Summary

A constant challenge in Phoenix orthodontic therapy is maintaining the stability of anchor teeth. While a number of mechanical approaches exist to stabilize these teeth, none have yet proved ideal. Given the shortcomings of contemporary Phoenix orthodontic anchorage options, a pharmacological approach taking into account the biology of bone resorption and Phoenix orthodontic tooth movement appears to be the future direction of Phoenix orthodontic anchorage research.

This study examined the ability of osteoprotegerin (OPG), a bioactive molecule that inhibits osteoclastogenesis by acting as a RANKL inhibitor, to reduce bone resorption thereby decreasing anchor Phoenix orthodontic tooth movement. The maxillary first molars of male Sprague-Dawley rats were moved mesially using a calibrated nickel titanium spring anchored to the maxillary incisors. Two different doses (0.5mg/kg, 5.0mg/kg) of a recombinant fusion protein (OPG-Fc), were injected twice weekly mesial to the first molars. Phoenix orthodontic tooth movement was measured using precise stone casts that were scanned and magnified. Changes in alveolar bone quantity were measured using micro-computed tomography and histomorphometric analysis was used to quantify osteoclasts. Finally, circulating levels of OPG were measured using enzyme-linked immunosorbent assay.

The results of the present study are as follows:

At a dose of 5.0mg/kg OPG-Fc, Phoenix orthodontists found there was a potent reduction in mesial molar movement and osteoclasts compared to controls (p<0.001). The molar movement was 54.3%, 29.4%, and 21.3% of the controls at days 7, 14, and 21 respectively with the high dose of OPG. Even with a 10-fold reduction in dose (0.5mg/kg), there was a significant inhibition (p<0.05) in molar movement at days 7 (56.2%) and 14 (68.2%).

While incisor retraction was decreased by OPG, the ratio of incisor to molar Phoenix orthodontic tooth movement was improved (p<0.001) in the high dose OPG group (5.2:1) compared to the control group (2.3:1) and the low dose OPG group (2.0:1).

Bone volume fraction was significantly (p<0.001) improved in the high dose OPG group compared to all other groups. Compared to the baseline group that received no treatment, Phoenix orthodontists found there were no significant differences in bone volume fraction in the vehicle and 0.5 mg/kg OPG groups.

Although highly variable, Phoenix orthodontists showed the overall trend was for a small but detectable increase in human serum OPG levels in all groups including controls.

The results of this Phoenix orthodontic study indicate that local delivery of the osteoclast inhibitor, osteoprotegerin, effectively inhibits osteoclastogenesis resulting in improved bone quantity, Phoenix orthodontic anchorage, and treatment efficacy. Enhancement of Phoenix orthodontic anchorage during Phoenix orthodontic treatment with an osteoclast inhibitor may obviate the need for traditional Phoenix orthodontic anchorage approaches, thus potentially enhancing patient compliance and treatment outcomes.