Evaluation of a new laboratory model for pulp healing: preliminary study.

AIM

To assess the feasibility of using the mouse as an in vivo model for studying pulpal healing in response to restorative procedures.

METHODOLOGY

Direct pulp capping on maxillary first molar teeth with mineral trioxide aggregate (MTA), overlaid with light-cured composite resin, was performed on nineteen 3-month-old mice. For control teeth, the composite resin was placed in direct contact with the pulp. Animals were killed at 3 days, 1 week, 2 weeks, 5 weeks and 11 weeks postoperatively. Extracted dental tissues were subsequently analysed by haematoxylin and eosin staining, immunohistochemistry for dentine sialophosphoprotein (DSPP) expression, scanning electronic microscopy and X-ray analysis to determine both pulpal response and dentine bridge formation.

RESULTS

Of the 19 mice initially used, 16 were subsequently studied. Histological analyses of pulps directly exposed to MTA for up to 2 weeks demonstrated a distinct structural change in the extracellular matrix. By weeks 5 and 11, a dentine bridge was present in all MTA-treated specimens in which DSPP immunoreactivity was clearly apparent. Scanning electronic microscopy and X-ray analysis enabled confirmation of calcification of the dentine bridge, and demonstrated that it had a globular surface morphology as opposed to the tubular appearance associated with orthodentine.

CONCLUSIONS

This is the first description of the utilization of a murine model for study of in vivo pulpal repair. This approach provides a novel opportunity to enable the use of genetically modified animals to explore cellular and molecular processes during reparative events.