Screening for salivary levels of deoxypyridinoline and bone-specific alkaline phosphatase during orthodontic tooth movement: a pilot study.

Deoxypyridinoline (DPD) and bone-specific alkaline phosphatase (BAP) have been regarded as systemic determinants of bone remodelling. Owing this fact, this study aimed to determine whether the variations in the salivary concentration of these two biomarkers as detected through a longitudinal follow-up with four consecutive visits may be linked with the different phases of orthodontic tooth movement (OTM). Twenty-two healthy subjects who required fixed appliance therapy not involving tooth extractions/surgical procedures were selected. Unstimulated whole saliva samples were collected from each patient prior to fitting the orthodontic appliances and 24-48 hours, 2 weeks, and 5 weeks after the activation. Salivary DPD and BAP concentrations were determined by enzyme-linked immunosorbent assay. The data were analysed using non-parametric statistics. There were no statistically significant differences in salivary levels of biomarkers regarding demographic and clinical parameters. Overall, although DPD values revealed an increasing nature after force application and BAP values showed a descending trend, only the former showed statistically significant changes over time. Furthermore, p ost hoc comparisons for DPD salivary levels revealed significant differences between every paired sampling times, except for the pair baseline test/24-48 hours test. Synchronously, a moderate positive significant correlation between both salivary biomarkers was observed at 2 weeks test. The findings indicate that although salivary levels of DPD and BAP may act as indicators of increased bone remodelling, it appears that DPD dominates the earlier phases of OTM, whereas BAP might serve as indicator of bone formation as soon as the tooth movement stops.

Immunohistochemical expression of RANK, GRalpha and CTR in central giant cell granuloma of the jaws.

The aim was to evaluate the phenotypic expression of various cellular osteotropic factors in central giant cell granuloma (CGCG). Paraffin-embedded tissue from 27 aggressive and 10 non-aggressive cases of CGCG was assessed for the expression of RANK, GRalpha and CTR using immunohistochemistry. In addition, a staining-intensity-distribution (SID) score (proportion of stained cells x staining intensity) was used to assess immunoreactivity of each marker. The results showed that the multinucleated giant cells (MGC), mononuclear stromal cells (MSC) and endothelial cells were intensely positives for GRalpha, moderate for RANK and weak-to-moderate for CTR in all clinical groups, whereas spindle-shaped cells were intensely immunoreactive to GRalpha and unreactive to CTR and RANK. Although neither difference in RANK and GRalpha expression nor the SID score between the clinical forms of CGCG was observed, a statistically significant difference for CTR was evident. Furthermore, the comparison of the marker expression and SID score showed a significant correlation for all three markers within the clinical groups, except for GRalpha in the non-aggressive lesions where a weak and no significant correlation was detected. It was concluded that although the MGC share some similarities with the osteoclasts, they demonstrate phenotypic differences from each other that suggest a distinct precursor. The expression of RANK, GRalpha and CTR also suggest a role for these receptors in the resorptive activity of different cellular groups in CGCG and may lead to a more effective use of therapeutic inhibitors of bone resorption for the treatment of these disorders.