Abstract : Purpose : The aim of this study was to evaluate the number of roots and root canal configurations of maxillary premolars in a Japanese population using dental cone-beam computed tomography (CBCT).
Materials and methods : We analyzed the CBCT images of 267 maxillary first premolars and 266 second premolars from a total of 145 patients for the following parameters : (1) the number of roots and root canals ; and (2) the classification of each root canal configuration based on Vertucci's classification.
Results : A majority of the maxillary premolars were found to have one root (74.2% of first premolars and 97.7% of second premolars), followed by two roots (24.3% of first premolars and 2.3% of second premolars), with three roots identified in only 1.5% of the first premolars. Regarding root canal configuration, Vertucci's typeⅡ and Ⅳ configurations for single-rooted maxillary first premolars, and typeⅠ and Ⅱ configurations for single-rooted second premolars were the most prevalent. Furthermore, all types of root canal configurations were observed in the single-rooted maxillary first premolars, with the exception of type Ⅵ.
Conclusion : The maxillary first premolars exhibited a high degree of variability and complexity in their root canal system. In contrast, the number of roots and root canal configurations of maxillary second premolars showed a lower degree of variability compared to the first premolars.
Abstract : Macrophage migration inhibitory factor (MIF) has been found to play a central role in controlling the inflammatory response and immune reaction. In this study, we demonstrated the expression of MIF and MIF receptor C-X-C motif chemokine receptor (CXCR) 4 in human acute pulpitis tissue, and that MIF stimulates an inflammatory response in human dental pulp cells. Expression of MIF and CXCR4 in human dental pulp tissue was analyzed by immunohistochemistry. The expression of COX-2 mRNA and COX-2 protein in human dental pulp cells was examined by real-time reverse transcription-polymerase chain reaction and immunoblotting, and the PGE2 concentration in the culture medium was measured using an enzyme immunoassay kit. When the cells were stimulated by MIF, PGE2 secretion was clearly increased in a dose and time-dependent manner. A strong signal to MIF and CXCR4 was detected in dental pulp cells located in the strong inflammatory part with the neutrophil infiltration. COX-2 mRNA and protein expressions were markedly enhanced by MIF. However, in the presence of the CXCR4 antagonist WZ811, these effects were suppressed. MIF is involved in COX-2 production and PGE2 secretion via CXCR4 activation, suggesting that it is involved in inflammation in human dental pulp.
Abstract : Dopamine (DA) is a catecholamine and is known as a neurotransmitter. Recent studies have revealed that DA is involved in osteoblastic differentiation. However, the expression of DA during odontoblastic differentiation has not been examined. In this study, we investigated the expression of DA in pulp tissue of rat mandibular incisors and a rat direct capping model by using immunohistochemical analysis. In the study, the expression of DA was detected in pre-odontoblasts and odontoblasts in normal pulp tissue and odontoblast-like cells in the direct capping model, which also expressed Nestin, an odontoblastic differentiation marker. These results suggested that the expression of DA might depend on odontoblastic differentiation not only in the physiological condition but also in the aseptic and invasive condition.
Abstract : Central cusp is an abnormal tooth on the occlusal surface. The most common position is the mandibular second premolar, with an appearance rate of 1 to 4%. Central cusp is considered to be a characteristic of Down syndrome. Regenerative endodontic therapy has been reported as a new treatment protocol for a fractured central cusp before completing the root of the tooth, in addition to conventional apexogenesis and apexification. The choice of treatment method depends on the degree of root canal infection. Regenerative endodontic therapy is recommended for cases of irreversible pulpitis and apical periodontitis before completing the root of the tooth. This report describes regenerative endodontic therapy for a case of fractured central cusp.