Abstract
Objective
To develop a novel mandible slice organ culture model to investigate the effects of externally applied force on the dentine–pulp complex.
Design
In vitro organ culture.
Setting
School of Dentistry, Birmingham, UK.
Materials and methods
Transverse 2 mm thick sections were cut from the mandibles of five 28-day-old male Wistar rats. Serial sections were used for control and test pairs. Springs made from 0.016-inch and 0.019 × 0.025-inch stainless steel wires were used to apply a 50 g tensile or compressive force, respectively, to test specimens. Control and test specimens were cultured for 5 days in a humidified incubator with 5% CO2 at 37°C and processed for routine histological investigation. Nine more rats were used to provide control and compression test pairs where the pulps were extirpated after 3 days culture and total RNA isolated for gene expression analysis by reverse transcriptase polymerase chain reaction (RT-PCR).
Results
Histology showed the dental and supporting tissues maintained a healthy appearance in the control cultures after culture. Histomorphometric analysis revealed a 20–27% increase in pulp fibroblast density in test specimens compared with controls. Gene expression analyses revealed up-regulation in the test groups of PCNA, c-Myc, Collagen 1α, TGF-β1 and alkaline phosphatase, whilst expression of osteocalcin was reduced.
Conclusions
The results demonstrated that the present organ culture technique provides a valuable in vitro experimental model for studying the effects of externally applied forces. These forces stimulated a cellular response in the pulp chamber characterized by altered gene expression and proliferation of fibroblasts; the latter being unaffected by the nature of the force in terms of compression or tension.
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