Spatiotemporal monitoring of hard tissue development reveals unknown features of tooth and bone development.

Mineralized tissues, such as bones or teeth, are essential structures of all vertebrates. They enable rapid movement, protection, and food processing, in addition to providing physiological functions. Although the development, regeneration, and pathogenesis of teeth and bones have been intensely studied, there is currently no tool to accurately follow the dynamics of growth and healing of these vital tissues in space and time. Here, we present the BEE-ST (Bones and tEEth Spatio-Temporal growth monitoring) approach, which allows precise quantification of development, regeneration, remodeling, and healing in any type of calcified tissue across different species. Using mouse teeth as model the turnover rate of continuously growing incisors was quantified, and role of hard/soft diet on molar root growth was shown. Furthermore, the dynamics of bones and teeth growth in lizards, frogs, birds, and zebrafish was uncovered. This approach represents an effective, highly reproducible, and versatile tool that opens up diverse possibilities in developmental biology, bone and tooth healing, tissue engineering, and disease modeling.

Wnt signaling from Gli1-expressing apical stem/progenitor cells is essential for the coordination of tooth root development.

Stem cell regulation plays a crucial role during development and homeostasis. Here, an essential source of Wnts from Gli1+ stem/progenitor cells was identified in the murine molar. Loss of Wnt production in Gli1+ apical stem/progenitor cells led to loss of Axin2 at the root apex, mis-regulation of SOX9, loss of BMP and Hh signaling, and truncation of root development. In the absence of Wnt signals, the root epithelium lost its integrity and epithelial identity. This phenotype could be partially mimicked by loss of Sox9 in the Gli1 population. Stabilization of Wnt signaling in the apical papilla led to rapid unordered differentiation of hard tissues and fragmentation of the epithelial root sheath. Wnt signaling from Gli1+ stem/progenitor cells, therefore, orchestrates root development, coordinating mesenchymal and epithelial interactions via SOX9 to regulate stem/progenitor cell expansion and differentiation. Our results demonstrate that disparate stem/progenitor cell populations are unified in their fundamental signaling interactions.

Hemangioendothelioma of palate: A case report with review of literature.

Hemangioendothelioma commonly occurs in the superficial or deep soft tissue of the extremities, lungs, liver, bone and lymph nodes, with oral cavity being a rare location. It is usually benign but can show variable grades of malignancy. According to the histological presentation, hemangioendothelioma has been classified as epithelioid, Kaposiform, hobnail (Dabska-Retiform), epithelioid sarcoma like and composite. We present a case of ulcerated swelling of palate clinically diagnosed as pyogenic granuloma which presented a diagnostically challenging histological picture. We discuss the differential diagnoses obtained from various oral pathologists and general pathologists and substantiate the diagnosis of hemangioendothelioma based on its clinical behavior, histological features and immunohistochemical findings. In addition, we attempt to highlight the diagnostic dilemma that such cases can pose to the attending pathologists.

Tuberculous osteomyelitis of mandibular condyle: A rare encounter.

Tuberculosis (TB), one of the oldest known microbial infectious diseases affecting humans has continued to burden our healthcare system over generations. Conventionally, primary TB usually manifests as a pulmonary infection. However, the last decade has witnessed increasing reports of extrapulmonary infections. It's often atypical clinical presentations require a high degree of clinical suspicion, especially in the developing countries with a high incidence of this infectious disease. In this report, we present one such case of tuberculous osteomyelitis of the mandibular condyle where the patient reported with the complaint of swelling on the left side of the face with no apparent systemic manifestation.