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Our previous studies have demonstrated that nuclear factor I-C (NFI-C) null mice developed short molar roots that contain aberrant odontoblasts and abnormal dentin formation. Based on these findings, we performed studies to elucidate the function of NFI-C in odontoblasts. Initial studies demonstrated that aberrant odontoblasts become dissociated and trapped in an osteodentin-like mineralized tissue. Abnormal odontoblasts exhibit strong bone sialoprotein expression but a decreased level of dentin sialophosphoprotein expression when compared with wild type odontoblasts. Loss of Nfic results in an increase in p-Smad2/3 expression in aberrant odontoblasts and pulp cells in the subodontoblastic layer in vivo and primary pulp cells from Nfic-deficient mice in vitro. Cell proliferation analysis of both cervical loop and ectomesenchymal cells of the Nfic-deficient mice revealed significantly decreased proliferative activity compared with wild type mice. In addition, Nfic-deficient primary pulp cells showed increased expression of p21 and p16 but decreased expression of cyclin D1 and cyclin B1, strongly suggesting cell growth arrest caused by a lack of Nfic activity. Analysis of the pulp and abnormal dentin in Nfic-deficient mice revealed an increase in apoptotic activity. Further, Nfic-deficient primary pulp cells exhibited an increase in caspase-8 and -3 activation, whereas the cleaved form of Bid was hardly detected. These results indicate that the loss of Nfic leads to the suppression of odontogenic cell proliferation and differentiation and induces apoptosis of aberrant odontoblasts during root formation, thereby contributing to the formation of short roots.Tooth development is a complex and well coordinated developmental process that is achieved through a series of reciprocal interactions between dental epithelium and neural crest-derived ectomesenchyme (EM).2 The dental epithelium gives rise to the outer and inner enamel epithelium from which ameloblasts differentiate, whereas EM cells differentiate into odontoblasts. The critical roles of several transcription factors and growth factors in crown formation have been well documented (1, 2). After completion of crown formation, the inner and outer enamel epithelial cells proliferate and form Hertwig's epithelial root sheath that plays a key role in root formation. It is believed, based on information derived from crown development, that Hertwig's epithelial root sheath induces the differentiation of EM cells from the radicular pulp area into odontoblasts that are responsible for root dentin formation. However, the molecular mechanisms responsible for root development are not well understood (3-5).The nuclear factor I (NFI) family of transcription/replication factors was first discovered as a family of proteins required for the replication of adenovirus DNA in vitro (6). The NFI gene family encodes site-specific transcription factors essential for the development of a number of organ systems (7). There are four NFI gene family members in vertebrates (Nfia, Nfib, Nfic...

Fluor‐hydroxyapatite (FHA) fabricated by a reaction between fluorapatite (FA) and hydroxyapatite (HA) was mixed with ZrO2 to produce FHA–ZrO2 composites. When the relative amount of FA to HA increased, the decomposition of the composite was decreased gradually because of the formation of thermally stable FHA solid solutions. With such suppression of decomposition, the FHA–ZrO2 composites retained fully densified bodies. As a result, significant enhancements in mechanical properties, such as hardness, flexural strength, and fracture toughness, were achieved as the relative amount of FA to HA increased. The highest values in strength and toughness were 220 MPa and 2.5 MPa·m1/2, respectively, with FHA–40 vol% ZrO2 composites. In vitro proliferation of osteoblast‐like cells (MG63) on the composites showed behavior similar to that observed on pure HA and FHA. Alkaline phosphatase (ALP) activity of the growing cells (HOS) on the composites was slightly down‐regulated compared with that on pure HA and FHA at prolonged periods.

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Given the high incidence of false positive signals in patients with pathologically determined localized disease, in our experience polymerase chain reaction based assays offer no immediate benefit for preoperative prostate cancer staging. The prognostic significance of detecting circulating prostate specific signals awaits longer followup in this cohort of patients, which is currently under study.