In vivo gene expression profile of guided bone regeneration associated with a microrough titanium surface

OBJECTIVES: To determine the gene expression profile characteristic of "guided bone regeneration" associated with a microrough titanium surface.

MATERIAL AND METHODS: Critical-size calvarial defects were treated with the principle of "guided bone regeneration," whereby the extracranial barriers were either polished (SMO) or microrough (SLA) titanium disks. After 7 and 14 days, the contents of the regenerating defect were collected, RNA was extracted and microarray analysis was carried out. At each time point, the healing associated with the microrough surface was compared with that associated with the polished titanium surface.

RESULTS: On comparing the SLA and SMO profiles, there were few genes different at day 7 (∼250), whereas there were a large number of genes different at day 14 (∼6500). At day 14, the list of genes that were differentially regulated in response to the SMO and SLA surfaces had an over-representation of genes associated with the functionally relevant gene ontology categories of regeneration, skeletogenesis, mesenchymal cell differentiation, angiogenesis and neurogenesis. There were a greater number of genes within each of these functionally relevant categories that were up-regulated on the SLA surface compared with the SMO surface. The main signalling pathway that was differentially regulated between the two surfaces at day 14 was the Wnt signaling pathway.

CONCLUSIONS: Minimal difference was observed between the SMO and the SLA samples at day 7, whereas significant differences were noted at day 14, including genes associated with a number of functionally relevant gene ontology groups. The differentially regulated biological processes provide an insight into the influence of surface topography on "guided bone regeneration" at the cellular and molecular level.