and Gregory classification and of horizontal position (36.3%) in angulation. Dentigerous cysts were thought to originate and grow commonly around deeply impacted third molars. The associated third molar with dentigerous cyst tends to have a mesial inclination. Dentigerous cysts do not appear to develop gradually after the crown formation has finished, but arise at various periods randomly.

Background: The purpose of this study was to characterize the radiobiological properties of stem/progenitor cells derived from apical papilla-derived cells (APDCs) compared to bulk APDCs. Methods: APDCs were isolated from freshly extracted human third molars with immature apices. Multipotent spheres, which are thought to contain an enriched population of stem/progenitor cells, were formed from the APDCs, using a neurosphere culture technique. After γ-irradiation, papillary sphere-forming cells (PSFCs) and bulk APDCs were subjected to radiosensitivity and hard tissue-forming assays. Results: Compared to bulk APDCs, the PSFCs exhibited a radioresistant phenotype and a higher capacity for DNA double strand break repair. Irradiation induced a significant increase in a senescence-like phenotype in both cell types. Neither type of cells exhibited a significant induction of apoptotic changes after 8 Gy of irradiation. Ability to form hard tissue in vivo was significantly decreased in PSFCs, but not in APDCs following 4 Gy of irradiation. Conclusions: We demonstrated for the first time that stem/progenitor cells derived from APDCs exhibit a radioresistant phenotype; however, the hard tissue forming ability in vivo, but not bulk APDCs, was significantly reduced after irradiation.

Bone morphogenetic protein 2 (BMP-2) has received considerable attention because of its osteoinductivity, but its use is limited owing to its instability and adverse effects. To reduce the dose of BMP-2, complexation with heparin is a promising approach, because heparin enhances the osteoinductivity of BMP-2. However, the clinical use of heparin is restricted because of its anticoagulant activity. Herein, to explore alternative polymers that show heparin-like activity, four polycarboxylates, poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(aspartic acid) (PAsp), and poly(glutamic acid) (PGlu), were selected and their capability to modulate the osteoinductivity of BMP-2 was evaluated. Dynamic light scattering indicated that these polycarboxylates formed polyelectrolyte complexes with BMP-2. The osteogenic differentiation efficiency of MC3T3-E1 cells treated with the polycarboxylate/BMP-2 complexes was investigated in comparison to that of the heparin/BMP-2 complex. As a result, PGlu/BMP-2 complex showed the highest activity of alkaline phosphatase, which is an early-stage marker of osteogenic differentiation, and rapid mineralization. Based on these observations, PGlu could serve as an alternative to heparin in the regenerative therapy of bone using BMP-2.