Osteopontin and bone sialoprotein expression in regenerating rat periodontal ligament and alveolar bone

BACKGROUND: Osteopontin (OPN) and bone sialoprotein (BSP) are differentially expressed over time in bone formation and remodelling. We have examined the expression of these proteins as phenotypic markers in studies of periodontal ligament (PL) and alveolar bone (AB) regeneration. METHODS: Window wounds (0.6 mm in diameter through alveolar bone) with either preservation or extirpation of PL were prepared under general anaesthesia in 30 Wistar male rats. Animals were killed on days 1, 3, 7, 14, and 28 after surgery, and OPN and BSP were detected with mouse monoclonal antirat antibodies. RESULTS: In regenerating alveolar bone, OPN was first detected on day 3, prior to the expression of BSP. However, only OPN could be detected in the PL where it localized to the border with the AB. Compared to wounds with PL extirpation, wounds with preservation of PL exhibited BSP staining within the AB compartment of the wound site in a significantly shorter period of time (day 7) and exhibited intense OPN and BSP staining by day 28. CONCLUSIONS: These studies show that early OPN and BSP expression and bone regeneration are enhanced by preservation of the PL and that during wound healing the PL contains cells that transiently express some osteoblastic protein markers but not mineralization.