Expression and roles of CCN2 in dental mesenchymal cells in primary culture—With findings in a case of odontogenic myxofibroma

Purpose of the researchTooth germ development involves multiple events, including cell proliferation and cell differentiation. Connective tissue growth factor (CTGF/CCN2) is a signaling protein involved in tooth germ development, and we investigated how it is expressed and what roles it may have in primary cultures of mesenchymal cells derived from the developing tooth germ. We also examined the expression of CCN2 in a human odontogenic myxofibroma, a benign tumor of odontogenic mesenchymal origin, and considered the possible roles of CCN2 in the development of myxofibromas.Materials and methodsMesenchymal cells of early bell-stage tooth germs were isolated from Day-90 bovine embryos and placed in primary culture. A resected specimen from a patient with odontogenic myxofibroma was prepared for immunohistochemical studies.Principal resultsThe CCN2 expression level in proliferating odontogenic mesenchymal cells freshly isolated from the early bell stage of developing bovine tooth germs and placed in primary culture was 3 times higher than that in the confluent non-proliferating cells. Recombinant CCN2 significantly increased the proliferation and type I collagen expression in odontogenic mesenchymal cells in primary culture. Immunohistochemical analysis on myxofibroma case revealed that CCN2 was detectable in MIB-1, a cellular marker of proliferation-positive odontogenic mesenchymal cells adjacent to capillary blood vessels and in the endothelial cells of the vessels in the tumor.Major conclusionCCN2 signaling would influence the proliferation of and extracellular matrix production by dental mesenchymal cells. Our results suggest that the same mechanisms of CCN2 action toward dental mesenchymal cells would also be operative in the odontogenic myxofibroma microenvironment.     

Three-unit bridge prostheses. With or without crowns?

Replacement of a single tooth by a fixed partial prosthesis is possible in several ways: a conventional bridge, a resin-bonded bridge or a UDA-bridge (Universal Dental Anchorage). Preservation of natural tooth substance, an optimal environment for the periodontal tissues and good esthetics are the main criteria for making a choice. Unrestored or minimally restored front teeth are an indication for a resin-bonded bridge. When an indication for a crown on the adjacent teeth is already present, a conventional bridge is the treatment of choice. Although the future promises metal free bridge solutions, the long-term prognosis of posterior bridges is best guaranteed by using metal-ceramic bridges. The UDA system requires improvement for general use.     

Prosthodontics: a past with a future?

As one of the oldest dental specialties, prosthodontics has a long history of innovation and adaptability. This overview of the field presents landmarks in the development of prosthodontics from mediaeval times to the present and speculates on some future trends. It effectively sets the stage for the other articles in this issue, which explore the many facets of prosthodontic evolution.     

Only a denture sore? Causes of a possible denture sore from a maxillary complete denture

This case presentation documents the treatment sequence of a 74 years old patient who complained about a sore spot of the palatal mucosa underneath the complete denture. The intraoral examination revealed a dark spot, redness and swelling of the mucosa around this spot and halitosis. The mucosa exhibited a perforation of 3 x 10 mm in diameter. A radiographic 3-D picture showed an impacted canine tooth, which was partly covered by the palatal bone. Firstly the denture base was relieved and the swelling gradually disappeared. Then a biopsy was taken for histological analysis to exclude any malignant process. In local anesthesia the tooth was extracted, which exhibited a deep carious lesion of the entire crown. After surgery a visible collapse of the jaw crest was observed. During a period of two months the denture was relined with a soft material to improve its fit and to enhance the healing process. With a final rebasement, the existing denture could be adapted again and the patient continued to wear it.