Pulsed electromagnetic fields promote bone formation around dental implants inserted into the femur of rabbits

The present study examined the effect of applying a pulsed electromagnetic field (PEMF) on bone formation around a rough-surfaced dental implant. A de ntal implant was inserted into the femur of Japanese white rabbits bilatera lly. A PEMF with a pulse width of 25 mu s and a pulse frequency of 100 Hz w as applied. PEMF stimulation was applied for 4 h or 8 h per day, at a magne tic intensity of 0.2 mT, 0.3 mT or 0.8 mT The animals were sacrificed 1, 2 or 4 weeks after implantation. After staining the resin sections with 2% ba sic fuchsin and 0.1% methylene blue, newly formed bone around the implant o n tissue sections was evaluated by computer image analysis. The bone contac t ratios of the PEMF-treated femurs were significantly larger than those of the control groups. Both the bone contact ratio and bone area ratio of the 0.2 mT- and 0.3 mT-treated femurs were significantly larger than the respe ctive value of the 0.8 mT-treated femurs (P<0.001). No significant differen ce in bone contact ratio or bone area ratio was observed whether PEMF was a pplied for 4 h/day or 8 h/day, Although a significantly greater amount of b one had formed around the implant of the 2-week treated femurs than the I-w eek treated femurs, no significant difference was observed between the 2-we ek and 4-week treated femurs. These results suggest that PEMF stimulation m ay be useful for promoting bone formation around rough-surfaced dental impl ants. It is important to select the proper magnetic intensity, duration per day, and length of treatment.